Question Motor Control Theory

Hello all!

I have recently started to play around with stepper motor control and I have gotten a little stuck and would like any advice on a way forward.

So far I have managed to use the SMC3 "Target" value to control a stepper motor and follow any waveform generated by the utility. But..... I have encountered a flaw in the accelstepper library in arduino. For those who don't know, the accelstepper library applies an acceleration/deceleration to any movement performed by the stepper motor. While this is great for moving point to point, I have found that when following a sine wave motion profile the motor will jitter into position. I think this is because a new target value is given in quick succession and the stepper motor does an acceleration/deceleration for each target value. The motor does not have enough time to complete the movement before a new target position is sent and thus the motor stops part way through the movement and tries to accelerate to the new position. One thought was to ignore any new positions until the first position was reached but the flaw in this design is that the motor will decelerate upon reaching the position, which is unwanted as the motor should move smoothly the whole path of the sine wave.
While it would be smoother there still would be jitter in moments when the motor gets to the given positions.

So, in my mind what needs to happen is to feed the positional data to the controller and get the motor to move there as usual. But only apply a deceleration if no new positional data is given, so while following a sine wave the controller should tell the motor to accelerate to the position and if a new position is given, continue to that position rather than calculate a new acceleration curve for every new position.

It is all well and good of me to say this but I am still very new to coding and I am not too sure how to handle this or if it is even the correct direction to go. I'm not asking anyone to write the code for me but any pointers or advice would be greatly appreciated.

@Alexey I like your approach, probably @BlazinH, @vthinsel or @RufusDufus may help here.