/* speed.c - Speed control. */
/* asserv - Position & speed motor control on AVR. {{{
*
* Copyright (C) 2005 Nicolas Schodet
*
* Robot APB Team/Efrei 2006.
* 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.
*
* }}} */
/**
* This file is responsible for speed control. It changes the current shafts
* positions using ramps. It can be controlled by a wanted speed or wanted
* shaft position.
*/
/** Current speed, f8.8. */
int16_t speed_theta_cur, speed_alpha_cur;
/** Consign speed, f8.8. */
int16_t speed_theta_cons, speed_alpha_cons;
/** Maximum speed for position consign, u8. */
int8_t speed_theta_max, speed_alpha_max;
/** Slow speed for position consign, u8. */
int8_t speed_theta_slow, speed_alpha_slow;
/** Consign position. */
uint32_t speed_theta_pos_cons, speed_alpha_pos_cons;
/** Weither to use the consign position (1) or not (0). */
uint8_t speed_pos;
/** Acceleration, uf8.8. */
int16_t speed_theta_acc, speed_alpha_acc;
/* +AutoDec */
/* -AutoDec */
/** Update shaft position consign according to a speed consign. */
static void
speed_update_by_speed (void)
{
/* Update current speed. */
if (UTILS_ABS (speed_theta_cons - speed_theta_cur) < speed_theta_acc)
speed_theta_cur = speed_theta_cons;
else if (speed_theta_cons > speed_theta_cur)
speed_theta_cur += speed_theta_acc;
else
speed_theta_cur -= speed_theta_acc;
if (UTILS_ABS (speed_alpha_cons - speed_alpha_cur) < speed_alpha_acc)
speed_alpha_cur = speed_alpha_cons;
else if (speed_alpha_cons > speed_alpha_cur)
speed_alpha_cur += speed_alpha_acc;
else
speed_alpha_cur -= speed_alpha_acc;
}
/** Compute maximum allowed speed according to: distance left, maximum speed,
* current speed and acceleration. */
static int16_t
speed_compute_max_speed (int32_t d, int16_t cur, int16_t acc, int8_t max)
{
int16_t s;
/* Compute maximum speed in order to be able to brake in time.
* s = sqrt (2 * a * d) */
s = fixed_sqrt_ui32 (2 * (acc >> 8) * UTILS_ABS (d));
/* Apply consign. */
s = UTILS_MIN (max, s);
/* Apply sign. */
if (d < 0)
s = -s;
/* Convert to f8.8 and check acceleration. */
s = s << 8;
UTILS_BOUND (s, cur - acc, cur + acc);
return s;
}
/** Update shaft position consign according to a position consign. */
static void
speed_update_by_position (void)
{
int32_t theta_d = speed_theta_pos_cons - pos_theta_cons;
int32_t alpha_d = speed_alpha_pos_cons - pos_alpha_cons;
if (theta_d >= -speed_theta_max && theta_d <= speed_theta_max)
speed_theta_cur = theta_d << 8;
else
speed_theta_cur = speed_compute_max_speed (theta_d, speed_theta_cur,
speed_theta_acc, speed_theta_max);
if (alpha_d >= -speed_alpha_max && alpha_d <= speed_alpha_max)
speed_alpha_cur = alpha_d << 8;
else
speed_alpha_cur = speed_compute_max_speed (alpha_d, speed_alpha_cur,
speed_alpha_acc, speed_alpha_max);
if (speed_theta_cur == 0 && speed_alpha_cur == 0)
main_sequence_finish = main_sequence;
}
/** Update shaft position consign according to consign. */
static void
speed_update (void)
{
/* Update speed. */
if (speed_pos)
speed_update_by_position ();
else
speed_update_by_speed ();
/* Update shaft position. */
pos_theta_cons += speed_theta_cur >> 8;
pos_alpha_cons += speed_alpha_cur >> 8;
}