Haptic Interface Modulating Feedback via Magnetorheological Fluid
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Solution Overview
Problem
Haptic interfaces struggle to maintain effective haptic feedback at high actuation speeds, leading to a decrease in perceived haptic feeling due to variations in resistive torque within narrow angular zones.
Innovation Solution
A haptic interface that modulates haptic patterns based on actuation speed, using slow and fast speed patterns and interpolation between them, along with sensors to detect user intention and torque or force, to generate appropriate stimulus values, thereby enhancing haptic control and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single haptic pattern is applied regardless of actuation speed, then the device complexity is reduced, but the haptic feeling decreases at high actuation speeds
Solution Approach 1:
The haptic interface dynamically adapts the haptic pattern based on the detected actuation speed. The control unit selects between a first haptic pattern (for low speeds) and a second haptic pattern (for high speeds), ensuring that the haptic feedback remains effective across the full range of actuation speeds. This dynamic adaptation resolves the contradiction by making the system complex only when necessary to maintain haptic feeling.
Solution Approach 2:
The system changes the parameters of the haptic pattern based on the actuation speed parameter. When the actuation speed exceeds a threshold, the control unit switches from the first haptic pattern to the second haptic pattern, which is specifically designed to maintain haptic feeling at higher speeds. This parameter-based adaptation allows the system to maintain reliability without requiring complex real-time adjustments.
2Reliability
If haptic patterns are adapted to actuation speed, then haptic feeling is maintained at high speeds, but the device complexity increases
Solution Approach 1:
The haptic control is segmented into distinct speed ranges, each associated with a specific haptic pattern. The control unit divides the actuation speed range into a first range (low speed) and a second range (high speed), applying the first haptic pattern to the first range and the second haptic pattern to the second range. This segmentation simplifies the control logic compared to continuous adjustment, maintaining haptic feeling while limiting complexity.
Solution Approach 2:
The system uses feedback from the actuation speed detection to automatically select the appropriate haptic pattern. The control unit continuously monitors the actuation speed and switches between haptic patterns based on this feedback, ensuring that the haptic feeling is maintained without requiring complex predictive or adaptive algorithms. The feedback mechanism is simple threshold-based comparison.
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
Improves haptic control by maintaining effective feedback across varying actuation speeds, preventing a reduction in haptic feeling at high speeds and enhancing user interaction precision.
Implementation Method 1
The resistant torque can be transmitted to the button via a magneto-rheological fluid whose apparent viscosity is modified by the application of a magnetic field in order to define the predefined haptic patterns.
Data Source
Figure 1A~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a haptic interface, which comprises: a button (1) moving in a first direction or in a second direction, an interaction element (12) for interacting with a magnetorheological fluid the viscosity of which varies in accordance with a magnetic field, a brake comprising a magnetorheological fluid and a generation system (6) for generating a magnetic field on command, a sensor (14) for detecting the current position of the button (1), means for determining the speed of the button (1), and a control unit (UC) capable of sending orders to said system for generating a magnetic field, said orders being generated according to the current position of the button (1) and the current actuation speed of the button (1).