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-rw-r--r--n/asserv/src/postrack.c94
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diff --git a/n/asserv/src/postrack.c b/n/asserv/src/postrack.c
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+/* 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;
+}