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Pose of Collision entity

asked 2013-03-28 05:12:59 -0500

Max Stähr gravatar image

Hi,

I am trying to retrieve the current Pose of all Collision entities. However I just can retrieve the initial Pose before starting the physics engine. The complete plugin code is pasted below.

include <boost bind.hpp=""> include <gazebo.hh> include <physics physics.hh=""> include <common common.hh=""> include <stdio.h>

using namespace std;

namespace gazebo
{   
  class ModelPush : public ModelPlugin
  {
    public: void Load(physics::ModelPtr _parent, sdf::ElementPtr /*_sdf*/) 
    {
      // Store the pointer to the model
      this->model = _parent;

      //frame
      frame=0;

      // Listen to the update event. This event is broadcast every
      // simulation iteration.
      this->updateConnection = event::Events::ConnectWorldUpdateBegin(
          boost::bind(&ModelPush::OnUpdate, this, _1));

    }

    // Called by the world update start event
    public: void OnUpdate(const common::UpdateInfo & /*_info*/)
    {
      // Apply a small linear velocity to the model.
      std::cout << "collision test" << std::endl;





      system("clear");
      cout << "frame\t" << frame << endl;
      frame = frame +1;

      physics::Link_V links = model->GetLinks();
      physics::Collision_V colls;
      for (unsigned int i = 0; i < links.size(); i++) {

          cout << links[i]->GetName() << "\t\t" <<links[i]->GetWorldPose() << endl;
          colls = links[i]->GetCollisions();
          for(unsigned i=0; i<colls.size(); i++)
          {
              colls[i]->Update();
              cout << colls[i]->GetName() << "\t\t" << colls[i]->GetWorldPose() << endl;
          }

      }

    }

    // Pointer to the model
    private: physics::ModelPtr model;

    // Pointer to the update event connection
    private: event::ConnectionPtr updateConnection;

    // Frame counter
    private: unsigned int frame;
  };

  // Register this plugin with the simulator
  GZ_REGISTER_MODEL_PLUGIN(ModelPush)
}

Can anyone help? What am I doing wrong?

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2 Answers

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answered 2013-03-28 06:50:17 -0500

Max Stähr gravatar image

Hi,

there is a litte missunderstanding. I don't want to detect a contact between the the collision entities, rather I would like to know the current pose if the collision entity at each time step. I can manage to retrieve the current Pose of each link but not of any collision geometry...

Cheers Max

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Comments

Oh sorry, so you are saying you get a constant value all the time? Is the object moving? Could you also post your sdf file?

AndreiHaidu gravatar imageAndreiHaidu ( 2013-03-28 07:24:41 -0500 )edit

Hi, I solved the problem myself. The WordPose of the corresponding Link is updated. By aggregating the relative Collision pose with the WorldLinkPose I can retrieve the WorldCollisionPose. However, it seems to be a bug in the Collision Code. The WorldPose of collision entities is not updated at runtime.

Max Stähr gravatar imageMax Stähr ( 2013-04-02 01:30:59 -0500 )edit

Hi, I solved the problem myself. The WordPose of the corresponding Link is updated. By aggregating the relative Collision pose with the WorldLinkPose I can retrieve the WorldCollisionPose. However, it seems to be a bug in the Collision Code. The WorldPose of collision entities is not updated at runtime.

Max Stähr gravatar imageMax Stähr ( 2013-04-02 01:31:03 -0500 )edit
0

answered 2013-03-28 05:56:48 -0500

AndreiHaidu gravatar image

Hi,

The way 'OnUpdate' is called on every world update, another function ('onContact') will be called when a collision is detected. Here is the main idea:

// set the collision you wish to check
physics::CollisionPtr collision = this->model->GetLink("link_name")->GetCollision("collision_name");

// during a collision the 'onContact' function will be called every update step
event::ConnectionPtr connection = collision->ConnectContact(boost::bind (&ModelPush::onContact, this, _1, _2));

// the 'onContact' function
void ModelPush::onContact(const std::string &_collisionName, const physics::Contact &_contact)
{ 
// do what you need with the contact 
 ...
}

Here you can find more about physics::Contact.

If you have any trouble implementing it, let me know.

Cheers, Andrei

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Asked: 2013-03-28 05:12:59 -0500

Seen: 4,265 times

Last updated: Mar 28 '13