Hi, This is my first question here. Pardon me for any mistakes.
I have spent some time looking this over the internet but could not find a working solution yet. Documentation doesn't have much on Sonar sensors..
I am trying to read the sonar sensor range values which the sensor plugin, SonarPlugin.cc gives me and publishes to the topic /gazebo/mtp_world/mtp_robot/left_sonar/mtp_sonar_sensor_left/sonar in the robot's model plugin, move_bot.cc using a transport node and a subscriber
I got this topic from gz topic -l and doing gz topic -e <this-topic-name> gives the required range outputs along with other sonar values.
I have a very basic understanding of topics work. The message returned from the subscriber is NULL for this topic.
Here are the relevant code snippets:
class MoveBot : public ModelPlugin {
private: physics::WorldPtr world;
private: physics::ModelPtr model;
private: event::ConnectionPtr updateConnection;
private: physics::JointPtr leftJoint;
private: physics::JointPtr rightJoint;
private: common::Time startTime;
private: transport::SubscriberPtr sub;
public: void Load(physics::ModelPtr _parent, sdf::ElementPtr /* _sdf */) {
this->model = _parent;
this->world = this->model->GetWorld();
this->leftJoint = this->model->GetJoint("left_wheel_hinge");
this->rightJoint = this->model->GetJoint("right_wheel_hinge");
transport::NodePtr node(new transport::Node());
node->Init();
this->sonarTopicLeft =
"/gazebo/mtp_world/mtp_robot/left_sonar/mtp_sonar_sensor_left/sonar";
this->sub = node->Subscribe(this->sonarTopicLeft, &MoveBot::cb, this);
this->updateConnection =
event::Events::ConnectWorldUpdateBegin(std::bind(&MoveBot::OnUpdate, this));
}
private: void cb(ConstSonarPtr &_msg) {
std::cout<< "callback!!!!!!!" << std::endl;
if (_msg == NULL) {
std::cout<< "NULL!!!!!!!" << std::endl;
return;
}
std::cout << "Message: " << _msg->range() << std::endl;
}
private: void onUpdate() {
// Some other code
}
}
I am expecting the cb(ConstSonarPtr &_msg) callback to print the range values but I only get NULL!!!!!!! printed.
Any help would be greatly appreciated! Thank you.
