Dual Motor Backlash Prevention via Pre-Load Torque Control
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Solution Overview
Problem
Conventional techniques fail to adequately prevent backlash between motors and driven shafts, especially when the inertia of the driven shaft exceeds that of the motors, leading to gear tooth separation and inaccurate rotation position control.
Innovation Solution
A control apparatus generates a first drive instruction value greater than or equal to 0 for the first motor and a second drive instruction value less than or equal to 0 for the second motor, ensuring continuous torque application in opposite directions to maintain gear contact and prevent backlash, even with large driven shaft inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional torque control methods are used with two motors driving one driven shaft, then the system can operate with standard control algorithms, but gear tooth separation occurs when driven shaft inertia exceeds motor inertia, causing backlash and inaccurate rotation position control
Solution Approach 1:
The control apparatus applies preliminary action by generating a drive instruction value that maintains pre-load torque on the gear mechanism before actual rotation occurs. This pre-load torque ensures gear teeth remain in contact during acceleration and deceleration phases, preventing backlash before it can occur. The control method calculates required pre-load torque based on acceleration commands and applies it in advance to maintain reliable gear engagement.
Solution Approach 2:
The invention changes the torque parameter dynamically by adjusting drive instruction values based on acceleration commands and current rotation state. The control apparatus modifies torque magnitude and direction in real-time, switching between motors as needed, and adjusting pre-load torque levels according to operational conditions. This parameter adaptation ensures optimal torque application for preventing backlash while maintaining accurate rotation control.
2Force
If the driven shaft has large inertia compared to the motors, then the system can handle heavy loads, but gear teeth separate during acceleration and deceleration, causing backlash
Solution Approach 1:
The control apparatus ensures continuity of useful action by maintaining continuous torque application through coordinated control of two motors. As one motor decelerates, the other accelerates, ensuring uninterrupted torque delivery to the driven shaft. This continuous torque application prevents gear tooth separation during transitions, maintaining reliable gear contact throughout the operation cycle despite large inertia variations.
Solution Approach 2:
The system uses counterbalancing torque application by applying pre-load torque in the opposite direction to the intended rotation acceleration. This counter-torque ensures gear teeth remain pressed together during acceleration and deceleration phases, counteracting the separating forces generated by large driven shaft inertia and preventing backlash.
3Use of energy by moving object
If torque is applied only in the direction of rotation, then the motor operates efficiently in its primary direction, but gear teeth separate during direction changes and acceleration phases
Solution Approach 1:
The control apparatus applies preliminary action by generating drive instruction values that maintain pre-load torque before actual rotation or direction change occurs. This pre-load ensures gear teeth are already engaged and pressed together when acceleration begins, preventing separation during the transition from stationary or during direction changes, while maintaining efficient motor operation.
Solution Approach 2:
The system dynamically adjusts torque application by switching between two motors based on rotation direction and acceleration requirements. The control apparatus continuously monitors rotation state and dynamically reassigns which motor provides driving torque and which provides pre-load torque, optimizing both gear engagement stability and motor efficiency throughout the operation cycle.
Data Source
AI summary
A control apparatus includes a drive instruction value generator configured to generate a first drive instruction value that is greater than or equal to 0, which corresponds to torque in a first rotation direction, for driving a first motor that applies the torque in the first rotation direction to a shaft, and a second drive instruction value that is less than or equal to 0, which corresponds to torque in a second rotation direction, for driving a second motor, which is different from the first motor, that applies the torque in the second rotation direction, which is an opposite direction to the first rotation direction, to the shaft.