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00001 /* 00002 * Copyright (c) 2008, Willow Garage, Inc. 00003 * All rights reserved. 00004 * 00005 * Redistribution and use in source and binary forms, with or without 00006 * modification, are permitted provided that the following conditions are met: 00007 * 00008 * * Redistributions of source code must retain the above copyright 00009 * notice, this list of conditions and the following disclaimer. 00010 * * Redistributions in binary form must reproduce the above copyright 00011 * notice, this list of conditions and the following disclaimer in the 00012 * documentation and/or other materials provided with the distribution. 00013 * * Neither the name of the Willow Garage, Inc. nor the names of its 00014 * contributors may be used to endorse or promote products derived from 00015 * this software without specific prior written permission. 00016 * 00017 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 00018 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 00019 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 00020 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 00021 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 00022 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 00023 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 00024 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 00025 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 00026 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00027 * POSSIBILITY OF SUCH DAMAGE. 00028 */ 00029 00030 /* 00031 * Author: Wim Meeussen 00032 */ 00033 00034 #include "robot_mechanism_controllers/cartesian_twist_controller.h" 00035 #include <algorithm> 00036 #include "kdl/chainfksolvervel_recursive.hpp" 00037 #include "pluginlib/class_list_macros.h" 00038 00039 using namespace KDL; 00040 00041 PLUGINLIB_DECLARE_CLASS(robot_mechanism_controllers, CartesianTwistController, controller::CartesianTwistController, pr2_controller_interface::Controller) 00042 00043 namespace controller { 00044 00045 00046 CartesianTwistController::CartesianTwistController() 00047 : robot_state_(NULL), 00048 jnt_to_twist_solver_(NULL) 00049 {} 00050 00051 00052 00053 CartesianTwistController::~CartesianTwistController() 00054 { 00055 sub_command_.shutdown(); 00056 } 00057 00058 00059 bool CartesianTwistController::init(pr2_mechanism_model::RobotState *robot_state, ros::NodeHandle &n) 00060 { 00061 node_ = n; 00062 00063 // get name of root and tip from the parameter server 00064 std::string root_name, tip_name; 00065 if (!node_.getParam("root_name", root_name)){ 00066 ROS_ERROR("CartesianTwistController: No root name found on parameter server (namespace: %s)", 00067 node_.getNamespace().c_str()); 00068 return false; 00069 } 00070 if (!node_.getParam("tip_name", tip_name)){ 00071 ROS_ERROR("CartesianTwistController: No tip name found on parameter server (namespace: %s)", 00072 node_.getNamespace().c_str()); 00073 return false; 00074 } 00075 00076 // test if we got robot pointer 00077 assert(robot_state); 00078 robot_state_ = robot_state; 00079 00080 // create robot chain from root to tip 00081 if (!chain_.init(robot_state, root_name, tip_name)) 00082 return false; 00083 if (!chain_.allCalibrated()) 00084 { 00085 ROS_ERROR("Not all joints in the chain are calibrated (namespace: %s)", node_.getNamespace().c_str()); 00086 return false; 00087 } 00088 chain_.toKDL(kdl_chain_); 00089 00090 // create solver 00091 jnt_to_twist_solver_.reset(new KDL::ChainFkSolverVel_recursive(kdl_chain_)); 00092 jac_solver_.reset(new ChainJntToJacSolver(kdl_chain_)); 00093 jnt_posvel_.resize(kdl_chain_.getNrOfJoints()); 00094 jnt_eff_.resize(kdl_chain_.getNrOfJoints()); 00095 jacobian_.resize(kdl_chain_.getNrOfJoints()); 00096 00097 // constructs 3 identical pid controllers: for the x,y and z translations 00098 control_toolbox::Pid pid_controller; 00099 if (!pid_controller.init(ros::NodeHandle(node_, "fb_trans"))) return false; 00100 for (unsigned int i=0; i<3; i++) 00101 fb_pid_controller_.push_back(pid_controller); 00102 00103 // constructs 3 identical pid controllers: for the x,y and z rotations 00104 if (!pid_controller.init(ros::NodeHandle(node_, "fb_rot"))) return false; 00105 for (unsigned int i=0; i<3; i++) 00106 fb_pid_controller_.push_back(pid_controller); 00107 00108 // get parameters 00109 node_.param("ff_trans", ff_trans_, 0.0) ; 00110 node_.param("ff_rot", ff_rot_, 0.0) ; 00111 00112 // subscribe to twist commands 00113 sub_command_ = node_.subscribe<geometry_msgs::Twist> 00114 ("command", 1, &CartesianTwistController::command, this); 00115 00116 return true; 00117 } 00118 00119 void CartesianTwistController::starting() 00120 { 00121 // reset pid controllers 00122 for (unsigned int i=0; i<6; i++) 00123 fb_pid_controller_[i].reset(); 00124 00125 // time 00126 last_time_ = robot_state_->getTime(); 00127 00128 // set disired twist to 0 00129 twist_desi_ = Twist::Zero(); 00130 } 00131 00132 00133 00134 void CartesianTwistController::update() 00135 { 00136 // check if joints are calibrated 00137 if (!chain_.allCalibrated()) 00138 return; 00139 00140 // get time 00141 ros::Time time = robot_state_->getTime(); 00142 ros::Duration dt = time - last_time_; 00143 last_time_ = time; 00144 00145 // get the joint positions and velocities 00146 chain_.getVelocities(jnt_posvel_); 00147 00148 // get cartesian twist error 00149 FrameVel twist; 00150 jnt_to_twist_solver_->JntToCart(jnt_posvel_, twist); 00151 twist_meas_ = twist.deriv(); 00152 Twist error = twist_meas_ - twist_desi_; 00153 00154 // get the chain jacobian 00155 jac_solver_->JntToJac(jnt_posvel_.q, jacobian_); 00156 00157 // pid feedback 00158 for (unsigned int i=0; i<3; i++) 00159 wrench_out_.force(i) = (twist_desi_.vel(i) * ff_trans_) + fb_pid_controller_[i].updatePid(error.vel(i), dt); 00160 00161 for (unsigned int i=0; i<3; i++) 00162 wrench_out_.torque(i) = (twist_desi_.rot(i) * ff_rot_) + fb_pid_controller_[i+3].updatePid(error.rot(i), dt); 00163 00164 // Converts the wrench into joint efforts with a jacbobian-transpose 00165 for (unsigned int i = 0; i < kdl_chain_.getNrOfJoints(); i++){ 00166 jnt_eff_(i) = 0; 00167 for (unsigned int j=0; j<6; j++) 00168 jnt_eff_(i) += (jacobian_(j,i) * wrench_out_(j)); 00169 } 00170 00171 // set effort to joints 00172 chain_.addEfforts(jnt_eff_); 00173 } 00174 00175 00176 void CartesianTwistController::command(const geometry_msgs::TwistConstPtr& twist_msg) 00177 { 00178 // convert to twist command 00179 twist_desi_.vel(0) = twist_msg->linear.x; 00180 twist_desi_.vel(1) = twist_msg->linear.y; 00181 twist_desi_.vel(2) = twist_msg->linear.z; 00182 twist_desi_.rot(0) = twist_msg->angular.x; 00183 twist_desi_.rot(1) = twist_msg->angular.y; 00184 twist_desi_.rot(2) = twist_msg->angular.z; 00185 } 00186 00187 } // namespace