Class PIDController<T>

Namespace: mobisim.Actors.Vehicle

Generic PID (Proportional-Integral-Derivative) controller base class. Computes a corrective output from a measured error signal to continuously drive a system toward a desired setpoint.

[Serializable]
public abstract class PIDController<T>

Type Parameters

Name	Type	Description
T		Numeric or vector type that the controller operates on.

Inheritance

object→PIDController<T>

Examples

Use the concrete FloatPIDController subclass to regulate vehicle throttle each FixedUpdate. The error is the difference between the desired speed and the current speed; GetOutput returns a throttle value that the car controller consumes:

[SerializeField] private FloatPIDController _throttlePID; // tuned in Inspector
[SerializeField] private PrometeoCarController _car;

private float _targetSpeed = 10f; // m/s

private void FixedUpdate()
{
    float error  = _targetSpeed - _car.CurrentSpeed;
    float throttle = _throttlePID.GetOutput(error, Time.fixedDeltaTime);
    _car.Move(new Vector2(0f, Mathf.Clamp(throttle, -1f, 1f)));
}

// Call Reset() whenever the setpoint changes abruptly — e.g. after a new waypoint
// is assigned — to flush the integral accumulator and prevent I-term windup from
// the previous tracking run.
private void OnNewWaypointAssigned()
{
    _throttlePID.Reset();
}

Remarks

A PID controller is used instead of simpler bang-bang control because it produces smooth, continuous outputs that avoid abrupt jerks in vehicle motion — important both for realistic simulation fidelity and for preventing motion sickness in VR participants.

The three terms serve distinct roles: the P term reacts proportionally to the current error (how far off-target the vehicle is now); the I term accumulates persistent error over time (removes steady-state offset, e.g. a constant speed deficit on an incline); the D term damps oscillations by opposing rapid error changes (prevents overshoot). Concrete subclasses FloatPIDController and Vector3PIDController implement the type-specific arithmetic.

Constructors

PIDController()

Initializes a new instance of the PIDController class with default coefficients.

public PIDController()

PIDController(float, float, float)

Initializes a new instance of the PIDController class with specified coefficients.

public PIDController(float pFactor, float iFactor, float dFactor)

Parameters

Name	Type	Description
pFactor	float	Proportional gain.
iFactor	float	Integral gain.
dFactor	float	Derivative gain.

Fields

Coefficients

Current set of PID tuning coefficients.

[SerializeField]
[FormerlySerializedAs("PIDCoefficients")]
public PIDController<T>.PIDFactors Coefficients

Field Value

PIDController<T>.PIDFactors

derivativeInitialized

Guards the derivative term against an infinite spike on the very first call. On frame zero previousError is the default value for T, so (error - previousError) / deltaTime would produce an enormous derivative output. This flag suppresses the D-term for the first tick and is cleared by Reset.

protected bool derivativeInitialized

Field Value

bool

iTerm

Accumulated integral term.

protected T iTerm

Field Value

T

previousError

The previous error value, used to compute the derivative term.

protected T previousError

Field Value

T

Methods

ComputeOutput(T, float)

Performs the type-specific PID computation: calculates the proportional, integral, and derivative contributions and combines them according to the tuning coefficients.

protected abstract T ComputeOutput(T error, float deltaTime)

Parameters

Name	Type	Description
error	T	The current error value.
deltaTime	float	Time in seconds since the last update.

Returns

T — The raw PID output before any external scaling or clamping.

GetOutput(T, float)

Computes the PID controller output based on the current error and elapsed time.

public T GetOutput(T error, float deltaTime)

Parameters

Name	Type	Description
error	T	The difference between the desired setpoint and the current value.
deltaTime	float	Time in seconds since the last update; must be greater than zero.

Returns

T — The control output calculated by the PID algorithm.

Reset()

Resets the controller's internal state (derivative initialization flag and integral accumulator) while retaining the current tuning coefficients.

public void Reset()

Remarks

Call this method whenever the tracking target changes abruptly — for example, after the vehicle is assigned a new waypoint, when the desired speed setpoint jumps discontinuously, or when a PID-controlled loop is re-enabled after being paused. Without a reset, the integral term retains error accumulated during the previous tracking run and will drive the output in the wrong direction immediately after the target change (I-term windup). Resetting also suppresses the spurious derivative spike that would otherwise occur on the first tick after re-activation, because previousError would hold a stale value from the prior run.