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/* goto.c */
/* asserv - Position & speed motor control on a ATmega128. {{{
 *
 * Copyright (C) 2005 Nicolas Schodet
 *
 * Robot APB Team/Efrei 2005.
 *        Web: http://assos.efrei.fr/robot/
 *      Email: robot AT efrei DOT fr
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * }}} */

/** Destination position, f24.8. */
int32_t goto_x, goto_y;
/** Destination angle, f8.24. */
int32_t goto_a;
/** Destination epsillon. */
int32_t goto_eps = 20L << 8;

/* +AutoDec */
/* -AutoDec */

/** Update the speed according to the desired destination. */
static inline void
goto_update (void)
{
    int32_t dx, dy, c, s, dl, da;
    /* Project in the robot base. */
    dx = goto_x - postrack_x;	/* f24.8 */
    dy = goto_y - postrack_y;
    if (dx < goto_eps && dx > -goto_eps && dy < goto_eps && dy > -goto_eps)
      {
	speed_left_aim = 0;
	speed_right_aim = 0;
      }
    else
      {
	c = dsp_cos (postrack_a);
	s = dsp_sin (postrack_a);
	dl = dsp_mul_f824 (dx, c) + dsp_mul_f824 (dy, s);
	da = dsp_mul_f824 (dy, c) - dsp_mul_f824 (dx, s);
	/* Convert da into a arc. This is a rough aproximation. */
	//da = da * postrack_footing / 2 / (dl >> 8);
	speed_distance (dl, da);
      }
}