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mpu6050_serial_to_imu_node.cpp
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mpu6050_serial_to_imu_node.cpp
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#include <geometry_msgs/Quaternion.h>
#include <ros/ros.h>
#include <serial/serial.h>
#include <sensor_msgs/TimeReference.h>
#include <sensor_msgs/Imu.h>
#include <sensor_msgs/Temperature.h>
#include <std_msgs/String.h>
#include <std_srvs/Empty.h>
#include <string>
//patrick-mod
#include <boost/algorithm/clamp.hpp>
#include <tf/transform_broadcaster.h>
#include <tf/transform_datatypes.h>
bool zero_orientation_set = false;
bool set_zero_orientation(std_srvs::Empty::Request&,
std_srvs::Empty::Response&)
{
ROS_INFO("Zero Orientation Set.");
zero_orientation_set = false;
return true;
}
int main(int argc, char** argv)
{
serial::Serial ser;
std::string port;
std::string tf_parent_frame_id;
std::string tf_frame_id;
std::string frame_id;
double time_offset_in_seconds;
bool broadcast_tf;
double linear_acceleration_stddev;
double angular_velocity_stddev;
double orientation_stddev;
uint8_t last_received_message_number;
bool received_message = false;
int data_packet_start;
//patrick-mod
using boost::algorithm::clamp;
tf::Quaternion orientation;
tf::Quaternion zero_orientation;
ros::init(argc, argv, "mpu6050_serial_to_imu_node");
ros::NodeHandle private_node_handle("~");
private_node_handle.param<std::string>("port", port, "/dev/ttyACM0");
private_node_handle.param<std::string>("tf_parent_frame_id", tf_parent_frame_id, "imu_base");
private_node_handle.param<std::string>("tf_frame_id", tf_frame_id, "imu_link");
private_node_handle.param<std::string>("frame_id", frame_id, "imu");
private_node_handle.param<double>("time_offset_in_seconds", time_offset_in_seconds, 0.0);
private_node_handle.param<bool>("broadcast_tf", broadcast_tf, false);
private_node_handle.param<double>("linear_acceleration_stddev", linear_acceleration_stddev, 0.0);
private_node_handle.param<double>("angular_velocity_stddev", angular_velocity_stddev, 0.0);
private_node_handle.param<double>("orientation_stddev", orientation_stddev, 0.0);
ros::NodeHandle nh("");
ros::Publisher imu_pub = nh.advertise<sensor_msgs::Imu>("imu0", 50);
ros::Publisher imu_temperature_pub = nh.advertise<sensor_msgs::Temperature>("temperature", 50);
ros::Publisher trigger_time_pub = nh.advertise<sensor_msgs::TimeReference>("trigger_time", 50);
ros::ServiceServer service = nh.advertiseService("set_zero_orientation", set_zero_orientation);
ros::Rate r(400); // 400 hz
sensor_msgs::Imu imu;
imu.linear_acceleration_covariance[0] = linear_acceleration_stddev;
imu.linear_acceleration_covariance[4] = linear_acceleration_stddev;
imu.linear_acceleration_covariance[8] = linear_acceleration_stddev;
imu.angular_velocity_covariance[0] = angular_velocity_stddev;
imu.angular_velocity_covariance[4] = angular_velocity_stddev;
imu.angular_velocity_covariance[8] = angular_velocity_stddev;
imu.orientation_covariance[0] = orientation_stddev;
imu.orientation_covariance[4] = orientation_stddev;
imu.orientation_covariance[8] = orientation_stddev;
sensor_msgs::TimeReference trigger_time_msg;
sensor_msgs::Temperature temperature_msg;
temperature_msg.variance = 0;
static tf::TransformBroadcaster tf_br;
tf::Transform transform;
transform.setOrigin(tf::Vector3(0,0,0));
std::string input;
std::string read;
uint32_t lastTriggerCounter = 0;
while(ros::ok())
{
try
{
if (ser.isOpen())
{
// read string from serial device
if(ser.available())
{
read = ser.read(ser.available());
ROS_DEBUG("read %i new characters from serial port, adding to %i characters of old input.", (int)read.size(), (int)input.size());
input += read;
while (input.length() >= 36) // while there might be a complete package in input
{
//parse for data packets
data_packet_start = input.find("$\x03");
if (data_packet_start != std::string::npos)
{
ROS_DEBUG("found possible start of data packet at position %d", data_packet_start);
if ((input.length() >= data_packet_start + 36) && (input.compare(data_packet_start + 34, 2, "\n\r"))) //check if positions 26,27 exist, then test values
{
ROS_DEBUG("seems to be a real data package: long enough and found end characters");
// get quaternion values
int16_t w = (((0xff &(char)input[data_packet_start + 2]) << 8) | 0xff &(char)input[data_packet_start + 3]);
int16_t x = (((0xff &(char)input[data_packet_start + 4]) << 8) | 0xff &(char)input[data_packet_start + 5]);
int16_t y = (((0xff &(char)input[data_packet_start + 6]) << 8) | 0xff &(char)input[data_packet_start + 7]);
int16_t z = (((0xff &(char)input[data_packet_start + 8]) << 8) | 0xff &(char)input[data_packet_start + 9]);
double wf = w/16384.0;
double xf = x/16384.0;
double yf = y/16384.0;
double zf = z/16384.0;
tf::Quaternion orientation(xf, yf, zf, wf);
if (!zero_orientation_set)
{
zero_orientation = orientation;
zero_orientation_set = true;
}
//http://answers.ros.org/question/10124/relative-rotation-between-two-quaternions/
tf::Quaternion differential_rotation;
differential_rotation = zero_orientation.inverse() * orientation;
// get gyro values
int16_t gx = (((0xff &(char)input[data_packet_start + 10]) << 8) | 0xff &(char)input[data_packet_start + 11]);
int16_t gy = (((0xff &(char)input[data_packet_start + 12]) << 8) | 0xff &(char)input[data_packet_start + 13]);
int16_t gz = (((0xff &(char)input[data_packet_start + 14]) << 8) | 0xff &(char)input[data_packet_start + 15]);
// calculate rotational velocities in rad/s
// without the last factor the velocities were too small
// http://www.i2cdevlib.com/forums/topic/106-get-angular-velocity-from-mpu-6050/
// FIFO frequency 100 Hz -> factor 10 ?
// seems 25 is the right factor
//TODO: check / test if rotational velocities are correct -- patrick-mod from 25 to 5
//patrick-mod == add clamping
double min = -8.0;
double max = 8.0;
double gxf = clamp ((gx * (4000.0/65536.0) * (M_PI/180.0) * 22.0), min, max);
double gyf = clamp ((gy * (4000.0/65536.0) * (M_PI/180.0) * 22.0), min, max);
double gzf = clamp ((gz * (4000.0/65536.0) * (M_PI/180.0) * 22.0), min, max);
// get acelerometer values
int16_t ax = (((0xff &(char)input[data_packet_start + 16]) << 8) | 0xff &(char)input[data_packet_start + 17]);
int16_t ay = (((0xff &(char)input[data_packet_start + 18]) << 8) | 0xff &(char)input[data_packet_start + 19]);
int16_t az = (((0xff &(char)input[data_packet_start + 20]) << 8) | 0xff &(char)input[data_packet_start + 21]);
// calculate accelerations in m/s²
double axf = ax * (8.0 / 65536.0) * 9.81;
double ayf = ay * (8.0 / 65536.0) * 9.81;
double azf = az * (8.0 / 65536.0) * 9.81;
// get temperature
int16_t temperature = (((0xff &(char)input[data_packet_start + 22]) << 8) | 0xff &(char)input[data_packet_start + 23]);
double temperature_in_C = (temperature / 340.0 ) + 36.53;
ROS_DEBUG_STREAM("Temperature [in C] " << temperature_in_C);
uint8_t received_message_number = input[data_packet_start + 25];
ROS_DEBUG("received message number: %i", received_message_number);
if (received_message) // can only check for continuous numbers if already received at least one packet
{
uint8_t message_distance = received_message_number - last_received_message_number;
if ( message_distance > 1 )
{
ROS_WARN_STREAM("Missed " << message_distance - 1 << " MPU6050 data packets from arduino.");
}
}
else
{
received_message = true;
}
last_received_message_number = received_message_number;
// calculate measurement time
uint32_t ts = ( ((0xff &(char)input[data_packet_start + 26]) << 24)
| ((0xff &(char)input[data_packet_start + 27]) << 16)
| ((0xff &(char)input[data_packet_start + 28]) << 8)
| 0xff &(char)input[data_packet_start + 29]);
// get trigger counter
uint32_t triggerCounter = ( ((0xff &(char)input[data_packet_start + 30]) << 24)
| ((0xff &(char)input[data_packet_start + 31]) << 16)
| ((0xff &(char)input[data_packet_start + 32]) << 8)
| 0xff &(char)input[data_packet_start + 33]);
//patrick-mod == set to local time for onboard companion computer
ros::Time measurement_time = ros::Time::now() + ros::Duration(time_offset_in_seconds);
//ros::Time measurement_time(ts / 1000, (ts % 1000) * 1000*1000); // sec, nsec
// publish imu message
imu.header.stamp = measurement_time;
imu.header.frame_id = frame_id;
//quaternionTFToMsg(differential_rotation, imu.orientation);
imu.angular_velocity.x = gxf;
imu.angular_velocity.y = gyf;
imu.angular_velocity.z = gzf;
imu.linear_acceleration.x = axf;
imu.linear_acceleration.y = ayf;
imu.linear_acceleration.z = azf;
imu_pub.publish(imu);
// publish temperature message
temperature_msg.header.stamp = measurement_time;
temperature_msg.header.frame_id = frame_id;
temperature_msg.temperature = temperature_in_C;
imu_temperature_pub.publish(temperature_msg);
// publish triggertime message
if (triggerCounter != lastTriggerCounter){
ros::Time time_ref(0, 0);
trigger_time_msg.header.frame_id = frame_id;
trigger_time_msg.header.stamp = measurement_time;
trigger_time_msg.time_ref = time_ref;
trigger_time_pub.publish(trigger_time_msg);
lastTriggerCounter = triggerCounter;
}
// publish tf transform
if (broadcast_tf)
{
transform.setRotation(differential_rotation);
tf_br.sendTransform(tf::StampedTransform(transform, measurement_time, tf_parent_frame_id, tf_frame_id));
}
input.erase(0, data_packet_start + 28); // delete everything up to and including the processed packet
}
else
{
if (input.length() >= data_packet_start + 36)
{
input.erase(0, data_packet_start + 1); // delete up to false data_packet_start character so it is not found again
}
else
{
// do not delete start character, maybe complete package has not arrived yet
input.erase(0, data_packet_start);
}
}
}
else
{
// no start character found in input, so delete everything
input.clear();
}
}
}
}
else
{
// try and open the serial port
try
{
ser.setPort(port);
//ser.setBaudrate(57600);
ser.setBaudrate(115200);
//ser.setBaudrate(230400);
serial::Timeout to = serial::Timeout::simpleTimeout(1000);
ser.setTimeout(to);
ser.open();
}
catch (serial::IOException& e)
{
ROS_ERROR_STREAM("Unable to open serial port " << ser.getPort() << ". Trying again in 5 seconds.");
ros::Duration(5).sleep();
}
if(ser.isOpen())
{
ROS_DEBUG_STREAM("Serial port " << ser.getPort() << " initialized and opened.");
}
}
}
catch (serial::IOException& e)
{
ROS_ERROR_STREAM("Error reading from the serial port " << ser.getPort() << ". Closing connection.");
ser.close();
}
ros::spinOnce();
r.sleep();
}
}