Controller Automatic Force Gain Calculation
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Solution Overview
Problem
The existing methods for setting and adjusting the force control gain in industrial robots are time-consuming, require skill, and often result in contradictions where components must be inserted with poor force control performance, especially in multi-axis systems, and can lead to instability or damage if not properly set.
Innovation Solution
A controller that calculates the force control gain using the time constant of the position control circuit and the rigidity value of the controlled object, allowing for automatic and accurate adjustment without the need for repeated trials, and enabling flexible adaptation to changes in robot or machine configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the force control gain is manually adjusted by gradually increasing it from a low value, then the amount of overshoot can be controlled within acceptable limits, but the adjustment process becomes time-consuming and requires skilled operators
Solution Approach 1:
The system performs self-diagnosis and automatic adjustment of the force control gain without requiring external operators. The determination unit automatically determines the upper limit value of the force control gain based on detected work environment parameters, eliminating the need for manual trial-and-error adjustment and making the system self-sufficient
Solution Approach 2:
The system changes the force control gain parameter automatically based on detected work environment parameters. By detecting parameters such as mass and inertia of the hand tool, spring constants, and robot posture, the system dynamically adjusts the force control gain to match the actual working conditions, resolving the contradiction between stability and adjustment time
2Ease of operation
If the force control gain is set automatically by gradually increasing it under program control, then the adjustment can be performed without operator skill, but the number of tries increases and damage risk remains if the initial value is too high
Solution Approach 1:
The system performs preliminary detection of work environment parameters before setting the force control gain. By detecting parameters such as mass and inertia of the hand tool, spring constants, and robot posture in advance, the system determines the upper limit value of the force control gain before actual operation begins, preventing potential damage from inappropriate gain values
Solution Approach 2:
The system uses feedback from detected work environment parameters to determine the appropriate force control gain. The determination unit continuously monitors parameters during operation and adjusts the force control gain accordingly, ensuring both ease of operation and system safety through closed-loop control
3Ease of manufacture
If the force control gain is adjusted in environments without physical contact with the workpiece, then the initial setup can be performed without contact, but the force control becomes unstable when contact occurs in actual operation
Solution Approach 1:
The system changes the force control gain parameter based on contact status detection. By detecting whether the robot is in contact with the workpiece and adjusting the force control gain accordingly, the system maintains stability during contact while allowing convenient initial setup without contact
Solution Approach 2:
The system dynamically adjusts the force control gain based on real-time detection of contact conditions. The gain value is not fixed but changes dynamically according to whether contact occurs, allowing the system to adapt to different operational phases and maintain stability during actual contact operations
4Manufacturing precision
If the force control gain is set for each of the six axes in a multi-axis robot, then precise force control can be achieved in all directions, but a great deal of time is required to accomplish the gain setting
Solution Approach 1:
The system merges the determination of force control gain for multiple axes into a unified process. By detecting work environment parameters once and determining upper limit values for all six axes simultaneously based on these parameters, the system achieves precise force control in all directions without requiring separate time-consuming adjustment for each axis
Data Source
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AI summary
A controller, for force-controlling a drive source (14) of a controlled object (1), having a position control circuit (8) inside a force control circuit (7) in order to define a relative position of the controlled object (1) to a workpiece (25), and a contact force occurred between the workpiece (25) and the controlled object (1), the controller including a first data acquiring portion (11) for acquiring a time constant of the position control circuit (8) based on a position command value to the drive source (14) and an actual position value, during operations of the controlled object (1); a second data acquiring portion (12) for acquiring a rigidity value for the controlled object (1) and the workpiece (25) based on a force data obtained when the controlled object (1) is brought into contact with the workpiece (25); and an automatic gain calculating portion (10) for calculating a force control gain of the force control circuit (7) from the time constant of the position control circuit (8) acquired by the first data acquiring portion (11) and the rigidity value acquired by the second data acquiring portion (12), under conditions where a time constant of the force control circuit (8) is larger than the time constant of the position control circuit (8).