Grasping model with schunk manipulator only finds grasps on slim objects (and no collision check)

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Uli
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Grasping model with schunk manipulator only finds grasps on slim objects (and no collision check)

Uli
I want to find grasps for a parallel gripper on some (very) simple objects (e.g. boxes). I have replaced the Barrett hand with a schunk parallel gripper on a WAM robot arm. See XML further below (the original parts for the Barrett hand are commented out). I have attached all relevant files: find_grasps.gz

I have a couple of issues with the grasps found:

1. The grasping module only finds grasps if the box extends by 0.02 (or less): e.g. <extents>0.08 0.02 0.04</extents>
If it extends by 0.21, than the list of valid grasps is empty ("volume" and "mindist" are almost always 0.0). I tried ti increase the joint limits of the gripper (changing values for <limits>0 0.034</limits> in schunk_manip.kinbody.xml) without an effect.

2. The grasps found use only the tip of the fingers (see image below)

3. The grasp found is in collision with the blue box (the blue box is placed such that it overlaps with the green box), see image below:




Replacement of Barrett hand with schunk parallel gripper:

<?xml version="1.0" encoding="utf-8"?>


<Robot name="BarrettWAM">
  <KinBody file="wam7.kinbody.xml"/>
 
  <KinBody file="/home/uli/temp/find_grasps/env/schunk_manip.kinbody.xml"/>

 <kinbody>
   
   <body name="gripper_base">
     <offsetfrom>wam7</offsetfrom>
   </body>
   <joint name="dummyhand" type="slider" enable="false">
     <body>wam7</body>
     
     <body>gripper_base</body>
     <limits>0 0</limits>
   </joint>
 </kinbody>

  <Manipulator name="arm">
    <base>wam0</base>
    <effector>wam7</effector>
    <iksolver>WAM7ikfast 0.05</iksolver>
    <Translation>0 0 0.16</Translation>
    <joints>jfinger_L</joints>
   
    <closingdirection>1</closingdirection>
   
    <direction>0 0 1</direction>
  </Manipulator>
</Robot>