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+/* speed.c - PI speed control. */
+/* 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.
+ *
+ * }}} */
+
+/** Actual speed. */
+int8_t speed_left, speed_right;
+/** Wanted speed. */
+int8_t speed_left_aim, speed_right_aim;
+/** Acceleration value. */
+uint8_t speed_acc = 8;
+/** Acceleration counter, speed gets updated when it reachs 0. */
+uint8_t speed_acc_cpt;
+/** Integral term. */
+int16_t speed_left_int, speed_right_int;
+/** Integral max value. */
+int16_t speed_int_max = 1024;
+/** Last error value. */
+int16_t speed_left_e_old, speed_right_e_old;
+/** P coeficients. 5.8 fixed point format. */
+uint16_t speed_kp = 2 * 255;
+/** I coeficients. 4.8 fixed point format. */
+uint16_t speed_ki = 1 * 255;
+
+/* +AutoDec */
+
+/** Initialise speed parameters. */
+static inline void
+speed_init (void);
+
+/** Update speeds according to the wanted speeds and the acceleration. */
+static inline void
+speed_update (void);
+
+/** Compute new pwm value for left motor. */
+static inline void
+speed_compute_left_pwm (void);
+
+/** Compute new pwm value for right motor. */
+static inline void
+speed_compute_right_pwm (void);
+
+/** Forget past event, usefull when the speed control is disabled for some
+ * time. */
+static inline void
+speed_restart (void);
+
+/* -AutoDec */
+
+/** Initialise speed parameters. */
+static inline void
+speed_init (void)
+{
+ speed_acc = 8;
+ speed_int_max = 1024;
+ speed_kp = 2 * 255;
+ speed_ki = 1 * 255;
+}
+
+/** Update speeds according to the wanted speeds and the acceleration. */
+static inline void
+speed_update (void)
+{
+ if (speed_acc)
+ {
+ speed_acc_cpt--;
+ if (speed_acc_cpt == 0)
+ {
+ speed_acc_cpt = speed_acc;
+ /* Update speeds. */
+ if (speed_left > speed_left_aim)
+ speed_left--;
+ else if (speed_left < speed_left_aim)
+ speed_left++;
+ if (speed_right > speed_right_aim)
+ speed_right--;
+ else if (speed_right < speed_right_aim)
+ speed_right++;
+ }
+ }
+ else
+ {
+ speed_left = speed_left_aim;
+ speed_right = speed_right_aim;
+ }
+}
+
+/** Compute new pwm value for left motor. */
+static inline void
+speed_compute_left_pwm (void)
+{
+ int16_t e;
+ int16_t pwm;
+ e = speed_left - counter_left_diff; /* 10b = 8b + 9b */
+ /* Integral update. */
+ speed_left_int += e; /* 12b = 11b + 10b */
+ if (speed_left_int > speed_int_max) /* 11b */
+ speed_left_int = speed_int_max;
+ else if (speed_left_int < -speed_int_max)
+ speed_left_int = -speed_int_max;
+ /* Compute PI. */ /* 16b = 15b + 15b */
+ pwm = dsp_mul_i16f88 (e, speed_kp) /* 15b = 10b * 5.8b */
+ + dsp_mul_i16f88 (speed_left_int, speed_ki); /* 15b = 11b * 4.8b */
+ /* Save result. */
+ speed_left_e_old = e;
+ pwm_left = pwm;
+}
+
+/** Compute new pwm value for right motor. */
+static inline void
+speed_compute_right_pwm (void)
+{
+ int16_t e;
+ int16_t pwm;
+ e = speed_right - counter_right_diff;
+ /* Integral update. */
+ speed_right_int += e;
+ if (speed_right_int > speed_int_max)
+ speed_right_int = speed_int_max;
+ else if (speed_right_int < -speed_int_max)
+ speed_right_int = -speed_int_max;
+ /* Compute PI. */
+ pwm = dsp_mul_i16f88 (e, speed_kp)
+ + dsp_mul_i16f88 (speed_right_int, speed_ki);
+ /* Save result. */
+ speed_right_e_old = e;
+ pwm_right = pwm;
+}
+
+/** Forget past event, usefull when the speed control is disabled for some
+ * time. */
+static inline void
+speed_restart (void)
+{
+ speed_left_int = 0;
+ speed_right_int = 0;
+ speed_left = 0;
+ speed_right = 0;
+}