Robot manipulator with modular torque controlled link
An example torque controlled actuator includes a frame, and one or more timing belt stages coupled in serial on the frame. The timing belt stages include an input stage for coupling to a motor and an output stage for coupling to a load, and the timing belt stages couple rotation of the motor to rotation of an output of the output stage. The torque controlled actuator also includes one or more belt idlers coupled to the frame that contact a timing belt of the output stage, and a strain gauge coupled to the frame to determine a tension of the timing belt of the output stage based on force applied by the timing belt of the output stage to the one or more belt idlers.
1. An actuator system comprising:
multiple torque controlled actuators arranged side-by-side, wherein a given torque controlled actuator of the multiple torque controlled actuators comprises one or more timing belt stages coupled in serial including an input stage for coupling to a motor and an output stage for coupling to a load, wherein the one or more timing belt stages couple rotation of the motor to rotation of an output of the output stage;
a common frame to couple the multiple torque controlled actuators in the side-by-side arrangement; and
a differential coupled to outputs of the multiple torque controlled actuators to create a multiple degree of freedom (DOF) actuated joint.
2. The actuator system of claim 1 , wherein the given torque controlled actuator further comprises:
one or more belt idlers to contact a timing belt of the output stage; and
a strain gauge coupled to determine a tension of the timing belt of the output stage based on force applied by the timing belt of the output stage to the one or more belt idlers.
3. The actuator system of claim 1 , wherein the common frame is configured as an exoskeleton structure, and the multiple torque controlled actuators are positioned inside the exoskeleton structure.
4. The actuator system of claim 1 , wherein the multiple torque controlled actuators comprise input hubs, and wherein the differential is configured such that rotation in a same direction at the input hubs yields output motion along a first DOF and rotation in an opposite direction at the input hubs yields output motion along a second DOF.
5. The actuator system of claim 1 , wherein the differential is configured to provide an output torque having a sum of torque outputs from the multiple torque controlled actuators along a first DOF and a difference of the torque outputs from the multiple torque controlled actuators along a second DOF.
6. The actuator system of claim 1 , wherein the differential is configured in a pitch-yaw configuration or in a pitch-roll configuration.
7. The actuator system of claim 1 , further comprising a motor for each of the one or more timing belt stages to drive each of the one or more timing belt stages.
8. The actuator system of claim 1 , wherein the multiple torque controlled actuators arranged side-by-side comprise a link, and the actuator system further comprises:
multiple links, wherein the link is one of the multiple links, coupled end-to-end via respective interfaces to form a robot manipulator.
9. The actuator system of claim 8 , further comprising:
multiple link interfaces, wherein the respective interfaces are some of the multiple link interface, to couple the multiple links in serial.
10. The actuator system of claim 8 , further comprising a control bus and power cables routed to the multiple links through a shaft of the interface for each of the multiple links.
11. The actuator system of claim 8 , wherein a respective link is a two DOF modular link.
12. The actuator system of claim 8 , wherein the multiple links comprise three modular links arranged in serial, and the interfaces provide a seven DOF robot manipulator.
13. The actuator system of claim 8 , further comprising a base link to couple one of the one or more interfaces to a base frame, and wherein the multiple links are arranged in serial such that the robot manipulator includes the base link as a shoulder pan, a trunk link as a shoulder pitch and roll, a bicep link as an elbow pitch and forearm roll, and a forearm link as a wrist pitch, roll, or yaw.
14. The actuator system of claim 1 , wherein the one or more timing belt stages include:
a stage input;
an output hub; and
a timing belt wrapped around the stage input and the output hub.
15. The actuator system of claim 14 , wherein the stage input and the output hub comprise pulleys mounted on rolling bearings.
16. The actuator system of claim 14 , further comprising an encoder coupled to the common frame to determine an angular position of the output hub.
17. The actuator system of claim 1 , further comprising:
one or more belt idlers that contact a timing belt of the output stage.
18. The actuator system of claim 17 , further comprising:
a strain gauge to determine a tension of the timing belt of the output stage based on force applied by the timing belt of the output stage to the one or more belt idlers.
19. The actuator system of claim 18 , further comprising:
a control bus and one or more processors, wherein the strain gauge outputs the tension of the timing belt of the output stage to the control bus, and the one or more processors are coupled to the control bus for determining output torque of the torque controlled actuator based on the tension of the timing belt of the output stage.
20. The actuator system of claim 1 , wherein a given timing belt stage provides a reduction of motor input and increases torque output.