Robot Controller Pseudo Inverse Matrix Determination

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Solution Overview

Problem

The existing methods for calculating the pseudo inverse matrix in robot controllers often result in discontinuous changes in manipulation amounts due to frequent adjustments of the adjustment parameter k, leading to impaired motion smoothness or prolonged control cycles.

Innovation Solution

A robot controller that uses a weight coefficient matrix W and adjusts the adjustment parameter k based on the n-th root of the error between the determinant and a predetermined threshold, ensuring efficient and smooth determination of the pseudo inverse matrix within each control cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a fixed increment is used to determine the adjustment parameter k in an exploratory manner, then the determination process is simple, but the motion smoothness of the robot is impaired due to discontinuous changes in manipulation amount

Engineering Contradiction:
Improvesimplicity of determination processVSAvoidmotion smoothness
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent applies dynamics by making the increment of the adjustment parameter k variable rather than fixed. The increment is dynamically adjusted based on the current value of k and the determinant value, allowing the determination process to adapt to different stages of calculation. This dynamic adjustment ensures that k changes smoothly and continuously, preventing discontinuous jumps in manipulation amount while maintaining the exploratory determination approach.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of increment from a fixed constant to a variable that depends on the current state of calculation. Specifically, the increment is set as a function of the current adjustment parameter k and the determinant value, allowing the system to automatically adjust the step size during the exploratory process. This parameter change enables both simple operation and smooth motion by adapting the increment to the calculation context.

Inventive Principle:
Principle #35Parameter changes

2Speed

If a relatively large increment is used for the adjustment parameter k, then the determination process is fast, but the value of k changes frequently causing discontinuous changes in manipulation amount

Engineering Contradiction:
Improvedetermination speedVSAvoidcontinuity of manipulation amount
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The patent makes the increment dynamic by setting it as a function of the current adjustment parameter k and the determinant value. When k is small, the increment is larger to speed up the determination process. When k approaches the optimal value or the determinant becomes sufficiently large, the increment automatically decreases to ensure smooth convergence. This dynamic behavior allows fast determination while preventing frequent large changes in k that would cause discontinuous manipulation amounts.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by using the determinant value and current k value to adjust the increment for the next step. The system continuously monitors the determinant value and adjusts the increment accordingly - reducing the increment when the determinant is already sufficiently large or when k is close to the optimal value. This feedback mechanism ensures that the determination process remains fast while maintaining continuity in manipulation amount by preventing excessive changes in k.

Inventive Principle:
Principle #23Feedback

3Stability of the object's composition

If a relatively small increment is used for the adjustment parameter k, then the manipulation amount changes smoothly, but the control cycle duration is prolonged

Engineering Contradiction:
Improvesmoothness of manipulation amountVSAvoidcontrol cycle duration
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the increment variable rather than uniformly small. The increment starts larger when k is small, allowing rapid initial progress. As k increases and approaches the optimal value, the increment automatically decreases to ensure smooth convergence. This dynamic adjustment maintains manipulation amount smoothness while minimizing control cycle duration by avoiding unnecessarily small increments during early stages of determination.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the increment parameter from a fixed small value to a variable that adapts to the calculation progress. The increment is set as a function of current k and determinant value, allowing it to be large when appropriate (reducing control cycle time) and small when necessary (maintaining smoothness). This parameter change resolves the contradiction by enabling the system to use small increments only when needed for smooth convergence, rather than using small increments throughout the entire process.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS8670869B2Robot controller
Publication Date: 2014.03.11 HONDA MOTOR CO LTD
  • US8670869B2 patent drawing
  • US8670869B2 patent drawing
  • US8670869B2 patent drawing

AI summary

An element 22 which determines a manipulation amount for controlling a motion state of each joint 4 of a robot 1 calculates a pseudo inverse matrix A* used for calculating the manipulation amount, using a value of an adjustment parameter k determined so that an absolute value of a determinant DET is equal to or more than a predetermined threshold. Setting a provisional value of the adjustment parameter k by gradually increasing the provisional value from a predetermined initial value, calculating the determinant DET using the set provisional value, and determining whether the absolute value of the calculated determinant DET is equal to or more than the predetermined threshold is repeated, and the provisional value of the adjustment parameter k when the determination result is true is determined as the value of the adjustment parameter k used for the calculation of the pseudo inverse matrix A*.