Software Design Limit Switches?

Wonder if anyone can give me some advice??

I’m using a Pololu trex dual motor controller to turn a gear wheel which drives a mechanical component from one end of travel to another .

The problem I have is the mechanisim I’m working with is VERY tight on space and fitting limit switches would be a nightmare.

Now the trex controller has a software defined current limit switch. I was thinking that if I set the current limit switch high enough to drive the motor but low enough to cut out when the motor reaches the endstop then all of my problems would be solved?

Is this bad practice or has anyone used this technique before or some similar alternative to a limit switch??




Whether you can use current sensing for your limit switch will depend on the particulars of your system. You will definitely want to monitor the current and actually stop driving the motors when you exceed your current limit, as opposed to maintaining the current at the limit (the TReX supports both of these modes).

Can you use some other sensor or timing to at least predict when your mechanism is about to crash into the end so that you could slow it down to limit the impact? On thing to keep in mind is that if you do lower the power to the motor, the current in the stalled case will also be lower.

- Jan

Thanks Jan, I think I will experiment a little and see what happens. First off I will build a small test rig and use the pololu TreX dashboard software to monitor what’s happenning with drive current and the effects of current limiting.