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AP_Mount: Siyi gets rate map, PI control, accel limit
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@rmackay9
rmackay9 committed Jul 17, 2024
1 parent 5190aee commit caefc40
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Showing 2 changed files with 192 additions and 15 deletions.
190 changes: 175 additions & 15 deletions libraries/AP_Mount/AP_Mount_Siyi.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,16 +6,23 @@
#include <GCS_MAVLink/GCS.h>
#include <GCS_MAVLink/include/mavlink/v2.0/checksum.h>
#include <AP_RTC/AP_RTC.h>
#include <AP_Logger/AP_Logger.h>

extern const AP_HAL::HAL& hal;

#define AP_MOUNT_SIYI_HEADER1 0x55 // first header byte
#define AP_MOUNT_SIYI_HEADER2 0x66 // second header byte
#define AP_MOUNT_SIYI_PACKETLEN_MIN 10 // minimum number of bytes in a packet. this is a packet with no data bytes
#define AP_MOUNT_SIYI_DATALEN_MAX (AP_MOUNT_SIYI_PACKETLEN_MAX-AP_MOUNT_SIYI_PACKETLEN_MIN) // max bytes for data portion of packet
#define AP_MOUNT_SIYI_RATE_MAX_RADS radians(90) // maximum physical rotation rate of gimbal in radans/sec
#define AP_MOUNT_SIYI_PITCH_P 1.50 // pitch controller P gain (converts pitch angle error to target rate)
#define AP_MOUNT_SIYI_YAW_P 1.50 // yaw controller P gain (converts yaw angle error to target rate)
#define AP_MOUNT_SIYI_RATE_MAX_RADS radians(70) // maximum physical rotation rate of gimbal in radans/sec
#define AP_MOUNT_SIYI_ACCEL_MAX_RADSS radians(100) // maximum acceleration of gimbal in rad/s/s
#define AP_MOUNT_SIYI_UPDATE_DT 0.02 // update called at 50hz
#define AP_MOUNT_SIYI_PITCH_P 1.5 // pitch controller P gain (converts pitch angle error to target rate)
#define AP_MOUNT_SIYI_PITCH_I 0.5 // pitch controller I gain (converts persistent pitch angle error to target rate)
#define AP_MOUNT_SIYI_PITCH_IMAX 0.3 // pitch controller IMAX (limits maximum I output)
#define AP_MOUNT_SIYI_YAW_P 1.5 // yaw controller P gain (converts yaw angle error to target rate)
#define AP_MOUNT_SIYI_YAW_I 0.5 // yaw controller I gain (converts persistent yaw angle error to target rate)
#define AP_MOUNT_SIYI_YAW_IMAX 0.3 // yaw controller IMAX (limits maximum I output)
#define AP_MOUNT_SIYI_TIMEOUT_MS 1000 // timeout for health and rangefinder readings

#define AP_MOUNT_SIYI_DEBUG 0
Expand All @@ -32,6 +39,26 @@ const AP_Mount_Siyi::HWInfo AP_Mount_Siyi::hardware_lookup_table[] {
{{'7','A'}, "ZT30"},
};

// rate mapping from radians/sec to scalars that can be sent to the gimbal (e.g. -100 to +100)
const AP_Mount_Siyi::RateMapping AP_Mount_Siyi::rate_mapping[] {
{radians(0), 0.0},
{radians(4), 0.0},
{radians(5), 1.75},
{radians(6), 3.0},
{radians(7), 4.7},
{radians(8), 6.0},
{radians(9), 7.5},
{radians(10), 9.0},
{radians(15), 16.2},
{radians(20), 23.8},
{radians(25), 31.2},
{radians(30), 38.6},
{radians(40), 53.4},
{radians(50), 68.1},
{radians(60), 83.4},
{radians(70), 98.0}
};

// update mount position - should be called periodically
void AP_Mount_Siyi::update()
{
Expand Down Expand Up @@ -670,13 +697,92 @@ bool AP_Mount_Siyi::set_motion_mode(const GimbalMotionMode mode, const bool forc
return sent;
}

// convert a rate in radians/sec to a scalar that can be sent to the gimbal (e.g. -100 to +100)
float AP_Mount_Siyi::get_rate_scalar(float rate_rads) const
{
// use absolute rate
float rate_rads_abs = fabsf(rate_rads);

// find first mapping array element with a desired rate greater than rate_rads_abs
uint8_t high_index = 0;
while (high_index < ARRAY_SIZE(rate_mapping) && (rate_rads_abs > rate_mapping[high_index].desired_rate_rads)) {
high_index++;
}

// check for out of range
if (high_index == 0) {
return 0.0;
}

// linear interpolate to find rate scalar
const float dir = rate_rads >= 0 ? 1.0 : -1.0;
const float rate_scalar = dir * linear_interpolate(rate_mapping[high_index-1].rate_scalar,
rate_mapping[high_index].rate_scalar,
rate_rads_abs,
rate_mapping[high_index-1].desired_rate_rads,
rate_mapping[high_index].desired_rate_rads);
return rate_scalar;
}

// send target pitch and yaw rates to gimbal
// yaw_is_ef should be true if yaw_rads target is an earth frame rate, false if body_frame
void AP_Mount_Siyi::send_target_rates(float pitch_rads, float yaw_rads, bool yaw_is_ef)
{
const float pitch_rate_scalar = constrain_float(100.0 * pitch_rads / AP_MOUNT_SIYI_RATE_MAX_RADS, -100, 100);
const float yaw_rate_scalar = constrain_float(100.0 * yaw_rads / AP_MOUNT_SIYI_RATE_MAX_RADS, -100, 100);
rotate_gimbal(pitch_rate_scalar, yaw_rate_scalar, yaw_is_ef);
// calculate maximum rate change
const float rate_change_max = AP_MOUNT_SIYI_ACCEL_MAX_RADSS * AP_MOUNT_SIYI_UPDATE_DT;

// apply limits to pitch rate
_pitch_control.rate_limited = (pitch_rads > _pitch_control.rate_prev + rate_change_max) || (pitch_rads < _pitch_control.rate_prev - rate_change_max) || (fabsf(pitch_rads) > AP_MOUNT_SIYI_RATE_MAX_RADS);
pitch_rads = constrain_float(pitch_rads, _pitch_control.rate_prev - rate_change_max, _pitch_control.rate_prev + rate_change_max);
pitch_rads = constrain_float(pitch_rads, -AP_MOUNT_SIYI_RATE_MAX_RADS, AP_MOUNT_SIYI_RATE_MAX_RADS);
_pitch_control.rate_prev = pitch_rads;

// apply limits to yaw rate
_yaw_control.rate_limited = (yaw_rads > _yaw_control.rate_prev + rate_change_max) || (yaw_rads < _yaw_control.rate_prev - rate_change_max) || (fabsf(yaw_rads) > AP_MOUNT_SIYI_RATE_MAX_RADS);
yaw_rads = constrain_float(yaw_rads, _yaw_control.rate_prev - rate_change_max, _yaw_control.rate_prev + rate_change_max);
yaw_rads = constrain_float(yaw_rads, -AP_MOUNT_SIYI_RATE_MAX_RADS, AP_MOUNT_SIYI_RATE_MAX_RADS);
_yaw_control.rate_prev = yaw_rads;

rotate_gimbal(get_rate_scalar(pitch_rads), get_rate_scalar(yaw_rads), yaw_is_ef);

#if AP_MOUNT_SIYI_DEBUG
// calculate actual pitch and yaw rates
static Vector3f prev_angle_rad;
static uint32_t prev_angle_rad_ms;
float dt = (_last_current_angle_rad_ms - prev_angle_rad_ms) / 1000.0;
if (!is_positive(dt)) {
return;
}
const Vector3f actual_rate = (_current_angle_rad - prev_angle_rad) / dt;
prev_angle_rad = _current_angle_rad;
prev_angle_rad_ms = _last_current_angle_rad_ms;

// @Description: Siyi Rate Debug
// @Field: TimeUS: Time since system startup
// @Field: DPR: Desired pitch rate
// @Field: PR: Actual pitch rate
// @Field: POut: Pitch controller output
// @Field: PL: Pitch controller rate limited
// @Field: DYaw: Desired yaw angle
// @Field: Yaw: Actual yaw angle
// @Field: YOut: Yaw controller output
// @Field: YL: Yaw controller rate limited
AP::logger().WriteStreaming(
"SIYR",
"TimeUS,DPR,PR,POut,PL,DYR,YR,YOut,YL",
"sdd--dd--",
"F00000000",
"Qfffbfffb",
AP_HAL::micros64(),
(double)degrees(pitch_rads),
(double)degrees(actual_rate.y),
(double)get_rate_scalar(pitch_rads),
(int)_pitch_control.rate_limited,
(double)degrees(yaw_rads),
(double)degrees(actual_rate.z),
(double)get_rate_scalar(yaw_rads),
(int)_yaw_control.rate_limited);
#endif // AP_MOUNT_SIYI_DEBUG
}

// send target pitch and yaw angles to gimbal
Expand All @@ -686,7 +792,9 @@ void AP_Mount_Siyi::send_target_angles(float pitch_rad, float yaw_rad, bool yaw_
// stop gimbal if no recent actual angles
uint32_t now_ms = AP_HAL::millis();
if (now_ms - _last_current_angle_rad_ms >= 200) {
rotate_gimbal(0, 0, false);
send_target_rates(0, 0, false);
_pitch_control.integrator = 0;
_yaw_control.integrator = 0;
return;
}

Expand All @@ -697,9 +805,14 @@ void AP_Mount_Siyi::send_target_angles(float pitch_rad, float yaw_rad, bool yaw_
current_angle_transformed.z = -_current_angle_rad.z;
}

// use simple P controller to convert pitch angle error (in radians) to a target rate scalar (-100 to +100)
const float pitch_err_rad = (pitch_rad - current_angle_transformed.y);
const float pitch_rate_scalar = constrain_float(100.0 * pitch_err_rad * AP_MOUNT_SIYI_PITCH_P / AP_MOUNT_SIYI_RATE_MAX_RADS, -100, 100);
// use PI controller to convert pitch angle error (in radians) to a target rate
const float pitch_err_rad = pitch_rad - current_angle_transformed.y;
const float pitch_control_P = pitch_err_rad * AP_MOUNT_SIYI_PITCH_P;
// calculate I term if not limited or error reduces I term
if (!_pitch_control.rate_limited || (pitch_err_rad > 0 && _pitch_control.integrator < 0) || (pitch_err_rad < 0 && _pitch_control.integrator > 0)) {
_pitch_control.integrator = constrain_float(_pitch_control.integrator + pitch_err_rad * AP_MOUNT_SIYI_PITCH_I * AP_MOUNT_SIYI_UPDATE_DT, -AP_MOUNT_SIYI_PITCH_IMAX, AP_MOUNT_SIYI_PITCH_IMAX);
}
const float pitch_rate_rads = pitch_control_P + _pitch_control.integrator;

// convert yaw angle to body-frame
float yaw_bf_rad = yaw_is_ef ? wrap_PI(yaw_rad - AP::ahrs().get_yaw()) : yaw_rad;
Expand All @@ -712,12 +825,59 @@ void AP_Mount_Siyi::send_target_angles(float pitch_rad, float yaw_rad, bool yaw_
yaw_is_ef = false;
}

// use simple P controller to convert yaw angle error to a target rate scalar (-100 to +100)
const float yaw_err_rad = (yaw_bf_rad - current_angle_transformed.z);
const float yaw_rate_scalar = constrain_float(100.0 * yaw_err_rad * AP_MOUNT_SIYI_YAW_P / AP_MOUNT_SIYI_RATE_MAX_RADS, -100, 100);
// use PI controller to convert yaw angle error (in radians) to a target rate
const float yaw_err_rad = yaw_bf_rad - current_angle_transformed.z;
const float yaw_control_P = yaw_err_rad * AP_MOUNT_SIYI_YAW_P;
// calculate I term if not limited or error reduces I term
if (!_yaw_control.rate_limited || (yaw_err_rad > 0 && _yaw_control.integrator < 0) || (yaw_err_rad < 0 && _yaw_control.integrator > 0)) {
_yaw_control.integrator = constrain_float(_yaw_control.integrator + yaw_err_rad * AP_MOUNT_SIYI_YAW_I * AP_MOUNT_SIYI_UPDATE_DT, -AP_MOUNT_SIYI_YAW_IMAX, AP_MOUNT_SIYI_YAW_IMAX);
}
const float yaw_rate_rads = yaw_control_P + _yaw_control.integrator;

// rotate gimbal. pitch_rate and yaw_rate are scalars in the range -100 ~ +100
rotate_gimbal(pitch_rate_scalar, yaw_rate_scalar, yaw_is_ef);
// send target rates to gimbal
send_target_rates(pitch_rate_rads, yaw_rate_rads, yaw_is_ef);

#if AP_MOUNT_SIYI_DEBUG
const float pitch_rate_scalar = get_rate_scalar(pitch_rate_rads);
const float yaw_rate_scalar = get_rate_scalar(yaw_rate_rads);
// @Description: Siyi Pitch Yaw Control
// @Field: TimeUS: Time since system startup
// @Field: DPit: Desired pitch angle
// @Field: Pit: Actual pitch angle
// @Field: PErr: Pitch angle error
// @Field: PP: Pitch controller P output
// @Field: PI: Pitch controller I output
// @Field: POut: Pitch controller output
// @Field: PL: Pitch controller rate limited
// @Field: DYaw: Desired yaw angle
// @Field: Yaw: Actual yaw angle
// @Field: YErr: Yaw angle error
// @Field: YP: Yaw controller P output
// @Field: YI: Yaw controller I output
// @Field: YOut: Yaw controller output
// @Field: YL: Yaw controller rate limited
AP::logger().WriteStreaming(
"SIYI",
"TimeUS,DPit,Pit,PErr,PP,PI,POut,PL,DYaw,Yaw,YErr,YP,YI,YOut,YL",
"sddd----ddd----",
"F00000000000000",
"Qffffffbffffffb",
AP_HAL::micros64(),
(double)degrees(pitch_rad),
(double)degrees(current_angle_transformed.y),
(double)degrees(pitch_err_rad),
(double)pitch_control_P,
(double)_pitch_control.integrator,
(double)pitch_rate_scalar,
(int)_pitch_control.rate_limited,
(double)degrees(yaw_bf_rad),
(double)degrees(current_angle_transformed.z),
(double)degrees(yaw_err_rad),
(double)yaw_control_P,
(double)_yaw_control.integrator,
(double)yaw_rate_scalar,
(int)_yaw_control.rate_limited);
#endif // AP_MOUNT_SIYI_DEBUG
}

// take a picture. returns true on success
Expand Down
17 changes: 17 additions & 0 deletions libraries/AP_Mount/AP_Mount_Siyi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -254,6 +254,9 @@ class AP_Mount_Siyi : public AP_Mount_Backend_Serial
void request_gimbal_attitude() { send_packet(SiyiCommandId::ACQUIRE_GIMBAL_ATTITUDE, nullptr, 0); }
void request_rangefinder_distance() { send_packet(SiyiCommandId::READ_RANGEFINDER, nullptr, 0); }

// convert a rate in radians/sec to a scalar that can be sent to the gimbal (e.g. -100 to +100)
float get_rate_scalar(float rate_rads) const;

// rotate gimbal. pitch_rate and yaw_rate are scalars in the range -100 ~ +100
// yaw_is_ef should be true if gimbal should maintain an earth-frame target (aka lock)
void rotate_gimbal(int8_t pitch_scalar, int8_t yaw_scalar, bool yaw_is_ef);
Expand Down Expand Up @@ -345,6 +348,20 @@ class AP_Mount_Siyi : public AP_Mount_Backend_Serial
};
static const HWInfo hardware_lookup_table[];

// rate mapping from radians/sec to scalars that can be sent to the gimbal (e.g. -100 to +100)
struct RateMapping {
float desired_rate_rads;
float rate_scalar;
};
static const RateMapping rate_mapping[];

// pitch and yaw controller
struct RateControl {
float integrator; // rate control integrator
float rate_prev; // previous target rate (used for acceleration limiting)
bool rate_limited; // true if rate was acceleration limited
} _pitch_control, _yaw_control;

// count of SET_TIME packets, we send 5 times to cope with packet loss
uint8_t sent_time_count;
};
Expand Down

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