Q.1 Which biosignal is most commonly used to control a myoelectric prosthetic hand?
Electroencephalogram (EEG)
Electromyogram (EMG)
Electrocardiogram (ECG)
Electrooculogram (EOG)
Explanation - EMG measures the electrical activity of muscles and provides a direct indication of user intent for prosthetic hand movement.
Correct answer is: Electromyogram (EMG)
Q.2 What does the term 'haptic feedback' refer to in a rehabilitation exoskeleton?
Visual cues displayed on a screen
Auditory tones indicating error
Tactile sensations delivered to the user
Wireless data transmission
Explanation - Haptic feedback provides the user with touch‑based cues, such as vibration or force, to convey information about the device’s state or performance.
Correct answer is: Tactile sensations delivered to the user
Q.3 Which communication protocol is most widely used for real‑time data exchange between a brain‑computer interface (BCI) and a computer?
USB 2.0
Bluetooth Low Energy (BLE)
IEEE 802.11 (Wi‑Fi)
RS‑232
Explanation - USB 2.0 offers low latency and high bandwidth, essential for streaming EEG data in real time for BCIs.
Correct answer is: USB 2.0
Q.4 In the context of assistive technology, what does the acronym 'FES' stand for?
Functional Electrical Stimulation
Fast Energy Storage
Fiber Optic Emission System
Force Evaluation Sensor
Explanation - FES uses electrical currents to elicit muscle contractions, helping restore or augment motor function in rehabilitation.
Correct answer is: Functional Electrical Stimulation
Q.5 Which sensor type is best suited for detecting joint angle in a powered orthosis?
Hall‑effect sensor
Piezoelectric pressure sensor
Optical encoder
Thermistor
Explanation - Optical encoders provide precise angular position measurements, essential for controlling joint movement.
Correct answer is: Optical encoder
Q.6 What is the primary purpose of a safety-rated controller (SRC) in a rehabilitation robot?
To improve processing speed
To reduce power consumption
To ensure the robot stops safely during faults
To enhance wireless connectivity
Explanation - SRCs monitor system health and initiate safe shutdowns to protect the user from hazardous motion.
Correct answer is: To ensure the robot stops safely during faults
Q.7 Which machine‑learning algorithm is commonly used for classifying EMG patterns for prosthetic hand gestures?
K‑Nearest Neighbors (KNN)
Support Vector Machine (SVM)
Linear Regression
Apriori Algorithm
Explanation - SVMs handle high‑dimensional EMG data well and can create robust decision boundaries for gesture classification.
Correct answer is: Support Vector Machine (SVM)
Q.8 A user interface for a wheelchair control system should prioritize which of the following design principles?
High visual complexity
Minimal cognitive load
Multiple simultaneous commands
Dynamic color changes
Explanation - Simplified interfaces reduce mental effort, enabling safe and efficient operation for users with limited attention capacity.
Correct answer is: Minimal cognitive load
Q.9 Which of the following is a standard that governs the electrical safety of medical devices, including rehabilitation equipment?
ISO 9001
IEC 60601
IEEE 802.3
ISO 14001
Explanation - IEC 60601 specifies safety and essential performance requirements for medical electrical equipment.
Correct answer is: IEC 60601
Q.10 What is the function of a ‘force‑feedback’ joystick in a virtual reality rehabilitation system?
To display video streams
To generate resistance proportional to virtual object interaction
To record heart rate
To transmit Wi‑Fi signals
Explanation - Force‑feedback provides realistic haptic sensations that mimic physical interactions within the virtual environment.
Correct answer is: To generate resistance proportional to virtual object interaction
Q.11 In a brain‑computer interface, the term 'epoch' refers to:
A hardware component
A time‑window of recorded EEG data
A power supply unit
A type of electrode
Explanation - An epoch is a segment of EEG signals used for feature extraction and classification.
Correct answer is: A time‑window of recorded EEG data
Q.12 Which of the following is a key advantage of using Bluetooth Low Energy (BLE) for wearable rehabilitation sensors?
Unlimited range
High power consumption
Low latency and low power usage
Requires wired connection
Explanation - BLE enables continuous data streaming with minimal battery drain, ideal for portable wearables.
Correct answer is: Low latency and low power usage
Q.13 What does the term 'degrees of freedom' (DoF) describe in a robotic prosthetic arm?
Number of power sources
Number of independent joint motions
Amount of battery life
Count of sensor types
Explanation - DoF indicates how many independent movements the prosthesis can perform, such as flexion, extension, rotation, etc.
Correct answer is: Number of independent joint motions
Q.14 Which signal processing step is essential before feeding EMG data into a classifier?
Fourier transform
Band‑pass filtering
Data compression
Signal amplification
Explanation - Band‑pass filtering removes noise and retains the frequency range where useful EMG information resides (typically 20‑450 Hz).
Correct answer is: Band‑pass filtering
Q.15 In an assistive robot, what is the purpose of an impedance controller?
To maintain constant speed
To regulate the relationship between force and motion
To increase battery voltage
To provide visual feedback
Explanation - Impedance control allows the robot to adapt its stiffness and damping, making interaction with humans safe and natural.
Correct answer is: To regulate the relationship between force and motion
Q.16 Which type of electrode is typically used for non‑invasive EEG acquisition?
Needle electrode
Surface Ag/AgCl electrode
Intracortical microelectrode
Optical fiber electrode
Explanation - Ag/AgCl electrodes placed on the scalp provide good signal quality for non‑invasive EEG recordings.
Correct answer is: Surface Ag/AgCl electrode
Q.17 What does the term 'latency' refer to in a human‑machine interface?
The power consumption of the device
The delay between user action and system response
The size of the data packet
The durability of the hardware
Explanation - Low latency is crucial for smooth and intuitive interaction, especially in real‑time rehabilitation tasks.
Correct answer is: The delay between user action and system response
Q.18 Which of the following is a common visual feedback method used in gait rehabilitation treadmills?
LED strip indicating step timing
Vibration motor on the ankle
Auditory beep for speed
Temperature display
Explanation - LEDs provide clear, immediate visual cues about timing, helping users synchronize their steps with the treadmill.
Correct answer is: LED strip indicating step timing
Q.19 In a myoelectric control system, the term 'signal‑to‑noise ratio' (SNR) indicates:
The ratio of battery voltage to current
The relative strength of the EMG signal compared to background noise
The number of electrodes used
The speed of data transmission
Explanation - A higher SNR means clearer muscle activity detection, leading to more reliable prosthetic control.
Correct answer is: The relative strength of the EMG signal compared to background noise
Q.20 Which of the following is an example of a multimodal HMI for a wheelchair?
Joystick only
Voice command plus head‑tilt sensor
Bluetooth connectivity only
LED status lights
Explanation - Combining voice and head‑tilt provides two independent input channels, increasing accessibility for users with limited hand function.
Correct answer is: Voice command plus head‑tilt sensor
Q.21 What is the main advantage of using a flexible printed circuit (FPC) in wearable rehabilitation devices?
Higher rigidity
Lower cost than rigid PCBs
Conformability to body curvature
Increased power consumption
Explanation - FPCs can bend and stretch with the body, improving comfort and sensor placement stability.
Correct answer is: Conformability to body curvature
Q.22 Which of the following algorithms is most suitable for real‑time gesture recognition from EMG using a sliding window approach?
Batch Gradient Descent
Hidden Markov Model (HMM)
Recursive Least Squares (RLS)
K‑means clustering
Explanation - HMMs model temporal sequences and can update predictions as new EMG windows arrive, suitable for real‑time applications.
Correct answer is: Hidden Markov Model (HMM)
Q.23 In a virtual‑reality rehabilitation system, the term 'presence' refers to:
The physical weight of the headset
The sense of being inside the virtual environment
The number of sensors used
Battery life of the system
Explanation - High presence enhances engagement and can improve therapeutic outcomes.
Correct answer is: The sense of being inside the virtual environment
Q.24 Which power source is commonly used for implanted neurostimulators in rehabilitation engineering?
Alkaline AA batteries
Solar cells
Lithium‑ion rechargeable batteries
Wind turbines
Explanation - Lithium‑ion cells provide high energy density and can be recharged transcutaneously, suitable for long‑term implants.
Correct answer is: Lithium‑ion rechargeable batteries
Q.25 What does the term 'closed‑loop control' imply in a functional electrical stimulation (FES) system?
The system runs without any feedback
The system adjusts stimulation based on sensed muscle response
The system uses only pre‑programmed patterns
The system operates only offline
Explanation - Closed‑loop FES uses real‑time feedback (e.g., torque or position) to modulate stimulation for accurate movement.
Correct answer is: The system adjusts stimulation based on sensed muscle response
Q.26 Which of the following is a typical sampling rate for acquiring EMG signals for prosthetic control?
50 Hz
200 Hz
1 kHz
10 kHz
Explanation - A 1 kHz sampling rate captures the necessary frequency content (up to ~500 Hz) of EMG without excessive data load.
Correct answer is: 1 kHz
Q.27 In the context of assistive HMI design, what does the acronym 'UX' stand for?
Universal eXchange
User Experience
Unbiased X‑axis
Ultra‑fast XML
Explanation - UX encompasses all aspects of the end‑user’s interaction with a system, crucial for accessibility and satisfaction.
Correct answer is: User Experience
Q.28 A ‘force sensor’ placed under a wheelchair seat is primarily used to:
Measure ambient temperature
Detect user weight distribution for posture monitoring
Control the speed of the wheelchair
Transmit data via Wi‑Fi
Explanation - Monitoring pressure distribution helps prevent pressure sores and assess seating ergonomics.
Correct answer is: Detect user weight distribution for posture monitoring
Q.29 Which of the following best describes an ‘event‑related potential’ (ERP) in EEG?
A constant background rhythm
A voltage change time‑locked to a stimulus
A type of muscle artifact
A battery voltage fluctuation
Explanation - ERPs are used in BCI to detect user intent based on brain responses to specific events.
Correct answer is: A voltage change time‑locked to a stimulus
Q.30 What is the main purpose of a ‘deadband’ in a joystick controller for a powered wheelchair?
To increase the maximum speed
To filter out small, unintentional joystick movements
To store battery energy
To amplify the signal
Explanation - A deadband creates a neutral zone that prevents jitter and unintended motion.
Correct answer is: To filter out small, unintentional joystick movements
Q.31 Which sensor technology can detect subtle finger movements for a hand‑exoskeleton control?
Capacitive touch sensor
Hall‑effect sensor
Strain gauge
Infrared proximity sensor
Explanation - Strain gauges measure deformation caused by finger flexion, providing high‑resolution control signals.
Correct answer is: Strain gauge
Q.32 In an HMI for a gait trainer, what does the term 'assist‑as‑needed' (AAN) refer to?
Providing constant assistance throughout the movement
Providing assistance only when the user cannot complete the step alone
Turning off the device after a set time
Increasing the speed automatically
Explanation - AAN encourages active participation by supporting the user only when necessary, promoting motor learning.
Correct answer is: Providing assistance only when the user cannot complete the step alone
Q.33 Which of the following is a key challenge when using vision‑based HMI for wheelchair navigation?
Low processing power
Limited field of view
Excessive battery consumption
Difficulty detecting obstacles in varying lighting
Explanation - Changes in illumination can cause vision algorithms to miss or misinterpret obstacles, compromising safety.
Correct answer is: Difficulty detecting obstacles in varying lighting
Q.34 What does the term 'gain' refer to in an EMG amplifier circuit?
The input impedance
The factor by which the input signal is amplified
The power supply voltage
The sampling rate
Explanation - Gain determines how much the small EMG voltage is increased to a usable level for processing.
Correct answer is: The factor by which the input signal is amplified
Q.35 Which of the following is a typical method for reducing motion artefacts in wearable EMG recordings?
Using higher sampling rates
Applying band‑stop filters at 50/60 Hz
Employing adhesive, pre‑gelled electrodes
Increasing the gain
Explanation - Secure electrode contact minimizes skin movement relative to the sensor, reducing artefacts.
Correct answer is: Employing adhesive, pre‑gelled electrodes
Q.36 A ‘soft actuator’ in a rehabilitation glove is most likely based on:
Hydraulic pistons
Pneumatic artificial muscles
Stepper motors
Piezoelectric crystals
Explanation - PAMs are lightweight, compliant, and can produce smooth finger flexion suitable for soft wearable devices.
Correct answer is: Pneumatic artificial muscles
Q.37 Which of the following is a widely used open‑source platform for rapid prototyping of HMIs in rehabilitation?
MATLAB Simulink
Arduino
LabVIEW
SolidWorks
Explanation - Arduino boards provide low‑cost, flexible hardware and extensive libraries for sensor‑actuator integration.
Correct answer is: Arduino
Q.38 In a prosthetic hand, what is the purpose of a 'cable‑driven' transmission system?
To provide electrical power
To convert motor torque into finger flexion
To sense temperature
To communicate wirelessly
Explanation - Cables transmit the rotational motion of a motor to linear finger movement, allowing compact designs.
Correct answer is: To convert motor torque into finger flexion
Q.39 What does the acronym 'BLE' stand for, and why is it favored for wearable rehab devices?
Binary Light Emission – for visual feedback
Bluetooth Low Energy – because of low power consumption
Broadband Line Extension – for high data rates
Basic Laser Encoder – for precise positioning
Explanation - BLE enables continuous wireless data transfer while preserving battery life, essential for long‑term wearables.
Correct answer is: Bluetooth Low Energy – because of low power consumption
Q.40 When designing an auditory feedback scheme for a rehabilitation robot, which parameter is most effective for indicating error magnitude?
Pitch of the tone
Color of the display
Vibration intensity
Temperature of the device
Explanation - Higher pitch can be mapped to larger errors, providing intuitive auditory cues without visual distraction.
Correct answer is: Pitch of the tone
Q.41 Which of the following is a benefit of using a 'modular' architecture in HMI hardware for rehab devices?
Reduced software complexity
Easier upgrade and maintenance of individual components
Higher power consumption
Limited scalability
Explanation - Modules can be swapped or added without redesigning the entire system, fostering adaptability.
Correct answer is: Easier upgrade and maintenance of individual components
Q.42 In EEG‑based BCI, the 'mu rhythm' (8‑13 Hz) is primarily associated with:
Visual processing
Motor imagery
Auditory perception
Cardiac activity
Explanation - Desynchronization of the mu rhythm occurs when a user imagines moving a limb, useful for controlling prosthetics.
Correct answer is: Motor imagery
Q.43 What is the purpose of a 'ground' electrode in an EMG acquisition system?
To supply power to the sensor
To reference the signal and reduce common‑mode noise
To amplify the signal
To store data
Explanation - The ground electrode provides a stable reference point, improving signal quality by cancelling interference.
Correct answer is: To reference the signal and reduce common‑mode noise
Q.44 A 'soft exosuit' differs from a traditional exoskeleton primarily by:
Using rigid metal frames
Being powered by hydraulic fluids
Employing textile‑based actuation and sensors
Having no power source
Explanation - Soft exosuits integrate flexible fabrics and lightweight actuators, offering greater comfort and freedom of movement.
Correct answer is: Employing textile‑based actuation and sensors
Q.45 Which of the following is an example of a 'passive' assistive device?
Motorized prosthetic arm
Battery‑powered wheelchair
Elastic orthotic brace
Brain‑computer interface
Explanation - Passive devices provide support without external power, relying on mechanical properties like elasticity.
Correct answer is: Elastic orthotic brace
Q.46 In a sensor fusion scheme for a robotic arm, data from an IMU and an optical encoder are combined to improve:
Battery life
Temperature monitoring
Pose estimation accuracy
Wireless range
Explanation - Fusion of inertial and positional data reduces drift and enhances the reliability of joint angle estimation.
Correct answer is: Pose estimation accuracy
Q.47 What does 'PWM' stand for, and why is it used to drive motors in rehabilitation robots?
Pulse Width Modulation – for efficient speed and torque control
Power Wave Management – to regulate voltage spikes
Parallel Wireless Messaging – for data transfer
Passive Weight Measurement – to monitor load
Explanation - PWM varies the duty cycle to control motor power without dissipating excess heat, crucial for smooth motion.
Correct answer is: Pulse Width Modulation – for efficient speed and torque control
Q.48 Which type of feedback is most effective for informing a user about the amount of force applied by a prosthetic hand?
Auditory beep
Vibrotactile actuator on the residual limb
LED brightness
Screen text
Explanation - Tactile feedback directly on the body provides an intuitive sense of grip force, aiding manipulation tasks.
Correct answer is: Vibrotactile actuator on the residual limb
Q.49 When calibrating a myoelectric prosthesis, the term 'MVC' refers to:
Maximum Voluntary Contraction
Motor Voltage Control
Microcontroller Voltage Converter
Median Vibration Coefficient
Explanation - MVC is the highest EMG amplitude a user can produce voluntarily and is used to scale control signals.
Correct answer is: Maximum Voluntary Contraction
Q.50 Which of the following is a primary benefit of using a 'touchscreen' as an HMI for a rehab treadmill?
Higher durability than physical buttons
Ability to present dynamic, context‑specific controls
Lower power consumption
Reduced latency compared to voice control
Explanation - Touchscreens can adapt the displayed interface to the current training mode or user level.
Correct answer is: Ability to present dynamic, context‑specific controls
Q.51 In a rehabilitation robot, why is a 'low‑pass filter' applied to the measured force signal before control?
To increase the signal amplitude
To remove high‑frequency noise and smooth the signal
To convert force to position
To encrypt the data
Explanation - Low‑pass filtering eliminates rapid fluctuations that could cause unstable control actions.
Correct answer is: To remove high‑frequency noise and smooth the signal
Q.52 Which of the following best describes 'latency jitter' in an HMI system?
Consistent, fixed delay
Variability in the delay between input and response
Increase in battery voltage
Change in sensor gain
Explanation - Jitter can make the system feel unpredictable and degrade performance, especially in real‑time control.
Correct answer is: Variability in the delay between input and response
Q.53 A 'force‑sensing resistor' (FSR) is typically used to:
Measure temperature
Detect pressure or force applied to its surface
Generate acoustic signals
Store energy
Explanation - FSRs change resistance according to applied force, enabling simple pressure sensing for HMIs.
Correct answer is: Detect pressure or force applied to its surface
Q.54 What is the main purpose of a 'safety stop' button on a rehabilitation robot?
To pause data logging
To immediately halt all motion in case of emergency
To switch the robot to low‑power mode
To reset the software
Explanation - The safety stop provides a quick, reliable way to prevent injury if the robot behaves unexpectedly.
Correct answer is: To immediately halt all motion in case of emergency
Q.55 Which of the following is a common technique for reducing the dimensionality of EMG feature vectors?
Principal Component Analysis (PCA)
Fast Fourier Transform (FFT)
Pulse Width Modulation (PWM)
Binary Search
Explanation - PCA transforms high‑dimensional data into a smaller set of orthogonal components while preserving variance.
Correct answer is: Principal Component Analysis (PCA)
Q.56 When using a voice‑controlled wheelchair, which of the following is a key consideration for robust operation?
Speaker volume
Ambient noise filtering
Battery color
Wheel diameter
Explanation - Effective speech recognition must distinguish commands from background sounds to avoid false actions.
Correct answer is: Ambient noise filtering
Q.57 Which of the following is a typical characteristic of a 'soft' sensor used in wearable rehabilitation garments?
Rigid metal housing
High stiffness
Flexibility and stretchability
Requires high voltage
Explanation - Soft sensors conform to body movements, providing accurate data without restricting motion.
Correct answer is: Flexibility and stretchability
Q.58 In a prosthetic hand, a 'grip force threshold' is set to:
Define the maximum speed of finger movement
Limit the maximum grip force to avoid object damage
Adjust the color of the device
Control the battery charging rate
Explanation - Setting a threshold prevents crushing delicate objects while still providing sufficient grip.
Correct answer is: Limit the maximum grip force to avoid object damage
Q.59 What does the term 'biocompatibility' refer to in the context of implantable HMI components?
Ability to conduct electricity
Compatibility with wireless standards
Non‑toxic interaction with body tissues
High mechanical strength
Explanation - Biocompatible materials avoid immune reactions, essential for long‑term implants.
Correct answer is: Non‑toxic interaction with body tissues
Q.60 Which of the following is a common method for providing visual feedback in a virtual‑reality gait training system?
Changing background music tempo
Displaying a real‑time avatar matching the user's stride
Vibrating the floor
Altering room temperature
Explanation - An avatar mirrors the user's movement, helping them adjust gait patterns visually.
Correct answer is: Displaying a real‑time avatar matching the user's stride
Q.61 In an HMI using a pressure‑sensing mat for balance training, the term 'center of pressure' (CoP) indicates:
The point where the user’s weight is concentrated on the mat
The maximum voltage of the sensor
The speed of the treadmill belt
The Bluetooth connection strength
Explanation - CoP trajectory provides insight into postural stability and weight shifting.
Correct answer is: The point where the user’s weight is concentrated on the mat
Q.62 Which of the following hardware components is essential for implementing a closed‑loop FES system that adapts to muscle fatigue?
Force sensor on the limb
LED display
Microphone
Solar panel
Explanation - Measuring output force allows the controller to increase stimulation when fatigue reduces muscle output.
Correct answer is: Force sensor on the limb
Q.63 What is the primary reason for using 'differential amplification' in EMG acquisition?
To increase the supply voltage
To reject common‑mode noise and improve signal quality
To convert analog to digital signals
To store data locally
Explanation - Differential amplifiers amplify the voltage difference between two electrodes while suppressing interference common to both.
Correct answer is: To reject common‑mode noise and improve signal quality
Q.64 Which of the following describes a 'brain‑spine interface' (BSI) in rehabilitation engineering?
A device that connects EEG to spinal cord stimulators for gait recovery
A wireless Wi‑Fi router for hospitals
A prosthetic hand controller
A visual display for VR training
Explanation - BSI uses brain signals to trigger spinal stimulation, aiming to restore locomotion after injury.
Correct answer is: A device that connects EEG to spinal cord stimulators for gait recovery
Q.65 In a myoelectric prosthetic limb, why is a 'low‑pass filter' often applied after full‑wave rectification of the EMG signal?
To increase the frequency content
To obtain the envelope of muscle activity for smoother control
To convert the signal to binary
To reduce power consumption
Explanation - Rectification followed by low‑pass filtering yields a smooth amplitude envelope that reflects overall muscle effort.
Correct answer is: To obtain the envelope of muscle activity for smoother control
Q.66 Which type of actuator is most suitable for providing compliant assistance in a soft exosuit for gait training?
Brushless DC motor with rigid gear
Pneumatic artificial muscle (PAM)
Hydraulic cylinder
Piezoelectric stack
Explanation - PAMs are lightweight, compliant, and can mimic natural muscle contraction patterns.
Correct answer is: Pneumatic artificial muscle (PAM)
Q.67 When designing a HMI for a pediatric rehabilitation robot, which design principle should be emphasized?
Complex multi‑layer menus
Bright colors and simple icons
High‑resolution technical graphs
Voice‑only commands
Explanation - Children respond better to clear, colorful visuals that reduce cognitive load.
Correct answer is: Bright colors and simple icons
Q.68 A 'state machine' model in HMI software is used to:
Store large datasets
Define discrete system states and transitions based on user inputs
Increase wireless range
Control battery voltage
Explanation - State machines simplify the logic of interaction flows, improving reliability.
Correct answer is: Define discrete system states and transitions based on user inputs
Q.69 Which of the following is a standard communication protocol for medical device networking, often used in HMI integration?
CANopen
Modbus RTU
HL7
I2C
Explanation - Health Level Seven (HL7) defines data exchange formats for medical applications, facilitating integration across systems.
Correct answer is: HL7
Q.70 In a rehabilitation exoskeleton, the term 'backdrivability' refers to:
The ability of the robot to be driven by external forces (e.g., user movement) without resistance
The speed of the controller
The wireless bandwidth
The color of the device
Explanation - High backdrivability ensures the exoskeleton does not hinder the user's natural motion when assistance is not needed.
Correct answer is: The ability of the robot to be driven by external forces (e.g., user movement) without resistance
Q.71 Which sensor would be most appropriate for detecting the slip of a foot during gait on a treadmill?
Accelerometer
Force‑sensing resistor (FSR)
Temperature sensor
Magnetometer
Explanation - FSRs placed under the foot can sense changes in pressure indicative of slip events.
Correct answer is: Force‑sensing resistor (FSR)
Q.72 What does 'haptic rendering' mean in a virtual‑reality rehabilitation environment?
Generating realistic tactile sensations through force feedback devices
Displaying high‑resolution graphics
Recording audio cues
Adjusting screen brightness
Explanation - Haptic rendering creates the sensation of touching virtual objects, enhancing immersion and training effectiveness.
Correct answer is: Generating realistic tactile sensations through force feedback devices
Q.73 A 'low‑pass FIR filter' is preferred over an IIR filter in some HMI applications because:
It has linear phase response, preserving signal shape
It requires less memory
It amplifies high frequencies
It is cheaper to implement
Explanation - Linear phase ensures that all frequency components are delayed equally, which is important for timing‑critical biosignals.
Correct answer is: It has linear phase response, preserving signal shape
Q.74 In an assistive robot, which of the following best describes the function of a 'compliance controller'?
Maintains a rigid trajectory regardless of external forces
Adjusts robot stiffness to allow safe interaction with the user
Increases battery voltage
Controls wireless data packets
Explanation - Compliance control lets the robot yield under contact, reducing the risk of injury.
Correct answer is: Adjusts robot stiffness to allow safe interaction with the user
Q.75 Which of the following is a typical use case for a 'sEMG' sensor in a rehabilitation exoskeleton?
Measuring heart rate
Detecting user intent to initiate movement
Providing GPS location
Controlling lighting
Explanation - Surface EMG captures muscle activation patterns that can trigger or modulate exoskeleton assistance.
Correct answer is: Detecting user intent to initiate movement
Q.76 When integrating multiple sensors in a rehabilitation device, the term 'sensor fusion' primarily aims to:
Reduce the number of wires
Combine data to obtain a more accurate estimate of the measured variable
Increase power consumption
Simplify the user interface
Explanation - Fusion leverages complementary strengths of sensors, improving reliability and robustness.
Correct answer is: Combine data to obtain a more accurate estimate of the measured variable
Q.77 A 'cognitive load' in HMI design refers to:
The amount of electrical power drawn by the device
The mental effort required by the user to operate the system
The physical weight of the hardware
The bandwidth of the wireless connection
Explanation - Lower cognitive load leads to easier and safer operation, especially for users with impairments.
Correct answer is: The mental effort required by the user to operate the system
Q.78 In a prosthetic hand, which control strategy maps the amplitude of EMG signals directly to motor speed?
Proportional control
Bang‑bang control
PID control
Fuzzy logic control
Explanation - Proportional control scales motor speed in proportion to the magnitude of the EMG signal, providing intuitive gradation.
Correct answer is: Proportional control
Q.79 Which of the following is an advantage of using a 'graphical user interface' (GUI) on a tablet for configuring a rehabilitation robot?
Requires programming knowledge
Provides intuitive, visual parameter adjustment
Consumes more power than command‑line interfaces
Limits the number of configurable options
Explanation - GUIs allow clinicians to set parameters quickly via sliders, icons, and real‑time plots.
Correct answer is: Provides intuitive, visual parameter adjustment
Q.80 What is the primary function of a 'digital isolator' in the signal chain of an HMI device?
To increase signal amplitude
To prevent ground loops and protect against high voltage spikes
To convert analog signals to digital
To store data
Explanation - Isolation maintains patient safety and signal integrity by separating circuitry grounds.
Correct answer is: To prevent ground loops and protect against high voltage spikes
Q.81 When a prosthetic hand uses 'pattern recognition' for gesture control, the classifier is trained on:
Pre‑programmed joint angles
EMG feature vectors associated with different intended motions
Battery voltage levels
Ambient light intensity
Explanation - Training the classifier on EMG patterns enables the device to differentiate between gestures such as grasp, pinch, or release.
Correct answer is: EMG feature vectors associated with different intended motions
Q.82 Which of the following is a typical characteristic of a 'soft' robot actuator made from shape‑memory alloy (SMA)?
High speed actuation with low power
Low force output but high compliance
Heat‑induced contraction when electrically heated
Magnetic field responsiveness
Explanation - SMAs change shape upon heating, providing actuation suitable for lightweight, compliant devices.
Correct answer is: Heat‑induced contraction when electrically heated
Q.83 In a rehabilitation HMI, the term 'latency budget' refers to:
The maximum allowable total delay from user action to system response
The amount of memory allocated for data logging
The power consumption limit of the device
The number of sensors that can be connected
Explanation - A latency budget ensures the system remains responsive enough for safe and effective interaction.
Correct answer is: The maximum allowable total delay from user action to system response
Q.84 Which of the following is a key factor when selecting an electrode material for long‑term EEG monitoring?
High thermal conductivity
Low skin‑electrode impedance and biocompatibility
Magnetic susceptibility
Transparency to visible light
Explanation - Low impedance ensures good signal quality, while biocompatibility prevents irritation over prolonged use.
Correct answer is: Low skin‑electrode impedance and biocompatibility
Q.85 What is the main advantage of using a 'ring‑shaped' haptic actuator on a finger for prosthetic control?
Provides uniform pressure around the digit, enhancing perception of grip force
Generates audible tones
Charges the battery wirelessly
Measures temperature
Explanation - Ring‑shaped actuators can deliver consistent vibrotactile feedback directly to the fingertip area.
Correct answer is: Provides uniform pressure around the digit, enhancing perception of grip force
Q.86 In a rehabilitation robot, a 'trajectory planner' is responsible for:
Generating a sequence of desired positions or joint angles over time
Measuring the user's heart rate
Controlling the Wi‑Fi module
Storing user preferences
Explanation - The planner defines the path the robot should follow to achieve a therapeutic movement.
Correct answer is: Generating a sequence of desired positions or joint angles over time
Q.87 Which of the following best describes the concept of 'intention detection' in a brain‑computer interface for rehabilitation?
Detecting the user's desired movement from brain signals
Measuring the temperature of the environment
Counting the number of steps taken
Recording audio commands
Explanation - Intention detection translates neural activity into control commands for assistive devices.
Correct answer is: Detecting the user's desired movement from brain signals
Q.88 When implementing a voice‑controlled wheelchair, which speech recognition method is most robust against user accent variations?
Template matching
Hidden Markov Model (HMM) with large acoustic models
Simple keyword spotting
Frequency modulation analysis
Explanation - HMM‑based recognizers can model a wide range of phonetic variations, improving accuracy across accents.
Correct answer is: Hidden Markov Model (HMM) with large acoustic models
Q.89 In a prosthetic hand, the term 'grip pattern library' refers to:
A collection of pre‑programmed hand postures that can be selected by the user
A list of battery charging cycles
A database of user passwords
A set of wireless communication protocols
Explanation - The library stores various grasp configurations (e.g., power grasp, precision pinch) that the controller can invoke.
Correct answer is: A collection of pre‑programmed hand postures that can be selected by the user
Q.90 Which of the following is a typical advantage of using a 'fiber‑optic' sensor for joint angle measurement in an exoskeleton?
Immunity to electromagnetic interference
Low cost compared to resistive sensors
High power consumption
Requires frequent calibration
Explanation - Fiber‑optic sensors are not affected by EM fields, making them reliable in electrically noisy environments.
Correct answer is: Immunity to electromagnetic interference
Q.91 What does the term 'shared control' denote in the context of HMI for rehabilitation robots?
The robot fully controls the movement without user input
The user and robot jointly determine the movement, combining human intent with autonomous assistance
Multiple users control the same robot simultaneously
Control is transferred to a remote operator
Explanation - Shared control blends user commands with robot assistance, improving performance while preserving user agency.
Correct answer is: The user and robot jointly determine the movement, combining human intent with autonomous assistance
Q.92 Which of the following is a common method for assessing the usability of a new HMI prototype for a rehabilitation device?
Measuring battery voltage
Conducting a System Usability Scale (SUS) questionnaire with users
Counting the number of LEDs
Testing Wi‑Fi range
Explanation - SUS provides a standardized metric to evaluate ease of use, learnability, and satisfaction.
Correct answer is: Conducting a System Usability Scale (SUS) questionnaire with users
Q.93 In a wearable rehabilitation glove, a 'flex sensor' is used to:
Detect temperature changes
Measure the degree of finger bending
Generate audio feedback
Charge the device
Explanation - Flex sensors change resistance proportionally to bending, allowing precise tracking of finger motion.
Correct answer is: Measure the degree of finger bending
Q.94 Which of the following safety standards specifically addresses the risk of electrical shock in medical devices?
ISO 14971
IEC 60601‑1
ISO 9001
IEEE 802.3
Explanation - IEC 60601‑1 outlines requirements to protect patients and users from electrical hazards.
Correct answer is: IEC 60601‑1
Q.95 What is the main purpose of using a 'Kalman filter' in a sensor fusion system for a rehabilitation robot?
To increase sensor noise
To optimally estimate the state (e.g., position, velocity) by combining noisy measurements
To convert analog signals to digital
To encrypt communication
Explanation - The Kalman filter recursively blends predictions and observations, yielding a smoother, more accurate estimate.
Correct answer is: To optimally estimate the state (e.g., position, velocity) by combining noisy measurements
Q.96 When designing a visual HMI for users with low vision, which design choice is most appropriate?
Use small fonts and low contrast
Employ high‑contrast colors and large fonts
Include fast‑flashing animations
Rely solely on color coding
Explanation - High contrast and large text improve readability for users with visual impairments.
Correct answer is: Employ high‑contrast colors and large fonts
Q.97 In the context of HMI for rehabilitation, 'latency' below 50 ms is generally considered:
Unacceptable
Adequate for real‑time control
Irrelevant
Too fast for human perception
Explanation - Latencies under ~50 ms are typically imperceptible and allow smooth interaction in most motor tasks.
Correct answer is: Adequate for real‑time control
Q.98 Which of the following is a typical output of an EMG‑based intent detection algorithm in a powered orthosis?
Desired joint torque command
Battery temperature reading
Wi‑Fi signal strength
Ambient light level
Explanation - The algorithm translates muscle activation into a torque request for the orthosis actuator.
Correct answer is: Desired joint torque command
Q.99 A 'force feedback joystick' used in a rehabilitation simulator primarily provides:
Visual cues on a screen
Tactile resistance proportional to virtual interactions
Audio alerts
Wireless charging
Explanation - The joystick exerts forces that simulate contact with virtual objects, enhancing immersion and training realism.
Correct answer is: Tactile resistance proportional to virtual interactions
Q.100 In an HMI, the term 'debounce' is used to describe:
A method for filtering out rapid, unintended button state changes
Increasing the voltage of a signal
A type of battery charger
A visual animation effect
Explanation - Debouncing prevents false triggers caused by mechanical contacts bouncing when pressed.
Correct answer is: A method for filtering out rapid, unintended button state changes
Q.101 Which of the following is a benefit of using a 'wireless charging' system for a wearable rehabilitation device?
Eliminates the need for cables, reducing infection risk
Increases device weight significantly
Reduces battery capacity
Limits data transmission
Explanation - Wireless charging allows recharging without opening the device enclosure, improving hygiene and convenience.
Correct answer is: Eliminates the need for cables, reducing infection risk
Q.102 When a prosthetic hand uses 'synergistic control', it means:
All fingers move independently based on separate commands
Multiple fingers are coordinated to move together based on a single control signal
The device is powered by solar energy
The hand can change color
Explanation - Synergistic control simplifies user input by grouping finger motions into functional grasps.
Correct answer is: Multiple fingers are coordinated to move together based on a single control signal
Q.103 Which of the following hardware platforms offers built‑in Bluetooth Low Energy (BLE) and is frequently used for rapid HMI prototyping?
Raspberry Pi 4
Arduino Nano 33 BLE
BeagleBone Black
Intel NUC
Explanation - The Nano 33 BLE integrates BLE radio, making it ideal for low‑power wearable prototypes.
Correct answer is: Arduino Nano 33 BLE
Q.104 In a rehabilitation system that uses a 'step counter' based on an accelerometer, the primary signal processing technique used to detect steps is:
Peak detection on the vertical acceleration axis
Fourier transform of the raw data
Voltage regulation
Magnetic field measurement
Explanation - Identifying periodic peaks corresponding to heel strikes enables reliable step counting.
Correct answer is: Peak detection on the vertical acceleration axis
Q.105 Which of the following best explains why a 'high‑resolution encoder' is preferred over a low‑resolution one for precise prosthetic finger control?
It consumes more power
It provides finer angular position measurements, enabling smoother movement
It reduces the size of the prosthetic hand
It eliminates the need for any control algorithm
Explanation - Higher resolution translates to smaller position increments, improving the dexterity of the prosthetic.
Correct answer is: It provides finer angular position measurements, enabling smoother movement
Q.106 When an HMI system logs data for later analysis, the preferred file format for storing time‑stamped sensor data is:
JPEG
CSV
MP3
PDF
Explanation - CSV (Comma‑Separated Values) is simple, human‑readable, and compatible with most data‑analysis tools.
Correct answer is: CSV
Q.107 In the context of assistive technology, the term 'assistive technology assessment' (ATA) primarily aims to:
Evaluate the financial cost of a device
Determine the most suitable technology for a user’s functional needs
Measure the device’s weight
Test Wi‑Fi signal strength
Explanation - ATA involves a systematic evaluation of a user’s abilities, environment, and goals to match appropriate technology.
Correct answer is: Determine the most suitable technology for a user’s functional needs
Q.108 Which of the following is an example of a non‑invasive HMI for controlling a powered wheelchair?
Implanted neural electrode array
Head‑mounted eye‑tracking camera
Spinal cord stimulator
Subdermal EMG needle
Explanation - Eye‑tracking systems detect gaze direction to issue movement commands without penetrating the skin.
Correct answer is: Head‑mounted eye‑tracking camera
Q.109 A 'finite state machine' (FSM) used in prosthetic control typically includes which of the following states?
Idle, Grasp, Release, Error
Charging, Discharging, Overheat
Transmit, Receive, Sleep
On, Off
Explanation - These states represent distinct functional modes of the prosthetic hand, with transitions based on user input.
Correct answer is: Idle, Grasp, Release, Error
Q.110 Which of the following is a primary advantage of using a 'soft silicone' interface between a prosthetic socket and residual limb?
Increases electrical conductivity
Provides cushioning and reduces pressure points
Generates power for the device
Blocks all sensor signals
Explanation - Soft silicone conforms to the limb shape, distributing pressure evenly and enhancing comfort.
Correct answer is: Provides cushioning and reduces pressure points
Q.111 In a rehabilitation HMI, what does the term 'feedback loop' describe?
A circular cable that powers the device
A process where sensor data is used to adjust actuator output continuously
A type of battery
A wireless communication protocol
Explanation - Feedback loops enable the system to respond dynamically to the user's performance.
Correct answer is: A process where sensor data is used to adjust actuator output continuously
Q.112 Which of the following sensor modalities is best suited for detecting the direction of a user's gaze in an eye‑tracking HMI?
Infrared camera with corneal reflection analysis
Accelerometer
Thermistor
Hall‑effect sensor
Explanation - Infrared eye‑trackers detect the pupil and corneal reflections to calculate gaze direction accurately.
Correct answer is: Infrared camera with corneal reflection analysis
Q.113 When integrating a haptic motor into a prosthetic hand, the term 'bandwidth' of the motor refers to:
The range of frequencies over which the motor can accurately reproduce vibration patterns
The battery capacity
The wireless data rate
The physical size of the motor
Explanation - Higher bandwidth enables richer tactile feedback, conveying more nuanced information to the user.
Correct answer is: The range of frequencies over which the motor can accurately reproduce vibration patterns
Q.114 Which of the following is an effective way to reduce the computational load of a real‑time EMG classifier on a low‑power microcontroller?
Increase the number of sensor channels
Use dimensionality reduction techniques such as PCA before classification
Sample at 10 kHz
Add more hidden layers to a deep neural network
Explanation - Reducing feature dimensionality decreases processing time while retaining essential information.
Correct answer is: Use dimensionality reduction techniques such as PCA before classification
Q.115 In a rehabilitation device, a 'tactile array' is primarily used to:
Measure temperature
Detect pressure distribution over a surface
Emit sound
Generate electrical power
Explanation - Tactile arrays consist of many small pressure sensors, useful for mapping contact forces on a limb or seat.
Correct answer is: Detect pressure distribution over a surface
Q.116 Which of the following best describes the function of a 'look‑up table' (LUT) in an HMI mapping EMG amplitudes to motor commands?
A dynamic algorithm that learns online
A pre‑computed set of input‑output pairs for fast translation
A wireless communication protocol
A power management scheme
Explanation - LUTs allow instantaneous mapping without heavy computation, suitable for resource‑limited devices.
Correct answer is: A pre‑computed set of input‑output pairs for fast translation
Q.117 When a rehabilitation robot provides "adaptive assistance", it means that:
The level of support changes based on the user's performance
The robot never changes its assistance level
The robot assists only when the user presses a button
The robot adapts its color
Explanation - Adaptive assistance tailors the amount of help, encouraging progressive skill development.
Correct answer is: The level of support changes based on the user's performance
Q.118 Which of the following is a major challenge when using EEG for HCI control in everyday environments?
Low signal amplitude and susceptibility to motion artefacts
Excessive battery life
Overly simple hardware
Lack of any data processing requirements
Explanation - EEG signals are weak and easily corrupted by movement, requiring robust filtering and artifact rejection.
Correct answer is: Low signal amplitude and susceptibility to motion artefacts
Q.119 In a prosthetic socket, the purpose of a 'suction liner' is to:
Generate electrical power
Create a secure, low‑profile fit by using negative pressure
Emit light for visual feedback
Measure temperature
Explanation - Suction liners improve socket retention and comfort by drawing the residual limb gently against the socket walls.
Correct answer is: Create a secure, low‑profile fit by using negative pressure
Q.120 Which of the following is an example of a 'context‑aware' HMI feature in a rehabilitation exoskeleton?
Adjusting assistance level based on the detected walking speed
Changing the LED color randomly
Increasing battery voltage
Sending a fixed beep every second
Explanation - Context‑aware systems sense the current activity (e.g., speed) and modify behavior accordingly.
Correct answer is: Adjusting assistance level based on the detected walking speed
Q.121 Which of the following best characterizes a 'soft sensor' made from conductive ink printed on fabric?
Rigid and non‑stretchable
Flexible, stretchable, and capable of detecting strain or pressure
Requires high voltage to operate
Only works underwater
Explanation - Conductive‑ink sensors conform to body movements, providing comfortable, wearable sensing.
Correct answer is: Flexible, stretchable, and capable of detecting strain or pressure
Q.122 In a prosthetic hand control system, the term 'deadzone' refers to:
A region of EMG amplitude that does not produce any motor command, preventing unintended movements
A part of the device that stores energy
The maximum grip strength
A type of battery
Explanation - Deadzones filter out low‑level noise and inadvertent muscle twitches.
Correct answer is: A region of EMG amplitude that does not produce any motor command, preventing unintended movements
Q.123 Which of the following is a key factor when selecting a battery chemistry for a long‑duration wearable rehabilitation device?
High energy density and safe operation under repeated charge cycles
Low cost regardless of safety
Maximum weight without regard to comfort
Requirement for high voltage output only
Explanation - Energy density determines runtime, while safety is critical for devices in close contact with the body.
Correct answer is: High energy density and safe operation under repeated charge cycles
Q.124 In a human‑machine interface, the term 'modal interaction' means:
The user can only interact with one device at a time
The system changes its interaction style based on the current mode (e.g., navigation vs. manipulation)
All inputs are treated identically
The interface only works in one language
Explanation - Modal interaction allows distinct sets of controls depending on the active task or state.
Correct answer is: The system changes its interaction style based on the current mode (e.g., navigation vs. manipulation)
Q.125 When designing a haptic interface that uses vibration to convey information, which parameter is most effective for representing different levels of urgency?
Amplitude (intensity) of the vibration
Color of the device housing
Battery voltage
Device weight
Explanation - Increasing vibration amplitude can signal higher urgency or stronger alerts.
Correct answer is: Amplitude (intensity) of the vibration
Q.126 Which of the following is a standard that defines the communication between a prosthetic controller and external devices over a wired link?
USB Human Interface Device (HID) class
IEEE 802.11
CANopen
ISO 13485
Explanation - The HID class provides a generic way for devices like prosthetic controllers to exchange data over USB.
Correct answer is: USB Human Interface Device (HID) class
Q.127 In a rehabilitation exoskeleton, the term 'zero‑gravity' mode refers to:
A mode where the robot provides no assistance, allowing the user to move freely
A mode that simulates weightlessness by counteracting gravity
A power‑saving mode that turns off all motors
A diagnostic test for battery health
Explanation - Zero‑gravity mode reduces the effort required to lift the limb, helping users practice movements without load.
Correct answer is: A mode that simulates weightlessness by counteracting gravity
Q.128 Which of the following best describes why 'low‑pass filtering' is applied after computing the RMS of an EMG signal?
To amplify the high‑frequency noise
To extract the smooth envelope representing muscle activation level
To convert the signal to digital format
To increase the sampling rate
Explanation - The RMS value fluctuates rapidly; low‑pass filtering creates a stable envelope for control purposes.
Correct answer is: To extract the smooth envelope representing muscle activation level
Q.129 What is the primary purpose of an 'EMG normalization' step in prosthetic control?
To convert EMG signals to voltage levels
To scale EMG amplitudes relative to a reference contraction (e.g., MVC)
To increase the battery life
To change the sensor's physical size
Explanation - Normalization makes control robust across sessions and users by accounting for signal variability.
Correct answer is: To scale EMG amplitudes relative to a reference contraction (e.g., MVC)
Q.130 In a HMI that uses a pressure‑sensing floor mat for balance training, a sudden shift of the center of pressure beyond a preset boundary should trigger:
A visual warning on a screen
An increase in battery voltage
A change in Wi‑Fi channel
A temperature alert
Explanation - Immediate visual feedback alerts the user to correct posture before a fall occurs.
Correct answer is: A visual warning on a screen
Q.131 Which of the following is a key consideration when selecting a microcontroller for a wearable HMI with real‑time EMG processing?
High clock speed with low power consumption
Large physical size
Only analog I/O pins
Lack of DMA support
Explanation - Real‑time processing demands sufficient computational power while maintaining low energy use for wearability.
Correct answer is: High clock speed with low power consumption
Q.132 When an HMI device provides "multisensory feedback", it means:
It uses at least two different types of sensory cues (e.g., visual and haptic)
It only uses auditory signals
It operates on multiple batteries simultaneously
It connects to multiple Wi‑Fi networks
Explanation - Combining modalities enhances perception and learning, especially for users with sensory deficits.
Correct answer is: It uses at least two different types of sensory cues (e.g., visual and haptic)
Q.133 Which of the following is a common metric for evaluating the classification performance of an EMG‑based gesture recognizer?
Accuracy
Battery temperature
Signal frequency
Wireless range
Explanation - Accuracy measures the proportion of correctly identified gestures, indicating system reliability.
Correct answer is: Accuracy
Q.134 In a rehabilitation robot, the term "impedance" is most closely related to:
The device's resistance to motion when a force is applied
The battery capacity
The Wi‑Fi signal strength
The color of the robot
Explanation - Impedance characterizes the relationship between applied force and resulting motion, crucial for safe interaction.
Correct answer is: The device's resistance to motion when a force is applied
Q.135 Which of the following is a typical advantage of using a 'graphical touch screen' over physical buttons in a rehabilitation device UI?
Higher power consumption
Ability to change the layout and display context‑specific controls dynamically
Reduced durability
Limited to a single function
Explanation - Touch screens can adapt interfaces on‑the‑fly, offering flexibility for different therapy modes.
Correct answer is: Ability to change the layout and display context‑specific controls dynamically