Compliant Haptic Test Probe for Accurate Trackpad Response Measurement
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Solution Overview
Problem
Existing measurement systems for haptic devices, such as rigidly mounted sensors, fail to accurately measure threshold forces and haptic responses due to the soft nature of haptic devices like trackpads, resulting in inconclusive and inconsistent results, making them unsuitable for high-volume production testing.
Innovation Solution
A test probe with a compliant element and sensors that can move relative to the haptic device, allowing simultaneous measurement of threshold force and haptic response characteristics at the same location, using an impedance head or resistive load cell for force measurement and a piezoelectric sensor for haptic response, with a mechanical impedance matching that of a human finger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigidly mounted sensor is used to measure haptic device forces, then the sensor remains stable and stationary, but the vast majority of the haptic effect is lost and measurement results are inconclusive and inconsistent
Solution Approach 1:
The patent transforms the rigidly mounted sensor into a dynamic system by introducing a compliant element that allows the sensor to move relative to the haptic device during actuation. This dynamic mounting enables the sensor to follow the haptic device's motion while maintaining measurement capability, resolving the contradiction between stability and haptic effect detection.
Solution Approach 2:
The compliant element acts as an intermediary between the rigid sensor and the soft haptic device. It transmits both force and motion information from the haptic device to the sensor, enabling accurate measurement of haptic effects while maintaining sensor stability. This intermediary component resolves the contradiction by mediating between the opposing requirements of rigidity and compliance.
2Ease of manufacture
If existing measurement systems are used on haptic devices, then the setup is simple, but the results are inconclusive and inconsistent due to the soft nature of haptic devices
Solution Approach 1:
The patent changes the mechanical parameter of the sensor mounting from rigid to compliant by introducing the compliant element with specific stiffness properties. This parameter change allows the measurement system to adapt to the soft nature of haptic devices, improving measurement accuracy while maintaining ease of manufacture through a modular design that can be integrated into existing systems.
3Measurement precision
If a compliant element is introduced to enable sensor movement, then haptic response measurement improves, but device complexity increases
Solution Approach 1:
The patent uses a compliant element in the form of a flexible component that allows sensor movement while maintaining a relatively simple overall structure. This flexible element provides the necessary compliance for accurate haptic response measurement without introducing complex mechanical mechanisms, thus improving measurement precision with minimal increase in device complexity.
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
Enables accurate and consistent measurement of haptic device performance by replicating finger-like interaction, providing reliable data for production environments.
Implementation Method 1
a piezoelectric sensor element configured for measuring the haptic response characteristic
Implementation Method 2
a compliant element configured for enabling the sensor to move relative to the haptic device
Data Source
AI summary
Inconclusive and inconsistent results from existing haptic testing systems, e.g. for trackpads, which include rigidly mounted resistive load cells and accelerometers, prevent accurate results, especially in a high-volume production context. The use of a rigidly mounted sensor is unsuitable because a trackpad will generally be softer than the actuation system, whereby, when the haptic event is fired, the vast majority of the energy will be lost in the trackpad, while the sensor remains almost stationary. Accordingly, an improved test probe for a haptic device configured for mounting on a robotic arm, comprises: a contact tip configured for contacting the haptic device; a sensor configured for measuring a threshold force of the piezoelectric actuator device, and an haptic characteristic, e.g. acceleration, of a resulting haptic response thereof at a same time and a same location; and a compliant element configured for enabling the sensor to move relative to the haptic device.