Redundant underactuated robot with multi-mode control framework

Patent metadata

Field	Value
Publication number	US-2018229366-A1
Application number	US-201715429241-A
Country	US
Kind code	A1
Filing date	Feb 10, 2017
Priority date	Feb 10, 2017
Publication date	Aug 16, 2018
Grant date	—

Abstract

A robotic system includes a jointed mechanism, position sensors, and a controller. The mechanism has an end-effector, and further includes actively-controlled joints and passive joints that are redundant with the actively-controlled joints. The position sensors are operable for measuring joint positions of the passive joints. The controller is in communication with the position sensors, and is programmed to execute a method to selectively control the actively-controlled joints in response to the measured joint positions using force control and/or a modeled impedance of the robotic mechanism. Possible control modes in impedance control include an Autonomous Mode in which an operator does not physically interact with the end-effector and a Cooperative Control Mode in which the operator physically interacts with the end-effector.

First claim

What is claimed is:

1 . A robotic system comprising:
a jointed mechanism having a plurality of actively-controlled joints and a plurality of passive joints that are redundant with the actively-controlled joints; an end-effector connected to and distally disposed with respect to the passive joints; a plurality of position sensors operable for measuring joint positions of the passive joints; and a controller in communication with the position sensors, and programmed to selectively control the actively-controlled joints in response to the measured joint positions using a modeled impedance of the robotic mechanism in a plurality of control modes, including an Autonomous Mode in which an operator does not physically interact with the end-effector during operation of the robotic mechanism and a Cooperative Control Mode in which the operator physically interacts with the end-effector during operation of the robotic mechanism.

2 . The robotic system of claim 1 , wherein the controller is programmed to execute force control over the end-effector in one or both of the Autonomous Mode and the Cooperative Control Mode to thereby regulate a force applied by the end-effector.

3 . The robotic system of claim 2 , wherein the controller is configured to limit a static force applied by the end-effector.

4 . The robotic system of claim 1 , wherein the controller is configured to detect a contact with the robotic system when operating in the Autonomous Mode, and to automatically initiate a control action in response to the detected contact.

5 . The robotic system of claim 4 , wherein the control action is an automatic transition from the Autonomous Mode to the Cooperative Control Mode.

6 . The robotic system of claim 4 , wherein the controller is programmed to detect the contact based on a deviation of a measured joint motion from an expected joint motion.

7 . The robotic system of claim 1 , wherein the controller is programmed to control the jointed mechanism in the Autonomous Mode so that the end-effector does not exhibit under-damped oscillations.

8 . The robotic system of claim 1 , wherein the modeled impedance is modeled as a spring-mass-damper system having stiffness and damping parameters, and wherein the controller is programmed to control the jointed mechanism by manipulating at least one of the stiffness parameter and the damping parameter.

9 . A method for controlling a robotic system having a jointed mechanism that includes a plurality of actively-controlled joints, a plurality of passive joints that are redundant with the actively-controlled joints, and an end-effector connected to and positioned distally with respect to the passive joints, the method comprising:
measuring joint positions of the passive joints using a plurality of position sensors; transmitting the measured joint positions to a controller that is programmed with a modeled impedance of the robotic mechanism; and selectively controlling the actively-controlled joints in response to the measured joint positions in a plurality of control modes using the modeled impedance, the control modes including an Autonomous Mode in which an operator does not physically interact with the end-effector and a Cooperative Control Mode in which the operator physically interacts with the end-effector.

10 . The method of claim 9 , further comprising applying a regulated force to an object via the end-effector while operating in the Autonomous Mode or in the Cooperative Control Mode.

11 . The method of claim 9 , wherein controlling the jointed mechanism includes manipulating at least one of a stiffness parameter and a damping parameter of the modeled impedance.

12 . The method of claim 9 , further comprising detecting contact with the robotic system when operating in the Autonomous Mode, and automatically initiating a control action in response to the detected contact.

13 . The method of claim 12 , wherein automatically initiating the control action includes transitioning from the Autonomous Mode to the Cooperative Control Mode.

14 . The method of claim 12 , wherein detecting the contact is based on a deviation of a measured joint motion from an expected joint motion.

15 . The method of claim 9 , further comprising controlling the jointed mechanism via the controller when operating in the Autonomous Mode such that the end-effector does not exhibit under-damped oscillations.

16 . A robotic system comprising:
a jointed mechanism having a plurality of actively-controlled joints and a plurality of passive joints; an end-effector connected to and positioned distally with respect to the passive joints and configured to apply a regulated force to an object; a plurality of position sensors operable for measuring joint positions of the passive joints; and a controller in communication with the position sensors, and programmed to selectively control a position of the actively-controlled joints in response to the measured joint positions to thereby command application of the regulated force to the object via the end-effector.

17 . The robotic system of claim 16 , wherein the end-effector is configured for physical interaction with an operator, and the controller is programmed to execute a Cooperative Control Mode in which the operator physically interacts with the end-effector.

18 . The robotic system of claim 17 , wherein the controller is programmed to control the jointed mechanism in the Autonomous Mode so that the end-effector does not exhibit under-damped oscillations.

19 . The robotic system of claim 16 , wherein the controller is programmed to receive data during the work task, and to identify an occurrence of an error or a completion of the work task using the received data.

20 . The robotic system of claim 16 , wherein the data includes at least one of position data, force data, and vision data.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Abdallah Muhammad E
• Wells James W

Classifications

• B25J9/023

  Cartesian coordinate type · CPC title

• B25J9/0081

  with leader teach-in means · CPC title

• B25J13/088

  with position, velocity or acceleration sensors · CPC title

• B25J19/023

  including video camera means · CPC title

• G05B2219/39195

  Control, avoid oscillation, vibration due to low rigidity · CPC title