Wire Rod Holding Mechanism for Stable Robot Torque Sensing
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Solution Overview
Problem
In multi-axis articulated robots, wire rods generate friction torque and internal forces that interfere with torque sensor measurements, making precise control of external forces difficult, especially during assembly work with minute loads, and leading to reduced sensor detection accuracy and wire rod lifespan.
Innovation Solution
A holding mechanism with bands that securely fasten wire rods using a contact portion and regulation portions, ensuring the bands are in contact with at least half of the wire rod's circumference, reducing movement and fluctuation of the wire rods, thereby stabilizing the internal forces detected by torque sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If wire rods are installed to transmit control signals and drive energy, then actuators can be driven and controlled, but friction torque and internal forces are generated that interfere with torque sensor measurements
Solution Approach 1:
The patent extracts the wire rod reaction force from the torque sensor detection target by separately measuring it through acceleration sensors and gravitational force calculations. This allows the torque sensor to focus on detecting external forces applied to the end effector, while the wire rod forces are measured and compensated separately, resolving the interference issue.
Solution Approach 2:
The patent implements feedback by continuously monitoring acceleration via acceleration sensors, calculating gravitational forces based on robot posture, and using these measurements to compensate for wire rod reaction forces in the torque sensor readings. This feedback loop enables accurate separation of external forces from internal wire rod forces.
2Stability of the object's composition
If wire rods are secured with conventional wiring guides, then some movement is regulated, but wire rod reaction force and bending force still occur during robot operation
Solution Approach 1:
The patent applies counterweight by positioning the wire rod holding portion at the gravitational center of the robot arm. This balances the gravitational force acting on the wire rods, preventing bending moments and reaction forces that would otherwise occur when the wire rods are subjected to gravitational loading during arm movement.
Solution Approach 2:
The patent uses multiple bands arranged at specific intervals around the wire rod, with each band providing partial support. The combined effect of multiple bands at strategically positioned locations provides excessive constraint that completely eliminates wire rod movement and reaction forces, going beyond what a single constraint would achieve.
3Measurement precision
If torque sensor resolution is increased to improve external force measurement, then detection precision improves, but the ratio of internal force to external force in detected torque remains large
Solution Approach 1:
The patent segments the torque sensor detection function from the wire rod reaction force measurement function. Torque sensors measure total torque while acceleration sensors and gravitational calculations separately measure wire rod forces. This segmentation allows independent optimization of each measurement system and enables mathematical separation of external and internal forces.
Solution Approach 2:
The patent introduces acceleration sensors and gravitational force calculations as intermediary measurement systems. These intermediaries provide independent data about wire rod reaction forces, which are then used to compensate torque sensor readings, effectively mediating between the torque sensor and the final external force measurement.
Data Source
AI summary
A holding mechanism configured to hold a wire rod includes a band configured to fasten the wire rod, and a holding member. The holding member includes a contact portion configured to come into contact with the wire rod, a first regulation portion configured to regulate a position of a first portion of the band, and a second regulation portion configured to regulate a position of a second portion of the band. A distance between the first regulation portion and the second regulation portion is smaller than a diameter of the wire rod.