I would use something similar to this
- (robotic arm from Maplin) but stronger so it could lift heavier objects and turn heavier dials such as bath taps. I would interface this with the Raspberry Pi and use the program to make certain buttons on the web site do certain moves on the program. I would try to do this without wires. I would use the the Pi also to move the linear motor that would make it variable height. This would be on a platform underneath the arm. A small scissor lift really.