130 lines
4.2 KiB
C++
130 lines
4.2 KiB
C++
/*
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* Copyright (C) 2012 Open Source Robotics Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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#include <string>
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#include "gazebo/physics/physics.hh"
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#include "gazebo/transport/transport.hh"
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#include "plugins/SkidSteerDrivePlugin.hh"
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using namespace gazebo;
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GZ_REGISTER_MODEL_PLUGIN(SkidSteerDrivePlugin)
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/////////////////////////////////////////////////
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SkidSteerDrivePlugin::SkidSteerDrivePlugin()
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{
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this->wheelRadius = 0.0;
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this->wheelSeparation = 0.0;
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}
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/////////////////////////////////////////////////
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int SkidSteerDrivePlugin::RegisterJoint(int _index, const std::string &_name)
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{
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// Bounds checking on index
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if (_index < 0 || _index >= NUMBER_OF_WHEELS)
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{
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gzerr << "Joint index " << _index << " out of bounds [0, "
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<< NUMBER_OF_WHEELS << "] in model " << this->model->GetName()
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<< "." << std::endl;
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return 1;
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}
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// Find the specified joint and add it to out list
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this->joints[_index] = this->model->GetJoint(_name);
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if (!this->joints[_index])
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{
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gzerr << "Unable to find the " << _name
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<< " joint in model " << this->model->GetName() << "." << std::endl;
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return 1;
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}
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// Success!
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return 0;
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}
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/////////////////////////////////////////////////
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void SkidSteerDrivePlugin::Load(physics::ModelPtr _model,
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sdf::ElementPtr /*_sdf*/)
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{
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this->model = _model;
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this->node = transport::NodePtr(new transport::Node());
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this->node->Init(this->model->GetWorld()->GetName());
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int err = 0;
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err += RegisterJoint(RIGHT_FRONT, "right_front");
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err += RegisterJoint(RIGHT_REAR, "right_rear");
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err += RegisterJoint(LEFT_FRONT, "left_front");
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err += RegisterJoint(LEFT_REAR, "left_rear");
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if (err > 0)
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return;
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// This assumes that front and rear wheel spacing is identical
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this->wheelSeparation = this->joints[RIGHT_FRONT]->GetAnchor(0).Distance(
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this->joints[LEFT_FRONT]->GetAnchor(0));
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// This assumes that the largest dimension of the wheel is the diameter
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// and that all wheels have the same diameter
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physics::EntityPtr wheelLink = boost::dynamic_pointer_cast<physics::Entity>(
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this->joints[RIGHT_FRONT]->GetChild() );
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if (wheelLink)
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{
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math::Box bb = wheelLink->GetBoundingBox();
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this->wheelRadius = bb.GetSize().GetMax() * 0.5;
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}
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// Validity checks...
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if (this->wheelSeparation <= 0)
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{
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gzerr << "Unable to find the wheel separation distance." << std::endl
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<< " This could mean that the right_front link and the left_front "
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<< "link are overlapping." << std::endl;
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return;
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}
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if (this->wheelRadius <= 0)
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{
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gzerr << "Unable to find the wheel radius." << std::endl
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<< " This could mean that the sdf is missing a wheel link on "
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<< "the right_front joint." << std::endl;
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return;
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}
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this->velSub = this->node->Subscribe(
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std::string("~/") + this->model->GetName() + std::string("/vel_cmd"),
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&SkidSteerDrivePlugin::OnVelMsg, this);
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}
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/////////////////////////////////////////////////
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void SkidSteerDrivePlugin::OnVelMsg(ConstPosePtr &_msg)
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{
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// gzmsg << "cmd_vel: " << msg->position().x() << ", "
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// << msgs::Convert(msg->orientation()).GetAsEuler().z << std::endl;
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double vel_lin = _msg->position().x() / this->wheelRadius;
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double vel_rot = -1 * msgs::ConvertIgn(_msg->orientation()).Euler().Z()
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* (this->wheelSeparation / this->wheelRadius);
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this->joints[RIGHT_FRONT]->SetVelocity(0, vel_lin - vel_rot);
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this->joints[RIGHT_REAR ]->SetVelocity(0, vel_lin - vel_rot);
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this->joints[LEFT_FRONT ]->SetVelocity(0, vel_lin + vel_rot);
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this->joints[LEFT_REAR ]->SetVelocity(0, vel_lin + vel_rot);
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}
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