1 // attitude_indicator.cxx - a vacuum-powered attitude indicator.
2 // Written by David Megginson, started 2002.
4 // This file is in the Public Domain and comes with no warranty.
13 #include <simgear/compiler.h>
19 #include <math.h> // fabs()
21 #include "attitude_indicator.hxx"
22 #include <Main/fg_props.hxx>
23 #include <Main/util.hxx>
27 AttitudeIndicator::AttitudeIndicator ( SGPropertyNode *node )
29 _name(node->getStringValue("name", "attitude-indicator")),
30 _num(node->getIntValue("number", 0)),
31 _suction(node->getStringValue("suction", "/systems/vacuum/suction-inhg")),
38 AttitudeIndicator::~AttitudeIndicator ()
43 AttitudeIndicator::init ()
46 branch = "/instrumentation/" + _name;
48 SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
51 _pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
52 _roll_in_node = fgGetNode("/orientation/roll-deg", true);
53 _suction_node = fgGetNode(_suction.c_str(), true);
54 SGPropertyNode *cnode = node->getChild("config", 0, true);
55 _tumble_flag_node = cnode->getChild("tumble-flag", 0, true);
56 _caged_node = node->getChild("caged-flag", 0, true);
57 _tumble_node = node->getChild("tumble-norm", 0, true);
58 if( ( n = cnode->getChild("spin-thresh", 0, false ) ) != NULL )
59 spin_thresh = n->getDoubleValue();
60 if( ( n = cnode->getChild("max-roll-error-deg", 0, false ) ) != NULL )
61 max_roll_error = n->getDoubleValue();
62 if( ( n = cnode->getChild("max-pitch-error-deg", 0, false ) ) != NULL )
63 max_pitch_error = n->getDoubleValue();
64 _pitch_int_node = node->getChild("internal-pitch-deg", 0, true);
65 _roll_int_node = node->getChild("internal-roll-deg", 0, true);
66 _pitch_out_node = node->getChild("indicated-pitch-deg", 0, true);
67 _roll_out_node = node->getChild("indicated-roll-deg", 0, true);
73 AttitudeIndicator::reinit ()
75 _roll_int_node->setDoubleValue(0.0);
76 _pitch_int_node->setDoubleValue(0.0);
81 AttitudeIndicator::bind ()
83 std::ostringstream temp;
86 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
88 fgTie((branch + "/serviceable").c_str(),
89 &_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
90 fgTie((branch + "/spin").c_str(),
91 &_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
95 AttitudeIndicator::unbind ()
97 std::ostringstream temp;
100 branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
102 fgUntie((branch + "/serviceable").c_str());
103 fgUntie((branch + "/spin").c_str());
107 AttitudeIndicator::update (double dt)
109 // If it's caged, it doesn't indicate
110 if (_caged_node->getBoolValue()) {
111 _roll_int_node->setDoubleValue(0.0);
112 _pitch_int_node->setDoubleValue(0.0);
116 // Get the spin from the gyro
117 _gyro.set_power_norm(_suction_node->getDoubleValue()/5.0);
119 double spin = _gyro.get_spin_norm();
121 // Calculate the responsiveness
122 double responsiveness = spin * spin * spin * spin * spin * spin;
124 // Get the indicated roll and pitch
125 double roll = _roll_in_node->getDoubleValue();
126 double pitch = _pitch_in_node->getDoubleValue();
128 // Calculate the tumble for the
130 if (_tumble_flag_node->getBoolValue()) {
131 double tumble = _tumble_node->getDoubleValue();
132 if (fabs(roll) > 45.0) {
133 double target = (fabs(roll) - 45.0) / 45.0;
134 target *= target; // exponential past +-45 degrees
138 if (fabs(target) > fabs(tumble))
143 else if (tumble < -1.0)
146 // Reerect in 5 minutes
147 double step = dt/300.0;
150 else if (tumble > step)
154 _tumble_node->setDoubleValue(tumble);
157 roll = fgGetLowPass(_roll_int_node->getDoubleValue(), roll,
159 pitch = fgGetLowPass(_pitch_int_node->getDoubleValue(), pitch,
162 // Assign the new values
163 _roll_int_node->setDoubleValue(roll);
164 _pitch_int_node->setDoubleValue(pitch);
166 // add in a gyro underspin "error" if gyro is spinning too slowly
169 if ( spin <= spin_thresh ) {
170 double roll_error_factor = (spin_thresh - spin) / spin_thresh;
171 double pitch_error_factor = (spin_thresh - spin) / spin_thresh;
172 roll_error = roll_error_factor * roll_error_factor * max_roll_error;
173 pitch_error = pitch_error_factor * pitch_error_factor * max_pitch_error;
179 _roll_out_node->setDoubleValue(roll + roll_error);
180 _pitch_out_node->setDoubleValue(pitch + pitch_error);
183 // end of attitude_indicator.cxx