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FETCH ROBOTICS

Robotics Software Intern

Summer 2016 - Fall 2016


 

1st Project

Development of an algorithm for creating sphere representation of complex objects which allows faster collision checking.


 
 

Purpose

 
 
  • Motion planning involves a lot of collision checking.
  • Reduction of the collision checking calculation is important for the real-time perception-based motion planning.
  • Therefore we would like to simplify meshes of robots into spheres.

 
 

Current Method

 
Artboard 3@2x.png
  • Current method takes only box shapes as inputs. It cannot deal with the objects of general shapes.
  • Output of the current method is just a series of spheres (array) which are not efficient for the collision checking calculation.
 

 

Approach

 
 
Artboard 4@2x.png
  • New method takes general shapes of objects as inputs.
  • Output of the new method is a hierarchical tree structure of spheres (sphere-tree) which is efficient for the collision checking calculation.
Hierarchical tree structure of spheres (sphere-tree)

Hierarchical tree structure of spheres (sphere-tree)

 

 

Number of Calculations for Collision Checking (Ex.)

 
 
 

Result

Bunny

Bunny

Elbow Flex Link

Elbow Flex Link

 
 
Artboard 5@2x.png
 

 

2ND PROJECT

Joystick teleoperation of the end-effector of Fetch
 

 

PURPOSE

 
Artboard 6@2x.png
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  • There are three kinds of control for manipulation: Pose(position), twist(velocity), wrench(torque).
  • It is necessary to enable a joystick to control the end-effector to check if the controller is working fine.
 

 

APPROACH

 
Reference frame (body: blue, End-effector: red)

Reference frame (body: blue, End-effector: red)

stick2.png
stick.png
 
 
  • Mapping linear and angular velocity to key #1, #2, and tilting motions.
  • Converting reference frame using key #11 and #9.
  • Using KDL library to solve 7 DOF arm kinematics.

 

RESULT

 

Code can be found at Fetch Robotics Github as an open source. Fetch users are now able to control the end-effector using the joystick.