Week 8: An Introduction to Robotics 1) What is a robot ? 2) The historical development of robotics 3) Industrial robot systems and components 4) Industrial robot configurations 5) Kinematic classification 6) Industrial applications, usage and world markets
“ A robot is a re-programmable, multifunctional machine designed to manipulate materials, parts, tools,or specialized devices, through variable programmed motions for the performance of a variety of tasks."
Robotics Industries Association
"A robot is an automatic device that performs functions normally ascribed to humans or a machine in the form of a human."
The word 'robot' was coined in the early 1920’s by the Czech playwright Karel Capek (pronounced "chap'ek") from the Czech word for forced labor
The term 'robotics' refers to the study and use of robots and was coined and first used by the Russian-born American scientist and writer Isaac Asimov (1942). Asimov also created the ‘Three Laws of Robotics’.
in the early 1940’s MIT developed a numerically controlled (NC) milling machine (the first NC machine tool)
In 1961 George Devol created his patent for parts transfer machines. Joe Engelberger teamed with Devol to form Unimation and was the first to market robots. As a result, Engelberger has been called the 'father of robotics.'
The first industrial modern robot - the Unimate - developed by Devol and Engelberger - was installed at GM (New Jersey) in 1961.
A Unimate serves Devol and Engelberger with a cocktail A Unimate employed more profitably
A Jointed Arm robot has three rotational axes connecting three rigid links and a base.
An Jointed Arm robot is frequently called an anthropomorphic arm because it closely resembles a human arm. The first joint above the base is referred to as the shoulder. The shoulder joint is connected to the upper arm, which is connected at the elbow joint.
Jointed Arm robots are suitable for a wide variety of industrial tasks, ranging from welding to assembly.
The acronym SCARA stands for Selective Compliance Assembly Robot Arm, a particular design developed in the late 1970's in the laboratory of Professor Hiroshi Makino of Yamanashi University, located in Kofu, Japan.
SCARA robots are a blend of the articulated and cylindrical robots, providing the benefits of each.
The basic configuration of a SCARA is a four degree-of-freedom robot with horizontal positioning accomplished much like a shoulder and elbow held perfectly parallel to the ground. The robot consists of three R and one P joints;
The robot arm unit can move up and down, and at an angle around the axis of the cylinder just as in a cylindrical robot, but the arm itself is jointed like a revolute coordinate robot to allow precise and rapid positioning.
SCARAs are know for their fast cycle times, excellent repeatability, good payload capacity and a large workspace, shaped somewhat like a donut.
Advantages and limitations of different configs: Cartesian: Pros : Position control is easy. Rigid structure so high payloads are possible Cons : Occupies a large volume (low robot to workspace ratio) All 3 axes exposed to environment Used for : pick and place, machine tool loading, electronics Cylindrical: Pros : Rigid structure and realtively easy position control. High payloads are possible. Cons : Can only operate close to base (or floor) Used for : Pick and place, palletizing, laboratory testing
Advantages and limitations of different configs: Polar: Pros : Versatile - large working envelope. Cons : More difficult to control end effector position Large space near the base that cannot be reached Used for : applications where a small number of vertical actions is required: loading a press, spot welding etc. Articulated: Pros : Extremely flexible - can reach anywhere within workspace. Joints can be completely sealed. Cons : Difficult to program - controller must be complex Payload can be low depending on build Used for : Almost anything - but good in harsh or clean room conditions.
Advantages and limitations of different configs: SCARA: Pros : Fast (3 m/s), high repeatability (0.02mm), Compact and can operate through 360 degrees (plan). Cons : Medium to low payload Limited vertical movement Used for : Soldering, welding, drilling, electronics assembly. Almost any ‘table-top’ application.
see page 75, Fig 6.4 for gripper types. An end effector is the device that is fixed to the end of the robot manipulator mounting flange. N.B.: Typically the manipulator also has a wrist (often R-R-R). GRIPPER rotational linear electrical pneumatic hydraulic Power Kinetic Energy
Week 8: Summary 1) What is a robot ? 2) The historical development of robotics 3) Industrial robot systems and components 4) Industrial robot configurations 5) Kinematic classification 6) Industrial applications, usage and world markets Week 9: Robot control & programming ...