Robot Arm Collision Detection Corrected by Gas Spring Pressure
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Solution Overview
Problem
Existing robot collision detection methods based on servomotor torque calculations can lead to false positives due to gas leakage in gas springs, which affects the accuracy of collision detection.
Innovation Solution
A robot with a gas spring balancer and an internal-pressure detecting unit that calculates an estimated disturbance value by comparing the torque command and actual torque of the servomotor, and corrects this value based on detected cylinder internal pressure to accurately determine collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If gas spring is used as a balancer for the arm, then the robot size and weight are reduced, but false collision detection occurs due to gas leakage
Solution Approach 1:
The patent implements a feedback mechanism by detecting the cylinder internal pressure of the gas spring and using this information to correct the estimated disturbance value in collision detection. The control device continuously monitors pressure changes and adjusts the disturbance calculation accordingly, creating a closed-loop system that compensates for gas leakage effects and maintains accurate collision detection despite the presence of the gas spring.
2Reliability
If collision detection is performed based on servomotor torque difference, then collision can be detected, but false positives occur when gas spring pressure changes
Solution Approach 1:
The patent introduces an intermediary measurement - the cylinder internal pressure detection - that serves as a mediator between the gas spring state and the collision detection calculation. This intermediate pressure measurement allows the system to distinguish between torque changes caused by gas leakage versus those caused by actual collisions, thereby improving measurement precision without sacrificing collision detection capability.
3Device complexity
If gas spring is used instead of coil spring, then device complexity is reduced, but torque calculation accuracy deteriorates due to pressure loss
Solution Approach 1:
The patent replaces the mechanical assumption of constant gas spring torque with a pressure-based measurement system. Instead of relying on fixed mechanical properties that degrade over time due to leakage, the system substitutes a pressure sensor and electronic correction mechanism that actively tracks and compensates for pressure changes, maintaining torque calculation precision despite the simpler gas spring structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents false collision detection and ensures accurate collision detection by accounting for changes in cylinder internal pressure, thereby improving the reliability of collision detection in robots.
Implementation Method 1
a gas spring that functions as a balancer for the arm of the robot body
Implementation Method 2
an internal-pressure detecting unit that detects a cylinder internal pressure of the gas spring
Data Source
AI summary
Provided is a robot including: a robot body that is provided with at least one arm; a gas spring that functions as a balancer for the arm of the robot body; an internal-pressure detecting unit that detects a cylinder internal pressure of the gas spring; and a control device that controls the robot body. The control device calculates, as an estimated disturbance value, the difference between a torque command value for a servomotor that drives the arm and a torque of the servomotor that is required to actually operate the arm, determines that the robot body has had a collision when the estimated disturbance value exceeds a predetermined threshold, and corrects the estimated disturbance value or the threshold on the basis of the cylinder internal pressure detected by the internal-pressure detecting unit.