Compact Torque Sensor in Articulated Robot Joints
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Solution Overview
Problem
Existing torque sensors for articulated robot arms are not compact enough for lightweight designs, add extra components, and impractical for continuous operation due to battery requirements at each motorized joint.
Innovation Solution
A compact motorized joint unit with integrated strain gauges and a printed circuit board (PCB) for torque sensing, where the PCB is connected to a controller, allowing for efficient power and signal transmission across motorized joints without additional batteries, enabling continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate torque sensors are added next to motorized joints, then torque measurement capability is improved, but device complexity and weight increase
Solution Approach 1:
The torque sensor functionality is merged with the motorized joint structure itself. Strain gauges are integrated onto the motor housing or joint components, eliminating the need for separate external torque sensors. This integration maintains torque measurement capability while reducing device complexity and component count.
Solution Approach 2:
The motorized joint components serve multiple functions: they provide motorization for movement while simultaneously acting as the mounting structure for torque measurement via integrated strain gauges. This multi-functionality reduces the need for additional dedicated components.
2Measurement precision
If strain gauges are added on thin wall sections of motors, then torque sensing is enabled, but power transmission between joints is restricted
Solution Approach 1:
The torque sensing system is segmented into independent strain gauge modules mounted on each motorized joint's housing. Each joint can be instrumented independently without affecting the mechanical coupling and power transmission between adjacent joints. This segmentation allows free joint movement while maintaining torque sensing capability.
3Use of energy by moving object
If batteries are placed at each motorized joint for strain gauge power, then strain gauge operation is enabled, but weight and maintenance complexity increase
Solution Approach 1:
The power supply function is extracted from the distributed battery-at-each-joint approach and consolidated into a centralized power source. Wires are routed through the articulated mechanism to provide power to strain gauges remotely, eliminating the need for heavy batteries at each joint while maintaining continuous operation capability.
4Weight of moving object
If compact torque sensing is implemented, then weight is reduced, but power transmission across joints becomes challenging
Solution Approach 1:
Wireless power transmission or inductive coupling mechanisms serve as intermediaries to transfer power across the articulated joints without physical wire connections that would restrict movement. This allows compact torque sensing implementation while solving the power transmission challenge across moving joints.
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
The solution provides a compact, efficient, and practical torque sensing mechanism that reduces weight and power consumption, enabling continuous operation of articulated robot arms without the need for batteries at each joint.
Implementation Method 1
at least one strain gauge located on said annular wall of the support
Data Source
AI summary
A motorized joint unit comprises a pair of shells defining an inner cavity, the pair of shells adapted to be connected to adjacent links of an articulated mechanism. A rotor and stator in the inner cavity are actuatable to cause a relative rotation therebetween. A shaft connected to the rotor to rotate with the rotor relative to the stator. A support coupled to the shaft by a mechanism, the support being connected to one of the shells to impart a rotation of the shaft to the shell, the support defining an annular wall. One or more strain gauges are located on said annular wall of the support. A printed circuit board (PCB) is applied against the annular wall and electrically connected to the at least one strain gauge, the PCB adapted to be electrically linked to a controller.