When selecting a Robot for a particular task a number of decisions have to be made. The first of these is the structure of the robot required. There are a number of different structures commonly available and each has its own set of limitations and benefits.

Jointed Arm
The jointed arm robot closely resembles the human arm. This structure is very flexible and has the ability to reach over obstructions. It can generally achieve any position and orientation within the working envelope in eight different ways. This can cause control problems. When driving these Robots in their natural co-ordinate system (joint space) the motion of the robot from one point to another can be difficult to visualise as the robot will move each joint through the minimum angle required. This means that the motion of the tool will not be a straight line. This structure of robots is used for a wide range of applications including paint spraying, arc and spot welding, machine tending, fettling, etc.

Scara (Selective Compliance Assembly Robot Arms)
SCARA robots are specifically designed for peg board type assembly and are heavily used in the electronics industry. They are very stiff in the vertical direction but have a degree of compliance in the horizontal plane that enables minor errors in placement of components to be accounted for. These robots tend to be fairly small and capable of operating very accurately and at high speed. They are used for assembly, palletisation and machine loading.

Tricept and Hexapod Robots
Tricept and hexapod robots use linear motors to control the position of the tool. The tricept uses three of these legs in conjunction with a central pillar to hold the head rigidly in position and then has a standard wrist mounted on it to achieve the orientation. A hexapod uses six legs and achieves both position and orientation using them. Both of these structures give very rigid robots but both have the disadvantage of small working envelopes and limited orientation ability. These structures tend to be used for machining operations where machine tool level tolerances are not required but greater flexibility is.

Next >> The Most Important Areas In The Design Of Robot Systems

Tech Materials (Free)

Robot Behaviors Exploring the T-Maze: Evolving Learning-Like Robot Behaviors using CTRNNs
Humanoid Robotics A Biochemical Subsystem for a Humanoid Robot
Industrial Automation Systems Applying Agents for Engineering of Industrial Automation Systems
Robot Team Cooperation A Descriptive Model of Robot Team and the Dynamic Evolution of Robot Team Cooperation
Kuka Robots For ONU ONU Robotics Technology Center of Excellence, powered by KUKA Robotics Corporation
Augmented reality Annotation System for Robotic Application
Modular Robots Self-Reconfiguration Planning Of Identical Modules
Autonomous robots A New Approach To Robotics
Robotic Mounting Flat Panel Displays With Robotic Mounting
Calibration of Industrial Robots A Photogrammetric Robot Calibration System Based On Off-The-Shelf Low Cost Hardware Components

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Amazon Books

	Creative Projects with LEGO Mindstorms by Benjamin Erwin Buy new: $20.64 / Used from: $13.00 A good place to start, especially for kids, with Lego Mindstorms
	A Practical Guide to Behavior-Based Robotics by Joe Jones Buy new: $20.67 / Used from: $15.13 Very good for programming not so much behavior as control. Language and controller agnostic