Reluctance Haptic Engine Control for Nonlinear Position Tracking
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Solution Overview
Problem
Conventional linear feedback controllers are insufficient for controlling reluctance haptic engines due to severe non-linearities in force and stiffness inherent to their design, which affect high-fidelity position tracking performance in haptic feedback applications.
Innovation Solution
A non-linear control system is introduced, comprising a linear state controller and a non-linear state observer, which generates control signals based on the difference between estimated and reference positions and velocities of the moving mass, and models stiffness and engine non-linearities with asymmetry, using a pseudo-linearized reluctance force to control the reluctance haptic engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear feedback controller is used to control the reluctance haptic engine, then the control system is simple and easy to implement, but the position tracking performance deteriorates due to severe non-linearities in force and stiffness
Solution Approach 1:
The patent transforms the control approach by changing from a linear feedback controller to a non-linear state observer that accounts for the inherent non-linearities in force and stiffness. This parameter change in the control strategy enables accurate position tracking by properly modeling the non-linear relationship between current, position, and force in the reluctance haptic engine.
Solution Approach 2:
The patent replaces the inadequate linear feedback control mechanism with a non-linear state observer that uses voltage input, coil current, and magnetic field sensor output to estimate position and velocity. This substitution of the control mechanism resolves the contradiction by maintaining simplicity while achieving high-fidelity position tracking through non-linear modeling.
2Measurement precision
If a non-linear control system is introduced to improve position tracking performance, then the accuracy of haptic feedback is enhanced, but the device complexity increases
Solution Approach 1:
The patent implements a non-linear state observer that continuously monitors voltage input, coil current, and magnetic field sensor output to generate accurate estimates of position and velocity. This feedback mechanism, while non-linear, is integrated into the existing control architecture, achieving high-fidelity position tracking without requiring a complete redesign of the control system.
Solution Approach 2:
The control system combines multiple measurement inputs (voltage, current, magnetic field sensor output) into a unified non-linear state observer that produces accurate position and velocity estimates. This composite approach integrates different sensing modalities to achieve high precision while maintaining a cohesive control structure.
3Ease of operation
If conventional linear feedback control is used, then the control implementation is straightforward, but the reliability of haptic feedback deteriorates due to insufficient handling of non-linearities
Solution Approach 1:
The patent applies preliminary action by pre-modeling the non-linearities in force and stiffness characteristics of the reluctance haptic engine. The non-linear state observer is configured with these pre-characterized non-linear models, enabling it to accurately predict and compensate for non-linear effects before they degrade haptic feedback reliability.
Solution Approach 2:
The patent substitutes the inadequate linear feedback control with a non-linear state observer that properly handles the non-linear dynamics. This substitution maintains ease of implementation by building upon the existing control architecture while significantly improving reliability through non-linear modeling of force and stiffness characteristics.
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 non-linear control system improves high-fidelity position tracking performance by effectively managing the non-linearities, enhancing the reliability and accuracy of haptic feedback in electronic devices with reluctance haptic engines.
Implementation Method 1
a sensor voltage output from a magnetic field sensor in the reluctance haptic engine that indicates a change in at least one magnetic field induced in the reluctance haptic engine due to the current in the at least one coil
Implementation Method 2
The electrical current may cause a magnetic flux that results in a reluctance force that pulls the attractor and the core together and causes the input structure to move
Data Source
AI summary
Embodiments are disclosed for non-linear control of a reluctance haptic actuator. A linear state feedback controller receives estimated position and velocity of a moving mass in a reluctance haptic engine and a reference position and velocity, generates a control signal based on the reference position and velocity and the estimated position and velocity. In response to the control signal, the drive electronics adjusts a current into at least one coil in the reluctance haptic engine to generate at least one magnetic field to control the moving mass. A non-linear state observer receives measurements of the voltage input into the reluctance haptic engine, the current, and an output voltage from a magnetic field sensor, and generates the estimated position and velocity of the moving mass based at least in part on the inputs, and sends the estimated position and velocity to the linear state feedback controller.