Multi-Priority Impedance Control for Robotic Manipulators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current robotic manipulators lack the ability to effectively control impedance at multiple points with prioritization, limiting their ability to manage forces and positions in complex assembly tasks, as they primarily operate with stiff, high-impedance systems that do not account for varying environmental forces.
Innovation Solution
A system and method for providing multiple priority impedance control in robotic manipulators, allowing for simultaneous realization of Cartesian and joint space impedance objectives with prioritization, using feedback from force sensors and control laws that adjust actuator torques to achieve desired impedance levels while minimizing errors in acceleration and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a robot manipulator uses stiff, high-impedance position control systems, then positioning accuracy is improved, but the ability to control forces and adapt to environmental forces deteriorates
Solution Approach 1:
The system dynamically adjusts impedance characteristics by switching between position control mode (for accuracy) and force control mode (for adaptability). The control system modulates the impedance of the manipulator based on task requirements, enabling transition from stiff high-impedance behavior to compliant low-impedance behavior as needed
Solution Approach 2:
The system changes the impedance parameters (stiffness, damping) of the manipulator based on operational context. By modifying these parameters dynamically, the system achieves both high positioning accuracy when needed and good force control capability when required, resolving the contradiction between these two opposing requirements
2Device complexity
If multiple impedance objectives are controlled simultaneously without prioritization, then system complexity increases, but control precision deteriorates due to conflicting objectives
Solution Approach 1:
The control system segments multiple impedance objectives into hierarchical priority levels. Each objective is assigned a priority rank, and the control system processes them in order from highest to lowest priority. This segmentation allows the system to manage multiple objectives without them conflicting, maintaining control precision while organizing complexity in a structured manner
Solution Approach 2:
The priority-based control architecture acts as an intermediary layer between multiple impedance objectives and the actuator torque generation. This intermediary processes and reconciles conflicting objectives by applying prioritization rules, ensuring that higher-priority objectives are satisfied first while still allowing lower-priority objectives to be accommodated when possible
3Force
If Cartesian space impedance control is prioritized over joint space impedance control, then end-effector force control is improved, but joint configuration flexibility deteriorates
Solution Approach 1:
The system operates in multiple dimensional spaces simultaneously - Cartesian space for end-effector force control and joint space for configuration flexibility. By maintaining control objectives in both spatial dimensions and prioritizing them appropriately, the system achieves precise end-effector force control while preserving the ability to adjust joint configurations through the lower-priority joint space objectives
Data Source
AI summary
A system and method for providing multiple priority impedance control for a robot manipulator where impedance laws are realized simultaneously and with a given order of priority. The method includes a control scheme for realizing a Cartesian space impedance objective as a first priority while also realizing a joint space impedance objective as a second priority. The method also includes a control scheme for realizing two Cartesian space impedance objectives with different levels of priority. The method includes instances of the control schemes that use feedback from force sensors mounted at an end-effector and other instances of the control schemes that do not use this feedback.