Method and system for quantifying an intention of movement of a user
A method for quantifying an intention of movement of a user, the method comprising: extracting a mechanomyogram (MMG) signal in response to surface vibration of a muscle of the user; and averaging the MMG signal by calculating the MMG root mean squared (RMS) amplitude or frequency variance in a predetermined time window; where an increasing RMS amplitude of the MMG signal corresponds to increasing muscle voluntary contraction or a decreasing frequency variance of the MMG signal corresponds to increasing muscle voluntary contraction.
1. A method for determining an intention of movement of a user, the method comprising:
extracting a mechanomyogram (MMG) signal from one or more vibration sensors in response to surface vibration of a muscle of the user;
averaging the MMG signal by calculating the MMG root mean squared (RMS) amplitude or frequency variance in a predetermined time window;
determining a change in the RMS amplitude or frequency variance of the MMG signal over time, wherein an increasing RMS amplitude or a decreasing frequency variance of the MMG signal is used to identify a voluntary contraction of the muscle; and
determining an intention of the user to contract the muscle based on the determined change in the RMS amplitude or frequency variance of the MMG signal.
2. The method according to claim 1 , wherein the frequency variance of the MMG signal is the scale or degree of frequency being spread out in a power density spectrum (PDS).
3. The method according to claim 1 , wherein both RMS MMG amplitude and the frequency variance of the MMG signal are used to estimate a level of muscle contraction.
4. The method according to claim 1 , wherein the muscle contraction level is normalized to a percentage of maximal voluntary contraction (MVC).
5. The method according to claim 4 , further comprising instructing a robotic system according to the estimated percentage of MVC.
6. The method according to claim 1 , wherein the RMS amplitude is normalized as a percentage of a span between a maximal and a minimum value.
7. The method according to claim 1 , wherein the frequency variance of the MMG signal is normalized as a percentage of a span between a maximal and a minimum value.
8. The method according to claim 1 , wherein the predetermined time window is 1 second with 100 ms step forward.
9. A system for determining an intention of movement of a user, the system comprising:
a measurement unit to extract a mechanomyogram (MMG) signal using one or more vibration sensors in response to surface vibration of a muscle of the user; and
a signal processing unit to average the MMG signal by calculating the MMG root mean squared (RMS) amplitude or frequency variance in a predetermined time window, to determine a change in the RMS amplitude or frequency variance of the MMG signal over time, wherein an increasing RMS amplitude or a decreasing frequency variance of the MMG signal is used to identify a voluntary contraction of the muscle, and to determine an intention of the user to contract the muscle based on the determined change in the RMS amplitude or frequency variance of the MMG signal.
10. The system according to claim 9 , further comprising another signal processing unit to pre-process a raw signal corresponding to the surface vibration of a muscle of the user.
11. The system according to claim 9 , further comprising a modeling unit to translate the RMS amplitude signal and the frequency variance of the MMG signal into a set of instructions for recording or actuating a robot or an actuation unit of the robot.
12. The system according to claim 9 , wherein the measurement unit comprises at least one sensor to detect surface vibration of the muscle and generate an output signal.
13. The system according to claim 9 , wherein the measurement unit weighs less than or is equal to five grams.
14. The system according to claim 12 , wherein the sensor is any one from the group consisting of: condenser microphones, piezoelectric transducers, dual-axis accelerometers, MEMS-based accelerometers and angle-measurement devices.
15. The system according to claim 12 , wherein the output signal is passed through a band pass filter from 2 to 40 Hz to extract the MMG signal from the output signal.
16. The system according to claim 9 , wherein the instructions are transmitted to a robotic system to control the robotic system.
17. The system according to claim 11 , wherein motion and environmental parameters of the robotic system are recorded by sensors and transmitted back to the modeling unit via a feedback signal.
18. The system according to claim 17 , wherein the motion parameters include dynamic parameters of: force or torque, and kinematic parameters any one from the group consisting of: linear and angular displacement, velocities, and accelerations.
19. The method according to claim 1 , wherein the vibration sensors include condenser microphones, piezoelectric transducers, and/or MEMS-based accelerometers.
20. The method according to claim 1 , wherein the quantifying comprises determining a direction of movement of the muscle and/or an amount of force intended by the user for moving the muscle.
21. The method according to claim 1 , wherein the frequency variance comprises a scale or a degree of the frequency being spread out.
22. The system according to claim 9 , wherein the frequency variance comprises a scale or a degree of the frequency being spread out.