Legged Robot Transmission With Integrated Slip Clutch Overload Protection
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Solution Overview
Problem
Existing robotic systems face challenges in achieving high performance characteristics due to high rotational inertia in actuators, which limits responsiveness and efficiency, especially in legged robots.
Innovation Solution
The implementation of a transmission system with integrated overload protection, featuring a motor, a harmonic drive, and a clutch system, which reduces rotational inertia and provides torque amplification while protecting against high torque loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high gear ratio transmission is used to amplify torque, then torque output is improved, but rotational inertia increases which reduces responsiveness
Solution Approach 1:
The transmission system is segmented into multiple independent components: harmonic drive for torque amplification, clutch assembly for inertia management, and friction pads for controlled engagement. This segmentation allows each component to optimize its function without compromising overall system responsiveness.
Solution Approach 2:
The clutch assembly dynamically engages and disengages the friction pads from the output member based on torque conditions. During high acceleration, the clutch disengages to reduce effective inertia; during steady-state operation, it engages to provide full torque amplification, thus dynamically adjusting the system characteristics.
2Force
If high gear ratio transmission is used to amplify torque, then torque output is improved, but device complexity increases
Solution Approach 1:
The clutch assembly is merged with the harmonic drive output, integrating the overload protection mechanism directly into the transmission system. This eliminates the need for separate clutch housings and mounting structures, reducing overall complexity while maintaining torque amplification capability.
Solution Approach 2:
The friction pads serve multiple functions: they provide controlled slippage during overload conditions, enable dynamic inertia management, and assist in torque transmission. This multi-functionality reduces the need for additional specialized components, simplifying the overall transmission design.
3Reliability
If friction pads are added to provide overload protection, then reliability is improved, but device complexity increases
Solution Approach 1:
The friction pads are integrated directly onto the output member, merging the overload protection function with the existing transmission structure. This eliminates the need for separate protection mechanisms and reduces the number of discrete components.
Solution Approach 2:
The friction pads automatically engage and disengage based on torque conditions without requiring external control systems. The spring-loaded mechanism self-regulates the clutch engagement, providing reliable overload protection while minimizing control complexity.
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 solution enhances the responsiveness and performance of legged robots by reducing rotational inertia and integrating overload protection, allowing for higher accelerations and improved control strategies.
Implementation Method 1
a spring configured to apply an axial preload on the pad
Implementation Method 2
a pad frictionally coupled to a side surface of the output member of the transmission
Data Source
AI summary
An example robot includes: a motor disposed at a joint configured to control motion of a member of the robot; a transmission including an input member coupled to and configured to rotate with the motor, an intermediate member, and an output member, where the intermediate member is fixed such that as the input member rotates, the output member rotates therewith at a different speed; a pad frictionally coupled to a side surface of the output member of the transmission and coupled to the member of the robot; and a spring configured to apply an axial preload on the pad, wherein the axial preload defines a torque limit that, when exceeded by a torque load on the member of the robot, the output member of the transmission slips relative to the pad.