1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
7 ------------- Copyright (C) 1999 Anthony K. Peden (apeden@earthlink.net) -------------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU General Public License as published by the Free Software
11 Foundation; either version 2 of the License, or (at your option) any later
14 This program is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
19 You should have received a copy of the GNU General Public License along with
20 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 Place - Suite 330, Boston, MA 02111-1307, USA.
23 Further information about the GNU General Public License can also be found on
24 the world wide web at http://www.gnu.org.
28 --------------------------------------------------------------------------------
32 FUNCTIONAL DESCRIPTION
33 --------------------------------------------------------------------------------
35 This class takes the given set of IC's and finds the aircraft state required to
36 maintain a specified flight condition. This flight condition can be
37 steady-level with non-zero sideslip, a steady turn, a pull-up or pushover.
38 On-ground conditions can be trimmed as well, but this is currently limited to
39 adjusting altitude and pitch angle only. It is implemented using an iterative,
40 one-axis-at-a-time scheme.
42 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
44 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
49 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
51 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
53 #include "FGFDMExec.h"
54 #include "FGJSBBase.h"
55 #include "FGTrimAxis.h"
59 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
61 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
63 #define ID_TRIM "$Id$"
65 #if defined(_WIN32) && !defined(__CYGWIN__)
66 #define snprintf _snprintf
69 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
71 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
75 typedef enum { tLongitudinal, tFull, tGround, tPullup,
79 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
81 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
83 /** FGTrim -- the trimming routine for JSBSim.
84 FGTrim finds the aircraft attitude and control settings needed to maintain
85 the steady state described by the FGInitialCondition object . It does this
86 iteratively by assigning a control to each state and adjusting that control
87 until the state is within a specified tolerance of zero. States include the
88 recti-linear accelerations udot, vdot, and wdot, the angular accelerations
89 qdot, pdot, and rdot, and the difference between heading and ground track.
90 Controls include the usual flight deck controls available to the pilot plus
91 angle of attack (alpha), sideslip angle(beta), flight path angle (gamma),
92 pitch attitude(theta), roll attitude(phi), and altitude above ground. The
93 last three are used for on-ground trimming. The state-control pairs used in
94 a given trim are completely user configurable and several pre-defined modes
95 are provided as well. They are:
96 - tLongitudinal: Trim wdot with alpha, udot with thrust, qdot with elevator
97 - tFull: tLongitudinal + vdot with phi, pdot with aileron, rdot with rudder
98 and heading minus ground track (hmgt) with beta
99 - tPullup: tLongitudinal but adjust alpha to achieve load factor input
101 - tGround: wdot with altitude, qdot with theta, and pdot with phi
103 The remaining modes include <b>tCustom</b>, which is completely user defined and
106 Note that trims can (and do) fail for reasons that are completely outside
107 the control of the trimming routine itself. The most common problem is the
108 initial conditions: is the model capable of steady state flight
109 at those conditions? Check the speed, altitude, configuration (flaps,
110 gear, etc.), weight, cg, and anything else that may be relevant.
113 FGFDMExec* FDMExec = new FGFDMExec();
115 FGInitialCondition* fgic = new FGInitialCondition(FDMExec);
116 FGTrim *fgt(FDMExec,fgic,tFull);
117 fgic->SetVcaibratedKtsIC(100);
118 fgic->SetAltitudeFtIC(1000);
119 fgic->SetClimbRate(500);
120 if( !fgt->DoTrim() ) {
121 cout << "Trim Failed" << endl;
123 fgt->ReportState(); </pre>
128 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
130 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
132 class FGTrim : public FGJSBBase
136 vector<FGTrimAxis*> TrimAxes;
137 unsigned int current_axis;
140 int DebugLevel, Debug;
141 double Tolerance, A_Tolerance;
142 double wdot,udot,qdot;
144 double *sub_iterations;
147 int max_sub_iterations;
153 unsigned int axis_count;
155 double xlo,xhi,alo,ahi;
159 double psidot,thetadot;
162 FGInitialCondition* fgic;
166 /** @return false if there is no change in the current axis accel
167 between accel(control_min) and accel(control_max). If there is a
168 change, sets solutionDomain to:
169 0 for no sign change,
170 -1 if sign change between accel(control_min) and accel(0)
171 1 if sign between accel(0) and accel(control_max)
173 bool findInterval(void);
175 bool checkLimits(void);
177 void setupPullup(void);
178 void setupTurn(void);
180 void updateRates(void);
185 /** Initializes the trimming class
186 @param FDMExec pointer to a JSBSim executive object.
189 FGTrim(FGFDMExec *FDMExec, TrimMode tm=tGround );
197 /** Print the results of the trim. For each axis trimmed, this
198 includes the final state value, control value, and tolerance
200 @return true if trim succeeds
204 /** Iteration statistics
208 /** Clear all state-control pairs and set a predefined trim mode
209 @param tm the set of axes to trim. Can be:
210 tLongitudinal, tFull, tGround, tCustom, or tNone
212 void SetMode(TrimMode tm);
214 /** Clear all state-control pairs from the current configuration.
215 The trimming routine must have at least one state-control pair
216 configured to be useful
218 void ClearStates(void);
220 /** Add a state-control pair to the current configuration. See the enums
221 State and Control in FGTrimAxis.h for the available options.
222 Will fail if the given state is already configured.
223 @param state the accel or other condition to zero
224 @param control the control used to zero the state
225 @return true if add is successful
227 bool AddState( State state, Control control );
229 /** Remove a specific state-control pair from the current configuration
230 @param state the state to remove
231 @return true if removal is successful
233 bool RemoveState( State state );
235 /** Change the control used to zero a state previously configured
236 @param state the accel or other condition to zero
237 @param new_control the control used to zero the state
239 bool EditState( State state, Control new_control );
241 /** automatically switch to trimming longitudinal acceleration with
242 flight path angle (gamma) once it becomes apparent that there
243 is not enough/too much thrust.
244 @param bb true to enable fallback
246 inline void SetGammaFallback(bool bb) { gamma_fallback=bb; }
248 /** query the fallback state
249 @return true if fallback is enabled.
251 inline bool GetGammaFallback(void) { return gamma_fallback; }
253 /** Set the iteration limit. DoTrim() will return false if limit
254 iterations are reached before trim is achieved. The default
255 is 60. This does not ordinarily need to be changed.
256 @param ii integer iteration limit
258 inline void SetMaxCycles(int ii) { max_iterations = ii; }
260 /** Set the per-axis iteration limit. Attempt to zero each state
261 by iterating limit times before moving on to the next. The
262 default limit is 100 and also does not ordinarily need to
264 @param ii integer iteration limit
266 inline void SetMaxCyclesPerAxis(int ii) { max_sub_iterations = ii; }
268 /** Set the tolerance for declaring a state trimmed. Angular accels are
269 held to a tolerance of 1/10th of the given. The default is
270 0.001 for the recti-linear accelerations and 0.0001 for the angular.
272 inline void SetTolerance(double tt) {
274 A_Tolerance = tt / 10;
278 Debug level 1 shows results of each top-level iteration
279 Debug level 2 shows level 1 & results of each per-axis iteration
281 inline void SetDebug(int level) { DebugLevel = level; }
282 inline void ClearDebug(void) { DebugLevel = 0; }
285 Output debug data for one of the axes
286 The State enum is defined in FGTrimAxis.h
288 inline void DebugState(State state) { debug_axis=state; }
290 inline void SetTargetNlf(float nlf) { targetNlf=nlf; }
291 inline double GetTargetNlf(void) { return targetNlf; }