an introduction to robotics 1)what is a robot ? 2)the historical development of robotics...
TRANSCRIPT
An Introduction to Robotics
1) What is a robot ? 2) The historical development of robotics3) Industrial robot systems and components4) Industrial robot configurations 5) Kinematic classification 6) Industrial applications, usage and world markets7) Telerobotics
What is a robot ? – “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."
Websters Dictionary
Historical development I - the beginning
– 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 employed more profitably
Historical development II - computers + sensors
– In 1964 Artficial Intelligence (AI) Labs open at MIT, Stanford (SRI) and University of Edinburgh
– The mobile robot ‘Shakey’ was developed at Stanford in the late sixties.It had a camera and touch sensors and could move about the lab floor
– SRI develop the ‘Stanford Arm’ - an electrically powered manipulator and then ‘WAVE’ - the first robot programming language. This was subsequently developed into VAL for use with Unimation robots
– In 1974 ASEA introduce the all electric drive IRb6. Cincinnati Milacron also introduce computer controlled T3 (The Tomorrow Tool) robot. Kawasaki use Unimation machines to weld motorbike frames.
– In 1976 Viking I & II space crafts equipped with robot arms land on Mars– Unimate PUMA’s introduced in 1978. SCARA’s (Selective Compliance
Articulated Robot Arm) introduced in 1979.– Vision based workcell demonstrated at University of Rhode Island in
1980 (Kirsch).
Evolution of computing power
Historical development III - the latest
New Techniques– walking robots
– co-operating arms or AGV’s
– biomedical engineering
– teleoperation
– Internet robotics
– micro and nanorobotics
New Applications– teleoperated robotics (space, surgery)
– service robots (teaching, retail, fast food outlets, bank tellers, garbage collection, security guards, cleaning vehicles etc etc…)
– UGV’s and UAV’s for hazardous environments
Historical development IV - science fiction
– early perception of robots was that they were the tools of scientists or aliens bent on world domination (The Day the Earth Stood Still, The Forbidden Planet)
– some robots even wanted to take over the world themselves (Dr. Who), or quite often went berserk (RUR, 2001, Westworld, Saturn 3)
– later they were viewed in more sympathetic light as often humaniod-like companions (Star Wars, Dr. Who, Short Circuit, Hitch Hikers Guide, Red Dwarf).
– we still however best enjoy the notion that robots are basically very scary (Terminator, Bladerunner, RoboCop)
– end result is that robots and their capabilities are still very poorly understood by the general public
Robots in sci-fi: seminal films I
– 1951 - The Day the Earth Stood Still (sci-fi drama) Michael Rennie, Patricia Neal. Story about aliens who come to Earth with an all-powerful robot called Gort.
– 1956 - Forbidden Planet (sci-fi drama) Leslie Nielsen. Classic movie robot Robby.
– 1965 - Dr. Who and the Daleks (sci-fi drama) Dr. Who helps
humans on a distant planet overcome their robot masters. – 1968 - 2001: A Space Odyssey (cult sci-fi drama) Not strictly a
robot, but an intelligent computer who kills members of his crew.
– 1973 - Sleeper (Comedy) - Woody Allen comedy with household
robots of the future. – 1973 - Westworld (sci-fi drama) - cult story about an entertainment
park filled with androids. Yul Brynner stars as an android gunslinger who goes berserk and starts killing the guests.
Robots in sci-fi: seminal films II
– 1977 - Star Wars (sci-fi epic)- Harrison Ford, Carrie Fisher. R2D2 robot & C3PO android steal the show.
– 1980 - Saturn 3 (sci-fi horror)- Kirk Douglas, Farah Fawcett, Harvey Keitel. Story about a couple on a space outpost who are about to be replaced by a
robot - which predictably goes berserk. – 1982 - Blade Runner (sci-fi drama) - Harrison Ford is hired to track down
and kill several androids including Rutger Hauer who steals the show.
– 1984 - The Terminator (sci-fi drama) - Arnold Schwartzenegger. A time-travelling cyborg comes back from the future to kill the mother of its nemesis.
– 1986 - Short Circuit (sci-fi drama) Ludicrously cute military robot (Johnny 5) gets hit by lightning and comes alive.
– 1987 - Robocop (sci-fi drama) Poor story of a cyborg cop - though well worth seeing for the ED-209 go beserk at the beginning.
– 1997 - Titanic (drama): Subsea ROV with stereo vision is overshadowed by
the tragic drowning of Leonardo de Caprio.
Robots in sci-fi:
TerminologySome Definitions:1) Robot – An electromechanical machine with more than one degrees-of-freedom(DOF) which is programmable to perform a variety of tasks. 2) Anthropomorphic: Similar to Humans.3) Manipulator - mechanical arm, with several DOF.4) Degrees-of-Freedom - the number of independently controllable motions in amechanical device. The number of motors in a serial manipulator.5) Mechanism - a 1-DOF machine element.6) Fixed Automation - designed to perform a single repetitive task.7) Flexible Automation - can be programmed to perform a variety of tasks.8) Robot system - manipulator(s), sensors, actuators, communication, computers,interface, hand controllers to accomplish a programmable task.9) Actuator - motor that drives a joint; generally rotary (revolute) or linear (prismatic);electric, hydraulic, pneumatic, piezoelectric.10) Cartesian Coordinate frame - dextral, orthogonal, XYZ
Terminology11)Kinematics - the study of motion without regard to forces. Cartesian Pose: position
and orientation of a coordinate frame.
a) Forward Kinematics - given the joint variables, calculate the Cartesian pose.
b) Inverse Kinematics - given the Cartesian pose, calculate the joint variables.
12) Position (Translation) - measure of location of a body in a reference frame.
13) Orientation (Rotation) - measure of attitude of a body (e.g. Roll, Pitch, Yaw) in a
reference frame.
14) Singularity - a configuration where the manipulator momentarily loses one or more
degrees-of-freedom due to its geometry.
15) Actuator Space - vector of actuator commands, connected to joint through gear train
or other drive.
16) Joint Space - vector of joint variables; basic control parameters.
17) Cartesian Space - Position vector and orientation representation of end-effector;
natural for humans.
Terminology18) End-effector - tool or hand at the end of a robot.19) Workspace - The volume in space that a robot’s end-effector can reach, both inposition and orientation.20) Dynamics - the study of motion with regard to forces (the study of the relationshipbetween forces/torques and motion). Composed of kinematics and kinetics.
a) Forward Dynamics (simulation) - given the actuator forces and torques, compute the motion.b) Inverse Dynamics (control) - given the desired motion, calculate the actuator forces and torques.
21) Control - causing the robot system to perform the desired task. Different levels.a) Teleoperation - human moves master, slave manipulator follows.b) Automation - computer controlled (using sensors).c) Telerobotics - combination of the b) and c)
22) Haptics - From the Greek, meaning “to touch”. Haptic interfaces give humanoperators the sense of touch and forces from the computer, either in virtual or real,remote environments. Also called force reflection.
industrial robot systems: overview
Today 90% of all robots used are found in factories and they are referred to as industrial robots.
An industrial robot typically has the following component parts:
– controller– arm– drive– end-effector– sensors
Components of an industrial robot system:
Controller
– Every robot is connected to a computer controller, which regulates the components of the arm and keeps them working together.
– The controller also allows the robot to be networked to other systems, so that it may work together with other machines, processes, or robots.
– Almost all robots are pre-programmed using "teaching" devices or off-line software programs (OLP).
– In the future, controllers with artificial intelligence (AI) could allow robots to think on their own, or even program themselves. This could make robots more self-reliant and independent.
Components of an industrial robot system:
Arm
– The arm is the part of the robot that positions the end-effector and sensors to do their pre-programmed business.
– Many are built to resemble human arms, and have shoulders, elbows, wrists, even fingers.
– Each joint is said to give the robot 1 degree of freedom. A simple robot arm with 3 degrees of freedom could move in 3 ways: up and down, left and right, forward and backward.
– Most working robots today have 6 degrees of freedom to allow them to reach any possible point in space within its work envelope (or ‘working volume’).
Components of an industrial robot system:
Drive
– The links (the sections between the joints) are moved into their desired position by the drive.
– Typically, a drive is powered by pneumatic or hydraulic pressure, or, most commonly, electricity.
– hydraulic drives: powerful, deliver large forces, require pumps
– pneumatic: cheap, practical (most factories have air lines), safe, difficult to control.
– electric: good precision, good accuracy, stepper or DC servo (most common),
Components of an industrial robot system:
End-effector (or tool)
– The end-effector could be thought of as the "hand" on the end of the robotic arm.
– There are many possible end-effectors including a gripper, a vacuum pump, tweezers, scalpel, blowtorch, welding gun, spray gun, axe, hair clippers, or just about anything that helps it do its job.
– Some robots can change end-effectors, and be reprogrammed for a different set of tasks.
Components of an industrial robot system:
Sensors
– A sensor sends information, in the form of electronic signals back to the controller.
– Sensors also give the robot controller information about its surroundings and lets it know the exact position of the arm, or the state of the world around it.
– One of the more interesting areas of sensor development is in the field of computer vision and object recognition.
– Other types of sensors include ultrasonic, lasers, force/touch etc.
Components of an industrial robot system:
Classification of joint types
– R - revolute (1 DOF)
– P - prismatic (1 DOF)
– helical (2 DOF)
– cylindrical ((2 DOF)
– universal (2 DOF)
– spherical (3 DOF)
Revolute joint, R Prismatic, P Helical joint, H
Cylindrical, C Universal , U Spherical, S
Kinematic Robot Arm Classifications
– In a ‘serial’ design: joints disposed sequentially; the total number of DOF’s is the sum of the DOF of all joints
– ‘Parallel’ design: a closed-loop linkage (most well known – Stewart platform)
– Robot arms are usually classified by the design of their mechanical system and by the shape of their working volume.
– Generally, there are five common robot configurations: 1) Cartesian (or rectangular),2) cylindrical, 3) spherical,4) jointed arm5) SCARA.
– Robots may also be categorised as being either ‘articulated’ (bending about an elbow to perform the task) or ‘non-articulated’ (retracting/ extending a boom).
– A further way of describing a robot is by its number of DoF.
Cartesian coordinate robots I
– CCRs are highly configurable, rectilinear robot systems which, in a basic configuration, include an X and Y axis.
– Three-axis CCRs, incorporating an X, Y, and Z axis, are also common for positioning tools, such as dispensers, cutters, drivers, and routers.
Cartesian coordinate robots II
– Each of the axis lengths are selectable– Payloads and speeds vary based on axis length and
support structures.– CCRs are typically very repeatable, have better inherent
accuracy than a SCARA or jointed arm, and perform 3D path-dependent motions with relative ease.
– However,the CCR’s key feature is its configurability – the ability you have to configure and size the CCR to best meet your application needs.
– A gantry robot is a special type of Cartesian robot whose structure resembles a gantry. This structure is used to minimize deflection along each axis. Many large robots are of this type.
Cylindrical Coordinate Robots
– A cylindrical robot has two linear axes and one rotary axis.– The robot derives its name from the operating envelope– The Z axis is located inside the base, resulting in a
compact end-of-arm design that allows the robot to "reach" into tight work envelopes without sacrificing speed or repeatability.
Spherical (or Polar) Coordinate Robots
– A spherical robot has one linear axis and two rotary axes– Spherical robots are used in a variety of industrial tasks
such as welding and material handling.
Jointed Arm Robots
– 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.
SCARA Robots I
• 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.
• SCARA’s can be referred to as ‘swivel’ robots
SCARA Robots II
• SCARA robots are a combination of the articulated arm and the cylindrical robot.
• They are used widely in electronic assembly. • The rotary axes are mounted vertically rather than horizontally
minimising the robot's deflection when it carries an object while moving at speed. The load is carried by the joint frame NOT the motor.
Summary of classifications in terms of joint types:
• Cartesian P-P-P• Cylindrical R-P-P• Spherical R-R-P• SCARA R-R-R-P• Jointed/articulated/revolute R-R-R
See Pg 73: Figure 6.2 in Lecture notes
Examples of robot kinematic configurations:
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.
Components of an industrial robot system:
Classification of end effectors + grippers
GRIPPERrotational
linear
electrical
pneumatic
hydraulic
Power Kinetic Energy
see page 75, Fig 6.4 for gripper types.
An end effector is the device that is fixed to the end of therobot manipulator mounting flange.
N.B.: Typically the manipulator also has a wrist (often R-R-R).
Other types of robot:
• Stewart platforms - parallel linkages• Mobile vehicles• Crawlers• biologically inspired systems
Stewart platform
A robotic camera head
A planeatry Rover vehicleIs this a robot ?
Uses of robots
– Today 90% of all robots used are found in factories and they are referred to as industrial robots.
– Ten years ago, 9 out of 10 robots were being bought by auto companies - now, only 50% of robots made today are bought by car manufacturers.
– Robots are slowly finding their way into warehouses, laboratories, research and exploration sites, energy plants, hospitals, even outer space.
– Robots are useful in industry for a variety of reasons. Installing robots is often a way business owners can be more competitive, because robots can do some things more efficiently than people.
Revolute and Prismatic DOF and a 6 DOF Robot Arm
Multiple Solutions, Singularity, and Redundant Links
Motion Coordination using
a. The Geometric Model
b. Variational Model
c. Principle of Virtual Work
Principle of Robot Dynamics
Integrated robot system Hierarchy
1. Robot arm
2. Sensor
3. Motion hierarchy
4. Sensor processing hierarchy
5. Environment model
6. Motion planning
7. Collision avoidance
8. Real-time OS
9. Programming
Integrated Telerobotic System 1. Client station
1. Master arm
2. Forwarding motion commands
3. Stereo visualization
4. Haptic and force display
5. Client software
6. Real-time OS
2. Server station
1. Salve arm
2. Haptic and force sensors
3. forwarding force data
4. Stereo cameras
5. forwarding streaming
6. Client software
7. Real-time OS
Internet Telerobotic System 1. Client station
1. Master arm
2. Streaming motion commands
3. Stereo visualization
4. Haptic and force display
5. Client software
6. Real-time OS
2. Server station
1. Salve arm
2. Haptic and force sensors
3. Streaming force data
4. Stereo cameras
5. Video streaming
6. Client software
7. Real-time OS
Summary
1) What is a robot ? 2) The historical development of robotics3) Industrial robot systems and components4) Industrial robot configurations 5) Kinematic classification 6) Industrial applications, usage and world markets7) Telerobotics