Touch Surface Angular Variation Detection Using Lookup Tables
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Solution Overview
Problem
Existing touch surface control systems for motor vehicle controls, such as multimedia screens and air-conditioning systems, face challenges in determining angular variations of control trajectories using microcontrollers with limited memory and processing capacity, as they require complex trigonometric calculations that are resource-intensive and incompatible with automotive industry constraints.
Innovation Solution
A method that measures elementary displacements along perpendicular axes, compares them to reference data, and ascribes angles using integer values, allowing for efficient determination and storage of elementary angles, which are then assembled to detect angular variations and compare with reference trajectories, reducing memory usage and calculation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trigonometric functions (such as arc tangent) are used to calculate angular variation of control trajectory, then measurement precision of angular variation is improved, but device complexity and memory capacity requirements increase significantly
Solution Approach 1:
The control trajectory is divided into multiple elementary displacements along perpendicular axes (X and Y axes). Each elementary displacement is processed independently by comparing with reference data tables, avoiding the need for complex holistic trigonometric calculations. This segmentation allows simple lookup operations instead of complex mathematical functions.
Solution Approach 2:
Reference data tables serve as intermediaries between the raw displacement measurements and the final angular variation results. The tables pre-store the relationship between displacement ratios and angular values, allowing the system to obtain angular information through simple table lookups rather than real-time trigonometric computations.
2Measurement precision
If trigonometric functions are used for calculating angular variation, then measurement precision is improved, but calculation time increases
Solution Approach 1:
The reference data tables are pre-computed and stored before the actual control operations. All complex trigonometric relationships are calculated in advance and stored as lookup tables, so that during runtime, only simple table access operations are needed, dramatically reducing calculation time while maintaining precision.
3Ease of manufacture
If small microcontrollers of low capacity are used to meet cost and bulkiness specifications, then ease of manufacture and cost are improved, but measurement precision and calculation capability deteriorate
Solution Approach 1:
Instead of implementing complex trigonometric calculation algorithms in the microcontroller, the system uses simplified lookup tables that copy pre-calculated angular relationships. This allows small microcontrollers to achieve the same functional result as larger systems would need for complex calculations, maintaining precision while reducing hardware requirements.
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
This approach enables rapid and cost-effective detection of control trajectories on touch surfaces, suitable for small-capacity microcontrollers, allowing for efficient control of various vehicle functions while minimizing memory consumption and calculation time.
Implementation Method 1
By exerting a pressure on the FSR layer, its ohmic resistance decreases, thus making it possible, by applying a suitable voltage, to measure the pressure applied and/or the location of the place where the pressure is exerted.
Data Source
AI summary
The invention relates to a method for determining the elementary angle of a control path on a touch surface, characterized in that it comprises measuring two elementary movement values (|dX|, |dY|) along two perpendicular axes (X, Y) for a predetermined duration (dT), comparing said values (|dX|, |dY|) with unitary value ranges of elementary movements (Xu, Yu) of a reference data table and allocating a reference data representative of an angle to an elementary angle (dθ) of the control path. The invention also relates to a method for detecting an angular variation of a control path on a touch surface, characterized in that it comprises implementing the above method for determining the elementary angle of a control path on a touch surface and storing the elementary angle (dθ) allocated during an elementary step, repeating the elementary step, and assembling in series the allocated elementary angles (dθ) in order to determine an angular variation of the control path. The invention further relates to a control module including a touch surface (1), characterized in that it comprises a processing unit for implementing the method for detecting an angular variation of a control path as described above.