Robotic system and training method for rehabilitation using EMG signals to provide mechanical help
A robotic system for rehabilitation using EMG signals to provide mechanical help includes EMG electrodes ( 6 ) sequentially connected in series, a DAS card ( 2 ) and a control portion ( 1 ), and further includes an actuator ( 3 ) connected to the DAS card ( 2 ) and an additional moment providing portion ( 4 ) connected to the actuator ( 3 ). The EMG electrodes sense EMG signals corresponding to the muscle of suffering joint, and input the sensed EMG signals to the control portion ( 1 ) through the DAS card ( 2 ). The control portion ( 1 ) uses the input EMG signals and a constant moment set as desired to calculate an additional moment to be applied to the suffering joint, and additional moment providing portion ( 4 ) is controlled to apply the corresponding additional moment to the suffering joint through the DAS card ( 2 ) and the actuator ( 3 ).
1. A robotic system for rehabilitation using electromyographic (EMG) signals to provide a mechanical help, comprising:
an EMG electrode;
a data acquisition card;
a control unit connecting to said EMG electrode and said data acquisition card in series;
a driver connecting to said data acquisition card;
an additional torque providing unit connecting to said driver,
wherein the EMG signals from the muscle corresponding to affected joints are detected by said EMG electrode, and inputted into said control unit via said data acquisition card; and
based on the inputted EMG signals and a preset constant torque required for the mechanical help, an additional torque to the affected joints is calculated by said control unit and further is provided via said data acquisition card to said driver;
said driver controls said additional torque providing unit to provide said additional torque for assisting the affected joints;
wherein a normalized EMG signal (NEMG j ) is calculated by said control unit under the following equation (1):
NEMG
j
=
w
j
-
w
r
w
mvc
-
w
r
(
1
)
wherein, w j is an amplitude of rectified and filtered EMG signals created by the current acting of the affected joints' muscle, w r is an amplitude rectified and filtered EMG signals created by the affected joints' muscle at rest, w mvc is the rectified and filtered maximum amplitude of EMG signals created during maximal voluntary contraction of the affected joints' muscle;
said additional torque T m is calculated by said control unit under the following equation (2):
T m =K 1 ×NEMG j −K 2 ×NEMG i +T 0 (2)
wherein, NEMG j is normalized EMG signal of an agonistic muscle of the affected joints' muscle, NEMG i is normalized EMG signal of an antagonistic muscle of the affected joints' muscle, K 1 is a weighting coefficient of the agonistic muscle, K 2 is a weighting coefficient of the antagonistic muscle, and T 0 is an additional constant torque that is provided according to requirement.
2. The system according to claim 1 , further comprising:
an amplifying and filtering circuit for rectifying and amplifying the EMG signals in full-wave, filtering with a moving window, and inputting into said data acquisition card.
3. The system according to claim 1 , further comprising:
an angle sensor fixed on said additional torque providing unit and connected to said data acquisition card for measuring the affected joints' angle and inputting said angle into said control unit via said data acquisition card; and
a display unit connected to said control unit for displaying information of the affected joints' angles to patient.
4. The system according to claim 3 , wherein said display unit further displays an objective angle to patient for displaying the affected joints' angle together with the objective angle.
5. The system according to claim 1 , further comprising:
a mechanical arm fixed on said additional torque providing unit for providing the additional torque; and
a motor connected to said mechanical arm for rotating the mechanical arm.
6. The system according to claim 5 , further comprising:
a torque sensor fixed on said additional torque providing unit and electrically connected to said data acquisition card for detecting an interactive torque between said mechanical arm and said motor;
a first coupling movably connecting said mechanical arm with one end of said torque sensor; and
a second coupling connecting said motor with another end of said torque sensor,
wherein said torque sensor, said first coupling, said second coupling, said mechanical arm and said motor all share a same axis.
7. An initiative rehabilitation training method for providing mechanical help using electromyographic (EMG) signals acquired from patients' affected side, such as elbows, wrists, knees, ankles and shoulders, said method comprising the steps of:
detecting the EMG signals from the muscle corresponding to affected joints by an EMG electrode;
inputting the EMG signals into a control unit via a data acquisition card;
calculating an additional torque to the affected joints based on the inputted EMG signals and a preset constant torque required for mechanical help by the control unit and further providing said additional torque to a driver via said data acquisition card;
controlling an additional torque providing unit to provide said additional torque for assisting the affected joints by said driver;
wherein a normalized EMG signal (NEMG j ) is calculated by said control unit under the following equation (1):
NEMG
j
=
w
j
-
w
r
w
mvc
-
w
r
(
1
)
wherein, w j is an amplitude of rectified and filtered EMG signals created by the current acting of the affected joints' muscle, w r is an amplitude rectified and filtered EMG signals created by the affected joints' muscle at rest, w mvc is the rectified and filtered maximum amplitude of EMG signals created during maximal voluntary contraction of the affected joints' muscle;
said additional torque T m in is calculated by said control unit under the following equation (2):
T m =K 1 ×NEMG j −K 2 ×NEMG i +T 0 (2)
wherein, NEMG j is normalized EMG signal of an agonistic muscle of the affected joints' muscle, NEMG i is normalized EMG signal of an antagonistic muscle of the affected joints' muscle, K 1 is a weighting coefficient of the agonistic muscle, K 2 is a weighting coefficient of the antagonistic muscle, and T 0 is an additional constant torque that is provided according to requirement.
8. The method according to claim 7 , further comprising the steps of:
rectifying and amplifying the EMG signals in full-wave, filtering with a moving window, and inputting into said data acquisition card by a amplifying and filtering circuit.
9. The method according to claim 7 , further comprising the step of:
measuring the affected joints angle by an angle sensor, and inputting said angle into said control unit via said data acquisition card; and
displaying information of said affected joints' angles to patient on a display unit controlled by said control unit.
10. The method according to claim 9 ,
wherein said display unit further displays an objective angle to patient for displaying the affected joints' angle together with the objective angle.