Robot Arm Speed Control for Dynamic Collision Avoidance

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Solution Overview

Problem

Existing cooperative work systems between robots and moving bodies, such as workers, face challenges in preventing collisions without increasing the distance between them, leading to reduced productivity due to unnecessary deceleration and emergency stops.

Innovation Solution

A robot control system with a detection unit using sensors to monitor the relative positional relationship with moving bodies, generating drive control signals to adjust the robot's speed and movement, allowing for safe operation without increasing the distance between the robot and the moving body, thereby preventing collisions and maintaining productivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a maximum region is secured for robot movement to ensure safety distance from moving bodies, then safety of the moving body is improved, but the robot's operational area is reduced and productivity decreases

Engineering Contradiction:
Improvesafety of moving bodyVSAvoidrobot operational area
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by making the robot entry prohibition region variable rather than fixed. The control unit dynamically adjusts the prohibition region based on real-time relative position and relative speed between the robot and moving body. When relative speed is high, the prohibition region expands; when relative speed is low or negative (moving away), the prohibition region contracts or disappears, allowing the robot to utilize the full operational area while maintaining safety

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of the prohibition region size based on relative speed. The control unit calculates relative speed from detection unit data and modifies the prohibition region parameters accordingly. This parameter change allows the system to maintain safety margins when needed while maximizing operational area when safety risks are low

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the robot decelerates based on distance between robot and worker, then collision prevention is improved, but unnecessary deceleration occurs even when worker does not move, reducing productivity

Engineering Contradiction:
Improvecollision preventionVSAvoidrobot speed maintenance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements feedback by continuously monitoring relative speed in addition to relative position. The detection unit provides real-time data on both position and speed, and the control unit uses this feedback to make intelligent decisions. Only when relative speed indicates approaching motion does the system activate deceleration or prohibition, eliminating unnecessary deceleration events and maintaining productivity while ensuring collision prevention

Inventive Principle:
Principle #23Feedback

3Reliability

If a fixed robot entry prohibition region is established to prevent collision, then safety is improved, but the robot cannot utilize the full operational area, reducing productivity

Engineering Contradiction:
Improvecollision preventionVSAvoidrobot movement freedom
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent transforms the fixed prohibition region into a dynamic one that adapts to real-time conditions. The control unit continuously calculates relative speed and adjusts the prohibition region boundaries accordingly. This dynamic adjustment allows the robot to move freely in areas where the moving body is stationary or moving away, while automatically restricting access only when necessary for safety

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3446837B1Robot control device, robot system, robot control method, and robot control program
Publication Date: 2023.06.07 OMRON CORP
  • EP3446837B1 patent drawingFigure 1
  • EP3446837B1 patent drawingFigure 2
  • EP3446837B1 patent drawingFigure 3

AI summary

Provided is a technology which secures safety of a moving body and prevents collision between a robot and the moving body. A detection unit (15B) detects a relative positional relationship between a robot arm (11) by a sensor (15) attached to the robot arm. A control unit (3B) generates a drive control signal of an actuator which causes the robot arm (11) to be able to move on the basis of a change in the relative positional relationship between the robot arm (11) and the moving body (2) detected by a detecting unit (15B). An output unit (3C) outputs the drive control signal generated by the control unit (3B) to the actuator. The control unit (3B) generates the drive control signal which changes a speed at which the robot arm (11) is able to move in accordance with the change in the relative positional relationship with the moving body (2).