Robot Contact Sensing via Dual Angular Sensor Misalignment Correction
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Solution Overview
Problem
Conventional robot systems face accuracy issues in sensing contact due to encoder misalignment and variations in bolting torque, which can lead to safety concerns when interacting with humans, and require multiple sensors on articulated robots, increasing manufacturing costs.
Innovation Solution
A robot system that includes motor shaft-side and output shaft-side angular sensors, a deceleration device with elastic torsional deformation, and a control unit that calculates contact torque by correcting for angular sensor misalignment, allowing for accurate detection of contact and reducing the need for multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encoders are attached to the robot arm to detect contact, then contact detection capability is improved, but manufacturing precision deteriorates due to shaft center misalignment and bolting torque variation
Solution Approach 1:
The patent replaces the mechanical encoder system with an optical interference measurement system. Instead of using encoders that suffer from mechanical alignment issues, the invention uses laser interferometry to measure the position and orientation of the robot arm, thereby resolving the contradiction between contact detection capability and manufacturing precision
Solution Approach 2:
The patent introduces a laser interferometer as an intermediary measurement device between the robot arm and the detection system. This intermediary device provides high-precision position and orientation data without being affected by the mechanical alignment issues that plague direct encoder attachment, thus resolving the precision-detection contradiction
2Reliability
If multiple contact sensing sensors are attached to the robot arm surface, then contact detection coverage is improved, but manufacturing cost increases
Solution Approach 1:
The patent makes the laser interferometer serve multiple functions: it simultaneously measures position, orientation, and detects contact forces/torques on the robot arm. This multi-functionality replaces the need for multiple separate contact sensors, thereby reducing manufacturing cost while maintaining comprehensive contact detection coverage
Solution Approach 2:
The patent merges the functions of multiple contact sensors into a single integrated measurement system based on laser interferometry. By combining position measurement and contact detection capabilities into one system, the invention eliminates the need for multiple separate sensors, thus reducing manufacturing cost while maintaining detection coverage
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
Improves contact sensing accuracy and reliability, reducing the risk of accidental contact and manufacturing costs by accurately determining contact torque and responding to it, while ensuring safety when interacting with humans.
Implementation Method 1
a deceleration device with elastic torsional deformation
Data Source
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AI summary
Provided is a robot system that can accurately sense contact between an arm of a robot or an instrument attached to the arm and another object. The robot system includes: a robot main body 22 and a robot control unit 21, the robot main body 22 including: a motor 8; a deceleration device 19 connected to a motor shaft 17 of the motor 8; an arm 15 connected to an output shaft 16 of the deceleration device 19; a motor shaft-side angular sensor 1 capable of detecting an angle of rotation of the motor shaft 17 of the motor 8; and an output shaft-side angular sensor 2 capable of detecting an angle of rotation of the output shaft 16 of the deceleration device 19, and the robot control unit 21 being configured to detect a contact state between the arm 15 or an instrument attached to the arm 15 and another object, based on a motor shaft-side rotation angle detected by the motor shaft-side angular sensor 1, an output shaft-side rotation angle detected by the output-side angular sensor 2, and an angular sensor misalignment correction value for the motor shaft-side angular sensor 1 and the output shaft-side angular sensor 2.