[Ether]

Originally Posted by Aero

our elevator is really fast. It's about 0.75 seconds from bottom to top.

First, take Adam's advice about gearing (post#13). Then...

Originally Posted by Aero

motion profiling really is what we want. How inefficient would it be to generate a new motion profile every time we change setpoints?

Well it depends on your definition of inefficient I guess.

If you need to change the setpoint only when the speed is zero, it's pretty straightforward to generate a sinusoidal profile for smooth acceleration and deceleration.

Given the max desired acceleration M and the distance D to the new position, compute the constants T, K₁, K₂, and K₃ as shown in the equations. Then you can use the functions a(t), v(t), and x(t) to generate a nice smooth trajectory to the new target. "t" is elapsed time from start of profile.

Note that T will be the time-to-destination and K₂ will be the maximum speed.

See the example profile for M=3.5 ft/s² and D=5 ft.