gravity_compensation_node.cpp

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/*
 *  gravity_compensation_node.cpp
 *
 *  Created on: Nov 12, 2013
 *  Authors:   Francisco Viña
 *            fevb <at> kth.se
 */

/* Copyright (c) 2013, Francisco Viña, CVAP, KTH
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
      * Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.
      * Neither the name of KTH nor the
        names of its contributors may be used to endorse or promote products
        derived from this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED. IN NO EVENT SHALL KTH BE LIABLE FOR ANY
   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <ros/ros.h>
#include <gravity_compensation/gravity_compensation.h>
#include <gravity_compensation/gravity_compensation_params.h>
#include <sensor_msgs/Imu.h>
#include <eigen3/Eigen/Core>
#include <eigen3/Eigen/Geometry>
#include <tf_conversions/tf_eigen.h>
#include <tf/transform_datatypes.h>
#include <tf/transform_broadcaster.h>
#include <eigen_conversions/eigen_msg.h>
#include <boost/thread.hpp>
#include <std_srvs/Empty.h>


class GravityCompensationNode
{
public:
        ros::NodeHandle n_;

        // subscribe to accelerometer (imu) readings
        ros::Subscriber topicSub_imu_;
        ros::Subscriber topicSub_ft_raw_;

        ros::Publisher topicPub_ft_zeroed_;
        ros::Publisher topicPub_ft_compensated_;

    ros::ServiceServer calibrate_bias_srv_server_;

        tf::TransformBroadcaster tf_br_;


        GravityCompensationNode()
        {
                n_ = ros::NodeHandle("~");
                m_g_comp_params  = new GravityCompensationParams();
                m_g_comp = NULL;
                m_received_imu = false;
        m_calibrate_bias = false;
        m_calib_measurements = 0;
        m_ft_bias = Eigen::Matrix<double, 6, 1>::Zero();

                // subscribe to accelerometer topic and raw F/T sensor topic
                topicSub_imu_ = n_.subscribe("imu", 1, &GravityCompensationNode::topicCallback_imu, this);
                topicSub_ft_raw_ = n_.subscribe("ft_raw", 1, &GravityCompensationNode::topicCallback_ft_raw, this);

        // bias calibration service
        calibrate_bias_srv_server_ = n_.advertiseService("calibrate_bias", &GravityCompensationNode::calibrateBiasSrvCallback, this);

                std::string ns;
                if(n_.hasParam("ns"))
                {
                        n_.getParam("ns", ns);
                        topicPub_ft_zeroed_ = n_.advertise<geometry_msgs::WrenchStamped> (ns+std::string("/ft_zeroed"), 1);
                        topicPub_ft_compensated_ = n_.advertise<geometry_msgs::WrenchStamped> (ns+std::string("/ft_compensated"), 1);
                }

                else
                {
                        topicPub_ft_zeroed_ = n_.advertise<geometry_msgs::WrenchStamped> ("ft_zeroed", 1);
                        topicPub_ft_compensated_ = n_.advertise<geometry_msgs::WrenchStamped> ("ft_compensated", 1);
                }
        }

        ~GravityCompensationNode()
        {
                delete m_g_comp;
                delete m_g_comp_params;
        }

        bool getROSParameters()
        {
                XmlRpc::XmlRpcValue biasXmlRpc;
                Eigen::Matrix<double, 6, 1> bias;
                if (n_.hasParam("bias"))
                {
                        n_.getParam("bias", biasXmlRpc);
                }

                else
                {
                        ROS_ERROR("Parameter 'bias' not set, shutting down node...");
                        n_.shutdown();
                        return false;
                }


                if(biasXmlRpc.size()!=6)
                {
                        ROS_ERROR("Invalid F/T bias parameter size (should be size 6), shutting down node");
                        n_.shutdown();
                        return false;
                }

                for (int i = 0; i < biasXmlRpc.size(); i++)
                {
                        bias(i) = (double)biasXmlRpc[i];
                }


                // get the mass of the gripper
                double gripper_mass;
                if (n_.hasParam("gripper_mass"))
                {
                        n_.getParam("gripper_mass", gripper_mass);
                }

                else
                {
                        ROS_ERROR("Parameter 'gripper_mass' not available");
                        n_.shutdown();
                        return false;
                }

                if(gripper_mass<0.0)
                {
                        ROS_ERROR("Parameter 'gripper_mass' < 0");
                        n_.shutdown();
                        return false;
                }

                // get the pose of the COM of the gripper
                // we assume that it is fixed with respect to FT sensor frame
                // first get the frame ID
                tf::StampedTransform gripper_com;
                std::string gripper_com_frame_id;
                if (n_.hasParam("gripper_com_frame_id"))
                {
                        n_.getParam("gripper_com_frame_id", gripper_com_frame_id);
                }

                else
                {
                        ROS_ERROR("Parameter 'gripper_com_frame_id' not available");
                        n_.shutdown();
                        return false;
                }

                gripper_com.frame_id_ = gripper_com_frame_id;

                // now get the CHILD frame ID
                std::string gripper_com_child_frame_id;
                if (n_.hasParam("gripper_com_child_frame_id"))
                {
                        n_.getParam("gripper_com_child_frame_id", gripper_com_child_frame_id);
                }

                else
                {
                        ROS_ERROR("Parameter 'gripper_com_child_frame_id' not available");
                        n_.shutdown();
                        return false;
                }

                gripper_com.child_frame_id_ = gripper_com_child_frame_id;

                // now get the actual gripper COM pose
                Eigen::Matrix<double, 6, 1> gripper_com_pose;
                XmlRpc::XmlRpcValue gripper_com_pose_XmlRpc;
                if (n_.hasParam("gripper_com_pose"))
                {
                        n_.getParam("gripper_com_pose", gripper_com_pose_XmlRpc);
                }

                else
                {
                        ROS_ERROR("Parameter 'gripper_com_pose' not set, shutting down node...");
                        n_.shutdown();
                        return false;
                }


                if(gripper_com_pose_XmlRpc.size()!=6)
                {
                        ROS_ERROR("Invalid 'gripper_com_pose' parameter size (should be size 6), shutting down node");
                        n_.shutdown();
                        return false;
                }

                for(unsigned int i=0; i<gripper_com_pose_XmlRpc.size(); i++)
                {
                        gripper_com_pose(i) = gripper_com_pose_XmlRpc[i];
                }

                tf::Vector3 p;
                tf::vectorEigenToTF(gripper_com_pose.topRows(3), p);
                tf::Quaternion q;
                q.setRPY((double)gripper_com_pose(3),
                                (double)gripper_com_pose(4),
                                (double)gripper_com_pose(5));

                gripper_com = tf::StampedTransform(tf::Transform(q, p),
                                ros::Time::now(),
                                gripper_com_frame_id,
                                gripper_com_child_frame_id);

                // get the publish frequency for the gripper
                // center of mass tf
                n_.param("gripper_com_broadcast_frequency",
                                m_gripper_com_broadcast_frequency, 100.0);

                m_g_comp_params->setBias(bias);
                m_g_comp_params->setGripperMass(gripper_mass);
                m_g_comp_params->setGripperCOM(gripper_com);

                m_g_comp = new GravityCompensation(m_g_comp_params);
                return true;
        }

        void topicCallback_imu(const sensor_msgs::Imu::ConstPtr &msg)
        {
                m_imu = *msg;
                m_received_imu = true;
        }

        void topicCallback_ft_raw(const geometry_msgs::WrenchStamped::ConstPtr &msg)
        {
                static int error_msg_count=0;

                if(!m_received_imu)
                {
                        return;
                }

                if((ros::Time::now()-m_imu.header.stamp).toSec() > 0.1)
                {
                        error_msg_count++;
                        if(error_msg_count % 10==0)
                                ROS_ERROR("Imu reading too old, not able to g-compensate ft measurement");
                        return;
                }

                geometry_msgs::WrenchStamped ft_zeroed;
                m_g_comp->Zero(*msg, ft_zeroed);
                topicPub_ft_zeroed_.publish(ft_zeroed);

                geometry_msgs::WrenchStamped ft_compensated;
                m_g_comp->Compensate(ft_zeroed, m_imu, ft_compensated);
                topicPub_ft_compensated_.publish(ft_compensated);

                if(m_calibrate_bias)
    {
        if(m_calib_measurements++<100)
        {
            m_ft_bias(0) += ft_compensated.wrench.force.x;
            m_ft_bias(1) += ft_compensated.wrench.force.y;
            m_ft_bias(2) += ft_compensated.wrench.force.z;
            m_ft_bias(3) += ft_compensated.wrench.torque.x;
            m_ft_bias(4) += ft_compensated.wrench.torque.y;
            m_ft_bias(5) += ft_compensated.wrench.torque.z;
        }

        // set the new bias
        if(m_calib_measurements == 100)
        {
            m_ft_bias = m_ft_bias/100;
            m_g_comp_params->setBias(m_g_comp_params->getBias() + m_ft_bias);
            m_ft_bias = Eigen::Matrix<double, 6, 1>::Zero();
            m_calibrate_bias = false;
            m_calib_measurements = 0;
        }

    }
        }

        // thread function for publishing the gripper center of mass transform
        void publish_gripper_com_tf()
        {
                static ros::Rate gripper_com_broadcast_rate(m_gripper_com_broadcast_frequency);
                try
                {
                        while(ros::ok())
                        {
                                tf::StampedTransform gripper_com = m_g_comp_params->getGripperCOM();
                                gripper_com.stamp_ = ros::Time::now();
                                tf_br_.sendTransform(gripper_com);

                                gripper_com_broadcast_rate.sleep();
                        }
                }

                catch(boost::thread_interrupted&)
                {
                        return;
                }
        }

    // only to be called when the robot is standing still and
    // while not holding anything / applying any forces
    bool calibrateBiasSrvCallback(std_srvs::Empty::Request &req,
                                  std_srvs::Empty::Response &res)
    {
        m_calibrate_bias = true;
        return true;
    }

private:

        GravityCompensationParams *m_g_comp_params;
        GravityCompensation *m_g_comp;
        sensor_msgs::Imu m_imu;
        bool m_received_imu;
        double m_gripper_com_broadcast_frequency;

    bool m_calibrate_bias;
    unsigned int m_calib_measurements;
    Eigen::Matrix<double, 6, 1> m_ft_bias;

};

int main(int argc, char **argv)
{

        ros::init(argc, argv, "gravity_compensation");
        GravityCompensationNode g_comp_node;

        if(!g_comp_node.getROSParameters())
        {
                ROS_ERROR("Error getting ROS parameters");
                return 0;
        }

        // loop frequency
        double loop_rate_;
        g_comp_node.n_.param("loop_rate", loop_rate_, 1000.0);
        ros::Rate loop_rate(loop_rate_);

        // add a thread for publishing the gripper COM transform frame
        boost::thread t_tf(boost::bind(&GravityCompensationNode::publish_gripper_com_tf, &g_comp_node));

//      ros::AsyncSpinner s(2);
//      s.start();

        while(ros::ok())
        {
                ros::spinOnce();
                loop_rate.sleep();
        }

        t_tf.join();


        return 0;
}