Haptic Feedback Actuator with Dynamic Force Threshold Control
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Solution Overview
Problem
Existing operating devices for motor vehicles experience a time delay between exceeding the force threshold and triggering haptic feedback, leading to a higher perceived trigger force and variable release force, which affects ease of use and driving safety due to inconsistencies in actuation characteristics.
Innovation Solution
An evaluation device determines the time-related gradient of the force applied to a touch-sensitive surface, adjusting the force threshold accordingly to maintain a consistent perceived triggering force, independent of actuation speed, by reducing the threshold value based on the gradient and system delay time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a force threshold is set to trigger haptic feedback, then the user receives clear feedback that an action has been recognized, but due to system delay the actual triggering occurs later at a higher force, making the perceived trigger force variable and inconsistent
Solution Approach 1:
The system performs preliminary detection of the force gradient before the force threshold is reached. By evaluating the rate of force increase in advance, the system can predict when the threshold will be exceeded and compensate for the system delay, ensuring the haptic feedback is triggered at the intended moment rather than later when the force has already increased further.
Solution Approach 2:
The evaluation unit dynamically adjusts the triggering decision based on the real-time force gradient. Instead of using a static force threshold alone, the system adapts its triggering behavior according to the rate of force application, making the trigger force perception consistent regardless of whether the user presses slowly or rapidly.
2Device complexity
If the force threshold is kept constant, then the system operation is simple and cost-effective, but the perceived trigger force varies with actuation speed due to system delay
Solution Approach 1:
The system changes the parameter used for triggering from a static force threshold alone to a dynamic evaluation that incorporates the force gradient. By monitoring how quickly force is applied and using this information to adjust the triggering decision, the system maintains reliable and consistent perceived trigger force across different actuation speeds while building upon the simple constant threshold foundation.
3Speed
If haptic feedback is triggered immediately when force threshold is exceeded, then the response is fast, but system delay causes the actual triggering to occur at higher force values, creating variable effective trigger force
Solution Approach 1:
The system performs preliminary detection of the force gradient before the force threshold is reached. By evaluating the rate of force increase in advance, the system can predict when the threshold will be exceeded and compensate for the system delay, ensuring the haptic feedback is triggered at the intended moment rather than later when the force has already increased further.
Solution Approach 2:
The system uses the detected force gradient as feedback to adjust its triggering behavior. By continuously monitoring the rate of force application and using this information to modulate the triggering decision, the system compensates for system delay and maintains consistent perceived trigger force across different actuation speeds.
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 ensures a consistent and reliable haptic feedback experience, improving the ease of use and driving safety by maintaining a constant perceived trigger force regardless of actuation speed, and compensating for system latency.
Implementation Method 1
An actuator (28) serves to generate haptic feedback to the user depending on whether a force threshold is exceeded
Implementation Method 2
means for detecting a force applied by a user to at least one area of the touch-sensitive surface
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an operating device (10) and the method for controlling functional units of a motor vehicle comprising a touch-sensitive surface (14), comprising means (16) for detecting a force (F), which can be applied by a user to at least one area of the touch-sensitive surface (14), and comprising an actuator (28) for generating a haptic feedback to the user according to the exceeding of a threshold value of the force (F). An evaluation unit (30) of the operating device (10) is designed to determine a time-related gradient of the force (F) and to change the threshold value of the force (F) according to the determined gradient. The invention further relates to a motor vehicle having an operating device (10) of this type.