Backlash Compensation in Dual-Motor Gear Trains
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Solution Overview
Problem
Existing backlash compensation systems in gearing and motorized systems face challenges in achieving precise positional control and motor load balancing, often resulting in positional delays, errors, and overloading due to the complexity of prior art methods and limitations in controlling relative motor positions under varying loads.
Innovation Solution
A phase-based backlash compensation system utilizing a phasing algorithm that adjusts the phase set points of multiple motors to maintain torque thresholds, ensuring efficient distribution of loads and eliminating backlash by integrating motor position and torque feedback for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque based backlash control approach is used with two motors, then backlash compensation is achieved, but the relative motor positions become uncontrollable and significant beating between pinions and bearing gear flanks appears under load variations
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the actual positions of both motors and adjusts the torque distribution accordingly. The controller receives position feedback from encoders on each motor and uses this information to maintain precise positional control while compensating for backlash, preventing the uncontrollable position drift that occurs in pure torque-based approaches.
Solution Approach 2:
The system dynamically adjusts the torque distribution between the two motors based on real-time operating conditions and measured positions. Rather than using a fixed torque bias, the controller continuously optimizes the torque split to maintain optimal engagement of both pinions with the bearing gear flanks, eliminating beating under varying load conditions.
2Reliability
If an idler gear on an adjustable bracket is used for backlash adjustment, then backlash control is achieved, but the system requires positioning the center distances between the idler gear and both mating gears
Solution Approach 1:
The patent replaces the mechanical adjustment system (idler gear on adjustable bracket requiring precise center distance positioning) with an active control system using two motors and a controller. Instead of mechanically adjusting gear positions to eliminate backlash, the system uses controlled torque application and position feedback to maintain optimal gear engagement, eliminating the need for precise mechanical center distance positioning.
3Reliability
If torque bias is added to one motor and subtracted from the other, then backlash compensation is achieved, but even distribution of motor loads under varying external loads cannot be maintained
Solution Approach 1:
The controller continuously monitors the operating conditions and torque requirements of both motors, using feedback information to dynamically adjust the torque distribution. This ensures that under varying external loads, the torque bias is optimally distributed between the two motors to maintain even load sharing while still achieving effective backlash compensation.
Data Source
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AI summary
A device for preventing backlash in a gear train, comprising a first and second drive gear, driven by a first and second motor, with a driven gear, a system controller defining a nominal trajectory of said driven gear, a position feedback controller for calculating a speed set point, a phase controller for calculating a difference between said first and second motor torque, providing torque upper and lower levels, comparing said difference to said upper and lower levels and adjusting the phase set point for said first and second motors based at least upon the comparing, where the phase is reduced if said difference is greater than or equal to said upper level, said phase is increased if said difference is less than or equal to said lower level, and said phase is kept constant if said difference is greater than said lower level and less than said upper level.