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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;
/** Max speed for automatic movements. */
int8_t speed_max_l = 0x08, speed_max_a = 0x05;
/** Acceleration value. */
uint8_t speed_acc = 0x60;
/** Acceleration counter, speed gets updated when it reachs 0. */
uint8_t speed_acc_cpt;
/** Error saturation. */
int16_t speed_e_sat = 1023;
/** Integral saturation. */
int16_t speed_int_sat = 8191;
/** P coeficients. 4.8 fixed point format. */
uint16_t speed_left_kp = 0x0fff, speed_right_kp = 0x0fff;
/** I coeficients. 3.8 fixed point format. */
uint16_t speed_left_ki = 0x0008, speed_right_ki = 0x0008;
/** D coeficients. 3.8 fixed point format. */
uint16_t speed_left_kd = 0x0fff, speed_right_kd = 0x0fff;
/** D sample period. */
uint8_t speed_ds = 2;
/** Integral term. */
int16_t speed_left_int, speed_right_int;
/** Last error value. */
int16_t speed_left_e_old, speed_right_e_old;
/** D history. */
int16_t speed_left_d_hist[16], speed_right_d_hist[16];
/** D history pointer. */
uint8_t speed_d_hist_ptr;
/** D history sum. */
int16_t speed_left_d_hist_sum, speed_right_d_hist_sum;
/** Counter value wanted. */
uint16_t speed_left_counter, speed_right_counter;
/** Do not update counter. */
uint8_t speed_counter_updated = 0;

/* +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);

/** Set maximum speed in order to be able to brake before a distance and
 * angle, inputs are f24.8 */
static inline void
speed_distance (int32_t dist, int32_t arc);

/** Set maximum left & right speeds in order to be able to brake. Inputs are
 * f24.8 */
static inline void
speed_distance_lr (int32_t left, int32_t right);

/* -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)
{
    /* Accelerate. */
    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;
      }
    /* Update counter. */
    if (speed_counter_updated)
      {
	speed_counter_updated = 0;
      }
    else
      {
	speed_left_counter += speed_left;
	speed_right_counter += speed_right;
      }
    /* Compute pwm. */
    speed_compute_left_pwm ();
    speed_compute_right_pwm ();
    /* Update D history pointer. */
    speed_d_hist_ptr++;
    if (speed_d_hist_ptr >= speed_ds)
	speed_d_hist_ptr = 0;
}

/** Compute new pwm value for left motor. */
static inline void
speed_compute_left_pwm (void)
{
    int16_t e, diff, pwm;
    /* Get and saturate error. */
    e = speed_left_counter - counter_left;
    if (e > speed_e_sat)
	e = speed_e_sat;
    else if (e < -speed_e_sat)
	e = -speed_e_sat;
    /* Integral update. */
    speed_left_int += e;
    if (speed_left_int > speed_int_sat)
	speed_left_int = speed_int_sat;
    else if (speed_left_int < -speed_int_sat)
	speed_left_int = -speed_int_sat;
    /* Differential value. */
    diff = e - speed_left_e_old;
    speed_left_d_hist_sum += diff;
    speed_left_d_hist_sum -= speed_left_d_hist[speed_d_hist_ptr];
    speed_left_d_hist[speed_d_hist_ptr] = diff;
    /* Compute PI. */				/* 16b = 15b + 14b + 14b */
    pwm = dsp_mul_i16f88 (e, speed_left_kp)
	+ dsp_mul_i16f88 (speed_left_int, speed_left_ki)
	+ dsp_mul_i16f88 (speed_left_d_hist_sum, speed_left_kd);
    /* 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, diff, pwm;
    /* Get and saturate error. */
    e = speed_right_counter - counter_right;
    if (e > speed_e_sat)
	e = speed_e_sat;
    else if (e < -speed_e_sat)
	e = -speed_e_sat;
    /* Integral update. */
    speed_right_int += e;
    if (speed_right_int > speed_int_sat)
	speed_right_int = speed_int_sat;
    else if (speed_right_int < -speed_int_sat)
	speed_right_int = -speed_int_sat;
    /* Differential value. */
    diff = e - speed_right_e_old;
    speed_right_d_hist_sum += diff;
    speed_right_d_hist_sum -= speed_right_d_hist[speed_d_hist_ptr];
    speed_right_d_hist[speed_d_hist_ptr] = diff;
    /* Compute PI. */				/* 16b = 15b + 14b + 14b */
    pwm = dsp_mul_i16f88 (e, speed_right_kp)
	+ dsp_mul_i16f88 (speed_right_int, speed_right_ki)
	+ dsp_mul_i16f88 (speed_right_d_hist_sum, speed_right_kd);
    /* 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)
{
    int i;
    speed_left_int = 0;
    speed_right_int = 0;
    speed_left = 0;
    speed_right = 0;
    speed_left_counter = counter_left;
    speed_right_counter = counter_right;
    speed_left_d_hist_sum = 0;
    speed_right_d_hist_sum = 0;
    speed_d_hist_ptr = 0;
    for (i = 0; i < sizeof (speed_left_d_hist)
	 / sizeof (speed_left_d_hist[0]); i++)
      {
	speed_left_d_hist[i] = 0;
	speed_right_d_hist[i] = 0;
      }
}

/** Set maximum speed in order to be able to brake before a distance and
 * angle, inputs are f24.8 */
static inline void
speed_distance (int32_t dist, int32_t arc)
{
    /* XXX: There are some buggy assertions there if dist and arc are both
     * big. */
    uint8_t vls, vas;
    uint32_t vl248, va248;
    int8_t vl, va;
    /* Drop sign. */
    vls = dist < 0;
    if (vls) dist = -dist;
    vas = arc < 0;
    if (vas) arc = -arc;
    /* Compute speed.
     * v = sqrt (2 * a * d), a = 1/speed_acc */
    vl248 = dsp_sqrt_f248 (dist * 2 / speed_acc);
    vl = (vl248 >> 8) & 0xff;
    va248 = dsp_sqrt_f248 (arc * 2 / speed_acc);
    va = (va248 >> 8) & 0xff;
    /* Saturate. */
    if (vl248 & 0xffff0000 || vl > speed_max_l)
	vl = speed_max_l;
    if (va248 & 0xffff0000 || va > speed_max_a)
	va = speed_max_a;
    /* Get sign back. */
    if (vls) vl = -vl;
    if (vas) va = -va;
    speed_left_aim = vl - va;
    speed_right_aim = vl + va;
}

/** Set maximum left & right speeds in order to be able to brake. Inputs are
 * f24.8 */
static inline void
speed_distance_lr (int32_t left, int32_t right)
{
    uint8_t vls, vrs;
    uint32_t vl248, vr248;
    int8_t vl, vr;
    uint8_t max;
    /* Drop sign. */
    vls = left < 0;
    if (vls) left = -left;
    vrs = right < 0;
    if (vrs) right = -right;
    /* Compute speed.
     * v = sqrt (2 * a * d), a = 1/speed_acc */
    vl248 = dsp_sqrt_f248 (left * 2 / speed_acc);
    vl = (vl248 >> 8) & 0xff;
    vr248 = dsp_sqrt_f248 (right * 2 / speed_acc);
    vr = (vr248 >> 8) & 0xff;
    /* Saturate. */
    if (vls != vrs)
	max = speed_max_l;
    else
	max = speed_max_a;
    if (vl248 & 0xffff0000 || vl > max)
	vl = max;
    if (vr248 & 0xffff0000 || vr > max)
	vr = max;
    /* Get sign back. */
    if (vls) vl = -vl;
    if (vrs) vr = -vr;
    speed_left_aim = vl;
    speed_right_aim = vr;
}