Robot Joint Transmission With 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 electromechanical actuators, which limits responsiveness and effectiveness in controlling robot movements, especially in high torque and acceleration scenarios.
Innovation Solution
The integration of a transmission with an overload protection system, featuring a motor, a harmonic drive, and a clutch mechanism, which reduces the size and inertia of the motor and transmission, allowing for higher acceleration capabilities while protecting against high torque impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a motor and transmission are designed for high torque capability, then the torque capacity is improved, but the rotational inertia increases, reducing responsiveness
Solution Approach 1:
The transmission system is divided into multiple independent components: a first transmission element (harmonic drive) for high torque multiplication, a second transmission element (clutch mechanism) for overload protection, and a third transmission element for motion control. This segmentation allows each component to be optimized for its specific function, enabling high torque capacity while maintaining responsiveness by only engaging high-torque components when needed.
Solution Approach 2:
The system dynamically switches between different transmission paths based on operational requirements. The clutch mechanism can disengage the high-inertia harmonic drive during high-speed, low-torque operations, and engage it during high-torque operations. This dynamic reconfiguration optimizes the balance between torque capacity and responsiveness in real-time.
2Speed
If a transmission system is designed for high acceleration capability, then the acceleration performance is improved, but the system becomes vulnerable to damage from high torque impacts
Solution Approach 1:
The clutch mechanism is pre-configured as an overload protection device that automatically engages to limit torque transmission when impact forces exceed predetermined thresholds. This beforehand cushioning protects the high-acceleration transmission components from damage during sudden impacts or unexpected loads, ensuring reliability without compromising acceleration performance during normal operation.
3Speed
If the motor size is reduced to lower inertia, then the rotational inertia is improved, but the torque capacity decreases
Solution Approach 1:
The harmonic drive acts as an intermediary between the small, low-inertia motor and the high-torque requirements of the robot joint. It provides substantial torque multiplication, allowing a compact motor to generate high output torque. The clutch mechanism serves as another intermediary, selectively engaging or disengaging the harmonic drive based on operational needs, thus decoupling the motor size from the required torque capacity.
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 robotic systems by reducing rotational inertia and integrating overload protection, enabling efficient torque management and preventing damage from sudden impacts.
Implementation Method 1
a spring configured to apply an axial preload on the pad, where the axial preload defines a torque limit
Implementation Method 2
a pad frictionally coupled to a side surface of the output member of the transmission and coupled to the member of the robot
Implementation Method 3
an output flexure member disposed between and interfacing with the pad and the spring, wherein the output flexure member is coupled to the member of the robot, and wherein the output flexure is torsionally stiff and axially flexible
Data Source
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AI summary
An example robot (300) includes: a motor (1300) disposed at a joint (403) configured to control motion of a member of the robot; a transmission (1200) including an input member (1312) coupled to and configured to rotate with the motor, an intermediate member (1314), and an output member (1318), where the intermediate member is fixed such that as the input member rotates, the output member rotates therewith at a different speed; a pad (1320) frictionally coupled to a side surface of the output member of the transmission and coupled to the member of the robot; and a spring (1328) 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.