Depends what is going to be on the conveyor. Is it a 7ft stack of bagged gelatin or a 1ft cube of dense foam?
The simplest solution that works is usually best, so if it's anything that can handle some jostling then I'd say a couple of mechanical hard stops and motion control by a timer is sufficient. A little slip in the mechanical drive train by a clutch or belt so it can (intentionally, and semi-gracefully) hit the hard stop 5000 times per day without destroying itself. You probably don't even need a VFD; just a reversing contactor pair. There is only one parameter that can be screwed with (timer) and it would only ever need to be screwed with once. After that it should be accurate, repeatable, simple and obvious in its operation, and easy to service. Not very ***y though.
If it's stacked jelly bags though, then you need something more. I would still put in hard stops but they should never be reached except in an over travel event. Ramp profiles based on encoder position. It should gently accelerate, decelerate, and stop based on encoder counts. Prox sensors at both ends (and maybe one in the middle) of travel to confirm/auto-calibrate position and/or generate an error, but not as the signal to actually stop.
The simplest solution that works is usually best, so if it's anything that can handle some jostling then I'd say a couple of mechanical hard stops and motion control by a timer is sufficient. A little slip in the mechanical drive train by a clutch or belt so it can (intentionally, and semi-gracefully) hit the hard stop 5000 times per day without destroying itself. You probably don't even need a VFD; just a reversing contactor pair. There is only one parameter that can be screwed with (timer) and it would only ever need to be screwed with once. After that it should be accurate, repeatable, simple and obvious in its operation, and easy to service. Not very ***y though.
If it's stacked jelly bags though, then you need something more. I would still put in hard stops but they should never be reached except in an over travel event. Ramp profiles based on encoder position. It should gently accelerate, decelerate, and stop based on encoder counts. Prox sensors at both ends (and maybe one in the middle) of travel to confirm/auto-calibrate position and/or generate an error, but not as the signal to actually stop.