Paparazzi UAS  v5.18.0_stable-1-g6993852-dirty
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stabilization_indi_simple.c
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1 /*
2  * Copyright (C) Ewoud Smeur <ewoud_smeur@msn.com>
3  * MAVLab Delft University of Technology
4  *
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22 
37 
38 #include "state.h"
39 #include "generated/airframe.h"
40 #include "paparazzi.h"
42 
43 #if !defined(STABILIZATION_INDI_ACT_DYN_P) && !defined(STABILIZATION_INDI_ACT_DYN_Q) && !defined(STABILIZATION_INDI_ACT_DYN_R)
44 #error You have to define the first order time constant of the actuator dynamics!
45 #endif
46 
47 // these parameters are used in the filtering of the angular acceleration
48 // define them in the airframe file if different values are required
49 #ifndef STABILIZATION_INDI_FILT_CUTOFF
50 #define STABILIZATION_INDI_FILT_CUTOFF 8.0
51 #endif
52 
53 // the yaw sometimes requires more filtering
54 #ifndef STABILIZATION_INDI_FILT_CUTOFF_R
55 #define STABILIZATION_INDI_FILT_CUTOFF_R STABILIZATION_INDI_FILT_CUTOFF
56 #endif
57 
58 #ifndef STABILIZATION_INDI_MAX_RATE
59 #define STABILIZATION_INDI_MAX_RATE 6.0
60 #endif
61 
62 #if STABILIZATION_INDI_USE_ADAPTIVE
63 #warning "Use caution with adaptive indi. See the wiki for more info"
64 #endif
65 
66 #ifndef STABILIZATION_INDI_MAX_R
67 #define STABILIZATION_INDI_MAX_R STABILIZATION_ATTITUDE_SP_MAX_R
68 #endif
69 
70 #ifndef STABILIZATION_INDI_ESTIMATION_FILT_CUTOFF
71 #define STABILIZATION_INDI_ESTIMATION_FILT_CUTOFF 4.0
72 #endif
73 
76 
78 
79 static inline void lms_estimation(void);
80 static void indi_init_filters(void);
81 
82 //The G values are scaled to avoid numerical problems during the estimation
83 #define INDI_EST_SCALE 0.001
84 
85 struct IndiVariables indi = {
87  .attitude_max_yaw_rate = STABILIZATION_INDI_MAX_R,
88 
89  .g1 = {STABILIZATION_INDI_G1_P, STABILIZATION_INDI_G1_Q, STABILIZATION_INDI_G1_R},
90  .g2 = STABILIZATION_INDI_G2_R,
91  .gains = {
92  .att = {
93  STABILIZATION_INDI_REF_ERR_P,
94  STABILIZATION_INDI_REF_ERR_Q,
95  STABILIZATION_INDI_REF_ERR_R
96  },
97  .rate = {
98  STABILIZATION_INDI_REF_RATE_P,
99  STABILIZATION_INDI_REF_RATE_Q,
100  STABILIZATION_INDI_REF_RATE_R
101  },
102  },
103 
104  /* Estimation parameters for adaptive INDI */
105  .est = {
106  .g1 = {
107  STABILIZATION_INDI_G1_P / INDI_EST_SCALE,
108  STABILIZATION_INDI_G1_Q / INDI_EST_SCALE,
109  STABILIZATION_INDI_G1_R / INDI_EST_SCALE
110  },
111  .g2 = STABILIZATION_INDI_G2_R / INDI_EST_SCALE,
112  .mu = STABILIZATION_INDI_ADAPTIVE_MU,
113  },
114 
115 #if STABILIZATION_INDI_USE_ADAPTIVE
116  .adaptive = TRUE,
117 #else
118  .adaptive = FALSE,
119 #endif
120 };
121 
122 #if PERIODIC_TELEMETRY
124 
125 static void send_att_indi(struct transport_tx *trans, struct link_device *dev)
126 {
127  //The estimated G values are scaled, so scale them back before sending
128  struct FloatRates g1_disp;
129  RATES_SMUL(g1_disp, indi.est.g1, INDI_EST_SCALE);
130  float g2_disp = indi.est.g2 * INDI_EST_SCALE;
131 
132  pprz_msg_send_STAB_ATTITUDE_INDI(trans, dev, AC_ID,
133  &indi.rate_d[0],
134  &indi.rate_d[1],
135  &indi.rate_d[2],
136  &indi.angular_accel_ref.p,
137  &indi.angular_accel_ref.q,
138  &indi.angular_accel_ref.r,
139  &g1_disp.p,
140  &g1_disp.q,
141  &g1_disp.r,
142  &g2_disp);
143 }
144 
145 static void send_ahrs_ref_quat(struct transport_tx *trans, struct link_device *dev)
146 {
147  struct Int32Quat *quat = stateGetNedToBodyQuat_i();
148  pprz_msg_send_AHRS_REF_QUAT(trans, dev, AC_ID,
153  &(quat->qi),
154  &(quat->qx),
155  &(quat->qy),
156  &(quat->qz));
157 }
158 #endif
159 
161 {
162  // Initialize filters
164 
165 #if PERIODIC_TELEMETRY
166  register_periodic_telemetry(DefaultPeriodic, PPRZ_MSG_ID_STAB_ATTITUDE_INDI, send_att_indi);
168 #endif
169 }
170 
172 {
173  // tau = 1/(2*pi*Fc)
174  float tau = 1.0 / (2.0 * M_PI * STABILIZATION_INDI_FILT_CUTOFF);
175  float tau_r = 1.0 / (2.0 * M_PI * STABILIZATION_INDI_FILT_CUTOFF_R);
176  float tau_axis[3] = {tau, tau, tau_r};
177  float tau_est = 1.0 / (2.0 * M_PI * STABILIZATION_INDI_ESTIMATION_FILT_CUTOFF);
178  float sample_time = 1.0 / PERIODIC_FREQUENCY;
179  // Filtering of gyroscope and actuators
180  for (int8_t i = 0; i < 3; i++) {
181  init_butterworth_2_low_pass(&indi.u[i], tau_axis[i], sample_time, 0.0);
182  init_butterworth_2_low_pass(&indi.rate[i], tau_axis[i], sample_time, 0.0);
183  init_butterworth_2_low_pass(&indi.est.u[i], tau_est, sample_time, 0.0);
184  init_butterworth_2_low_pass(&indi.est.rate[i], tau_est, sample_time, 0.0);
185  }
186  // Init rate filter for feedback
188 }
189 
191 {
192  /* reset psi setpoint to current psi angle */
194 
197  FLOAT_RATES_ZERO(indi.u_in);
198 
199  // Re-initialize filters
201 }
202 
204 {
205  /* set failsafe to zero roll/pitch and current heading */
208  stab_att_sp_quat.qx = 0;
209  stab_att_sp_quat.qy = 0;
211 }
212 
219 {
220  // stab_att_sp_euler.psi still used in ref..
221  stab_att_sp_euler = *rpy;
222 
224 }
225 
233 {
234  // stab_att_sp_euler.psi still used in ref..
236 
237  // compute sp_euler phi/theta for debugging/telemetry
238  /* Rotate horizontal commands to body frame by psi */
240  int32_t s_psi, c_psi;
241  PPRZ_ITRIG_SIN(s_psi, psi);
242  PPRZ_ITRIG_COS(c_psi, psi);
243  stab_att_sp_euler.phi = (-s_psi * cmd->x + c_psi * cmd->y) >> INT32_TRIG_FRAC;
244  stab_att_sp_euler.theta = -(c_psi * cmd->x + s_psi * cmd->y) >> INT32_TRIG_FRAC;
245 
246  quat_from_earth_cmd_i(&stab_att_sp_quat, cmd, heading);
247 }
248 
255 static inline void filter_pqr(Butterworth2LowPass *filter, struct FloatRates *new_values)
256 {
257  update_butterworth_2_low_pass(&filter[0], new_values->p);
258  update_butterworth_2_low_pass(&filter[1], new_values->q);
259  update_butterworth_2_low_pass(&filter[2], new_values->r);
260 }
261 
269 static inline void finite_difference_from_filter(float *output, Butterworth2LowPass *filter)
270 {
271  for (int8_t i = 0; i < 3; i++) {
272  output[i] = (filter[i].o[0] - filter[i].o[1]) * PERIODIC_FREQUENCY;
273  }
274 }
275 
283 static inline void finite_difference(float output[3], float new[3], float old[3])
284 {
285  for (int8_t i = 0; i < 3; i++) {
286  output[i] = (new[i] - old[i])*PERIODIC_FREQUENCY;
287  }
288 }
289 
296 void stabilization_indi_rate_run(struct FloatRates rate_sp, bool in_flight __attribute__((unused)))
297 {
298  //Propagate input filters
299  //first order actuator dynamics
300  indi.u_act_dyn.p = indi.u_act_dyn.p + STABILIZATION_INDI_ACT_DYN_P * (indi.u_in.p - indi.u_act_dyn.p);
301  indi.u_act_dyn.q = indi.u_act_dyn.q + STABILIZATION_INDI_ACT_DYN_Q * (indi.u_in.q - indi.u_act_dyn.q);
302  indi.u_act_dyn.r = indi.u_act_dyn.r + STABILIZATION_INDI_ACT_DYN_R * (indi.u_in.r - indi.u_act_dyn.r);
303 
304  // Propagate the filter on the gyroscopes and actuators
305  struct FloatRates *body_rates = stateGetBodyRates_f();
306  filter_pqr(indi.u, &indi.u_act_dyn);
307  filter_pqr(indi.rate, body_rates);
308 
309  // Calculate the derivative of the rates
311 
312  //The rates used for feedback are by default the measured rates. If needed they can be filtered (see below)
313 
314  //If there is a lot of noise on the gyroscope, it might be good to use the filtered value for feedback.
315  //Note that due to the delay, the PD controller can not be as aggressive.
316 #if STABILIZATION_INDI_FILTER_ROLL_RATE
317  rates_filt_fo.p = (rates_filt_fo.p*3+body_rates->p)/4;
318 #else
319  rates_filt_fo.p = body_rates->p;
320 #endif
321 #if STABILIZATION_INDI_FILTER_PITCH_RATE
322  rates_filt_fo.q = (rates_filt_fo.q*3+body_rates->q)/4;
323 #else
324  rates_filt_fo.q = body_rates->q;
325 #endif
326 #if STABILIZATION_INDI_FILTER_YAW_RATE
327  rates_filt_fo.r = (rates_filt_fo.r*3+body_rates->r)/4;
328 #else
329  rates_filt_fo.r = body_rates->r;
330 #endif
331 
332  //This separates the P and D controller and lets you impose a maximum yaw rate.
333  BoundAbs(rate_sp.r, indi.attitude_max_yaw_rate);
334 
335  // Compute reference angular acceleration:
336  indi.angular_accel_ref.p = (rate_sp.p - rates_filt_fo.p) * indi.gains.rate.p;
337  indi.angular_accel_ref.q = (rate_sp.q - rates_filt_fo.q) * indi.gains.rate.q;
338  indi.angular_accel_ref.r = (rate_sp.r - rates_filt_fo.r) * indi.gains.rate.r;
339 
340  //Increment in angular acceleration requires increment in control input
341  //G1 is the control effectiveness. In the yaw axis, we need something additional: G2.
342  //It takes care of the angular acceleration caused by the change in rotation rate of the propellers
343  //(they have significant inertia, see the paper mentioned in the header for more explanation)
344  indi.du.p = 1.0 / indi.g1.p * (indi.angular_accel_ref.p - indi.rate_d[0]);
345  indi.du.q = 1.0 / indi.g1.q * (indi.angular_accel_ref.q - indi.rate_d[1]);
346  indi.du.r = 1.0 / (indi.g1.r + indi.g2) * (indi.angular_accel_ref.r - indi.rate_d[2] + indi.g2 * indi.du.r);
347 
348  //Don't increment if thrust is off and on the ground
349  //without this the inputs will increment to the maximum before even getting in the air.
350  if (stabilization_cmd[COMMAND_THRUST] < 300 && !in_flight) {
351  FLOAT_RATES_ZERO(indi.u_in);
352 
353  // If on the gournd, no increments, just proportional control
354  indi.u_in.p = indi.du.p;
355  indi.u_in.q = indi.du.q;
356  indi.u_in.r = indi.du.r;
357  } else {
358  //add the increment to the total control input
359  indi.u_in.p = indi.u[0].o[0] + indi.du.p;
360  indi.u_in.q = indi.u[1].o[0] + indi.du.q;
361  indi.u_in.r = indi.u[2].o[0] + indi.du.r;
362 
363  // only run the estimation if the commands are not zero.
364  lms_estimation();
365  }
366 
367  //bound the total control input
368 #if STABILIZATION_INDI_FULL_AUTHORITY
369  Bound(indi.u_in.p, -9600, 9600);
370  Bound(indi.u_in.q, -9600, 9600);
371  float rlim = 9600 - fabs(indi.u_in.q);
372  Bound(indi.u_in.r, -rlim, rlim);
373  Bound(indi.u_in.r, -9600, 9600);
374 #else
375  Bound(indi.u_in.p, -4500, 4500);
376  Bound(indi.u_in.q, -4500, 4500);
377  Bound(indi.u_in.r, -4500, 4500);
378 #endif
379 
380  /* INDI feedback */
381  stabilization_cmd[COMMAND_ROLL] = indi.u_in.p;
382  stabilization_cmd[COMMAND_PITCH] = indi.u_in.q;
383  stabilization_cmd[COMMAND_YAW] = indi.u_in.r;
384 
385  /* bound the result */
386  BoundAbs(stabilization_cmd[COMMAND_ROLL], MAX_PPRZ);
387  BoundAbs(stabilization_cmd[COMMAND_PITCH], MAX_PPRZ);
388  BoundAbs(stabilization_cmd[COMMAND_YAW], MAX_PPRZ);
389 }
390 
397 void stabilization_indi_attitude_run(struct Int32Quat quat_sp, bool in_flight __attribute__((unused)))
398 {
399  /* attitude error */
400  struct Int32Quat att_err;
401  struct Int32Quat *att_quat = stateGetNedToBodyQuat_i();
402  int32_quat_inv_comp(&att_err, att_quat, &quat_sp);
403  /* wrap it in the shortest direction */
404  int32_quat_wrap_shortest(&att_err);
405  int32_quat_normalize(&att_err);
406 
407  struct FloatRates rate_sp;
408  // Divide by rate gain to make it equivalent to a parallel structure
409  rate_sp.p = indi.gains.att.p * QUAT1_FLOAT_OF_BFP(att_err.qx) / indi.gains.rate.p;
410  rate_sp.q = indi.gains.att.q * QUAT1_FLOAT_OF_BFP(att_err.qy) / indi.gains.rate.q;
411  rate_sp.r = indi.gains.att.r * QUAT1_FLOAT_OF_BFP(att_err.qz) / indi.gains.rate.r;
412 
413  /* compute the INDI command */
414  stabilization_indi_rate_run(rate_sp, in_flight);
415 }
416 
422 void stabilization_indi_read_rc(bool in_flight, bool in_carefree, bool coordinated_turn)
423 {
424  struct FloatQuat q_sp;
425 #if USE_EARTH_BOUND_RC_SETPOINT
426  stabilization_attitude_read_rc_setpoint_quat_earth_bound_f(&q_sp, in_flight, in_carefree, coordinated_turn);
427 #else
428  stabilization_attitude_read_rc_setpoint_quat_f(&q_sp, in_flight, in_carefree, coordinated_turn);
429 #endif
431 }
432 
439 static inline void lms_estimation(void)
440 {
441  static struct IndiEstimation *est = &indi.est;
442  // Only pass really low frequencies so you don't adapt to noise
443  struct FloatRates *body_rates = stateGetBodyRates_f();
444  filter_pqr(est->u, &indi.u_act_dyn);
445  filter_pqr(est->rate, body_rates);
446 
447  // Calculate the first and second derivatives of the rates and actuators
448  float rate_d_prev[3];
449  float u_d_prev[3];
450  float_vect_copy(rate_d_prev, est->rate_d, 3);
451  float_vect_copy(u_d_prev, est->u_d, 3);
453  finite_difference_from_filter(est->u_d, est->u);
454  finite_difference(est->rate_dd, est->rate_d, rate_d_prev);
455  finite_difference(est->u_dd, est->u_d, u_d_prev);
456 
457  // The inputs are scaled in order to avoid overflows
458  float du[3];
459  float_vect_copy(du, est->u_d, 3);
461  est->g1.p = est->g1.p - (est->g1.p * du[0] - est->rate_dd[0]) * du[0] * est->mu;
462  est->g1.q = est->g1.q - (est->g1.q * du[1] - est->rate_dd[1]) * du[1] * est->mu;
463  float ddu = est->u_dd[2] * INDI_EST_SCALE / PERIODIC_FREQUENCY;
464  float error = (est->g1.r * du[2] + est->g2 * ddu - est->rate_dd[2]);
465  est->g1.r = est->g1.r - error * du[2] * est->mu / 3;
466  est->g2 = est->g2 - error * 1000 * ddu * est->mu / 3;
467 
468  //the g values should be larger than zero, otherwise there is positive feedback, the command will go to max and there is nothing to learn anymore...
469  if (est->g1.p < 0.01) { est->g1.p = 0.01; }
470  if (est->g1.q < 0.01) { est->g1.q = 0.01; }
471  if (est->g1.r < 0.01) { est->g1.r = 0.01; }
472  if (est->g2 < 0.01) { est->g2 = 0.01; }
473 
474  if (indi.adaptive) {
475  //Commit the estimated G values and apply the scaling
476  indi.g1.p = est->g1.p * INDI_EST_SCALE;
477  indi.g1.q = est->g1.q * INDI_EST_SCALE;
478  indi.g1.r = est->g1.r * INDI_EST_SCALE;
479  indi.g2 = est->g2 * INDI_EST_SCALE;
480  }
481 }
int32_t psi
in rad with INT32_ANGLE_FRAC
struct Int32Quat stab_att_sp_quat
with INT32_QUAT_FRAC
static float update_butterworth_2_low_pass(Butterworth2LowPass *filter, float value)
Update second order Butterworth low pass filter state with a new value.
#define STABILIZATION_INDI_MAX_R
void stabilization_attitude_read_rc_setpoint_quat_f(struct FloatQuat *q_sp, bool in_flight, bool in_carefree, bool coordinated_turn)
Read attitude setpoint from RC as quaternion Interprets the stick positions as axes.
static void init_butterworth_2_low_pass(Butterworth2LowPass *filter, float tau, float sample_time, float value)
Init a second order Butterworth filter.
static void int32_quat_normalize(struct Int32Quat *q)
normalize a quaternion inplace
bool adaptive
Enable adataptive estimation.
struct FloatRates att
void int32_quat_inv_comp(struct Int32Quat *b2c, struct Int32Quat *a2b, struct Int32Quat *a2c)
Composition (multiplication) of two quaternions.
#define STABILIZATION_INDI_MAX_RATE
float heading
Definition: wedgebug.c:258
static void indi_init_filters(void)
Quaternion transformation functions.
struct FloatRates du
struct FloatRates g1
void stabilization_indi_read_rc(bool in_flight, bool in_carefree, bool coordinated_turn)
This function reads rc commands.
static void send_att_indi(struct transport_tx *trans, struct link_device *dev)
Periodic telemetry system header (includes downlink utility and generated code).
General attitude stabilization interface for rotorcrafts.
#define INDI_EST_SCALE
void stabilization_indi_enter(void)
Function that resets important values upon engaging INDI.
int32_t theta
in rad with INT32_ANGLE_FRAC
struct FloatRates u_in
static void send_ahrs_ref_quat(struct transport_tx *trans, struct link_device *dev)
void int32_quat_of_eulers(struct Int32Quat *q, struct Int32Eulers *e)
Quaternion from Euler angles.
int32_t stabilization_attitude_get_heading_i(void)
float r
in rad/s
Read an attitude setpoint from the RC.
float max_rate
Maximum rate in rate control in rad/s.
static void filter_pqr(Butterworth2LowPass *filter, struct FloatRates *new_values)
Update butterworth filter for p, q and r of a FloatRates struct.
#define FLOAT_RATES_ZERO(_r)
void stabilization_indi_set_failsafe_setpoint(void)
Function that calculates the failsafe setpoint.
float q
in rad/s
struct Indi_gains gains
float p
in rad/s
static struct Int32Quat * stateGetNedToBodyQuat_i(void)
Get vehicle body attitude quaternion (int).
Definition: state.h:1113
#define FALSE
Definition: std.h:5
void stabilization_indi_init(void)
Function that initializes important values upon engaging INDI.
float o[2]
output history
Roation quaternion.
void stabilization_indi_attitude_run(struct Int32Quat quat_sp, bool in_flight)
runs stabilization indi
void stabilization_attitude_read_rc_setpoint_quat_earth_bound_f(struct FloatQuat *q_sp, bool in_flight, bool in_carefree, bool coordinated_turn)
static void finite_difference(float output[3], float new[3], float old[3])
Calculate derivative of an array via finite difference.
#define PPRZ_ITRIG_SIN(_s, _a)
#define TRUE
Definition: std.h:4
#define STABILIZATION_INDI_FILT_CUTOFF_R
struct IndiVariables indi
void stabilization_indi_rate_run(struct FloatRates rate_sp, bool in_flight)
Does the INDI calculations.
Butterworth2LowPass rate[3]
Butterworth2LowPass rate[3]
euler angles
#define QUAT_BFP_OF_REAL(_qi, _qf)
Definition: pprz_algebra.h:752
#define DefaultPeriodic
Set default periodic telemetry.
Definition: telemetry.h:66
static void lms_estimation(void)
This is a Least Mean Squares adaptive filter It estimates the actuator effectiveness online...
struct IndiEstimation est
Estimation parameters for adaptive INDI.
struct Int32Eulers stab_att_sp_euler
with INT32_ANGLE_FRAC
#define STABILIZATION_INDI_ESTIMATION_FILT_CUTOFF
static void finite_difference_from_filter(float *output, Butterworth2LowPass *filter)
Caclulate finite difference form a filter array The filter already contains the previous values...
void quat_from_earth_cmd_i(struct Int32Quat *quat, struct Int32Vect2 *cmd, int32_t heading)
#define RATES_SMUL(_ro, _ri, _s)
Definition: pprz_algebra.h:379
void stabilization_indi_set_rpy_setpoint_i(struct Int32Eulers *rpy)
Set attitude quaternion setpoint from rpy.
static struct FloatRates * stateGetBodyRates_f(void)
Get vehicle body angular rate (float).
Definition: state.h:1200
signed long int32_t
Definition: types.h:19
#define QUAT1_FLOAT_OF_BFP(_qi)
static const struct usb_device_descriptor dev
Definition: usb_ser_hw.c:74
#define INT32_TRIG_FRAC
#define STABILIZATION_INDI_FILT_CUTOFF
void stabilization_indi_set_earth_cmd_i(struct Int32Vect2 *cmd, int32_t heading)
Set attitude setpoint from command in earth axes.
int32_t phi
in rad with INT32_ANGLE_FRAC
struct FloatRates angular_accel_ref
API to get/set the generic vehicle states.
Butterworth2LowPass u[3]
static void float_vect_scale(float *a, const float s, const int n)
a *= s
struct FloatRates rate
static void int32_quat_wrap_shortest(struct Int32Quat *q)
static void float_vect_copy(float *a, const float *b, const int n)
a = b
int32_t stabilization_cmd[COMMANDS_NB]
Stabilization commands.
Definition: stabilization.c:32
#define RATES_COPY(_a, _b)
Definition: pprz_algebra.h:337
Second order low pass filter structure.
#define MAX_PPRZ
Definition: paparazzi.h:8
float attitude_max_yaw_rate
Maximum yaw rate in atttiude control in rad/s.
Butterworth2LowPass u[3]
signed char int8_t
Definition: types.h:15
static struct Int32Eulers * stateGetNedToBodyEulers_i(void)
Get vehicle body attitude euler angles (int).
Definition: state.h:1125
Rotation quaternion.
struct FloatRates rates_filt_fo
angular rates
struct FloatRates u_act_dyn
int8_t register_periodic_telemetry(struct periodic_telemetry *_pt, uint8_t _id, telemetry_cb _cb)
Register a telemetry callback function.
Definition: telemetry.c:46
struct FloatRates g1
#define PPRZ_ITRIG_COS(_c, _a)