However, I am worried about pinch points. In the video, they are moving things in and out of the compartment. Even if the odds are small, I would rather not build a potential finger chopping machine.
Short of making a complicated light curtain, is this something unavoidable if I were to make it?
CoreyW384:
I was hoping to make a coffee table with a motorized cutout in the center that can rise to reveal glasses or whatever party trick you want. It is much like this one: https://www.youtube.com/watch?v=z9wSrrgJBDc
However, I am worried about pinch points. In the video, they are moving things in and out of the compartment. Even if the odds are small, I would rather not build a potential finger chopping machine.
Short of making a complicated light curtain, is this something unavoidable if I were to make it?
I wouldn't rely on software or an Arduino for safety. Leave a gap around the moving and non-moving parts sufficient for a finger to fit without being pinched. Fill the gap with a brush-like gap filler.
Maybe fit the mechanical side of things with a clutch of sorts that will only allow a certain force to be transferred before slipping.
You can add speed and over-current testing to the motor control logic (a stalled motor draws more current than one running normally) but I wouldn't rely only on software/Arduino measures for safety.
For inspiration look at the behaviour of the sliding tray mechanism used in old CD players.
Mechanical - Use a drive belt or clutch that slips above a specific torque.
Electronic - If the measured motion doesn't correlate with the drive signal then reverse the direction, pause for two seconds and try again. After some number of attempts, stay open and flag an error.