Have an idea for a project, inspired by Braille readers, creating either a single character cell (2x3 or 2x4) or even fewer mechanical pins, connected to a couple of ultrasonic distance sensors, for a handheld (battery powered) device for scanning surroundings in darkness (or if blind), with feedback to a finger, by vibrating pins at different intensity, for an interactive feel.
This is the hard part, although I know from experience that ultrasonic sensors can be quite unreliable, depending on textures and stuff, but I think of this as a handheld device, that one would point around, scanning horizontally or vertically, covering a lot of angles quickly, and getting feedback whenever there is an echo.
The mechanical feedback, vibrating a pin in contact with your thumb is the problem.
I've looked into solenoids, but they seem to draw a lot of current, even when pulsed, as such a device would more or less pulse one or more pins at any time, with differing intensity according to measurements from sonars. Also solenoids tend to be bulky.
I'm considering making my own inductor coils, using thin copper wire.
But first I just wanted to ask for ideas.
The aim is to vibrate small rods, with minimal power requirements, and just enough force to be felt on the skin.