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1/*
2 * Copyright (c) Contributors, http://opensimulator.org/
3 * See CONTRIBUTORS.TXT for a full list of copyright holders.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of the OpenSimulator Project nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28using System;
29using System.Collections.Generic;
30using System.Text;
31using OpenMetaverse;
32using OpenSim.Framework;
33
34namespace OpenSim.Region.Physics.BulletSNPlugin
35{
36public abstract class BSMotor
37{
38 // Timescales and other things can be turned off by setting them to 'infinite'.
39 public const float Infinite = 12345.6f;
40 public readonly static Vector3 InfiniteVector = new Vector3(BSMotor.Infinite, BSMotor.Infinite, BSMotor.Infinite);
41
42 public BSMotor(string useName)
43 {
44 UseName = useName;
45 PhysicsScene = null;
46 Enabled = true;
47 }
48 public virtual bool Enabled { get; set; }
49 public virtual void Reset() { }
50 public virtual void Zero() { }
51 public virtual void GenerateTestOutput(float timeStep) { }
52
53 // A name passed at motor creation for easily identifyable debugging messages.
54 public string UseName { get; private set; }
55
56 // Used only for outputting debug information. Might not be set so check for null.
57 public BSScene PhysicsScene { get; set; }
58 protected void MDetailLog(string msg, params Object[] parms)
59 {
60 if (PhysicsScene != null)
61 {
62 if (PhysicsScene.VehicleLoggingEnabled)
63 {
64 PhysicsScene.DetailLog(msg, parms);
65 }
66 }
67 }
68}
69
70// Motor which moves CurrentValue to TargetValue over TimeScale seconds.
71// The TargetValue decays in TargetValueDecayTimeScale and
72// the CurrentValue will be held back by FrictionTimeScale.
73// This motor will "zero itself" over time in that the targetValue will
74// decay to zero and the currentValue will follow it to that zero.
75// The overall effect is for the returned correction value to go from large
76// values (the total difference between current and target minus friction)
77// to small and eventually zero values.
78// TimeScale and TargetDelayTimeScale may be 'infinite' which means no decay.
79
80// For instance, if something is moving at speed X and the desired speed is Y,
81// CurrentValue is X and TargetValue is Y. As the motor is stepped, new
82// values of CurrentValue are returned that approach the TargetValue.
83// The feature of decaying TargetValue is so vehicles will eventually
84// come to a stop rather than run forever. This can be disabled by
85// setting TargetValueDecayTimescale to 'infinite'.
86// The change from CurrentValue to TargetValue is linear over TimeScale seconds.
87public class BSVMotor : BSMotor
88{
89 // public Vector3 FrameOfReference { get; set; }
90 // public Vector3 Offset { get; set; }
91
92 public virtual float TimeScale { get; set; }
93 public virtual float TargetValueDecayTimeScale { get; set; }
94 public virtual Vector3 FrictionTimescale { get; set; }
95 public virtual float Efficiency { get; set; }
96
97 public virtual float ErrorZeroThreshold { get; set; }
98
99 public virtual Vector3 TargetValue { get; protected set; }
100 public virtual Vector3 CurrentValue { get; protected set; }
101 public virtual Vector3 LastError { get; protected set; }
102
103 public virtual bool ErrorIsZero
104 { get {
105 return (LastError == Vector3.Zero || LastError.LengthSquared() <= ErrorZeroThreshold);
106 }
107 }
108
109 public BSVMotor(string useName)
110 : base(useName)
111 {
112 TimeScale = TargetValueDecayTimeScale = BSMotor.Infinite;
113 Efficiency = 1f;
114 FrictionTimescale = BSMotor.InfiniteVector;
115 CurrentValue = TargetValue = Vector3.Zero;
116 ErrorZeroThreshold = 0.001f;
117 }
118 public BSVMotor(string useName, float timeScale, float decayTimeScale, Vector3 frictionTimeScale, float efficiency)
119 : this(useName)
120 {
121 TimeScale = timeScale;
122 TargetValueDecayTimeScale = decayTimeScale;
123 FrictionTimescale = frictionTimeScale;
124 Efficiency = efficiency;
125 CurrentValue = TargetValue = Vector3.Zero;
126 }
127 public void SetCurrent(Vector3 current)
128 {
129 CurrentValue = current;
130 }
131 public void SetTarget(Vector3 target)
132 {
133 TargetValue = target;
134 }
135 public override void Zero()
136 {
137 base.Zero();
138 CurrentValue = TargetValue = Vector3.Zero;
139 }
140
141 // Compute the next step and return the new current value
142 public virtual Vector3 Step(float timeStep)
143 {
144 if (!Enabled) return TargetValue;
145
146 Vector3 origTarget = TargetValue; // DEBUG
147 Vector3 origCurrVal = CurrentValue; // DEBUG
148
149 Vector3 correction = Vector3.Zero;
150 Vector3 error = TargetValue - CurrentValue;
151 if (!error.ApproxEquals(Vector3.Zero, ErrorZeroThreshold))
152 {
153 correction = Step(timeStep, error);
154
155 CurrentValue += correction;
156
157 // The desired value reduces to zero which also reduces the difference with current.
158 // If the decay time is infinite, don't decay at all.
159 float decayFactor = 0f;
160 if (TargetValueDecayTimeScale != BSMotor.Infinite)
161 {
162 decayFactor = (1.0f / TargetValueDecayTimeScale) * timeStep;
163 TargetValue *= (1f - decayFactor);
164 }
165
166 // The amount we can correct the error is reduced by the friction
167 Vector3 frictionFactor = Vector3.Zero;
168 if (FrictionTimescale != BSMotor.InfiniteVector)
169 {
170 // frictionFactor = (Vector3.One / FrictionTimescale) * timeStep;
171 // Individual friction components can be 'infinite' so compute each separately.
172 frictionFactor.X = (FrictionTimescale.X == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.X);
173 frictionFactor.Y = (FrictionTimescale.Y == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.Y);
174 frictionFactor.Z = (FrictionTimescale.Z == BSMotor.Infinite) ? 0f : (1f / FrictionTimescale.Z);
175 frictionFactor *= timeStep;
176 CurrentValue *= (Vector3.One - frictionFactor);
177 }
178
179 MDetailLog("{0}, BSVMotor.Step,nonZero,{1},origCurr={2},origTarget={3},timeStep={4},err={5},corr={6}",
180 BSScene.DetailLogZero, UseName, origCurrVal, origTarget,
181 timeStep, error, correction);
182 MDetailLog("{0}, BSVMotor.Step,nonZero,{1},tgtDecayTS={2},decayFact={3},frictTS={4},frictFact={5},tgt={6},curr={7}",
183 BSScene.DetailLogZero, UseName,
184 TargetValueDecayTimeScale, decayFactor, FrictionTimescale, frictionFactor,
185 TargetValue, CurrentValue);
186 }
187 else
188 {
189 // Difference between what we have and target is small. Motor is done.
190 CurrentValue = TargetValue;
191 MDetailLog("{0}, BSVMotor.Step,zero,{1},origTgt={2},origCurr={3},ret={4}",
192 BSScene.DetailLogZero, UseName, origCurrVal, origTarget, CurrentValue);
193 }
194
195 return CurrentValue;
196 }
197 public virtual Vector3 Step(float timeStep, Vector3 error)
198 {
199 if (!Enabled) return Vector3.Zero;
200
201 LastError = error;
202 Vector3 returnCorrection = Vector3.Zero;
203 if (!error.ApproxEquals(Vector3.Zero, ErrorZeroThreshold))
204 {
205 // correction = error / secondsItShouldTakeToCorrect
206 Vector3 correctionAmount;
207 if (TimeScale == 0f || TimeScale == BSMotor.Infinite)
208 correctionAmount = error * timeStep;
209 else
210 correctionAmount = error / TimeScale * timeStep;
211
212 returnCorrection = correctionAmount;
213 MDetailLog("{0}, BSVMotor.Step,nonZero,{1},timeStep={2},timeScale={3},err={4},corr={5}",
214 BSScene.DetailLogZero, UseName, timeStep, TimeScale, error, correctionAmount);
215 }
216 return returnCorrection;
217 }
218
219 // The user sets all the parameters and calls this which outputs values until error is zero.
220 public override void GenerateTestOutput(float timeStep)
221 {
222 // maximum number of outputs to generate.
223 int maxOutput = 50;
224 MDetailLog("{0},BSVMotor.Test,{1},===================================== BEGIN Test Output", BSScene.DetailLogZero, UseName);
225 MDetailLog("{0},BSVMotor.Test,{1},timeScale={2},targDlyTS={3},frictTS={4},eff={5},curr={6},tgt={7}",
226 BSScene.DetailLogZero, UseName,
227 TimeScale, TargetValueDecayTimeScale, FrictionTimescale, Efficiency,
228 CurrentValue, TargetValue);
229
230 LastError = BSMotor.InfiniteVector;
231 while (maxOutput-- > 0 && !LastError.ApproxEquals(Vector3.Zero, ErrorZeroThreshold))
232 {
233 Vector3 lastStep = Step(timeStep);
234 MDetailLog("{0},BSVMotor.Test,{1},cur={2},tgt={3},lastError={4},lastStep={5}",
235 BSScene.DetailLogZero, UseName, CurrentValue, TargetValue, LastError, lastStep);
236 }
237 MDetailLog("{0},BSVMotor.Test,{1},===================================== END Test Output", BSScene.DetailLogZero, UseName);
238
239
240 }
241
242 public override string ToString()
243 {
244 return String.Format("<{0},curr={1},targ={2},decayTS={3},frictTS={4}>",
245 UseName, CurrentValue, TargetValue, TargetValueDecayTimeScale, FrictionTimescale);
246 }
247}
248
249public class BSFMotor : BSMotor
250{
251 public float TimeScale { get; set; }
252 public float DecayTimeScale { get; set; }
253 public float Friction { get; set; }
254 public float Efficiency { get; set; }
255
256 public float Target { get; private set; }
257 public float CurrentValue { get; private set; }
258
259 public BSFMotor(string useName, float timeScale, float decayTimescale, float friction, float efficiency)
260 : base(useName)
261 {
262 }
263 public void SetCurrent(float target)
264 {
265 }
266 public void SetTarget(float target)
267 {
268 }
269 public virtual float Step(float timeStep)
270 {
271 return 0f;
272 }
273}
274
275// Proportional, Integral, Derivitive Motor
276// Good description at http://www.answers.com/topic/pid-controller . Includes processes for choosing p, i and d factors.
277public class BSPIDVMotor : BSVMotor
278{
279 // Larger makes more overshoot, smaller means converge quicker. Range of 0.1 to 10.
280 public Vector3 proportionFactor { get; set; }
281 public Vector3 integralFactor { get; set; }
282 public Vector3 derivFactor { get; set; }
283
284 // Arbritrary factor range.
285 // EfficiencyHigh means move quickly to the correct number. EfficiencyLow means might over correct.
286 public float EfficiencyHigh = 0.4f;
287 public float EfficiencyLow = 4.0f;
288
289 // Running integration of the error
290 Vector3 RunningIntegration { get; set; }
291
292 public BSPIDVMotor(string useName)
293 : base(useName)
294 {
295 proportionFactor = new Vector3(1.00f, 1.00f, 1.00f);
296 integralFactor = new Vector3(1.00f, 1.00f, 1.00f);
297 derivFactor = new Vector3(1.00f, 1.00f, 1.00f);
298 RunningIntegration = Vector3.Zero;
299 LastError = Vector3.Zero;
300 }
301
302 public override void Zero()
303 {
304 base.Zero();
305 }
306
307 public override float Efficiency
308 {
309 get { return base.Efficiency; }
310 set
311 {
312 base.Efficiency = Util.Clamp(value, 0f, 1f);
313 // Compute factors based on efficiency.
314 // If efficiency is high (1f), use a factor value that moves the error value to zero with little overshoot.
315 // If efficiency is low (0f), use a factor value that overcorrects.
316 // TODO: might want to vary contribution of different factor depending on efficiency.
317 float factor = ((1f - this.Efficiency) * EfficiencyHigh + EfficiencyLow) / 3f;
318 // float factor = (1f - this.Efficiency) * EfficiencyHigh + EfficiencyLow;
319 proportionFactor = new Vector3(factor, factor, factor);
320 integralFactor = new Vector3(factor, factor, factor);
321 derivFactor = new Vector3(factor, factor, factor);
322 }
323 }
324
325 // Ignore Current and Target Values and just advance the PID computation on this error.
326 public override Vector3 Step(float timeStep, Vector3 error)
327 {
328 if (!Enabled) return Vector3.Zero;
329
330 // Add up the error so we can integrate over the accumulated errors
331 RunningIntegration += error * timeStep;
332
333 // A simple derivitive is the rate of change from the last error.
334 Vector3 derivFactor = (error - LastError) * timeStep;
335 LastError = error;
336
337 // Correction = -(proportionOfPresentError + accumulationOfPastError + rateOfChangeOfError)
338 Vector3 ret = -(
339 error * proportionFactor
340 + RunningIntegration * integralFactor
341 + derivFactor * derivFactor
342 );
343
344 return ret;
345 }
346}
347}