FPGA-based Controllers for Compact Low Power Refreshable Braille Display

Refreshable Braille Displays (RBD) are electromechanical devices used by people with visual impairment to access textual e-content using a tactile display interface. RBD systems developed using the Shape Memory Alloy (SMA) wires pose various challenges of controlling a large number of SMA actuators, supplying high driving current for quick response and implementing an active closed loop control for encompassing variations in operating conditions and mechanical tolerances. These challenges can be addressed with two different hardware architectures: a microcontroller-based and an FPGA-based power controller. In this paper, a novel FPGA-based embedded power controller is proposed and implemented for the SMA actuators used in RBD. It further compares the device's performance, size, cost and energy efficiency with the microcontroller-based system and also emphasizes the role of programmable logic devices like FPGAs in replicating a closed loop actuator control where multiple channels like SMA actuators are involved.