Estimating joint friction and tracking error of a robotics end effector
AssigneeVerb Surgical Inc.
InventorAlireza Hariri
Life of this patent
Estimating the term…
Abstract
A computerized method for estimating joint friction in a joint of a robotic wrist of an end effector. Sensor measurements of force or torque in a transmission that mechanically couples a robotic wrist to an actuator, are produced. Joint friction in a joint of the robotic wrist that is driven by the actuator is computed by applying the sensor measurements of force or torque to a closed form mathematical expression that relates transmission force or torque variables to a joint friction variable. A tracking error of the end effector is also computed, using a closed form mathematical expression that relates the joint friction variable to the tracking error. Other aspects are also described and claimed.
Claims20
A computerized method for controlling movement of an end effector having a robotic wrist, the method comprising the following operations performed by a computer system:
- producing sensor measurements of force or torque in a transmission that mechanically couples the robotic wrist to an actuator, wherein the sensor measurements are cable force measurements;
- estimating joint friction in a joint of the robotic wrist, based on the cable force measurements, using a first closed form mathematical expression that relates the cable force measurements to a joint friction variable;
- and
- performing control tasks to control movement of the end effector, by using the estimated joint friction to compensate for tracking error of the end effector.
An article of manufacture comprising a computer-readable storage medium having stored therein instructions that configure a processor to:
- produce sensor measurements of force or torque in a transmission, wherein the transmission mechanically couples a robotic wrist of an end effector to an actuator so the actuator can drive a joint of the robotic wrist and the sensor measurements are cable force measurements;
- estimate joint friction in the joint of the robotic wrist based on the cable force measurements, using a first closed form mathematical expression that relates the cable force measurements to a joint friction variable;
- and
- perform control tasks to control movement of the end effector, by using the estimated joint friction to compensate for tracking error of the end effector.
The article of manufacture of 19 wherein the computer-readable storage medium has stored therein further instructions that configure the processor to compute the tracking error using a second closed form mathematical expression that relates the joint friction variable to the tracking error.
Dependencies are inferred from the claim text.