In the process of researching something else i ran across a really interesting very early multi dimensional electronic keyboard.
It’s called the Moog Eaton Multiple-Touch-Sensitive ( MTS ) Keyboard. It was developed collaboratively by composer musician John Eaton and Bob Moog over the course of 20 years or so starting in 1970.
When complete it could sense five dimensions of expression. You might find this familiar. ( Compare it to the ROLI Seaboard. ) Here’s the description of those dimensions, taken from a short report written about that project.
Each key, independently of all the others, sends out five independent eight-bit data streams that tell the current values of a) the left-to-right position of the player’s finger, b) the front-to-back position of the player’s finger, c) the area of the surface of the player’s finger that is touching the key surface, d) the depth to which the key is depressed, and e) the force with which the key is depressed after it reaches the lower limit of its travel.
There are various articles about this, so here is just one.
There’s a great product recreation for the present day Moog corporation to take on, using modern electronics.