1 // ray.cxx -- "RayWoodworth" motion chair support
3 // Written by Alexander Perry, started May 2000
5 // Copyright (C) 2000, Alexander Perry, alex.perry@ieee.org
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 #include <simgear/constants.h>
28 #include <simgear/debug/logstream.hxx>
29 #include <simgear/io/iochannel.hxx>
31 #include <FDM/flight.hxx>
40 chair_vertical[0] = 0.0;
41 chair_vertical[1] = 0.0;
42 // chair_FILE = stderr;
51 // Ray Woodworth (949) 262-9118 has a three axis motion chair.
53 // It expects +/- 5V signals for full scale. In channel order, axes are:
54 // roll, pitch, yaw, sway, surge, heave
55 // The drivers are capable of generating (in the same order)
56 // +/- 30deg, 30deg, 30deg, 12in, 12in, 12in
57 // The signs of the motion are such that positive volts gives
58 // head right, head back, feet right, body right, body back, body up
60 // In this code implementation, the voltage outputs are generated
61 // using a ComputerBoards DDA06/Jr card and the associated Linux driver.
62 // Data is written to the device /dev/dda06jr-A as byte triplets;
63 // The first byte is the channel number (0-5 respectively) and
64 // the remaining two bytes are an unsigned short for the signal.
67 bool FGRAY::gen_message() {
68 // cout << "generating RayWoodworth message" << endl;
69 FGInterface *f = cur_fdm_state;
71 const double fullscale[6] = { -0.5, -0.5, -0.5, /* radians */
72 -0.3, -0.3, -0.15 /* meters */ };
74 /* Figure out how big our timesteps are */
75 double dt = 0.05; /* seconds */
77 /* get basic information about gravity */
78 double grav_acc = -9.81;
79 double vert_acc = f->get_A_Z_pilot() * 0.3;
80 if ( -3.0 < vert_acc )
83 for ( axis = 0; axis < 3; axis++ )
84 { /* Compute each angular axis together with the linear
85 axis which is coupled by smooth coordinated flight
88 double lin_pos, lin_acc;
90 /* Retrieve the desired components */
92 case 0: ang_pos = f->get_Phi();
93 lin_acc = f->get_A_Y_pilot() * 0.3;
95 case 1: ang_pos = f->get_Theta();
96 lin_acc = f->get_A_X_pilot() * 0.3;
98 case 2: ang_pos = f->get_Psi();
99 lin_acc = grav_acc - vert_acc;
107 /* Make sure the angles are reasonable onscale */
108 /* We use an asymmetric mapping so that the chair behaves
109 reasonably when upside down. Otherwise it oscillates. */
110 while ( ang_pos < -SGD_2PI/3 ) {
113 while ( ang_pos > 2*SGD_2PI/3 ) {
117 /* Tell interested parties what the situation is */
119 fprintf ( chair_FILE, "RAY %s, %8.3f rad %8.3f m/s/s =>",
120 ((axis==0)?"Roll ":((axis==1)?"Pitch":"Yaw ")),
124 /* The upward direction and axis are special cases */
128 /* Integrate vertical acceleration into velocity,
129 diluted by 50% and with a 0.2 second high pass */
130 chair_rising += ( lin_acc - chair_rising ) * dt * 0.5;
131 /* Integrate velocity into position, 0.2 sec high pass */
132 chair_height += ( chair_rising - chair_height ) * dt * 0.5;
133 lin_pos = chair_height;
136 /* Make sure that we walk through North cleanly */
137 if ( fabs ( ang_pos - chair_heading ) > SGD_PI )
138 { /* Need to swing chair by 360 degrees */
139 if ( ang_pos < chair_heading )
140 chair_heading -= SGD_2PI;
141 else chair_heading += SGD_2PI;
143 /* Remove the chair heading from the true heading */
144 ang_pos -= chair_heading;
145 /* Wash out the error at 5 sec timeconstant because
146 a standard rate turn is 3 deg/sec and the chair
147 can just about represent 30 degrees full scale. */
148 chair_heading += ang_pos * dt * 0.2;
149 /* If they turn fast, at 90 deg error subtract 30 deg */
150 if ( fabs(ang_pos) > SGD_PI_2 )
151 chair_heading += ang_pos / 3;
154 { /* 3 second low pass to find attitude and gravity vector */
155 chair_vertical[axis] += ( dt / 3 ) *
156 ( lin_acc / vert_acc + ang_pos
157 - chair_vertical[axis] );
158 /* find out how much linear acceleration is left */
159 lin_acc -= chair_vertical[axis] * vert_acc;
160 /* reposition the pilot tilt relative to the chair */
161 ang_pos -= chair_vertical[axis];
162 /* integrate linear acceleration into a position */
163 lin_pos = lin_acc; /* HACK */
166 /* Tell interested parties what we'll do */
168 fprintf ( chair_FILE, " %8.3f deg %8.3f cm.\n",
169 ang_pos * 60.0, lin_pos * 100.0 );
172 /* Write the resulting numbers to the command buffer */
173 /* The first pass number is linear, second pass is angle */
174 for ( subaxis = axis; subaxis < 6; subaxis += 3 )
175 { unsigned short *dac;
176 /* Select the DAC in the command buffer */
177 buf [ 3*subaxis ] = subaxis;
178 dac = (unsigned short *) ( buf + 1 + 3*subaxis );
179 /* Select the relevant number to put there */
180 double propose = ( subaxis < 3 ) ? ang_pos : lin_pos;
181 /* Scale to the hardware's full scale range */
182 propose /= fullscale [ subaxis ];
183 /* Use a sine shaped washout on all axes */
184 if ( propose < -SGD_PI_2 ) *dac = 0x0000; else
185 if ( propose > SGD_PI_2 ) *dac = 0xFFFF; else
186 *dac = (unsigned short) ( 32767 *
187 ( 1.0 + sin ( propose ) ) );
190 /* That concludes the per-axis calculations */
193 /* Tell the caller what we did */
201 bool FGRAY::parse_message() {
202 SG_LOG( SG_IO, SG_ALERT, "RAY input not supported" );
208 // process work for this port
209 bool FGRAY::process() {
210 SGIOChannel *io = get_io_channel();
212 if ( get_direction() == SG_IO_OUT ) {
214 if ( ! io->write( buf, length ) ) {
215 SG_LOG( SG_IO, SG_ALERT, "Error writing data." );
218 } else if ( get_direction() == SG_IO_IN ) {
219 SG_LOG( SG_IO, SG_ALERT, "in direction not supported for RAY." );