/* 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 . */ /* gimbal simulator class for MAVLink gimbal */ #include "SIM_Gimbal.h" #include #include "SIM_Aircraft.h" extern const AP_HAL::HAL& hal; namespace SITL { Gimbal::Gimbal(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 Gimbal::update(void) { // 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; // see if we should do a report send_report(); } /* send a report to the vehicle control code over MAVLink */ void Gimbal::send_report(void) { if (AP_HAL::millis() < 10000) { // simulated aircraft don't appear until 10s after startup. This avoids a windows // threading issue with non-blocking sockets and the initial wait on uartA return; } if (!mavlink.connected && mav_socket.connect(target_address, target_port)) { ::printf("Gimbal connected to %s:%u\n", target_address, (unsigned)target_port); mavlink.connected = true; } if (!mavlink.connected) { return; } // check for incoming MAVLink messages uint8_t buf[100]; ssize_t ret; while ((ret=mav_socket.recv(buf, sizeof(buf), 0)) > 0) { for (uint8_t i=0; i= 1000) { mavlink_heartbeat_t heartbeat; heartbeat.type = MAV_TYPE_GIMBAL; heartbeat.autopilot = MAV_AUTOPILOT_ARDUPILOTMEGA; heartbeat.base_mode = 0; heartbeat.system_status = 0; heartbeat.mavlink_version = 0; heartbeat.custom_mode = 0; /* save and restore sequence number for chan0, as it is used by generated encode functions */ mavlink_status_t *chan0_status = mavlink_get_channel_status(MAVLINK_COMM_0); uint8_t saved_seq = chan0_status->current_tx_seq; chan0_status->current_tx_seq = mavlink.seq; len = mavlink_msg_heartbeat_encode(vehicle_system_id, vehicle_component_id, &msg, &heartbeat); chan0_status->current_tx_seq = saved_seq; mav_socket.send(&msg.magic, len); last_heartbeat_ms = now; } /* send a GIMBAL_REPORT message */ 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; gimbal_report.target_system = vehicle_system_id; gimbal_report.target_component = vehicle_component_id; gimbal_report.delta_time = delta_time; gimbal_report.delta_angle_x = delta_angle.x; gimbal_report.delta_angle_y = delta_angle.y; gimbal_report.delta_angle_z = delta_angle.z; gimbal_report.delta_velocity_x = delta_velocity.x; gimbal_report.delta_velocity_y = delta_velocity.y; gimbal_report.delta_velocity_z = delta_velocity.z; gimbal_report.joint_roll = joint_angles.x; gimbal_report.joint_el = joint_angles.y; gimbal_report.joint_az = joint_angles.z; mavlink_status_t *chan0_status = mavlink_get_channel_status(MAVLINK_COMM_0); uint8_t saved_seq = chan0_status->current_tx_seq; chan0_status->current_tx_seq = mavlink.seq; len = mavlink_msg_gimbal_report_encode(vehicle_system_id, vehicle_component_id, &msg, &gimbal_report); chan0_status->current_tx_seq = saved_seq; uint8_t msgbuf[len]; len = mavlink_msg_to_send_buffer(msgbuf, &msg); if (len > 0) { mav_socket.send(msgbuf, len); } delta_velocity.zero(); delta_angle.zero(); } } } // namespace SITL