The client’s movement ability is restricted to one hand which can operate a computer mouse. The request was for a device to enable him to bring a cup (and straw) into the drinking position when required and to retract the cup as needed.
A frame holding bearings and a light vertical shaft with an arm to hold the cup was made. The drive is by a disc on the shaft, against which the output shaft of a small, low voltage motor/gearbox is spring loaded. Control gear enables the client to advance or retract the cup holder by pressing one of two buttons.
The carers can leave a drink for the client and he can access it at will. The advantage is that the cup holder cannot hurt the client even if he holds the button down for too long.