/* pos.c - Position motor control. */ /* asserv - Position & speed motor control on AVR. {{{ * * Copyright (C) 2005 Nicolas Schodet * * APBTeam: * Web: http://apbteam.org/ * Email: team AT apbteam DOT org * * 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. * * }}} */ #include "common.h" #include "pos.h" #include "modules/utils/utils.h" #include "modules/math/fixed/fixed.h" #include "counter.h" #include "pwm.h" #include "state.h" /** * This file is responsible for position motor control. The consign is a * position of the motor shafts, as theta/alpha. Theta is the sum of right * and left position, alpha is the difference between the right and the left * position. * 16 bits are enough as long as there is no long blocking (see 2005 cup!). */ /** Theta/alpha control states. */ struct pos_t pos_theta, pos_alpha; /** Auxiliaries control states. */ struct pos_t pos_aux0; /** Error saturation. */ int32_t pos_e_sat = 1023; /** Integral saturation. */ int32_t pos_i_sat = 1023; /** Differential saturation. */ int32_t pos_d_sat = 1023; /** Blocking detection: error limit. */ int32_t pos_blocked_error_limit = 2048; /** Blocking detection: speed limit. */ int32_t pos_blocked_speed_limit = 0x10; /** Blocking detection: counter limit. */ int32_t pos_blocked_counter_limit = 20; /** Compute a PID. * How to compute maximum numbers size: * Result is 24 bits (16 bits kept after shift). * If e_sat == 1023, e max is 11 bits (do not forget the sign bit), and diff * max is 12 bits (can be saturated with d_sat). * If i_sat == 1023, i max is 11 bits. * In the final addition, let's give 23 bits to the p part, and 22 bits to the * i and d part (23b + 22b + 22b => 23b + 23b => 24b). * Therefore, kp can be 23 - 11 = 12 bits (f4.8). * ki can be 22 - 11 = 11 bits (f3.8). * kd can be 22 - 12 = 10 bits (f2.8). * How to increase this number: * - lower the shift. * - bound the value returned. * - lower e, i & d saturation. */ static inline int16_t pos_compute_pid (int32_t e, struct pos_t *pos) { int32_t diff, pid; /* Saturate error. */ UTILS_BOUND (e, -pos_e_sat, pos_e_sat); /* Integral update. */ pos->i += e; UTILS_BOUND (pos->i, -pos_i_sat, pos_i_sat); /* Differential value. */ diff = e - pos->e_old; UTILS_BOUND (diff, -pos_d_sat, pos_d_sat); /* Compute PID. */ pid = e * pos->kp + pos->i * pos->ki + diff * pos->kd; /* Save result. */ pos->e_old = e; return pid >> 8; } /** Update PWM according to consign. */ void pos_update (void) { if (state_main.mode >= MODE_POS) { int16_t pid_theta, pid_alpha; int32_t diff_theta, diff_alpha; /* Update current shaft positions. */ pos_theta.cur += counter_left_diff + counter_right_diff; pos_alpha.cur += counter_right_diff - counter_left_diff; if (state_main.variant & 1) pos_reset (&pos_theta); if (state_main.variant & 2) pos_reset (&pos_alpha); /* Compute PID. */ diff_theta = pos_theta.cons - pos_theta.cur; diff_alpha = pos_alpha.cons - pos_alpha.cur; /* Compute actual speed and test for blocking. */ int32_t cur_speed_theta = pos_theta.cur - pos_theta.cur_old; pos_theta.cur_old = pos_theta.cur; int32_t cur_speed_alpha = pos_alpha.cur - pos_alpha.cur_old; pos_alpha.cur_old = pos_alpha.cur; if ((UTILS_ABS (diff_theta) > pos_blocked_error_limit && UTILS_ABS (cur_speed_theta) < pos_blocked_speed_limit)) pos_theta.blocked_counter++; else pos_theta.blocked_counter = 0; if ((UTILS_ABS (diff_alpha) > pos_blocked_error_limit && UTILS_ABS (cur_speed_alpha) < pos_blocked_speed_limit)) pos_alpha.blocked_counter++; else pos_alpha.blocked_counter = 0; if (pos_theta.blocked_counter > pos_blocked_counter_limit || pos_alpha.blocked_counter > pos_blocked_counter_limit) { /* Blocked. */ pos_reset (&pos_theta); pos_reset (&pos_alpha); state_blocked (&state_main); pwm_left = 0; pwm_right = 0; } else { pid_theta = pos_compute_pid (diff_theta, &pos_theta); pid_alpha = pos_compute_pid (diff_alpha, &pos_alpha); /* Update PWM. */ PWM_SET (pwm_left, pid_theta - pid_alpha); PWM_SET (pwm_right, pid_theta + pid_alpha); } } if (state_aux0.mode >= MODE_POS) { int16_t pid; int32_t diff; /* Update current shaft position. */ pos_aux0.cur += counter_aux0_diff; /* Compute PID. */ diff = pos_aux0.cons - pos_aux0.cur; if (UTILS_ABS (diff) > 5000) { /* Blocked. */ pos_reset (&pos_aux0); state_blocked (&state_aux0); pwm_aux0 = 0; } else { pid = pos_compute_pid (diff, &pos_aux0); /* Update PWM. */ PWM_SET (pwm_aux0, pid); } } } /** Reset position control state. To be called when the position control is * deactivated. */ void pos_reset (struct pos_t *pos) { pos->i = 0; pos->cur = 0; pos->cons = 0; pos->e_old = 0; pos->cur_old = 0; pos->blocked_counter = 0; }