Robot Arm Angle Range Calculation for Joint Safety

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Solution Overview

Problem

Current methods lack a reliable way to determine the arm angle range of a robot arm's joints, which can lead to damage when the rotation range exceeds the limit, necessitating a method to calculate this range to prevent joint overload.

Innovation Solution

A method involving determining the pose at the tail end of the robot arm, constructing position matrices using DH parameters, and calculating the arm angle feasible region to identify the safe rotation range, accounting for primary and secondary position joints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the joint rotation range is extended to increase robot arm flexibility, then the robot arm can achieve more positions and orientations, but the joints may exceed their rotation limits and get damaged

Engineering Contradiction:

Improverobot arm flexibilityVSAvoidjoint safety

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent calculates the arm angle range in advance before actual robot operation. By determining the feasible region of arm angles that satisfy all joint rotation limits beforehand, the system establishes safe operation boundaries that prevent joints from exceeding their limits during motion execution.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent transforms the joint rotation limit constraints into arm angle range constraints through mathematical transformation. By changing the parameter representation from joint angles to arm angles and using position matrices to describe the relationship, the system identifies the feasible arm angle range that ensures all joints remain within their rotation limits.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the arm angle range is calculated to prevent joint damage, then joint safety is improved, but the calculation complexity increases due to multiple position matrices and joint constraints

Engineering Contradiction:

Improvejoint safetyVSAvoidcalculation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the robot arm into multiple segments (links) and describes each segment's position and orientation using separate position matrices. By segmenting the kinematic chain and establishing position matrices for each link, the system systematically handles the complex relationships between multiple joints and derives the arm angle range through step-by-step matrix operations.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11458619B2Method for controlling the motion of a robot arm, computing device and robot

Publication Date: 2022.10.04 CHONGQING XINGJIE SHUXING TECHNOLOGY PARTNERSHIP ENTERPRISE (LLP)

AI summary

A method for calculating an arm angle range of a robot arm includes: determining a pose at an tail end position of the robot arm; judging whether an angle of an elbow joint is within a limit thereof when an arm angle is 180 degrees; if yes, constructing a first position matrix characterizing the elbow joint by using the pose and the arm angle; constructing a second position matrix of the elbow joint by using DH parameters of other joints of the robot arm; calculating, according to the first position matrix and the second position matrix, a first arm angle feasible region satisfying a limit of a position joint; judging whether the robot arm has a secondary position joint; and intersecting with the calculated first arm angle feasible region to obtain an arm angle range if no secondary position joint is present at the robot arm.