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APM_Control: added pid_info and FF to steering controller

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used for realtime ground steering tuning
This commit is contained in:
Andrew Tridgell 2015-06-08 21:08:14 +10:00
parent bc6a52f8db
commit 5105d510b8
2 changed files with 25 additions and 7 deletions
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25
libraries/APM_Control/AP_SteerController.cpp
View File

@ -75,6 +75,15 @@ const AP_Param::GroupInfo AP_SteerController::var_info[] PROGMEM = {
// @User: User
AP_GROUPINFO("MINSPD", 6, AP_SteerController, _minspeed, 1.0f),
// @Param: FF
// @DisplayName: Steering feed forward
// @Description: The feed forward gain for steering this is the ratio of the achieved turn rate to applied steering. A value of 1 means that the vehicle would yaw at a rate of 45 degrees per second with full steering deflection at 1m/s ground speed.
// @Range: 0.0 10.0
// @Increment: 0.1
// @User: User
AP_GROUPINFO("FF", 7, AP_SteerController, _K_FF, 0),
AP_GROUPEND
};
@ -102,6 +111,8 @@ int32_t AP_SteerController::get_steering_out_rate(float desired_rate)
// equation for a ground vehicle. It returns steering as an angle from -45 to 45
float scaler = 1.0f / speed;
_pid_info.desired = desired_rate;
// Calculate the steering rate error (deg/sec) and apply gain scaler
float rate_error = (desired_rate - ToDeg(_ahrs.get_gyro().z)) * scaler;
@ -109,6 +120,7 @@ int32_t AP_SteerController::get_steering_out_rate(float desired_rate)
// No conversion is required for K_D
float ki_rate = _K_I * _tau * 45.0f;
float kp_ff = max((_K_P - _K_I * _tau) * _tau - _K_D , 0) * 45.0f;
float k_ff = _K_FF * 45.0f;
float delta_time = (float)dt * 0.001f;
// Multiply roll rate error by _ki_rate and integrate
@ -124,20 +136,23 @@ int32_t AP_SteerController::get_steering_out_rate(float desired_rate)
// prevent the integrator from decreasing if steering defln demand is below the lower limit
integrator_delta = min(integrator_delta, 0);
}
_integrator += integrator_delta;
_pid_info.I += integrator_delta;
}
} else {
_integrator = 0;
_pid_info.I = 0;
}
// Scale the integration limit
float intLimScaled = _imax * 0.01f;
// Constrain the integrator state
_integrator = constrain_float(_integrator, -intLimScaled, intLimScaled);
_pid_info.I = constrain_float(_pid_info.I, -intLimScaled, intLimScaled);
_pid_info.D = rate_error * _K_D * 4.0f;
_pid_info.FF = (ToRad(desired_rate) * kp_ff) * scaler;
// Calculate the demanded control surface deflection
_last_out = (rate_error * _K_D * 4.0f) + (ToRad(desired_rate) * kp_ff) * scaler + _integrator;
_last_out = _pid_info.D + _pid_info.FF + _pid_info.I;
// Convert to centi-degrees and constrain
return constrain_float(_last_out * 100, -4500, 4500);
@ -179,6 +194,6 @@ int32_t AP_SteerController::get_steering_out_angle_error(int32_t angle_err)
void AP_SteerController::reset_I()
{
_integrator = 0;
_pid_info.I = 0;
}

7
libraries/APM_Control/AP_SteerController.h
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@ -6,7 +6,7 @@
#include <AP_AHRS.h>
#include <AP_Common.h>
#include <AP_Vehicle.h>
#include <math.h>
#include <DataFlash.h>
class AP_SteerController {
public:
@ -45,8 +45,11 @@ public:
static const struct AP_Param::GroupInfo var_info[];
const DataFlash_Class::PID_Info& get_pid_info(void) const { return _pid_info; }
private:
AP_Float _tau;
AP_Float _K_FF;
AP_Float _K_P;
AP_Float _K_I;
AP_Float _K_D;
@ -55,7 +58,7 @@ private:
uint32_t _last_t;
float _last_out;
float _integrator;
DataFlash_Class::PID_Info _pid_info {};
AP_AHRS &_ahrs;
};