Dual-Motor Drive Backlash Control via Voltage Threshold Switching
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Solution Overview
Problem
Existing driving systems with two motors driving a shared shaft often experience backlash and vibration due to frequent torque direction switches at angular velocity thresholds, which are not effectively addressed by existing technologies.
Innovation Solution
A driving apparatus with a control unit and switching unit that adjusts control patterns based on a voltage command value, ensuring the torque direction from one motor remains consistent with the shaft direction by switching between control patterns when the voltage command value crosses predetermined thresholds, thereby eliminating backlash and reducing vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the direction of torque of the second motor is switched using a predetermined threshold as a boundary, then the driving torque of the driving shaft is improved and backlash is eliminated, but the torque direction switches frequently when angular velocity is maintained around the threshold, causing vibration
Solution Approach 1:
The patent changes the control parameter from angular velocity to voltage command value for switching control patterns. This parameter change eliminates the frequent switching issue because the voltage command value directly reflects the motor's operational state without the intermediate conversion through angular velocity, providing more stable and responsive control that prevents vibration while maintaining high driving torque.
Solution Approach 2:
The patent implements feedback control by using the voltage command value as the switching criterion. The control system continuously monitors the voltage command value and switches control patterns based on this real-time feedback, ensuring that torque direction changes occur only when necessary and avoiding frequent switching that would cause vibration.
2Reliability
If pre-torques acting in opposite directions are applied to eliminate backlash, then backlash between the load shaft and motors is eliminated, but the control complexity increases due to the need for threshold-based switching
Solution Approach 1:
The patent simplifies control by changing the switching parameter from angular velocity to voltage command value. This single parameter change maintains the backlash elimination function while reducing control complexity, as the voltage command value provides direct feedback on the motor's operational state without requiring complex threshold-based angular velocity conversions.
Data Source
AI summary
A driving apparatus allowing two motors to drive a same driving shaft is provided. When a voltage command value is less than a predetermined threshold, a control unit outputs driving command values based on one control pattern such that a direction of a torque of one of the motors becomes different from a driving direction of the driving shaft. Also, when the voltage command value becomes greater than or equal to the predetermined threshold, the control unit outputs the driving command values based on another control pattern, such that the direction of the torque of the one of the motors becomes the same as the driving direction of the driving shaft when the voltage command value is greater than or equal to the predetermined threshold, and does not become different from the driving direction of the driving shaft when the voltage command value drops below the predetermined threshold.