Logistics

• Change in due dates – discussion re “dress rehearsal”
• Review Robotics Term Projects

Manipulators

Kinematic Chains

• A set of links and joints together form a kinematic chain
• If one end is attached to something fixed (like the floor) it is “grounded”
• The other end will usually have some kind of gripper, sensor, or effector
• This system can be complex and can be analyzed mathematically

Coordinate Frames

• Ground based mobile robots have two important coordinate frames: the map and robot frames.
• Robot arms have many more coordinate systems.
• The links are fixed and of known length
• The joints are all in a known position represented by one or more angles
• Joint space and task space
• In ROS, names in URDF are used to name the frames

Forward and Reverse

• Forward Kinematics
  1. If you set all the joint angles a certain way, where will the end be in space?
  2. This has a single solution and is tractable
• Reverse Kinematics
  1. If you want the end to be in a certain location, what should the joint angles be?
  2. This might have zero (out of reach), or more solutions

Simple case

Charlie Arm

PythonRobotics Learning Samples

• Let’s skim some code: Arm Navigation
• Lets run that code too

Thank you. Questions?  (random Image from picsum.photos)