Bezier curve smoothing

Hey I've made an app that connects to bluetooth(my arduino). The function of the app is dividing a curve into a number of points and sendin the difference in slope from previous slope(change in heading) to my arduino. However the change in heading it sends is very arbitrary and ive figured its likely due to handdrawing the curve. Are there any extensions to smoothen the curve or any method. I've tried EMA and the average method but it doesnt help at all. P.S: if there are any non-software ways of solving this like a specific pen or drawing style lmk

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