Collaborative Robot Arm Speed Control by Joint Angle Threshold
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Solution Overview
Problem
Conventional monitoring devices for robots that work collaboratively with humans are not optimal as they fail to effectively balance the robot's workability and operator safety due to varying effects of the robotic arm's position and posture, leading to a trade-off between faster operation and safety.
Innovation Solution
A control device for robotic arms that includes an angle calculating module to monitor joint angles and control motor speed, stopping operations when the angle is below a certain threshold to prevent collisions and ensure operator safety, while allowing faster operation when the angle is above the threshold, along with an external force detecting module to further enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the robot operates faster to improve workability, then productivity increases, but operator safety deteriorates due to higher collision risk
Solution Approach 1:
The patent applies dynamics by making the robot's operating speed variable rather than constant. The control device dynamically adjusts the motor speed based on the real-time joint angle of the robotic arm. When the joint angle indicates a potential pinching hazard (below threshold), the speed is reduced to a safe level; when the angle is safe (above threshold), the speed can be increased to maintain productivity. This dynamic speed adjustment resolves the contradiction between workability and safety.
Solution Approach 2:
The patent changes the operational parameters (motor speed) based on the joint angle parameter. By monitoring the joint angle and comparing it to a threshold value, the system adjusts the motor speed parameter accordingly. This parameter change strategy allows the robot to operate at high speed when safe and slow down when potential hazards are detected, thus balancing productivity and operator safety.
2Object-affected harmful factors
If the robot operates slower to ensure operator safety, then safety improves, but workability deteriorates due to reduced productivity
Solution Approach 1:
The system dynamically adjusts operating speed based on real-time joint angle monitoring. Instead of maintaining a constantly slow speed, the robot operates at high speed when the joint angle is above the threshold (no pinching hazard), and only reduces speed when the angle falls below the threshold (potential hazard). This dynamic approach ensures safety without unnecessarily sacrificing productivity during safe operating conditions.
Solution Approach 2:
The control device changes the motor speed parameter based on the joint angle parameter. When the joint angle exceeds the threshold value, the system allows higher motor speeds to maintain productivity. When the joint angle drops below the threshold, the motor speed is reduced to ensure safety. This conditional parameter change resolves the contradiction by allowing high productivity during safe conditions while maintaining safety when hazards are present.
3Device complexity
If conventional monitoring devices are used without joint angle consideration, then device complexity remains low, but measurement precision deteriorates in detecting actual pinching hazards
Solution Approach 1:
The patent replaces complex external monitoring systems with a simpler solution that utilizes the robot's existing joint angle sensors and control system. Instead of adding sophisticated external cameras or sensors to detect pinching hazards, the system substitutes by calculating the pinching risk directly from the joint angle parameter, which is already available in the robot's control system. This substitution maintains low device complexity while significantly improving hazard detection precision.
Solution Approach 2:
The robot's own control system provides the hazard detection function by utilizing its existing joint angle measurement capabilities. The control device calculates the pinching hazard level based on the joint angle data that the robot already collects for its normal operation. This self-service approach eliminates the need for additional complex monitoring equipment while achieving accurate hazard detection through intelligent processing of existing data.
Data Source
AI summary
A control device for a robot is configured to control operation of a robotic arm having a plurality of links coupled to each other through a rotation axis, and a motor for drive provided to the rotation axis. The control device includes an angle calculating module configured to calculate an angle formed by the two links adjacent to each other through the rotation axis, and an angle monitoring module configured to monitor whether the angle calculated by the angle calculating module is a given angle or below.