Differential Robot Drive Layout for Static Friction Control
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Solution Overview
Problem
Existing drive systems for multi-link structures, such as robots, face challenges in accurately controlling position and force due to frictional influences, particularly static friction, which complicates smooth motion and can lead to stick-slip operations, especially at low speeds.
Innovation Solution
A drive device comprising three drive units and two differential units connected through a control system that maintains constant speed for one drive unit while adjusting the relative speeds of the other two units, utilizing differential gear mechanisms to cancel out static friction without requiring identical motors or additional mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a twin drive system with two constantly rotating motors is used for one drive axis, then the influence of static friction is removed, but the number of motors doubles, greatly increasing manufacturing costs and mechanical inertia
Solution Approach 1:
The patent merges the functions of two separate drive systems into a unified three-motor configuration. The first and third drive units work together through the first differential unit to drive one drive axis, while the second and third drive units work together through the second differential unit to drive another drive axis. This combining approach eliminates the need for duplicate motors on each axis while maintaining the friction-reduction benefits of multiple drive units.
Solution Approach 2:
The third drive unit serves dual functions by being connected to both the first and second differential units. It participates in driving both the first drive axis (through the first differential unit) and the second drive axis (through the second differential unit). This multi-functionality reduces the total motor count while maintaining the constant rotation capability needed to eliminate static friction effects.
2Object-affected harmful factors
If a twin drive system with two constantly rotating motors is used for one drive axis, then the influence of static friction is removed, but the size of the mechanism increases
Solution Approach 1:
The patent merges the functions of two separate drive systems into a unified three-motor configuration. The first and third drive units work together through the first differential unit to drive one drive axis, while the second and third drive units work together through the second differential unit to drive another drive axis. This combining approach eliminates the need for duplicate motors on each axis while maintaining the friction-reduction benefits of multiple drive units.
3Quantity of substance
If three drive units and two differential units are used to reduce friction influence, then manufacturing costs and mechanical inertia are reduced, but the device complexity increases
Solution Approach 1:
The differential units automatically perform the complex task of coordinating the rotational speeds and torques from multiple drive units. The mechanical structure of the differential units inherently handles the speed differentiation and torque distribution, eliminating the need for complex electronic control systems or additional sensors. The system serves itself by using the natural properties of differential mechanisms to manage the multi-drive configuration.
Data Source
AI summary
Provided is a drive device that can remove the influence of static friction by driving two drive axes with three drive units. A drive device includes: a first drive unit; a second drive unit; a third drive unit; a first differential unit connected to the first drive unit and the second drive unit; a second differential unit connected to the second drive unit and the third drive unit; and a control unit that controls the first to third drive units. The control unit controls the second drive unit at a constant speed, and controls a speed of each of the first drive unit and the third drive unit relative to that of the second drive unit.