public void compute(
FrameVector output,
FrameOrientation desiredOrientation,
FrameVector desiredAngularVelocity,
FrameVector currentAngularVelocity,
FrameVector feedForward) {
computeProportionalTerm(desiredOrientation);
if (currentAngularVelocity != null)
computeDerivativeTerm(desiredAngularVelocity, currentAngularVelocity);
computeIntegralTerm();
output.setToZero(proportionalTerm.getReferenceFrame());
output.add(proportionalTerm);
output.add(derivativeTerm);
output.add(integralTerm);
// Limit the max acceleration of the feedback, but not of the feedforward...
// JEP changed 150430 based on Atlas hitting limit stops.
double feedbackAngularActionMagnitude = output.length();
double maximumAction = gains.getMaximumFeedback();
if (feedbackAngularActionMagnitude > maximumAction) {
output.scale(maximumAction / feedbackAngularActionMagnitude);
}
feedbackAngularAction.set(output);
rateLimitedFeedbackAngularAction.update();
rateLimitedFeedbackAngularAction.getFrameTuple(output);
feedForward.changeFrame(bodyFrame);
output.add(feedForward);
}
@ContinuousIntegrationTest(estimatedDuration = 0.0)
@Test(timeout = 30000)
public void testSingleRigidBodyRotation() {
Random random = new Random(1766L);
RigidBody elevator = new RigidBody("elevator", world);
Vector3d jointAxis = RandomTools.generateRandomVector(random);
jointAxis.normalize();
RigidBodyTransform transformToParent = new RigidBodyTransform();
transformToParent.setIdentity();
RevoluteJoint joint =
ScrewTools.addRevoluteJoint("joint", elevator, transformToParent, jointAxis);
RigidBody body =
ScrewTools.addRigidBody(
"body",
joint,
RandomTools.generateRandomDiagonalMatrix3d(random),
random.nextDouble(),
new Vector3d());
joint.setQ(random.nextDouble());
joint.setQd(random.nextDouble());
Momentum momentum = computeMomentum(elevator, world);
momentum.changeFrame(world);
FrameVector linearMomentum =
new FrameVector(momentum.getExpressedInFrame(), momentum.getLinearPartCopy());
FrameVector angularMomentum =
new FrameVector(momentum.getExpressedInFrame(), momentum.getAngularPartCopy());
FrameVector linearMomentumCheck = new FrameVector(world);
Matrix3d inertia = body.getInertia().getMassMomentOfInertiaPartCopy();
Vector3d angularMomentumCheckVector = new Vector3d(jointAxis);
angularMomentumCheckVector.scale(joint.getQd());
inertia.transform(angularMomentumCheckVector);
FrameVector angularMomentumCheck =
new FrameVector(body.getInertia().getExpressedInFrame(), angularMomentumCheckVector);
angularMomentumCheck.changeFrame(world);
double epsilon = 1e-9;
JUnitTools.assertTuple3dEquals(
linearMomentumCheck.getVector(), linearMomentum.getVector(), epsilon);
JUnitTools.assertTuple3dEquals(
angularMomentumCheck.getVector(), angularMomentum.getVector(), epsilon);
assertTrue(angularMomentum.length() > epsilon);
}
private void computeDerivativeTerm(
FrameVector desiredAngularVelocity, FrameVector currentAngularVelocity) {
desiredAngularVelocity.changeFrame(bodyFrame);
currentAngularVelocity.changeFrame(bodyFrame);
derivativeTerm.sub(desiredAngularVelocity, currentAngularVelocity);
// Limit the maximum velocity error considered for control action
double maximumVelocityError = gains.getMaximumDerivativeError();
double velocityErrorMagnitude = derivativeTerm.length();
if (velocityErrorMagnitude > maximumVelocityError) {
derivativeTerm.scale(maximumVelocityError / velocityErrorMagnitude);
}
velocityError.set(derivativeTerm);
derivativeGainMatrix.transform(derivativeTerm.getVector());
}