diff options
Diffstat (limited to 'src/modules/systemlib/pid/pid.c')
| -rw-r--r-- | src/modules/systemlib/pid/pid.c | 65 |
1 files changed, 40 insertions, 25 deletions
diff --git a/src/modules/systemlib/pid/pid.c b/src/modules/systemlib/pid/pid.c index 49315cdc9..4996a8f66 100644 --- a/src/modules/systemlib/pid/pid.c +++ b/src/modules/systemlib/pid/pid.c @@ -1,9 +1,11 @@ /**************************************************************************** * - * Copyright (C) 2008-2012 PX4 Development Team. All rights reserved. - * Author: @author Laurens Mackay <mackayl@student.ethz.ch> - * @author Tobias Naegeli <naegelit@student.ethz.ch> - * @author Martin Rutschmann <rutmarti@student.ethz.ch> + * Copyright (C) 2008-2013 PX4 Development Team. All rights reserved. + * Author: Laurens Mackay <mackayl@student.ethz.ch> + * Tobias Naegeli <naegelit@student.ethz.ch> + * Martin Rutschmann <rutmarti@student.ethz.ch> + * Anton Babushkin <anton.babushkin@me.com> + * Julian Oes <joes@student.ethz.ch> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -36,14 +38,21 @@ /** * @file pid.c - * Implementation of generic PID control interface + * + * Implementation of generic PID control interface. + * + * @author Laurens Mackay <mackayl@student.ethz.ch> + * @author Tobias Naegeli <naegelit@student.ethz.ch> + * @author Martin Rutschmann <rutmarti@student.ethz.ch> + * @author Anton Babushkin <anton.babushkin@me.com> + * @author Julian Oes <joes@student.ethz.ch> */ #include "pid.h" #include <math.h> __EXPORT void pid_init(PID_t *pid, float kp, float ki, float kd, float intmax, - float limit, uint8_t mode) + float limit, uint8_t mode, float dt_min) { pid->kp = kp; pid->ki = ki; @@ -51,13 +60,13 @@ __EXPORT void pid_init(PID_t *pid, float kp, float ki, float kd, float intmax, pid->intmax = intmax; pid->limit = limit; pid->mode = mode; - pid->count = 0; - pid->saturated = 0; - pid->last_output = 0; - - pid->sp = 0; - pid->error_previous = 0; - pid->integral = 0; + pid->dt_min = dt_min; + pid->count = 0.0f; + pid->saturated = 0.0f; + pid->last_output = 0.0f; + pid->sp = 0.0f; + pid->error_previous = 0.0f; + pid->integral = 0.0f; } __EXPORT int pid_set_parameters(PID_t *pid, float kp, float ki, float kd, float intmax, float limit) { @@ -136,14 +145,14 @@ __EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, flo // Calculated current error value float error = pid->sp - val; - if (isfinite(error)) { // Why is this necessary? DEW - pid->error_previous = error; - } - // Calculate or measured current error derivative - if (pid->mode == PID_MODE_DERIVATIV_CALC) { - d = (error - pid->error_previous) / dt; + d = (error - pid->error_previous) / fmaxf(dt, pid->dt_min); + pid->error_previous = error; + + } else if (pid->mode == PID_MODE_DERIVATIV_CALC_NO_SP) { + d = (-val - pid->error_previous) / fmaxf(dt, pid->dt_min); + pid->error_previous = -val; } else if (pid->mode == PID_MODE_DERIVATIV_SET) { d = -val_dot; @@ -152,6 +161,10 @@ __EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, flo d = 0.0f; } + if (!isfinite(d)) { + d = 0.0f; + } + // Calculate the error integral and check for saturation i = pid->integral + (error * dt); @@ -162,7 +175,7 @@ __EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, flo } else { if (!isfinite(i)) { - i = 0; + i = 0.0f; } pid->integral = i; @@ -170,17 +183,19 @@ __EXPORT float pid_calculate(PID_t *pid, float sp, float val, float val_dot, flo } // Calculate the output. Limit output magnitude to pid->limit - float output = (pid->error_previous * pid->kp) + (i * pid->ki) + (d * pid->kd); + float output = (error * pid->kp) + (i * pid->ki) + (d * pid->kd); - if (output > pid->limit) output = pid->limit; + if (isfinite(output)) { + if (output > pid->limit) { + output = pid->limit; - if (output < -pid->limit) output = -pid->limit; + } else if (output < -pid->limit) { + output = -pid->limit; + } - if (isfinite(output)) { pid->last_output = output; } - return pid->last_output; } |