Instrumented prosthetic foot
An instrumented prosthetic foot for use with an actuated leg prosthesis controlled by a controller, the instrumented prosthetic foot comprising a connector to connect the instrumented prosthetic foot to the leg prosthesis, an ankle structure connected to the connector, a ground engaging member connected to the ankle, at least one sensor for detecting changes in weight distribution along the foot, and an interface for transmitting signals from the sensor to the controller.
1. An instrumented prosthetic foot, the instrumented prosthetic foot comprising:
an elongated foot plate having a top and a bottom part;
an ankle structure pivotally connected to the elongated foot plate top part;
a connector to operably connect the instrumented prosthetic foot to a user;
a first rotational sensor positioned on the ankle structure about its pivot axis with the elongated foot plate, the first sensor being configured to measure the rotation of the ankle structure about its pivot axis; and
a second sensor interposed between the connector and the ankle structure, the second sensor being configured to measure the pressure force on the connector;
wherein the ankle structure and second sensor are connected between the connector and the top part.
2. An instrumented prosthetic foot according to claim 1 , wherein: the first sensor is an optical encoder.
3. An instrumented prosthetic foot according to claim 1 , wherein: the second sensor is a load cell.
4. An instrumented prosthetic foot according to claim 1 , wherein: the first and second sensor are configured to transmit signals to a controller of an actuated leg prosthesis using a wired connection.
5. An instrumented prosthetic foot according to claim 1 , wherein: the first and second sensor are configured to transmit signals to a controller of an actuated leg prosthesis using a wireless connection.
6. An instrumented prosthetic foot according to claim 1 , wherein: the first and second sensor are configured to transmit signals to a controller of an actuated leg prosthesis using an optical interface.
7. An instrumented prosthetic foot according to claim 1 , wherein: the connector removably connects the instrumented prosthetic foot to a leg prosthesis.
8. An instrumented prosthetic foot system, the system comprising:
an instrumented foot comprising an elongated foot plate having a top and a bottom part and a toe and a heel region;
an ankle structure pivotally connected to the elongated foot plate top part;
a connector to operably connect the instrumented prosthetic foot to a user;
a first rotational sensor positioned on the ankle structure about its pivot axis with the elongated foot plate configured to measure the rotation of the ankle structure about its pivot axis;
a second sensor interposed between the connector and the ankle structure configured to measure the pressure force on the connector; and
a controller configured to receive data relative to the position of the ankle structure about its pivot axis from the first sensor and to the pressure force on the connector from the second sensor, and configured to determine the torque between the elongated foot plate top part and the connector using the received data.
9. An instrumented prosthetic foot system according to claim 8 , wherein: the controller further determines the pressure force on the toe and the heel region of the elongated foot plate using the received data.
10. An instrumented prosthetic foot system according to claim 8 , wherein the controller determines the torque via the following equation:
M=R ANKLE R CONST ;
where
M is the torque;
R ANKLE is the data relative to rotation of the ankle structure about its pivot axis measured by the first sensor;
R CONST is a constant associated with the rotation of the ankle about its axis.
11. An instrumented prosthetic foot system according to claim 10 , wherein the controller further determines the pressure force on the toe and the heel region of the elongated foot plate via the following equation:
F TOE =( M+F S2 L HEEL )/( L HEEL +L TOE );
F HEEL =(− M+F S2 L TOE )/( L •HEEL +L TOE );
where
F S2 is the pressure force measured by the second sensor;
F TOE is the pressure force on the toe region of the elongated foot plate;
F HEEL is the pressure force on the heel region of the elongated foot plate;
L TOE is the distance between a center of the connector and a center of the toe region; and
L •HEEL is the distance between the center of the connector and a center of the heel region.
12. An instrumented prosthetic foot system according to claim 8 , wherein: the first and second sensor transmit signals to the controller using a wired connection.
13. An instrumented prosthetic foot system according to claim 8 , wherein: the first and second sensor transmit signals to the controller using a wireless connection.
14. An instrumented prosthetic foot system according to claim 8 , wherein: the first and second sensor transmit signals to the controller using an optical interface.
15. An instrumented prosthetic foot system according to claim 8 , wherein: the connector removably connects the instrumented prosthetic foot to a leg prosthesis.
16. An instrumented prosthetic foot system according to claim 8 , wherein: the first sensor is an optical encoder.
17. An instrumented prosthetic foot system according to claim 8 , wherein: the second sensor is a load cell.
18. An instrumented prosthetic foot according to claim 1 , wherein: the second sensor is configured to measure an axial force on the connector.
19. An instrumented prosthetic foot system according to claim 8 , wherein: the second sensor is configured to measure an axial force on the connector.