opensim – Rev 1
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using System;
using System.Collections.Generic;
using System.Text;
using OpenMetaverse;
using OpenSim.Framework;
namespace OpenSim.Region.Physics.BulletSPlugin
{
public abstract class BSMotor
{
// Timescales and other things can be turned off by setting them to 'infinite'.
public const float Infinite = 12345.6f;
public readonly static Vector3 InfiniteVector = new Vector3(BSMotor.Infinite, BSMotor.Infinite, BSMotor.Infinite);
public BSMotor(string useName)
{
UseName = useName;
PhysicsScene = null;
Enabled = true;
}
public virtual bool Enabled { get; set; }
public virtual void Reset() { }
public virtual void Zero() { }
public virtual void GenerateTestOutput(float timeStep) { }
// A name passed at motor creation for easily identifyable debugging messages.
public string UseName { get; private set; }
// Used only for outputting debug information. Might not be set so check for null.
public BSScene PhysicsScene { get; set; }
protected void MDetailLog(string msg, params Object[] parms)
{
if (PhysicsScene != null)
{
PhysicsScene.DetailLog(msg, parms);
}
}
}
// Motor which moves CurrentValue to TargetValue over TimeScale seconds.
// The TargetValue decays in TargetValueDecayTimeScale.
// This motor will "zero itself" over time in that the targetValue will
// decay to zero and the currentValue will follow it to that zero.
// The overall effect is for the returned correction value to go from large
// values to small and eventually zero values.
// TimeScale and TargetDelayTimeScale may be 'infinite' which means no decay.
// For instance, if something is moving at speed X and the desired speed is Y,
// CurrentValue is X and TargetValue is Y. As the motor is stepped, new
// values of CurrentValue are returned that approach the TargetValue.
// The feature of decaying TargetValue is so vehicles will eventually
// come to a stop rather than run forever. This can be disabled by
// setting TargetValueDecayTimescale to 'infinite'.
// The change from CurrentValue to TargetValue is linear over TimeScale seconds.
public class BSVMotor : BSMotor
{
// public Vector3 FrameOfReference { get; set; }
// public Vector3 Offset { get; set; }
public virtual float TimeScale { get; set; }
public virtual float TargetValueDecayTimeScale { get; set; }
public virtual float Efficiency { get; set; }
public virtual float ErrorZeroThreshold { get; set; }
public virtual Vector3 TargetValue { get; protected set; }
public virtual Vector3 CurrentValue { get; protected set; }
public virtual Vector3 LastError { get; protected set; }
public virtual bool ErrorIsZero()
{
return ErrorIsZero(LastError);
}
public virtual bool ErrorIsZero(Vector3 err)
{
return (err == Vector3.Zero || err.ApproxEquals(Vector3.Zero, ErrorZeroThreshold));
}
public BSVMotor(string useName)
: base(useName)
{
TimeScale = TargetValueDecayTimeScale = BSMotor.Infinite;
Efficiency = 1f;
CurrentValue = TargetValue = Vector3.Zero;
ErrorZeroThreshold = 0.001f;
}
public BSVMotor(string useName, float timeScale, float decayTimeScale, float efficiency)
: this(useName)
{
TimeScale = timeScale;
TargetValueDecayTimeScale = decayTimeScale;
Efficiency = efficiency;
CurrentValue = TargetValue = Vector3.Zero;
}
public void SetCurrent(Vector3 current)
{
CurrentValue = current;
}
public void SetTarget(Vector3 target)
{
TargetValue = target;
}
public override void Zero()
{
base.Zero();
CurrentValue = TargetValue = Vector3.Zero;
}
// Compute the next step and return the new current value.
// Returns the correction needed to move 'current' to 'target'.
public virtual Vector3 Step(float timeStep)
{
if (!Enabled) return TargetValue;
Vector3 origTarget = TargetValue; // DEBUG
Vector3 origCurrVal = CurrentValue; // DEBUG
Vector3 correction = Vector3.Zero;
Vector3 error = TargetValue - CurrentValue;
if (!ErrorIsZero(error))
{
correction = StepError(timeStep, error);
CurrentValue += correction;
// The desired value reduces to zero which also reduces the difference with current.
// If the decay time is infinite, don't decay at all.
float decayFactor = 0f;
if (TargetValueDecayTimeScale != BSMotor.Infinite)
{
decayFactor = (1.0f / TargetValueDecayTimeScale) * timeStep;
TargetValue *= (1f - decayFactor);
}
MDetailLog("{0}, BSVMotor.Step,nonZero,{1},origCurr={2},origTarget={3},timeStep={4},err={5},corr={6}",
BSScene.DetailLogZero, UseName, origCurrVal, origTarget,
timeStep, error, correction);
MDetailLog("{0}, BSVMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},tgt={4},curr={5}",
BSScene.DetailLogZero, UseName, TargetValueDecayTimeScale, decayFactor, TargetValue, CurrentValue);
}
else
{
// Difference between what we have and target is small. Motor is done.
if (TargetValue.ApproxEquals(Vector3.Zero, ErrorZeroThreshold))
{
// The target can step down to nearly zero but not get there. If close to zero
// it is really zero.
TargetValue = Vector3.Zero;
}
CurrentValue = TargetValue;
MDetailLog("{0}, BSVMotor.Step,zero,{1},origTgt={2},origCurr={3},currTgt={4},currCurr={5}",
BSScene.DetailLogZero, UseName, origCurrVal, origTarget, TargetValue, CurrentValue);
}
LastError = error;
return correction;
}
// version of step that sets the current value before doing the step
public virtual Vector3 Step(float timeStep, Vector3 current)
{
CurrentValue = current;
return Step(timeStep);
}
// Given and error, computer a correction for this step.
// Simple scaling of the error by the timestep.
public virtual Vector3 StepError(float timeStep, Vector3 error)
{
if (!Enabled) return Vector3.Zero;
Vector3 returnCorrection = Vector3.Zero;
if (!ErrorIsZero(error))
{
// correction = error / secondsItShouldTakeToCorrect
Vector3 correctionAmount;
if (TimeScale == 0f || TimeScale == BSMotor.Infinite)
correctionAmount = error * timeStep;
else
correctionAmount = error / TimeScale * timeStep;
returnCorrection = correctionAmount;
MDetailLog("{0}, BSVMotor.Step,nonZero,{1},timeStep={2},timeScale={3},err={4},corr={5}",
BSScene.DetailLogZero, UseName, timeStep, TimeScale, error, correctionAmount);
}
return returnCorrection;
}
// The user sets all the parameters and calls this which outputs values until error is zero.
public override void GenerateTestOutput(float timeStep)
{
// maximum number of outputs to generate.
int maxOutput = 50;
MDetailLog("{0},BSVMotor.Test,{1},===================================== BEGIN Test Output", BSScene.DetailLogZero, UseName);
MDetailLog("{0},BSVMotor.Test,{1},timeScale={2},targDlyTS={3},eff={4},curr={5},tgt={6}",
BSScene.DetailLogZero, UseName,
TimeScale, TargetValueDecayTimeScale, Efficiency,
CurrentValue, TargetValue);
LastError = BSMotor.InfiniteVector;
while (maxOutput-- > 0 && !ErrorIsZero())
{
Vector3 lastStep = Step(timeStep);
MDetailLog("{0},BSVMotor.Test,{1},cur={2},tgt={3},lastError={4},lastStep={5}",
BSScene.DetailLogZero, UseName, CurrentValue, TargetValue, LastError, lastStep);
}
MDetailLog("{0},BSVMotor.Test,{1},===================================== END Test Output", BSScene.DetailLogZero, UseName);
}
public override string ToString()
{
return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4}>",
UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale);
}
}
// ============================================================================
// ============================================================================
public class BSFMotor : BSMotor
{
public virtual float TimeScale { get; set; }
public virtual float TargetValueDecayTimeScale { get; set; }
public virtual float Efficiency { get; set; }
public virtual float ErrorZeroThreshold { get; set; }
public virtual float TargetValue { get; protected set; }
public virtual float CurrentValue { get; protected set; }
public virtual float LastError { get; protected set; }
public virtual bool ErrorIsZero()
{
return ErrorIsZero(LastError);
}
public virtual bool ErrorIsZero(float err)
{
return (err >= -ErrorZeroThreshold && err <= ErrorZeroThreshold);
}
public BSFMotor(string useName, float timeScale, float decayTimescale, float efficiency)
: base(useName)
{
TimeScale = TargetValueDecayTimeScale = BSMotor.Infinite;
Efficiency = 1f;
CurrentValue = TargetValue = 0f;
ErrorZeroThreshold = 0.01f;
}
public void SetCurrent(float current)
{
CurrentValue = current;
}
public void SetTarget(float target)
{
TargetValue = target;
}
public override void Zero()
{
base.Zero();
CurrentValue = TargetValue = 0f;
}
public virtual float Step(float timeStep)
{
if (!Enabled) return TargetValue;
float origTarget = TargetValue; // DEBUG
float origCurrVal = CurrentValue; // DEBUG
float correction = 0f;
float error = TargetValue - CurrentValue;
if (!ErrorIsZero(error))
{
correction = StepError(timeStep, error);
CurrentValue += correction;
// The desired value reduces to zero which also reduces the difference with current.
// If the decay time is infinite, don't decay at all.
float decayFactor = 0f;
if (TargetValueDecayTimeScale != BSMotor.Infinite)
{
decayFactor = (1.0f / TargetValueDecayTimeScale) * timeStep;
TargetValue *= (1f - decayFactor);
}
MDetailLog("{0}, BSFMotor.Step,nonZero,{1},origCurr={2},origTarget={3},timeStep={4},err={5},corr={6}",
BSScene.DetailLogZero, UseName, origCurrVal, origTarget,
timeStep, error, correction);
MDetailLog("{0}, BSFMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},tgt={4},curr={5}",
BSScene.DetailLogZero, UseName, TargetValueDecayTimeScale, decayFactor, TargetValue, CurrentValue);
}
else
{
// Difference between what we have and target is small. Motor is done.
if (Util.InRange<float>(TargetValue, -ErrorZeroThreshold, ErrorZeroThreshold))
{
// The target can step down to nearly zero but not get there. If close to zero
// it is really zero.
TargetValue = 0f;
}
CurrentValue = TargetValue;
MDetailLog("{0}, BSFMotor.Step,zero,{1},origTgt={2},origCurr={3},ret={4}",
BSScene.DetailLogZero, UseName, origCurrVal, origTarget, CurrentValue);
}
LastError = error;
return CurrentValue;
}
public virtual float StepError(float timeStep, float error)
{
if (!Enabled) return 0f;
float returnCorrection = 0f;
if (!ErrorIsZero(error))
{
// correction = error / secondsItShouldTakeToCorrect
float correctionAmount;
if (TimeScale == 0f || TimeScale == BSMotor.Infinite)
correctionAmount = error * timeStep;
else
correctionAmount = error / TimeScale * timeStep;
returnCorrection = correctionAmount;
MDetailLog("{0}, BSFMotor.Step,nonZero,{1},timeStep={2},timeScale={3},err={4},corr={5}",
BSScene.DetailLogZero, UseName, timeStep, TimeScale, error, correctionAmount);
}
return returnCorrection;
}
public override string ToString()
{
return String.Format("<{0},curr={1},targ={2},lastErr={3},decayTS={4}>",
UseName, CurrentValue, TargetValue, LastError, TargetValueDecayTimeScale);
}
}
// ============================================================================
// ============================================================================
// Proportional, Integral, Derivitive ("PID") Motor
// Good description at http://www.answers.com/topic/pid-controller . Includes processes for choosing p, i and d factors.
public class BSPIDVMotor : BSVMotor
{
// Larger makes more overshoot, smaller means converge quicker. Range of 0.1 to 10.
public Vector3 proportionFactor { get; set; }
public Vector3 integralFactor { get; set; }
public Vector3 derivFactor { get; set; }
// The factors are vectors for the three dimensions. This is the proportional of each
// that is applied. This could be multiplied through the actual factors but it
// is sometimes easier to manipulate the factors and their mix separately.
public Vector3 FactorMix;
// Arbritrary factor range.
// EfficiencyHigh means move quickly to the correct number. EfficiencyLow means might over correct.
public float EfficiencyHigh = 0.4f;
public float EfficiencyLow = 4.0f;
// Running integration of the error
Vector3 RunningIntegration { get; set; }
public BSPIDVMotor(string useName)
: base(useName)
{
proportionFactor = new Vector3(1.00f, 1.00f, 1.00f);
integralFactor = new Vector3(1.00f, 1.00f, 1.00f);
derivFactor = new Vector3(1.00f, 1.00f, 1.00f);
FactorMix = new Vector3(0.5f, 0.25f, 0.25f);
RunningIntegration = Vector3.Zero;
LastError = Vector3.Zero;
}
public override void Zero()
{
base.Zero();
}
public override float Efficiency
{
get { return base.Efficiency; }
set
{
base.Efficiency = Util.Clamp(value, 0f, 1f);
// Compute factors based on efficiency.
// If efficiency is high (1f), use a factor value that moves the error value to zero with little overshoot.
// If efficiency is low (0f), use a factor value that overcorrects.
// TODO: might want to vary contribution of different factor depending on efficiency.
// float factor = ((1f - this.Efficiency) * EfficiencyHigh + EfficiencyLow) / 3f;
float factor = (1f - this.Efficiency) * EfficiencyHigh + EfficiencyLow;
proportionFactor = new Vector3(factor, factor, factor);
integralFactor = new Vector3(factor, factor, factor);
derivFactor = new Vector3(factor, factor, factor);
MDetailLog("{0}, BSPIDVMotor.setEfficiency,eff={1},factor={2}", BSScene.DetailLogZero, Efficiency, factor);
}
}
// Advance the PID computation on this error.
public override Vector3 StepError(float timeStep, Vector3 error)
{
if (!Enabled) return Vector3.Zero;
// Add up the error so we can integrate over the accumulated errors
RunningIntegration += error * timeStep;
// A simple derivitive is the rate of change from the last error.
Vector3 derivitive = (error - LastError) * timeStep;
// Correction = (proportionOfPresentError + accumulationOfPastError + rateOfChangeOfError)
Vector3 ret = error / TimeScale * timeStep * proportionFactor * FactorMix.X
+ RunningIntegration / TimeScale * integralFactor * FactorMix.Y
+ derivitive / TimeScale * derivFactor * FactorMix.Z
;
MDetailLog("{0}, BSPIDVMotor.step,ts={1},err={2},lerr={3},runnInt={4},deriv={5},ret={6}",
BSScene.DetailLogZero, timeStep, error, LastError, RunningIntegration, derivitive, ret);
return ret;
}
}
}