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2011-09-02 12:44:34 -0500 marked best answer tf id frame odom_combined and base_footprint does not exist error

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2011-08-11 11:17:21 -0500 marked best answer What's the best way to texture a large surface in gazebo?

An easier way to do it in Blender is using UV/Image texture. Here you can find a step-by-step tutorial.
There are many tutorials about it. Check about UV texture.

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2011-07-28 04:31:16 -0500 commented answer What's the best way to texture a large surface in gazebo?
Thanks. I'll check it out :)
2011-07-27 10:44:43 -0500 commented question What's the best way to texture a large surface in gazebo?
Thanks for your help :)
2011-07-27 08:32:39 -0500 asked a question What's the best way to texture a large surface in gazebo?

Hey everybody! Long time no write. I hope everyone's projects are going as good as possible.

I again find myself with a dumb question about gazebo. I need to do a world that looks like a soccer field. I know how to do the field, the walls and goals. But I have no idea on how to do the field lines. You know the goal line, the middle-field circle. Is just and aesthetics matter you see, since any rule concerning this lines can be easily done by code. Any way I'll like to make them. Know any example the gives me a hint? I've checked but the worlds I've seen just have walls. Should I make a Blender mesh? or texture? or what is supposed to be that?.

TLDR: What's the easiest way to add a "skin" to my soccer field world?

Thanks again for your time and help guys. Have a nice day ;)

2011-07-13 01:01:09 -0500 received badge  Teacher (source)
2011-07-08 07:23:25 -0500 answered a question Simulation with a simple car model in Gazebo

Hey! I used this two tutorials of the pr2 and they helped me a lot. Check them out. Hope it helps you:

http://www.ros.org/wiki/pr2_controllers/Tutorials/Using%20the%20robot%20base%20controllers%20to%20drive%20the%20robot

http://www.ros.org/wiki/pr2_controllers/Tutorials/Using%20the%20base%20controller%20with%20odometry%20and%20transform%20information

Good luck. I'm also stuck with making a sad car just to move in gazebo so I understand your pain XD.

2011-07-08 07:20:42 -0500 answered a question Moving a robot in Gazebo

If you're still interested this two tutorials helped me a lot in a very similar problem. I use the pr2 controllers 'cause I don't have the time to make my own so I just build my own stats over the pr2. Hope it helps you:

http://www.ros.org/wiki/pr2_controllers/Tutorials/Using%20the%20robot%20base%20controllers%20to%20drive%20the%20robot

http://www.ros.org/wiki/pr2_controllers/Tutorials/Using%20the%20base%20controller%20with%20odometry%20and%20transform%20information

2011-07-08 07:13:02 -0500 answered a question Gazebo services problems

Thanks hsu :). I checked and I wasn't using a rosservice (SetModelState) but a rostopic (ModelState) so of course my code did nothing. Now I have my running client :). Also I accidentally found out what was wrong with my model, I just had to switch the kd and kp values and voila! problem solved ;).

2011-07-07 10:25:46 -0500 asked a question Gazebo services problems

Hey guys it's me again, how r ya doin'? :)

I have today two dumb questions about gazebo.

First: I'm trying to simulate a simple soccer ball. To do this I'm using a simple URDF file with an sphere and gazebo services. Do you know of any example of how to make a client for this gazebo services on cpp? I've checked the how to write a service/client tutorial and also run into a few examples but the one I tried to make doesn't do anything (it compiles when I 'make' the pack, but if I call it the terminal freezes), I must be missing a few things. This is my code (its the only thing I do, I start gazebo empty_world, spawn the model and run the executable of this client) this one is called move_ball.cpp:

int main(int argc, char** argv){
  ros::init(argc, argv, "move_ball");
  ros::NodeHandle node;
  ros::Publisher ball_state = node.advertise<gazebo_msgs::ModelState>("ball/ModelState", 10);
  ros::Rate rate(10.0);
  while (node.ok()){
    gazebo_msgs::ModelState msg;
    msg.model_name = "ball";
    msg.pose.position.x = 0;
    msg.pose.position.y = 0;
    msg.pose.position.z = 0;
    msg.pose.orientation.x = 0;
    msg.pose.orientation.y = 0;
    msg.pose.orientation.z = 0;
    msg.pose.orientation.w = 0;
    msg.twist.linear.x = 0;
    msg.twist.linear.y = 0;
    msg.twist.linear.z = 0;
    msg.twist.angular.x = 0;
    msg.twist.angular.y = 0;
    msg.twist.angular.z = 0;
    ball_state.publish(msg);
    rate.sleep();
  }
  return 0;
};

I've also tried to do a spawn client with the SpawnModel service, but when I run it it tells me that the SpawnModel service it's not advertised. Is this something I have to do in the cpp file? any instruction I'm missing? this one is called spawn_ball.cpp

int main(int argc, char** argv){
  ros::init(argc, argv, "my_spawn_model");
  ros::NodeHandle node;
  ros::service::waitForService("SpawnModel");
  ros::ServiceClient add_model = node.serviceClient<gazebo_msgs::SpawnModel>  ("SpawnModel");
  gazebo_msgs::SpawnModel srv;
  srv.request.model_name= "ball.urdf";
  srv.request.model_xml= "urdf";
  srv.request.initial_pose.position.x= 0;
  srv.request.initial_pose.position.y= 0;
  srv.request.initial_pose.position.z= 0;
  srv.request.initial_pose.orientation.x= 0;
  srv.request.initial_pose.orientation.y= 0;
  srv.request.initial_pose.orientation.z= 0;
  srv.request.initial_pose.orientation.w= 0;
  add_model.call(srv);
 return 0;
};

Second: what I want to do is move the ball to simulate a "kick" by using gazebo service ModelState. But something funny happens. When I use the pose command to move the ball from one point to another, the ball disappears for one second, and when it appears it falls from the sky just above the selected point. This happens the same way if instead of pose I send a twist command, disappears, fall and then execute. I've done this before with the gazebo default models (cup, coffe_cup) without this problem. The just move smoothly. I have changed physics to the exact same configuration as this default models and nothing ... (more)

2011-07-07 00:47:50 -0500 commented answer tf id frame odom_combined and base_footprint does not exist error
Yes robot_pose_ekf is running. If I use the command bin/odometry_base many times it eventually works. The failure must be the rate differences between frames then. Still I'll like to know how to create a world frame in gazebo since I'm creating my own robot URDF. Is odom_combined a world frame?
2011-07-06 08:26:25 -0500 commented answer tf id frame odom_combined and base_footprint does not exist error
If I run view_frames I can see the base_link frame (which is parent of base_footprint) but no mention of odom_combined :s that I forgot to mention, is the main reason of my question... I can't find the dumb thing anywhere...:(
2011-07-06 03:31:31 -0500 received badge  Editor (source)
2011-07-01 11:51:59 -0500 asked a question tf id frame odom_combined and base_footprint does not exist error

Hi, how are you doing guys? Hope you are doing great.

I'm writing this message because I'm having problems with the pr2_controller tutorial: "Using the base controller with odometry and transform information", even though that the first time I ran it it worked fine. Let me explain everything I've done to see if anybody can find what is wrong.

The first time I ran it it gave me this error:

drive_base_tutorial$ bin/odometry_base terminate called after throwing an instance of 'tf::LookupException' what(): Frame id /base_footprint does not exist! When trying to transform between /odom_combined and /base_footprint. Aborted

After looking a little on the internet (I after realized that this was explained on the tutorial too) I found a girl with the exact same problem and somebody told her to use:

bin/odometry_base cmd_vel:=base_controller/command

I did it and it worked. I tried to use the same instruction on the same terminal to move the robot again, but the terminal froze. I dismissed this incident believing that I couldn't use the same instruction on the same terminal two times. I closed the terminal, ended the simulation, turned off the computer and went to lunch. I came back and tried to run it again and now everything is screwed. I try to run the simulation again and I keep getting:

drive_base_tutorial$  bin/odometry_base cmd_vel:=base_controller/command terminate called after throwing an instance of 'tf::LookupException'  what():  Frame id /base_footprint does not exist! When trying to transform between /odom_combined and /base_footprint. Aborted

or even

drive_base_tutorial$  bin/odometry_base cmd_vel:=base_controller/command terminate called after throwing an instance of 'tf::LookupException' what():  Frame id /odom_combined does not exist! When trying to transform between /odom_combined and /base_footprint. Aborted

I've checked

rosrun tf tf_monitor base_footprint odom_combined

and it just keeps drawing points without telling me nothing. I've also tried:

rosrun tf tf_echo base_footprint odom_combined

and again it tells me that one of the frames do not exist. I erased the package drive_base_tutorial and did everything from the beginning and nothing. My questions are: What is this frame odom_combined? I know that base_footprint is created on the pr2 URDF, but I can't find this odom_combined anywhere. Is it in any controller of the pr2? which one?.

Can't I change it for other existing frame? on the turtlesim/tf tutorials they use a "world" frame. Is there a world frame for gazebo? if there is, how is it called? I've tried changing odom_combined for world but this frame doesn't exist either.

I've found tutorials that teaches you how to add a new frame, but is a new child frame, can I create a world frame from scratch? how?

Please help me. Also consider that I'm very new to programming so please have patience. Sorry it was such a long history, but I do really want to understand what is going on.

Thanks for you time, patience and for any help you can give me.

By ... (more)

2011-07-01 11:36:37 -0500 answered a question How can I create robot model and simulate with ROS?

I'm also very interested in this topic. Did you find anything usefull? I'm trying to do a robosoccer simulation, I have the models but no idea how to move them around. It seems that you need controllers to move the joints, but where or how do I write a source code that uses does controllers to give robots more complex behaviors? (plays and stuff). Please if you found anything let me know.