Robot Arm Joint Structure for Accurate Torque Sensing
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Solution Overview
Problem
Conventional multijoint robots face challenges in accurately detecting forces around the driving axis of a joint due to interference from forces in other axial directions, leading to measurement errors and preventing precise control of forces on lightweight or fragile objects.
Innovation Solution
A driving mechanism with a constraining part that allows movement in the desired direction while constraining motion in other directions, coupled with a force sensor configuration that simplifies the transfer pathway of forces in other axial directions, enabling accurate detection and correction of measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a force sensor is mounted on a joint to detect torque around the driving axis, then force control capability is improved, but measurement precision deteriorates due to interference from forces in other axial directions
Solution Approach 1:
The force sensor is divided into multiple detection elements arranged in specific orientations. Each element detects forces in specific directions, allowing the system to segment and separately measure forces in different axial directions, then combine the data to obtain accurate torque around the driving axis while compensating for interference forces.
Solution Approach 2:
Different portions of the force sensor have different detection characteristics optimized for specific directions. The sensor structure incorporates elements with varying sensitivity to forces in different directions, enabling local optimization of detection quality for the driving axis torque while accounting for forces in other directions.
2Device complexity
If a conventional force sensor structure is used, then device complexity is reduced, but measurement precision deteriorates due to interference from forces in other axial directions
Solution Approach 1:
The force sensor is designed with multi-functional detection capability. A single sensor structure simultaneously detects forces in multiple directions (including the driving axis and other axial directions), eliminating the need for separate sensors for each direction while maintaining structural simplicity and improving measurement precision through integrated measurement and calculation.
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
Enables high-precision force control, allowing multijoint robots to handle delicate tasks such as attaching soft or low-strength components with precision, correcting sensor detection errors and enhancing the robot's ability to perform processes previously difficult with conventional systems.
Implementation Method 1
a force sensor of a type that includes a deformable part and determines the force by detecting an amount of deformation occurred in the deformable part
Data Source
AI summary
A sensor detection error at a joint of a robot arm is correctly detected. A joint structure that joins links and of a robot arm includes a sensor for determining force acting between the links. A driving apparatus that generates a driving force of a joint includes first and second driving parts. A constraining part that constrains the joint movable in a driving direction of the joint and be unmovable in another direction includes first and second supporting parts that are movable relative to each other in the driving direction of the joint. The driving part of the driving apparatus is fixed to the link, and the supporting part of the constraining part is fixed to the link. Also, the supporting part of the constraining part is fixed to the driving part of the driving apparatus. The sensor is fixed so as to link the supporting part and the link.