diff options
Diffstat (limited to 'src/modules/multirotor_pos_control/thrust_pid.c')
| -rw-r--r-- | src/modules/multirotor_pos_control/thrust_pid.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/src/modules/multirotor_pos_control/thrust_pid.c b/src/modules/multirotor_pos_control/thrust_pid.c new file mode 100644 index 000000000..b985630ae --- /dev/null +++ b/src/modules/multirotor_pos_control/thrust_pid.c @@ -0,0 +1,189 @@ +/**************************************************************************** + * + * Copyright (C) 2013 PX4 Development Team. All rights reserved. + * Author: Anton Babushkin <anton.babushkin@me.com> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name PX4 nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/** + * @file thrust_pid.c + * + * Implementation of thrust control PID. + * + * @author Anton Babushkin <anton.babushkin@me.com> + */ + +#include "thrust_pid.h" +#include <math.h> + +__EXPORT void thrust_pid_init(thrust_pid_t *pid, float kp, float ki, float kd, float limit_min, float limit_max, uint8_t mode, float dt_min) +{ + pid->kp = kp; + pid->ki = ki; + pid->kd = kd; + pid->limit_min = limit_min; + pid->limit_max = limit_max; + pid->mode = mode; + pid->dt_min = dt_min; + pid->last_output = 0.0f; + pid->sp = 0.0f; + pid->error_previous = 0.0f; + pid->integral = 0.0f; +} + +__EXPORT int thrust_pid_set_parameters(thrust_pid_t *pid, float kp, float ki, float kd, float limit_min, float limit_max) +{ + int ret = 0; + + if (isfinite(kp)) { + pid->kp = kp; + + } else { + ret = 1; + } + + if (isfinite(ki)) { + pid->ki = ki; + + } else { + ret = 1; + } + + if (isfinite(kd)) { + pid->kd = kd; + + } else { + ret = 1; + } + + if (isfinite(limit_min)) { + pid->limit_min = limit_min; + + } else { + ret = 1; + } + + if (isfinite(limit_max)) { + pid->limit_max = limit_max; + + } else { + ret = 1; + } + + return ret; +} + +__EXPORT float thrust_pid_calculate(thrust_pid_t *pid, float sp, float val, float dt, float r22) +{ + /* Alternative integral component calculation + * + * start: + * error = setpoint - current_value + * integral = integral + (Ki * error * dt) + * derivative = (error - previous_error) / dt + * previous_error = error + * output = (Kp * error) + integral + (Kd * derivative) + * wait(dt) + * goto start + */ + + if (!isfinite(sp) || !isfinite(val) || !isfinite(dt)) { + return pid->last_output; + } + + float i, d; + pid->sp = sp; + + // Calculated current error value + float error = pid->sp - val; + + // Calculate or measured current error derivative + if (pid->mode == THRUST_PID_MODE_DERIVATIV_CALC) { + d = (error - pid->error_previous) / fmaxf(dt, pid->dt_min); + pid->error_previous = error; + + } else if (pid->mode == THRUST_PID_MODE_DERIVATIV_CALC_NO_SP) { + d = (-val - pid->error_previous) / fmaxf(dt, pid->dt_min); + pid->error_previous = -val; + + } else { + d = 0.0f; + } + + if (!isfinite(d)) { + d = 0.0f; + } + + /* calculate the error integral */ + i = pid->integral + (pid->ki * error * dt); + + /* attitude-thrust compensation + * r22 is (2, 2) componet of rotation matrix for current attitude */ + float att_comp; + + if (r22 > 0.8f) + att_comp = 1.0f / r22; + else if (r22 > 0.0f) + att_comp = ((1.0f / 0.8f - 1.0f) / 0.8f) * r22 + 1.0f; + else + att_comp = 1.0f; + + /* calculate output */ + float output = ((error * pid->kp) + i + (d * pid->kd)) * att_comp; + + /* check for saturation */ + if (output < pid->limit_min || output > pid->limit_max) { + /* saturated, recalculate output with old integral */ + output = (error * pid->kp) + pid->integral + (d * pid->kd); + + } else { + if (isfinite(i)) { + pid->integral = i; + } + } + + if (isfinite(output)) { + if (output > pid->limit_max) { + output = pid->limit_max; + + } else if (output < pid->limit_min) { + output = pid->limit_min; + } + + pid->last_output = output; + } + + return pid->last_output; +} + +__EXPORT void thrust_pid_set_integral(thrust_pid_t *pid, float i) +{ + pid->integral = i; +} |