A FPGA haptics controller

Wearable haptics necessitates using low power, small, inexpensive tactors that are typically used as pager motors in cellular phones. One of their limitations is that it appears that control of their amplitude and frequency of operation is inherently linked. Existing haptics controllers have shortcomings such as limiting the electrical stimulation frequency to a single one or multiples of one, being confined to only a square wave, not being able to change the polarity and duty cycle on the fly to name a few. In order to explore and help define the electrical to mechanical mapping for electromagnetic (and other) tactors, a tighter controller is necessary. We report on such a controller that we developed based on FPGA (Field Programmable Gate Array) technology. The FPGA gate control program is hardware-based and is not limited by micro-controller event handling. The paper reports on our FPGA controller design and provides some examples of its use.