Lead Screw Linear Joint for Leak-Free Legged Robot Actuation
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Solution Overview
Problem
Legged robots using hydraulic cylinders face complexity and risk of oil leakage, while those using reducers have high costs and low efficiency, necessitating a simpler and more efficient motion control solution.
Innovation Solution
A linear joint with a motor assembly, transmission mechanism, and anti-rotation mechanism, which converts rotational motion into linear motion using a lead screw mechanism, eliminating the need for hydraulic systems and reducing friction and cost, while preventing oil leakage and simplifying control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic cylinders are used for actuation, then motion control is achieved, but the structure becomes complicated and oil leakage risk increases
Solution Approach 1:
The patent extracts and eliminates the hydraulic system components (oil pump, servo valve, pipelines) from the actuation system, replacing them with a direct motor-reducer-rod mechanism. This removes the source of oil leakage risk while significantly simplifying the overall system structure.
Solution Approach 2:
The patent replaces the hydraulic mechanical system with an electromechanical system using motors and reducers. This substitution eliminates the need for hydraulic fluid and associated components, thereby removing oil leakage risks while maintaining actuation functionality.
2Ease of operation
If reducers are used with motors for actuation, then control ease is improved, but cost increases and efficiency decreases
Solution Approach 1:
The patent employs dynamic adjustment mechanisms in the reducer design, allowing optimal gear engagement and minimal sliding friction during operation. This dynamic optimization maintains high efficiency while preserving the ease of control provided by the motor-reducer configuration.
Solution Approach 2:
The patent optimizes the reducer parameters including gear ratio, friction coefficients, and engagement characteristics to minimize energy loss. By carefully selecting and adjusting these parameters, the system achieves both ease of control and high actuation efficiency.
3Ease of operation
If traditional motor-reducer systems are used, then control is easy, but friction loss increases reducing efficiency
Solution Approach 1:
The patent implements dynamic compensation mechanisms that actively counteract friction forces during motor-reducer operation. This includes real-time adjustment of lubrication and gear engagement parameters to minimize sliding friction, thereby reducing energy loss while maintaining ease of control.
Solution Approach 2:
The patent replaces traditional high-friction mechanical transmission elements with low-friction alternatives such as precision ball screw mechanisms or planetary gear systems with optimized contact surfaces. This substitution reduces friction loss while preserving the controllable nature of the motor-reducer system.
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 linear joint provides a simple, cost-effective, and efficient motion control system with low friction, no risk of oil leakage, and easy control, enhancing the performance of legged robots by reducing complexity and operational risks.
Implementation Method 1
The transmission mechanism (20) converts rotational motion of the rotating shaft (113) into a linear motion of the rod (30) in an axial direction of the rotating shaft (113)
Data Source
AI summary
A linear joint includes a motor assembly includes a rotating shaft for outputting motion; a transmission mechanism including a screw and a nut threadedly connected to the screw, the nut being coaxial with respect to and securely connected to the rotating shaft so as to be rotatable together with the rotating shaft; and a rod connected to a first end of the screw so as to move together with the screw along a lengthwise direction of the screw.