bigjogle:
PeterH:
I think you'll really struggle to achieve that if the only position feedback you've got is a couple of limit switches.It would be possible to achieve this using a constant motor speed and a mechanical crank system to give a sinusoidal speed output if you want
The mechanical method is out (scotch yoke provides rotational to linear sinusoidal motion). This will be in use for a number of years and the wear on a mechanical system is too great. (btw this will be running for 25000 cycles per test, ~40 tests per year, should last about 3 yrs w/o too many expensive replacements)
Those numbers come out at 3 million revolutions of a cam, and sound more like an answer than a problem. The same sort of number a farm pump might come up with in less than a month of operation.