Novel Dynamic Braille Characters: Cam Based Actuation

The goal was to create an affordable, dependable, and integrated device that could supplement or even replace current piezoelectric technology-based solutions. To address these challenges, mechanical cams with varying shapes and actuators have been utilized to regulate the position of the pins that construct the Braille character. Cams possess the capability to achieve precise movements and withstand high external forces. Three Braille cell designs that are based on cams have been developed through an iterative process as miniaturization of components posed new issues due to the limited surface area allotted by the standard, roughly 5x10 mm for a character consisting of 6 dots. In particular, a first version based on multi-cycle camshafts was created, i.e. cams that completes more than one rise/fall cycle for each full revolution. Then, a way to more easily couple stepper motors became necessary in order to enhance integrability, so a similar version of the mechanism was therefore created. It is equipped with cylindrical cams nested from the bottom instead of simple cams from the side. This not only allowed direct coupling of the motors to the shafts, but also increased their diameter, thus reducing pressure angles with the followers (namely the pins that will form the characters) and the risk of jamming. A complete prototype of the first device was also built, including motors and control hardware, while for the second one, the focus was only on mechanical aspects. At the end a new design has been developed using Shape Memory Alloys as core actuators, allowing each actuation cam to operate independently from the others, simplifying not only the control algorithm, but also the shape of the cams themselves. As they no longer need to complete multiple cycles for each rotation, they now have a simpler profile that is easier to miniaturize.