Robot Joint Constraint Structure for Torque Error Correction
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Solution Overview
Problem
Conventional multijoint robots struggle to accurately detect and correct for interference in axial directions, leading to errors in force measurement around the driving axis, making it difficult to handle delicate tasks such as attaching soft or low-strength objects.
Innovation Solution
A driving mechanism with a constraining part that allows for precise detection of forces in another axial direction by simplifying the transfer pathway and using a torque sensor with a deformable part to measure forces around the driving axis, correcting for interference through a sensitivity matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is mounted on a joint to detect torque around the driving axis, then force measurement capability is improved, but interference from forces in other axial directions causes measurement errors
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 sensor to distinguish between torque around the driving axis and interfering forces from other directions through differential measurement.
Solution Approach 2:
Different portions of the force sensor have different structural properties optimized for detecting specific force components. The sensor incorporates deformation parts with varying rigidity and orientation to selectively respond to torque around the driving axis while minimizing response to forces in other directions.
2Measurement precision
If a torque sensor with deformable part is used to measure forces around the driving axis, then measurement capability is improved, but the deformable part is affected by forces in other axial directions
Solution Approach 1:
The deformable part is designed with asymmetric geometry that is sensitive to torque around the driving axis but insensitive to forces in other directions. The asymmetric structure ensures that only the intended measurement component produces significant deformation, while interfering forces produce minimal or detectable-only deformation.
Solution Approach 2:
The force sensor utilizes three-dimensional deformation analysis to distinguish between forces in different directions. By measuring deformation in multiple dimensions and applying mathematical transformation, the sensor isolates the torque component around the driving axis from interfering forces in other axial directions.
3Device complexity
If conventional force sensors are used without interference correction, then device complexity is reduced, but measurement accuracy deteriorates due to uncorrected interference
Solution Approach 1:
The force sensor incorporates feedback mechanisms where deformation measurements from multiple elements are continuously processed and used to correct for interference. The system dynamically compensates for forces in other axial directions by using real-time deformation data to calculate and subtract interference components from the torque measurement.
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 tasks requiring precise force application, such as attaching soft or low-strength objects, by accurately measuring and correcting for interference in axial directions.
Implementation Method 1
using a torque sensor with a deformable part to measure forces around the driving axis
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.