9.2.2.1 - Robotic Arms

• Typical joint types are,

Revolute - rotary joints often driven by electric motors and chain/belt/gear transmissions, or by hydraulic cylinders and levers.

Prismatic - slider joints in which the link is supported on a linear slider bearing, and linearly actuated by ball screws and motors or cylinders.

• Basic configurations are,

Cartesian/Rectilinear/Gantry - Positioning is done in the workspace with prismatic joints. This configuration is well used when a large workspace must be covered, or when consistent accuracy is expected from the robot.

Cylindrical - The robot has a revolute motion about a base, a prismatic joint for height, and a prismatic joint for radius. This robot is well suited to round workspaces.

Spherical - Two revolute joints and one prismatic joint allow the robot to point in many directions, and then reach out some radial distance.

Articulated/Jointed Spherical/Revolute - The robot uses 3 revolute joints to position the robot. Generally the work volume is spherical. This robot most resembles the human arm, with a waist, shoulder, elbow, wrist.

Scara (Selective Compliance Arm for Robotic Assembly) - This robot conforms to cylindrical coordinates, but the radius and rotation is obtained by a two planar links with revolute joints.