Robotic Joint Dual-Sensor Measurement via Nested Pulleys
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Solution Overview
Problem
Existing robotic joints lack accurate measurement capabilities for position, velocity, and acceleration, particularly due to limitations in sensor placement and reliance on motor-side sensors for joint movement analysis.
Innovation Solution
A robotic joint design incorporating a motor, joint-side sensor, and motor-side sensor, with a controller that connects both sensors to accurately measure and calculate position, velocity, and acceleration, utilizing concentric pulley systems to align sensors off the central axis for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor-side sensors are used for joint movement analysis, then device complexity is reduced, but measurement precision deteriorates due to inability to directly measure joint-side parameters
Solution Approach 1:
The system segments the measurement function by using separate sensors for different purposes: motor-side sensors measure motor parameters (position, velocity) while joint-side sensors measure joint parameters (position, velocity). This segmentation allows each sensor to optimize for its specific measurement task, improving overall measurement precision without requiring a single complex sensor system.
Solution Approach 2:
The joint-side sensor is positioned within the hollow motor-side drive shaft, creating a nested configuration where the joint-side measurement system is embedded within the motor-side drive structure. This nesting allows dual measurement capabilities in a compact arrangement, improving measurement precision without proportionally increasing device complexity.
2Measurement precision
If sensors are placed on the central axis, then device complexity is minimized, but measurement precision deteriorates due to noise and delay in calculations
Solution Approach 1:
The joint-side sensor is positioned off the central axis of the joint, utilizing a different spatial dimension for measurement. This off-axis positioning allows the sensor to measure joint parameters more accurately by avoiding interference from central axis components, improving measurement precision while the sensor remains integrated within the drive shaft structure.
3Measurement precision
If concentric pulley systems are used to align sensors off-axis, then measurement precision improves, but device complexity increases
Solution Approach 1:
The concentric pulley system is nested within the hollow motor-side drive shaft structure, with the joint-side target pulley and motor-side target pulley arranged concentrically. This nesting allows the pulley alignment mechanism to be integrated into the existing drive shaft, improving sensor alignment accuracy without adding significant external complexity to the overall device.
Data Source
AI summary
A joint includes: a motor coupled to the joint, the motor configured to move the joint; a joint side sensor configured to measure a parameter of interest of a joint side target; a motor side sensor configured to measure the parameter of interest of the motor; and a controller configured to control the motor, the controller operably connected to the joint side sensor, the controller operably connected to the motor side sensor.