Adjustable Servo Stiffness for Robot Control Stability
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Solution Overview
Problem
Existing robot control systems experience instability and oscillation due to hypersensitive control of driving sections like motors during force and position control, leading to unstable tool states.
Innovation Solution
A robot control apparatus that includes a control section for acquiring and stabilizing the driving position and operation force of a robot, and a changing section that adjusts the servo stiffness by combining first and second controls based on driving position and operation force, respectively, to suppress hypersensitive control and stabilize the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force control based on position control or velocity control is performed, then the pressing force of the tool can be controlled to a set value, but the driving section becomes hypersensitively controlled and the tool state becomes unstable with oscillation
Solution Approach 1:
The patent applies dynamics by making the servo stiffness adjustable rather than fixed. The control section dynamically changes the servo stiffness of the robot based on operational requirements, allowing the system to adapt between high stiffness for positioning accuracy and low stiffness for stable force control, thereby resolving the contradiction between force control precision and tool state stability
Solution Approach 2:
The patent implements parameter changes by modifying the servo stiffness parameter of the robot. The control section changes this parameter according to the operational phase: using higher stiffness during positioning and lower stiffness during force control operations. This parameter adjustment prevents hypersensitive control of the driving section while maintaining the ability to achieve set pressing forces
2Manufacturing precision
If high servo stiffness is used for precise position control, then position accuracy is improved, but the system becomes hypersensitive to tool state changes causing oscillation
Solution Approach 1:
The system dynamically adjusts servo stiffness based on the operational context. During positioning phases, high stiffness is applied to achieve precise position control. During force control phases, the stiffness is reduced to prevent hypersensitivity and oscillation. This dynamic adaptation allows the system to maintain both high position accuracy when needed and control stability during force interactions
Solution Approach 2:
The control section changes the servo stiffness parameter according to the operational requirements. By adjusting this parameter, the system can achieve high position accuracy when positioning is critical while preventing control instability and oscillation during force control operations, thus resolving the contradiction between manufacturing precision and reliability
Data Source
AI summary
In order to stabilize control of a driving section, a robot control apparatus includes a control section that acquires a driving position of the driving section that drives a robot and an operation force that is a force operating on the robot, and performs first control of the driving section based on the driving position and second control of the driving section based on the operation force; and a changing section that changes a size of servo stiffness of the robot that is realized by the control of the control section.