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gin66 / FastAccelStepper

A high speed stepper library for Atmega 168/328p (nano), Atmega32u4, Atmega 2560, ESP32, ESP32S2, ESP32S3, ESP32C3 and Atmel SAM Due
MIT License
282 stars 67 forks source link

Multistage ramps #229

Closed Matesxs closed 5 months ago

Matesxs commented 5 months ago

Hi, thank you for pretty awesome library, but I have one request to make. I am working on application that will require multistage acceleration something like TMC motion controllers provide. image Obviously I could invest in this motion controller and get that functionality but that will only add cost to this device so I would like to ask if it would be possible to add similar functionality to this library. I dont need separated accelleration and deccelleration speeds like shown on that graph I only need two ramps with different accelleration values.

gin66 commented 5 months ago

Don‘t get it. You need different values for acceleration and deceleration ? Or different acceleration values and/or deceleration values according to the ramp (speed) ? Or different acceleration for two consecutive ramps ?

In the first case, the application could just evaluate rampState() in the main loop. If it changes to RAMP_STATE_ACCELERATE, call setAcceleration() with the required acceleration value and followed by applySpeedAcceleration(). If the rampState() changes to RAMP_STATE_DECELERATE, call setAcceleration() with the required deceleration value and again followed by applySpeedAcceleration(). Recommended is to call setAcceleration() once on change of ramp state and not during every main loop iteration.

For different acceleration values along the ramp, the same can be done using getCurrentSpeedInxxx() and the speed values, where the acceleration value shall change.

For different values of consecutive ramps, just change the acceleration value before the next ramp starts.

Matesxs commented 5 months ago

No no, I dont need separated accellerations and decellerations, only different (smaller) acceleration values at the beggining and end of the ramp. Here is example what I would want to do: If speed is below like 50mm/s accelleration should be 200mm/s^2 and if speed is above 50mm/s then it should be 1000mm/s^2. Thas what I meant by multistage ramps.

gin66 commented 5 months ago

Ok. So you could use the proposed approach from the first case.

Or you look into setLinearAcceleration(), which allows to linearly increase the acceleration from 0 to the configured acceleration at begin and end of ramp.

Matesxs commented 5 months ago

Thank you for all your suggestions, at the end I endup using only setLinearAcceleration, it was good enough for my application but I still think that adding support for more complex linear ramps can be good thing. Thank you for your help :)