Dual Servo Motor Torque Control via Single Loop
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Solution Overview
Problem
Existing systems with single servo motor and drive configurations often face challenges in handling increased mechanical power or torque requirements, leading to higher system costs and packaging issues when upgrading to larger components, and AC servo motor systems are costly for incremental power gains.
Innovation Solution
Using two servo motors with a single outer control loop to drive a common mechanical load, where one motor provides a traditional control loop and the second motor receives the same torque command, effectively doubling output torque while maintaining system stability and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger single motor and drive are used to meet increased power or torque requirements, then the output power or torque is improved, but the system cost and component size increase
Solution Approach 1:
The patent divides the single motor system into multiple motor segments (first servo motor and second servo motor) that work together to drive the common mechanical load. Each motor can be smaller and less expensive than a single large motor, while collectively providing the required power and torque output.
2Power
If AC servo motor systems are used to achieve higher output torque or power, then the power capability is improved, but the system cost increases disproportionably
Solution Approach 1:
The patent segments the power delivery function across multiple motors, allowing the use of more cost-effective motor types (such as DC servo motors) in each segment rather than requiring an expensive AC servo motor system to provide the total required power.
3Power
If multiple outer control loops are used to control multiple motors, then the torque output is improved, but system stability deteriorates due to complex instabilities
Solution Approach 1:
The patent merges the control functions by using a single outer control loop that generates a common torque command signal distributed to multiple motors. This consolidation of control authority eliminates the stability problems associated with multiple independent control loops while maintaining the torque multiplication benefits of multiple motors.
Solution Approach 2:
The patent introduces a signal converter as an intermediary device that receives the position error signal and derives the torque command signal that is distributed to multiple motors. This intermediary ensures coordinated control of multiple motors while maintaining system stability.
Data Source
AI summary
The solution involves the use of two or more motors to drive a common mechanism. The single control loop includes a position sensing device coupled to only a first of the plurality of servo motors and generating a position signal. A signal comparator receives the position signal and compares the position signal with a predetermined desired position based on a desired motion profile. The difference from the actual position and the motion profile is output as a position error signal. A signal converter receives the position error signal and derives a conversion signal based on the error signal. The conversion signal is provided to a plurality of signal amplifiers, which in turn are coupled to the plurality of servo motors. The amplifiers provide power to the motors for driving the mechanical load.