Robot Wrist Torque Sensor Layout for Compact High-Torque Joints
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Solution Overview
Problem
Designing a robot arm wrist that balances compactness, high torque transfer, stiffness, and accurate sensor integration is challenging, as existing designs often compromise on these criteria, particularly in fitting motors, gearing, torque sensors, and position sensors within a small, circularly symmetrical space.
Innovation Solution
The robot arm features a joint mechanism with sector gears and a torque sensor arrangement that includes a deflectable torsion member with a deflection sensor, and a rotary position sensor system using magnetic rings and sensors, allowing for compact and accurate torque and position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional gear elements are designated as sacrificial to minimize backlash, then backlash is reduced, but maintenance requirements increase and gear particles are liberated within the arm
Solution Approach 1:
The patent replaces conventional mechanical gear elements with a flexible coupling mechanism comprising a first flexible element and a second flexible element that can elastically deform to accommodate backlash. This substitution eliminates the need for sacrificial gear elements while maintaining backlash minimization, thereby reducing maintenance requirements and preventing gear particle liberation.
Solution Approach 2:
The patent changes the mechanical parameters of the coupling system by introducing flexible elements with specific elasticity characteristics. The flexible elements are designed with controlled stiffness and deformation ranges to absorb backlash dynamically, transforming the rigid mechanical system into a compliant one that self-regulates backlash without requiring sacrificial components.
2Volume of moving object
If the wrist is made compact to allow multiple robot arms to work in close proximity, then the robot arm size is reduced, but the ability to deliver high torque is compromised
Solution Approach 1:
The patent employs a nested arrangement where the flexible coupling elements are integrated within the compact wrist structure. The first and second flexible elements are positioned concentrically around the rotation axis, with drive gears nested within the flexible element housing. This nesting allows high-torque transmission components to be packed into a minimal volume, maintaining both compactness and torque delivery capability.
Solution Approach 2:
The patent utilizes the axial dimension along the rotation axis to accommodate torque transmission components. Instead of expanding the radial profile of the wrist, the flexible elements and drive gears are arranged along the length of the rotation axis, allowing high-torque components to fit within the compact radial envelope while maintaining full torque transmission capability.
3Weight of moving object
If the distal portion of the arm is made lightweight to reduce force on proximal joints, then the force requirement is reduced, but the ability to deliver high acceleration to the tool tip is compromised
Solution Approach 1:
The patent employs composite materials in the construction of the flexible coupling elements and wrist components. The flexible elements are made from composite materials that provide high strength-to-weight ratio, allowing the distal portion to remain lightweight while maintaining the structural integrity and stiffness required for high acceleration. The composite structure enables reduced mass without compromising the dynamic performance and torque transmission capability.
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
This configuration provides a compact, mechanically advantageous drive arrangement with high torque transfer and accurate sensor integration, enabling a wide range of motion while maintaining a compact and lightweight design, suitable for surgical and industrial robots.
Implementation Method 1
a torque sensor arrangement comprising: an interface member having on its exterior an engagement configuration for rotationally engaging the first part; a deflectable body attached at one end thereof to the interface member and comprising, at the other end of the deflectable body, an engagement configuration for rotationally engaging the second part
Implementation Method 2
a rotary position sensor system using magnetic rings and sensors
Data Source
AI summary
Aspects of the disclosure include a torque sensor arrangement configured to attach between a first part and a second part to sense torque therebetween, the torque sensor arrangement comprising an interface member having on its exterior an engagement configuration configured to rotationally engage the first part, a torsion member comprising a deflectable body attached at one end thereof to the interface member and comprising, at the other end of the deflectable body, an engagement configuration configured to fixedly engage the second part, and a deflection sensor attached to the deflectable body, wherein the interface member defines a rigid sleeve extending around the deflectable body and the torque sensor arrangement further comprises a bushing located between and in contact with both the sleeve and the deflectable body.