Robot Contact Stop Control Using Joint Torque and Distal Force Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing robot systems face challenges in accurately detecting external forces and preventing unnecessary stops due to high sensitivity of torque sensors when external forces act away from the sensor's position, which can hinder work operations like pressing tools against workpieces.
Innovation Solution
A robot system equipped with both torque and force sensors, where the control device determines whether to stop the robot based on detected forces and torques, using thresholds to differentiate between direct and indirect contact, and adjusts sensitivity to prevent false stops by using force sensors for accurate detection of external forces and torque sensors for proximity-based control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque sensors are used to detect external forces, then contact stop control sensitivity is improved, but false stops occur during work operations like pressing tools against workpieces
Solution Approach 1:
The patent segments the detection function into two parts: torque sensors detect torques at joint positions, while force sensors detect forces at distal end positions. This segmentation allows each sensor to operate in its optimal detection range, with torque sensors handling proximity-based control and force sensors handling distant contact detection, thereby resolving the contradiction between sensitivity and false stops
Solution Approach 2:
The patent introduces force sensors as intermediary devices between the torque sensors and the external work environment. These force sensors act as mediators that detect forces at positions farther from the joints, providing accurate information about external contacts without triggering false stops in torque sensors during normal pressing operations
2Ease of operation
If torque sensors are placed at joint positions, then proximity-based control is improved, but detection accuracy decreases when external forces act away from sensor position
Solution Approach 1:
The patent adds a spatial dimension to the detection system by placing force sensors at distal end positions farther from the joints. This dimensional extension allows the system to detect forces acting at different locations along the robot arm, complementing the torque sensors' proximity-based detection capability and improving overall measurement precision for distant forces
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
The system effectively prevents unnecessary stops during work operations by accurately detecting external forces and torques, ensuring reliable contact stop control without hindering the robot's functionality, and maintaining sensitivity within a controlled range.
Implementation Method 1
a torque sensor for detecting a first torque about an axis of the joint
Implementation Method 2
a force sensor for detecting a force
Data Source
AI summary
A robot system including a robot having one or more joints, and a control device that controls the robot, where the robot has, at at least one of the joints, a torque sensor for detecting a first torque about an axis of said joint, and has, at a position farther on a distal end side than the torque sensor, a force sensor for detecting a force. The control device determines whether or not to stop the robot on the basis of only the first torque, when the force detected by the force sensor is less than or equal to a prescribed first threshold.