Systems and methods for tendon-driven robotic mechanisms
Systems and methods for an actuation system including a plurality of single actuation units for modular control of a tendon-driven robotic mechanism are disclosed.
1. An actuation unit comprising:
a motor having an output shaft;
a ratcheting mechanism in operative engagement with the output shaft of the motor;
a pair of tendons having one end secured to the ratchet mechanism,
a cantilevered feature in operative engagement with the pair of tendons for enabling direct measurement of any tension being applied to the pair of tendons by measuring the degree of deflection of the cantilevered feature;
wherein the ratcheting mechanism comprises a first split output shaft defining a first set of teeth engaged to a second split output shaft having a second set of teeth;
wherein engagement between the first set of teeth with the second set of teeth allows rotational movement of the ratcheting mechanism in a first rotational direction and prevents rotational movement of the ratcheting mechanism in an opposite second rotational direction; and
a first pair of pulleys engaged to the pair of tendons, wherein each pulley of the first pair of pulleys is attached to the cantilevered feature such that any tension applied to the pair of tendons causes a deflection of the cantilevered feature.
2. The actuation unit of claim 1 , further comprising:
one or more strain gauges for measuring the degree of deflection of the cantilevered feature.
3. The actuation unit of claim 1 , further comprising:
a half Wheatstone bridge circuit in operative association with the cantilevered feature for measuring the degree of deflection of the cantilevered feature.
4. The actuation unit of claim 1 , wherein the first pair of pulleys comprises a first pulley and a second pulley;
wherein the pair of tendons comprises a flexor tendon and an extensor tendon; and
wherein the first pulley is engaged to the flexor tendon and the second pulley is engaged to the extensor tendon.
5. The actuation unit of claim 4 , further comprising:
a second pair of pulleys engaged to the pair of tendons, wherein the second pair of pulleys comprises a first pulley engaged to a first spring and a second pulley engaged to a second spring for maintaining a degree of tension to the pair of tendons.
6. The actuation unit of claim 5 , further comprising:
a third pair of pulleys engaged with the pair of tendons for redirecting the pair of tendons from a first orientation to a second orientation, wherein the pair of tendons comprise a first tendon in parallel relation to a second tendon.
7. The actuation unit of claim 1 , further comprising:
a processor in operative communication with the actuation unit for controlling the operation of the robotic mechanism.
8. The actuation unit of claim 1 , wherein the cantilevered feature comprises a cantilevered member having a distal free end and a proximal end, wherein the proximal end forms a part of a base plate in which the motor is mounted thereon.
9. The actuation unit of claim 1 , wherein the pair of tendons comprises a cable, a wire, or a thread.
10. The actuation unit of claim 9 , wherein the ratcheting mechanism comprises a first split output shaft defining a first set of teeth engaged to a second split output shaft having a second set of teeth; and
wherein engagement between the first set of teeth with the second set of teeth allows rotational movement of the ratcheting mechanism in a first rotational direction and prevents rotational movement of the ratcheting mechanism in an opposite second rotational direction.
11. An actuation unit comprising:
a motor having an output shaft;
a ratcheting mechanism in operative engagement with the output shaft of the motor;
a pair of tendons having one end secured to the ratchet mechanism;
a cantilevered feature in operative engagement with the pair of tendons for enabling direct measurement of any tension being applied to the pair of tendons by measuring the degree of deflection of the cantilevered feature; and
a first pair of pulleys engaged to the pair of tendons, wherein each pulley of the first pair of pulleys is attached to the cantilevered feature such that any tension applied to the pair of tendons causes a deflection of the cantilevered feature.
12. The actuation unit of claim 11 , wherein the first pair of pulleys comprises a first pulley and a second pulley;
wherein the pair of tendons comprises a flexor tendon and an extensor tendon; and
wherein the first pulley is engaged to the flexor tendon and the second pulley is engaged to the extensor tendon.
13. The actuation unit of claim 12 , further comprising:
a second pair of pulleys engaged to the pair of tendons, wherein the second pair of pulleys comprises a first pulley engaged to a first spring and a second pulley engaged to a second spring for maintaining a degree of tension to the pair of tendons.
14. The actuation unit of claim 13 , further comprising:
a third pair of pulleys engaged with the pair of tendons for redirecting the pair of tendons from a first orientation to a second orientation, wherein the pair of tendons comprise a first tendon in parallel relation to a second tendon.
15. The actuation unit of claim 11 , further comprising:
a processor in operative communication with the actuation unit for controlling the operation of the robotic mechanism.
16. The actuation unit of claim 11 , wherein the cantilevered feature comprises a cantilevered member having a distal free end and a proximal end, wherein the proximal end forms a part of a base plate in which the motor is mounted thereon.
17. The actuation unit of claim 11 , wherein the pair of tendons comprises a cable, a wire, or a thread.