Design Related - what kind of non linear curve for movement?

I was just adding acceleration and the inverse to Roaming Ralph, instead of being an on/off case for his forward input, and I thought the sin curve would be tight and responsive. Then, whenever the button is released, he needs to decelarate, and I thought a constant decrease would be more suitable. Here’s the code:

def move(self, task):
		# If a key is pressed, move Ralph in that direction
		if (self.keyMap["forward"] != 0):
			if self.counter < 90:
				self.counter += 6
				self.accel = 25 * sin(self.counter * pi/180)
			self.ralph.setY(self.ralph, -self.accel * globalClock.getDt())
			if self.counter > 0:
				self.counter -= 6
				self.deccel = 25 * self.counter/180
				self.ralph.setY(self.ralph, -self.deccel * globalClock.getDt())
		if (self.keyMap["left"] != 0):
			self.ralph.setH(self.ralph.getH() + 300 * globalClock.getDt())
		if (self.keyMap["right"] != 0):
			self.ralph.setH(self.ralph.getH() - 300 * globalClock.getDt())

The feel is nice, even if it was a small change. What I’m asking here is suggestions for other types of curves.

Hmm… Other than trying a simple linear acceleration, I’m not sure of what else to suggest; I imagine that sine would llkely be the curve that I’d use. I note that you’re using linear deceleration; have you tried sine for that, too?

I tried it, but I didn’t like it that much. It takes too long to decelerate.