First, Id just like to say thanks for the advice I got for my last letter. Now I have a couple of new questions.

How do you make a model fixed in the environment? So far I've been attaching my models to the groundplane to achieve this but I thought it best to find out how to do this properly. I saw something mentioned about having geoms without bodies but I haven't managed to figure out how this is done.

Is there supposed to be a panel in the GUI ( when running wxgazebo ) for grippers? I've tried playing around with the Pioneer2Gripper but I haven't been able to determine if it actually works, nothing happens when I click it in the simulation controls. I tried it with player and playerv and when I subscribe to the gripper I get the following error:

  playerc error   : got NACK from request
  playerv : error in dev_gripper.c
  get_geom failed : got NACK from request

Finally I want to ask about adding cameras to an environment. I added a couple of cameras, using the generic MonoCam, with reasonably high resolution ( image size 640 x 480) and updaterate (30 fps) and this made the simulation really sluggish. In fact, adding just one such camera made the simulation noticeably slower. Is this to be expected?

That is all I wanted to ask about this time, thanks in advance for any advice.