Step Motor Actuation System with Elastic Return Force
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Solution Overview
Problem
Actuation systems with step motors coupled to controlled elements, such as hydraulic valves, face challenges in maintaining precision due to wear, thermal effects, and manufacturing tolerances, leading to increased production and assembly costs and reduced reliability over time.
Innovation Solution
An actuation system that includes a control system with a step motor and an elastic part generating a return force, utilizing a process to detect mechanical clearance by measuring induced electric parameters after switching off the motor current, allowing for precise positioning and compensation for mechanical play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a well-defined clearance is required between the step motor and controlled element to achieve precision, then positioning precision is improved, but production and assembly costs increase due to high manufacturing precision requirements
Solution Approach 1:
The patent applies preliminary action by detecting and compensating for mechanical clearance (dead zone) before actual positioning operations. The control system performs a detection phase where the motor is moved in one direction, then reversed, and the induced voltage is measured to calculate the dead zone value. This pre-detection allows the system to compensate for clearance effects during normal operation, achieving high positioning precision without requiring extremely tight manufacturing tolerances.
2Measurement precision
If high precision coupling is used between the step motor and controlled element, then positioning accuracy is maintained, but reliability decreases over time due to wear and thermal effects
Solution Approach 1:
The patent implements feedback by continuously monitoring the induced voltage signal during motor reversal to detect the dead zone. The control system uses this feedback information to dynamically adjust positioning commands, compensating for clearance effects that arise from wear and thermal expansion over time. This closed-loop approach maintains positioning accuracy without requiring the coupling to remain perfectly tight throughout the system's service life.
3Ease of manufacture
If larger production tolerances are allowed to reduce costs, then manufacturing becomes easier and more economic, but measurement precision and positioning accuracy deteriorate
Solution Approach 1:
The system applies self-service by automatically detecting and compensating for its own mechanical clearance through the induced voltage measurement method. The control system performs self-diagnosis during operation, measuring the dead zone through motor reversal and induced voltage detection, then automatically adjusting positioning commands to account for the detected clearance. This self-compensation mechanism allows the system to maintain high positioning accuracy despite larger production tolerances in the mechanical components.
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
The system maintains precision and reliability across a wide temperature range, reduces production and assembly costs, and minimizes faults during mass production by accurately detecting and compensating for mechanical clearances, thereby extending the service life and improving economic viability.
Implementation Method 1
measuring an induced electric parameter (such as voltage, current, power) on said at least one phase of the stator after switching off the current of said at least one phase of the stator to detect a return of the rotor resulting from the elastic return force
Implementation Method 2
an elastic part capable of generating an elastic return force on the rotor of the motor or on the drive part
Data Source
AI summary
The actuation system including a control system, an actuator comprising a drive part and a step motor comprising a rotor and a stator with at least one electric phase, an actuated system comprising a controlled element coupled to the drive part, and an elastic part capable of generating an elastic return force on the rotor of the motor or on the drive part. The control system comprises means for measuring an induced electric parameter on the phase of the stator after switching off the current of said at least one phase of the stator to detect a return of the rotor resulting from elastic return force when a mechanical clearance is overtaken.