Motor Control Device Managing Current Saturation for Accurate Positioning
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Solution Overview
Problem
Existing motor control methods struggle to accurately stop a driven object at high speed due to limitations in controlling current saturation and maintaining precise positioning.
Innovation Solution
A motor control device with a switching unit that sequentially switches between first, second, and third control units, adjusting current limits based on rotation speed, displacement, and target trajectories to manage current saturation and ensure accurate stopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bang-bang control is used to drive the driven object at high speed, then the driving speed is improved, but the ability to stop at the target position accurately deteriorates
Solution Approach 1:
The control process is divided into three distinct control units: first control unit for high-speed driving, second control unit for transition control, and third control unit for precise stopping. This segmentation allows each control stage to be optimized independently, resolving the contradiction between high-speed driving and accurate positioning.
Solution Approach 2:
The control system dynamically switches between different control strategies based on the current state. The switching unit transitions from bang-bang control to feedback control based on target profile as the driven object approaches the target position, adapting the control method to the current operational phase to maintain both speed and accuracy.
2Manufacturing precision
If feedback control based on target profile is used to stop at target position, then the positioning accuracy is improved, but the driving speed deteriorates
Solution Approach 1:
The control process is divided into three distinct control units: first control unit for high-speed driving, second control unit for transition control, and third control unit for precise stopping. This segmentation allows each control stage to be optimized independently, resolving the contradiction between high-speed driving and accurate positioning.
Solution Approach 2:
The control system applies different control methods in periodic stages: initially using bang-bang control for rapid movement, then transitioning to feedback control based on target profile for precise positioning. This periodic application of different control strategies ensures both high speed and high accuracy are achieved at appropriate phases.
3Power
If current upper limit is adjusted based on counter-electromotive force, then the power utilization is improved, but the control complexity increases
Solution Approach 1:
The first control unit uses feedback from the counter-electromotive force to dynamically adjust the current upper limit. By monitoring the back-EMF signal and using it to modulate the current command, the system optimizes power utilization while maintaining controllable complexity through a well-defined feedback loop.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-speed, accurate positioning of driven objects by managing current saturation and smoothly transitioning between control stages, preventing excessive current flow and ensuring precise stopping.
Implementation Method 1
a current upper limit, which is an upper limit of current applicable to the motor and is adjusted by current degradation caused by a counter-electromotive force
Data Source
AI summary
A motor control device comprises: a motor control unit; and a signal output unit, wherein the motor control unit controls a motor based on an output signal of the signal output unit, wherein the motor control unit is configured to function as: a first control unit performs a first motor control, in which a current upper limit is estimated based on a rotation speed of the motor and is input to the motor, a second control unit performs a second motor control, in which a second driving current, which is a driving current lower than the first driving current at the end of the first motor control is input, a third control unit performs a third motor control, in which a third driving current to be input to the motor is determined, and a switching unit that sequentially switches the first, second, and third control units.