/* postrack.c */ /* asserv - Position & speed motor control on a ATmega128. {{{ * * Copyright (C) 2004 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. * * }}} */ /** Current position, f24.8. */ int32_t postrack_x, postrack_y; /** Current angle, f8.24. */ int32_t postrack_a; /** Distance between the weels, u16. */ uint16_t postrack_footing; /** Precomputed footing factor, f8.24. * postrack_footing_factor = 1 / postrack_footing */ int32_t postrack_footing_factor; /* +AutoDec */ /** Initialise the position tracker. */ static inline void postrack_init (void); /** Update the current position. */ static inline void postrack_update (void); /** Change the footing value. */ static inline void postrack_set_footing (uint16_t footing); /* -AutoDec */ /** Initialise the position tracker. */ static inline void postrack_init (void) { postrack_set_footing (5000); } /** Update the current position. */ static inline void postrack_update (void) { int32_t d, dd, da, r, na; d = counter_right_diff + counter_left_diff; d <<= 24 - 1; if (counter_right_diff == counter_left_diff) { postrack_x += dsp_mul_f824 (d, dsp_cos (postrack_a)) >> 16; postrack_y += dsp_mul_f824 (d, dsp_sin (postrack_a)) >> 16; } else { /* XXX: WARNING: dleft & dright 16 bits? * This code should not work at high speed (> 127). */ dd = counter_right_diff - counter_left_diff; dd <<= 24; da = dsp_mul_f824 (postrack_footing_factor, dd); r = dsp_div_f824 (d, da); na = postrack_a + da; postrack_x += dsp_mul_f824 (r, dsp_sin (na) - dsp_sin (postrack_a)) >> 16; postrack_y += dsp_mul_f824 (r, dsp_cos (postrack_a) - dsp_cos (na)) >> 16; postrack_a = na; } } /** Change the footing value. */ static inline void postrack_set_footing (uint16_t footing) { postrack_footing = footing; postrack_footing_factor = (1L << 24) / footing; }