Constant deceleration for chassis

Programming Support PROS Support
1

For my chassis, I would like to let it decelerate while moving towards a certain position. I don’t know if I should be using a linear motion profile controller (okapi), since it seems to also have an acceleration period at the start. I tried writing a piece of code that applies acceleration depending on a supplied function, but I haven’t tested it yet. Can anyone help me verify what I wrote? Or is it even necessary to achieve what I want?

The accel parameter takes in errors from the target in encoder ticks, and returns an acceleration in rpm/s.

accelerateTo(QLength itarget, double iinitialVel,
	std::function<double(int, int)> accel) {
	const double maxVelocity = toUnderlyingType(gearsetRatioPair.internalGearset);
	setMaxVelocity(maxVelocity);

	const int newTarget = itarget.convert(meter) * scales.straight * gearsetRatioPair.ratio;
	const QTime dt = 10_ms;
	const double timeRatio = dt.convert(second);

	double currentVel = iinitialVel;
	const auto encStartVals = chassisModel->getSensorVals();
	int leftError = newTarget;
	int rightError = newTarget;
	while (!settledUtil->isSettled(leftError) && !settledUtil->isSettled(rightError)) {
		chassisModel->left(currentVel / maxVelocity);
		chassisModel->right(currentVel / maxVelocity);
		currentVel += accel(leftError, rightError) * timeRatio;
		const auto enc = chassisModel->getSensorVals();
		leftError = newTarget - enc[0];
		rightError = newTarget - enc[1];
		rate->delayUntil(dt);
	}
	chassisModel->stop();
}
2

I would expect these lines to be at the beginning of the while. As it is dt time will pass between calculating error and using it.

This is essentially a P loop where the function accel() and timeRation somehow map to kp.

Also, const for a variable mean you cannot changes it value.

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