Ask or search…

Systems in Homeostasis

Throughout the world, systems containing many parts work together to achieve homeostasis; Our robot is no different.


Basic systems include, a single Estimator, a single Feedback controller, and a single Feedforward Controller.
BasicSystem(Estimator estimator, FeedbackController feedbackController,
FeedforwardController feedforwardController);
If you wish to not use any of these features that is okay! Just pass in the "No" or "Raw" versions of each interface!


This is a slightly more complex system that attempts to control both position and velocity at the same time. This uses two feedback controllers, two estimators, and a single feedforward.
public PositionVelocitySystem(Estimator positionEstimator,
Estimator velocityEstimator,
FeedforwardController feedforward,
FeedbackController positionFeedback,
FeedbackController velocityFeedback);

Example systems

Basic Motor Control

PIDCoefficients coefficients = new PIDCoefficients(0.3,0.04,0.01);
DoubleSupplier motorPosition = new DoubleSupplier() {
public double getAsDouble() {
return exampleMotor.getPosition();
BasicPID controller = new BasicPID(coefficients);
NoFeedforward feedforward = new NoFeedforward();
RawValue noFilter = new RawValue(motorPosition);
BasicSystem system = new BasicSystem(noFilter,controller,feedforward);
while (true) {
double command = system.update(referencePosition);
The above example demonstrates the basic syntax for systems.

Full State with PID

Effectively Full State feedback and Full State Estimation using two PID's and two Kalman Filters.
double Q = 0.3;
double R = 3;
int N = 3;
PIDCoefficients posCoefficients = new PIDCoefficients(0.1,0,0);
PIDCoefficients veloCoefficients = new PIDCoefficients(0.1,0,0);
BasicPID posControl = new BasicPID(posCoefficients);
BasicPID veloControl = new BasicPID(veloCoefficients);
DoubleSupplier motorPosition = new DoubleSupplier() {
public double getAsDouble() {
return exampleMotor.getPosition();
DoubleSupplier motorVelocity = new DoubleSupplier() {
public double getAsDouble() {
return exampleMotor.getVelocity();
KalmanEstimator positionFilter = new KalmanEstimator(motorPosition,Q,R,N);
KalmanEstimator velocityFilter = new KalmanEstimator(motorVelocity,Q,R,N);
FeedforwardCoefficients coefficientsFF = new FeedforwardCoefficients(0.1,0.3,0.001);
BasicFeedforward feedforward = new BasicFeedforward(coefficientsFF);
PositionVelocitySystem system =
new PositionVelocitySystem(positionFilter,
while (true) {
// x,v,a is short hand for position, velocity, acceleration targets
double command = system.update(x,v,a);

Feedforward Only

Sometimes we might not have a sensor available to us and as a result feedforward is our only option!
double Kv = 0.1;
double Ka = 0.3;
double Ks = 0.001;
double Kg = 0.1;
double Kcos = 0;
Estimator none = new NoSensor();
NoFeedback none2 = new NoFeedback();
FeedforwardCoefficientsEx coefficientsEx = new FeedforwardCoefficientsEx(Kv,Ka,Ks,Kg,Kcos);
FeedforwardEx controller = new FeedforwardEx(coefficientsEx);
BasicSystem system = new BasicSystem(none,none2,controller);
while (true) {
double command = system.update(x,v,a);
Last modified 1mo ago