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SITL: split MAVLink and physical gimbal simulations

This commit is contained in:
Peter Barker 2024-07-17 16:52:20 +10:00 committed by Peter Barker
parent ed3aeb39fd
commit ba135b9008
5 changed files with 313 additions and 199 deletions
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184
libraries/SITL/SIM_Gimbal.cpp Normal file
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@ -0,0 +1,184 @@
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
gimbal simulator class for gimbal
*/
#include "SIM_Gimbal.h"
#if AP_SIM_GIMBAL_ENABLED
#include <stdio.h>
#include "SIM_Aircraft.h"
extern const AP_HAL::HAL& hal;
#define GIMBAL_DEBUG 0
#if GIMBAL_DEBUG
#define debug(fmt, args...) do { printf("GIMBAL: " fmt, ##args); } while(0)
#else
#define debug(fmt, args...) do { } while(0)
#endif
namespace SITL {
/*
update the gimbal state
*/
void Gimbal::update(const class Aircraft &aircraft)
{
// calculate delta time in seconds
uint32_t now_us = AP_HAL::micros();
float delta_t = (now_us - last_update_us) * 1.0e-6f;
last_update_us = now_us;
const Matrix3f &vehicle_dcm = aircraft.get_dcm();
if (!init_done) {
dcm = vehicle_dcm;
}
const Vector3f &vehicle_gyro = AP::ins().get_gyro();
const Vector3f &vehicle_accel_body = AP::ins().get_accel();
// take a copy of the demanded rates to bypass the limiter function for testing
Vector3f demRateRaw = demanded_angular_rate;
// 1) Rotate the copters rotation rates into the gimbals frame of reference
// copterAngRate_G = transpose(DCMgimbal)*DCMcopter*copterAngRate
Vector3f copterAngRate_G = dcm.transposed()*vehicle_dcm*vehicle_gyro;
// 2) Subtract the copters body rates to obtain a copter relative rotational
// rate vector (X,Y,Z) in gimbal sensor frame
// relativeGimbalRate(X,Y,Z) = gimbalRateDemand - copterAngRate_G
Vector3f relativeGimbalRate = demanded_angular_rate - copterAngRate_G;
// calculate joint angles (euler312 order)
// calculate copter -> gimbal rotation matrix
Matrix3f rotmat_copter_gimbal = dcm.transposed() * vehicle_dcm;
joint_angles = rotmat_copter_gimbal.transposed().to_euler312();
/* 4) For each of the three joints, calculate upper and lower rate limits
from the corresponding angle limits and current joint angles
upperRatelimit = (jointAngle - lowerAngleLimit) * travelLimitGain
lowerRatelimit = (jointAngle - upperAngleLimit) * travelLimitGain
travelLimitGain is equal to the inverse of the bump stop time constant and
should be set to something like 20 initially. If set too high it can cause
the rates to 'ring' when they the limiter is in force, particularly given
we are using a first order numerical integration.
*/
Vector3f upperRatelimit = -(joint_angles - upper_joint_limits) * travelLimitGain;
Vector3f lowerRatelimit = -(joint_angles - lower_joint_limits) * travelLimitGain;
/*
5) Calculate the gimbal joint rates (roll, elevation, azimuth)
gimbalJointRates(roll, elev, azimuth) = Matrix*relativeGimbalRate(X,Y,Z)
where matrix =
+- -+
| cos(elevAngle), 0, sin(elevAngle) |
| |
| sin(elevAngle) tan(rollAngle), 1, -cos(elevAngle) tan(rollAngle) |
| |
| sin(elevAngle) cos(elevAngle) |
| - --------------, 0, -------------- |
| cos(rollAngle) cos(rollAngle) |
+- -+
*/
float rollAngle = joint_angles.x;
float elevAngle = joint_angles.y;
Matrix3f matrix = Matrix3f(Vector3f(cosf(elevAngle), 0, sinf(elevAngle)),
Vector3f(sinf(elevAngle)*tanf(rollAngle), 1, -cosf(elevAngle)*tanf(rollAngle)),
Vector3f(-sinf(elevAngle)/cosf(rollAngle), 0, cosf(elevAngle)/cosf(rollAngle)));
Vector3f gimbalJointRates = matrix * relativeGimbalRate;
// 6) Apply the rate limits from 4)
gimbalJointRates.x = constrain_float(gimbalJointRates.x, lowerRatelimit.x, upperRatelimit.x);
gimbalJointRates.y = constrain_float(gimbalJointRates.y, lowerRatelimit.y, upperRatelimit.y);
gimbalJointRates.z = constrain_float(gimbalJointRates.z, lowerRatelimit.z, upperRatelimit.z);
/*
7) Convert the modified gimbal joint rates to body rates (still copter
relative)
relativeGimbalRate(X,Y,Z) = Matrix * gimbalJointRates(roll, elev, azimuth)
where Matrix =
+- -+
| cos(elevAngle), 0, -cos(rollAngle) sin(elevAngle) |
| |
| 0, 1, sin(rollAngle) |
| |
| sin(elevAngle), 0, cos(elevAngle) cos(rollAngle) |
+- -+
*/
matrix = Matrix3f(Vector3f(cosf(elevAngle), 0, -cosf(rollAngle)*sinf(elevAngle)),
Vector3f(0, 1, sinf(rollAngle)),
Vector3f(sinf(elevAngle), 0, cosf(elevAngle)*cosf(rollAngle)));
relativeGimbalRate = matrix * gimbalJointRates;
// 8) Add to the result from step 1) to obtain the demanded gimbal body rates
// in an inertial frame of reference
// demandedGimbalRatesInertial(X,Y,Z) = relativeGimbalRate(X,Y,Z) + copterAngRate_G
// Vector3f demandedGimbalRatesInertial = relativeGimbalRate + copterAngRate_G;
// for the moment we will set gyros equal to demanded_angular_rate
gimbal_angular_rate = demRateRaw; // demandedGimbalRatesInertial + true_gyro_bias - supplied_gyro_bias
// update rotation of the gimbal
dcm.rotate(gimbal_angular_rate*delta_t);
dcm.normalize();
// calculate copter -> gimbal rotation matrix
rotmat_copter_gimbal = dcm.transposed() * vehicle_dcm;
// calculate joint angles (euler312 order)
joint_angles = rotmat_copter_gimbal.transposed().to_euler312();
// update observed gyro
gyro = gimbal_angular_rate + true_gyro_bias;
// update delta_angle (integrate)
delta_angle += gyro * delta_t;
// calculate accel in gimbal body frame
Vector3f copter_accel_earth = vehicle_dcm * vehicle_accel_body;
Vector3f accel = dcm.transposed() * copter_accel_earth;
// integrate velocity
delta_velocity += accel * delta_t;
}
void Gimbal::get_deltas(Vector3f &_delta_angle, Vector3f &_delta_velocity, uint32_t &_delta_time_us)
{
const uint32_t now_us = AP_HAL::micros();
_delta_angle = delta_angle;
_delta_velocity = delta_velocity;
_delta_time_us = now_us - delta_start_us;
delta_angle.zero();
delta_velocity.zero();
delta_start_us = now_us;
}
} // namespace SITL
#endif // AP_SIM_GIMBAL_ENABLED

96
libraries/SITL/SIM_Gimbal.h Normal file
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@ -0,0 +1,96 @@
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
gimbal simulator class
*/
#pragma once
#include "SIM_config.h"
#if AP_SIM_GIMBAL_ENABLED
#include <AP_Math/AP_Math.h>
#include <GCS_MAVLink/GCS.h>
namespace SITL {
class Gimbal {
public:
void update(const class Aircraft &aircraft);
void set_demanded_rates(const Vector3f &rates) {
demanded_angular_rate = rates;
}
void get_deltas(Vector3f &_delta_angle, Vector3f &_delta_velocity, uint32_t &_delta_time_us);
void get_joint_angles(Vector3f &_angles) { _angles = joint_angles; }
private:
// rotation matrix (gimbal body -> earth)
Matrix3f dcm;
bool init_done;
// time of last update
uint32_t last_update_us;
// true angular rate of gimbal in body frame (rad/s)
Vector3f gimbal_angular_rate;
// observed angular rate (including biases)
Vector3f gyro;
/* joint angles, in radians. in yaw/roll/pitch order. Relative to fwd.
So 0,0,0 points forward.
Pi/2,0,0 means pointing right
0, Pi/2, 0 means pointing fwd, but rolled 90 degrees to right
0, 0, -Pi/2, means pointing down
*/
Vector3f joint_angles;
// physical constraints on joint angles in (roll, pitch, azimuth) order
Vector3f lower_joint_limits{radians(-40), radians(-135), radians(-7.5)};
Vector3f upper_joint_limits{radians(40), radians(45), radians(7.5)};
const float travelLimitGain = 20;
// true gyro bias
Vector3f true_gyro_bias;
// time since delta angles/velocities returned
uint32_t delta_start_us;
// integral of gyro vector over last time interval. In radians
Vector3f delta_angle;
// integral of accel vector over last time interval. In m/s
Vector3f delta_velocity;
/*
control variables from the vehicle
*/
// angular rate in rad/s. In body frame of gimbal
Vector3f demanded_angular_rate;
// gyro bias provided by EKF on vehicle. In rad/s.
// Should be subtracted from the gyro readings to get true body
// rotatation rates
// Vector3f supplied_gyro_bias;
};
} // namespace SITL
#endif // AP_SIM_GIMBAL_ENABLED

163
libraries/SITL/SIM_SoloGimbal.cpp
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@ -36,149 +36,12 @@ extern const AP_HAL::HAL& hal;
namespace SITL {
SoloGimbal::SoloGimbal(const struct sitl_fdm &_fdm) :
fdm(_fdm),
target_address("127.0.0.1"),
target_port(5762),
lower_joint_limits(radians(-40), radians(-135), radians(-7.5)),
upper_joint_limits(radians(40), radians(45), radians(7.5)),
travelLimitGain(20),
reporting_period_ms(10),
seen_heartbeat(false),
seen_gimbal_control(false),
mav_socket(false)
{
memset(&mavlink, 0, sizeof(mavlink));
fdm.quaternion.rotation_matrix(dcm);
}
/*
update the gimbal state
*/
void SoloGimbal::update(void)
void SoloGimbal::update(const Aircraft &aircraft)
{
// calculate delta time in seconds
uint32_t now_us = AP_HAL::micros();
float delta_t = (now_us - last_update_us) * 1.0e-6f;
last_update_us = now_us;
Matrix3f vehicle_dcm;
fdm.quaternion.rotation_matrix(vehicle_dcm);
const Vector3f &vehicle_gyro = AP::ins().get_gyro();
const Vector3f &vehicle_accel_body = AP::ins().get_accel();
// take a copy of the demanded rates to bypass the limiter function for testing
Vector3f demRateRaw = demanded_angular_rate;
// 1) Rotate the copters rotation rates into the gimbals frame of reference
// copterAngRate_G = transpose(DCMgimbal)*DCMcopter*copterAngRate
Vector3f copterAngRate_G = dcm.transposed()*vehicle_dcm*vehicle_gyro;
// 2) Subtract the copters body rates to obtain a copter relative rotational
// rate vector (X,Y,Z) in gimbal sensor frame
// relativeGimbalRate(X,Y,Z) = gimbalRateDemand - copterAngRate_G
Vector3f relativeGimbalRate = demanded_angular_rate - copterAngRate_G;
// calculate joint angles (euler312 order)
// calculate copter -> gimbal rotation matrix
Matrix3f rotmat_copter_gimbal = dcm.transposed() * vehicle_dcm;
joint_angles = rotmat_copter_gimbal.transposed().to_euler312();
/* 4) For each of the three joints, calculate upper and lower rate limits
from the corresponding angle limits and current joint angles
upperRatelimit = (jointAngle - lowerAngleLimit) * travelLimitGain
lowerRatelimit = (jointAngle - upperAngleLimit) * travelLimitGain
travelLimitGain is equal to the inverse of the bump stop time constant and
should be set to something like 20 initially. If set too high it can cause
the rates to 'ring' when they the limiter is in force, particularly given
we are using a first order numerical integration.
*/
Vector3f upperRatelimit = -(joint_angles - upper_joint_limits) * travelLimitGain;
Vector3f lowerRatelimit = -(joint_angles - lower_joint_limits) * travelLimitGain;
/*
5) Calculate the gimbal joint rates (roll, elevation, azimuth)
gimbalJointRates(roll, elev, azimuth) = Matrix*relativeGimbalRate(X,Y,Z)
where matrix =
+- -+
| cos(elevAngle), 0, sin(elevAngle) |
| |
| sin(elevAngle) tan(rollAngle), 1, -cos(elevAngle) tan(rollAngle) |
| |
| sin(elevAngle) cos(elevAngle) |
| - --------------, 0, -------------- |
| cos(rollAngle) cos(rollAngle) |
+- -+
*/
float rollAngle = joint_angles.x;
float elevAngle = joint_angles.y;
Matrix3f matrix = Matrix3f(Vector3f(cosf(elevAngle), 0, sinf(elevAngle)),
Vector3f(sinf(elevAngle)*tanf(rollAngle), 1, -cosf(elevAngle)*tanf(rollAngle)),
Vector3f(-sinf(elevAngle)/cosf(rollAngle), 0, cosf(elevAngle)/cosf(rollAngle)));
Vector3f gimbalJointRates = matrix * relativeGimbalRate;
// 6) Apply the rate limits from 4)
gimbalJointRates.x = constrain_float(gimbalJointRates.x, lowerRatelimit.x, upperRatelimit.x);
gimbalJointRates.y = constrain_float(gimbalJointRates.y, lowerRatelimit.y, upperRatelimit.y);
gimbalJointRates.z = constrain_float(gimbalJointRates.z, lowerRatelimit.z, upperRatelimit.z);
/*
7) Convert the modified gimbal joint rates to body rates (still copter
relative)
relativeGimbalRate(X,Y,Z) = Matrix * gimbalJointRates(roll, elev, azimuth)
where Matrix =
+- -+
| cos(elevAngle), 0, -cos(rollAngle) sin(elevAngle) |
| |
| 0, 1, sin(rollAngle) |
| |
| sin(elevAngle), 0, cos(elevAngle) cos(rollAngle) |
+- -+
*/
matrix = Matrix3f(Vector3f(cosf(elevAngle), 0, -cosf(rollAngle)*sinf(elevAngle)),
Vector3f(0, 1, sinf(rollAngle)),
Vector3f(sinf(elevAngle), 0, cosf(elevAngle)*cosf(rollAngle)));
relativeGimbalRate = matrix * gimbalJointRates;
// 8) Add to the result from step 1) to obtain the demanded gimbal body rates
// in an inertial frame of reference
// demandedGimbalRatesInertial(X,Y,Z) = relativeGimbalRate(X,Y,Z) + copterAngRate_G
// Vector3f demandedGimbalRatesInertial = relativeGimbalRate + copterAngRate_G;
// for the moment we will set gyros equal to demanded_angular_rate
gimbal_angular_rate = demRateRaw; // demandedGimbalRatesInertial + true_gyro_bias - supplied_gyro_bias
// update rotation of the gimbal
dcm.rotate(gimbal_angular_rate*delta_t);
dcm.normalize();
// calculate copter -> gimbal rotation matrix
rotmat_copter_gimbal = dcm.transposed() * vehicle_dcm;
// calculate joint angles (euler312 order)
joint_angles = rotmat_copter_gimbal.transposed().to_euler312();
// update observed gyro
gyro = gimbal_angular_rate + true_gyro_bias;
// update delta_angle (integrate)
delta_angle += gyro * delta_t;
// calculate accel in gimbal body frame
Vector3f copter_accel_earth = vehicle_dcm * vehicle_accel_body;
Vector3f accel = dcm.transposed() * copter_accel_earth;
// integrate velocity
delta_velocity += accel * delta_t;
gimbal.update(aircraft);
// see if we should do a report
send_report();
@ -306,11 +169,9 @@ void SoloGimbal::send_report(void)
}
mavlink_gimbal_control_t pkt;
mavlink_msg_gimbal_control_decode(&msg, &pkt);
demanded_angular_rate = Vector3f(pkt.demanded_rate_x,
pkt.demanded_rate_y,
pkt.demanded_rate_z);
// no longer supply a bias
supplied_gyro_bias.zero();
gimbal.set_demanded_rates(Vector3f(pkt.demanded_rate_x,
pkt.demanded_rate_y,
pkt.demanded_rate_z));
seen_gimbal_control = true;
break;
}
@ -375,12 +236,20 @@ void SoloGimbal::send_report(void)
*/
uint32_t now_us = AP_HAL::micros();
if (now_us - last_report_us > reporting_period_ms*1000UL) {
mavlink_gimbal_report_t gimbal_report;
float delta_time = (now_us - last_report_us) * 1.0e-6f;
last_report_us = now_us;
uint32_t delta_time_us;
Vector3f delta_angle;
Vector3f delta_velocity;
gimbal.get_deltas(delta_angle, delta_velocity, delta_time_us);
Vector3f joint_angles;
gimbal.get_joint_angles(joint_angles);
mavlink_gimbal_report_t gimbal_report;
gimbal_report.target_system = vehicle_system_id;
gimbal_report.target_component = vehicle_component_id;
gimbal_report.delta_time = delta_time;
gimbal_report.delta_time = delta_time_us * 1e-6;
gimbal_report.delta_angle_x = delta_angle.x;
gimbal_report.delta_angle_y = delta_angle.y;
gimbal_report.delta_angle_z = delta_angle.z;

62
libraries/SITL/SIM_SoloGimbal.h
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@ -27,6 +27,8 @@ rc 6 1818 # for neutral pitch input
#if AP_SIM_SOLOGIMBAL_ENABLED
#include "SIM_Gimbal.h"
#include <AP_Math/AP_Math.h>
#include <GCS_MAVLink/GCS_MAVLink.h>
#include <AP_HAL/utility/Socket_native.h>
@ -35,65 +37,23 @@ namespace SITL {
class SoloGimbal {
public:
SoloGimbal(const struct sitl_fdm &_fdm);
void update(void);
SoloGimbal() {}
void update(const Aircraft &aicraft);
private:
const struct sitl_fdm &fdm;
const char *target_address;
const uint16_t target_port;
// rotation matrix (gimbal body -> earth)
Matrix3f dcm;
const char *target_address = "127.0.0.1";
const uint16_t target_port = 5762;
// time of last update
uint32_t last_update_us;
// true angular rate of gimbal in body frame (rad/s)
Vector3f gimbal_angular_rate;
// observed angular rate (including biases)
Vector3f gyro;
/* joint angles, in radians. in yaw/roll/pitch order. Relative to fwd.
So 0,0,0 points forward.
Pi/2,0,0 means pointing right
0, Pi/2, 0 means pointing fwd, but rolled 90 degrees to right
0, 0, -Pi/2, means pointing down
*/
Vector3f joint_angles;
// physical constraints on joint angles in (roll, pitch, azimuth) order
Vector3f lower_joint_limits;
Vector3f upper_joint_limits;
const float travelLimitGain;
// true gyro bias
Vector3f true_gyro_bias;
// physic simulation of gimbal:
Gimbal gimbal;
// reporting variables. gimbal pushes these to vehicle code over
// MAVLink at approx 100Hz
// reporting period in ms
const float reporting_period_ms;
// integral of gyro vector over last time interval. In radians
Vector3f delta_angle;
// integral of accel vector over last time interval. In m/s
Vector3f delta_velocity;
/*
control variables from the vehicle
*/
// angular rate in rad/s. In body frame of gimbal
Vector3f demanded_angular_rate;
// gyro bias provided by EKF on vehicle. In rad/s.
// Should be subtracted from the gyro readings to get true body
// rotatation rates
Vector3f supplied_gyro_bias;
const float reporting_period_ms = 10;
uint32_t last_report_us;
uint32_t last_heartbeat_ms;
@ -102,7 +62,7 @@ private:
uint8_t vehicle_system_id;
uint8_t vehicle_component_id;
SocketAPM_native mav_socket;
SocketAPM_native mav_socket{false};
struct {
// socket to telem2 on aircraft
bool connected;

7
libraries/SITL/SIM_config.h
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@ -123,5 +123,10 @@
#endif
#ifndef AP_SIM_SOLOGIMBAL_ENABLED
#define AP_SIM_SOLOGIMBAL_ENABLED (CONFIG_HAL_BOARD == HAL_BOARD_SITL)
#define AP_SIM_SOLOGIMBAL_ENABLED (CONFIG_HAL_BOARD == HAL_BOARD_SITL && HAL_MAVLINK_BINDINGS_ENABLED)
#endif
#ifndef AP_SIM_GIMBAL_ENABLED
#define AP_SIM_GIMBAL_ENABLED (AP_SIM_SOLOGIMBAL_ENABLED)
#endif