Haptic feedback solutions are not completely unknown in the automotive domain. For example, virtual buttons on display screens are already implemented in some series vehicles. However, such solutions can be found in just 5 to 6% of the cars worldwide, explains Harsha Rao, manager Haptics and Sensing at Cirrus Logic. Rao wants to change that – the company targets a margin of 20 to 25% of cars to be equipped with such solutions. Possible application fields are not only the known solutions for display screens but likewise similar haptics for all kinds of buttons across the car. “Touchpads, door handles, steering wheels – we see a potential of up to 100 million cars to use some kind of haptics”, explains Rao. “We are very early in this journey.”
There are several different approaches how haptic feedback in the context of a human-machine interface (HMI) can be implemented. According to Rao, today the use of of voice coil motors (VCMs) is prevalent, in particular in consumer devices such as smartphones. Another approach is linear resonant actuators (LRAs). “This technology is also well adopted in the smartphone market and available for automotive designs as well,” Rao says. More a theoretical choice is the piezo technology, because it needs relatively high operating voltages, which would lead to more complicated electronics.
To implement a haptic feedback solution that is perceived “natural” by the operator, the system needs to be fast, the feedback impulse must be felt with minimum delay; according to Rao, a maximum of about 50 milliseconds could be acceptable. To generate a “natural” feeling and enable users at the same time to create something like a “haptic brand identity”, Cirrus provides a free waveform design tool for customers of its haptic feedback devices.