Robots

An Introduction

Various Robot Fields:

Aerospace (air travel, space exploration)Exploration (underwater, space, volcanic)EntertainmentMedicalManufacturingMilitary

Robot Fields: Medical

See http://www.childrenshospital.org/clinicalservices/Site1860/mainpageS1860P0.html

Robot Fields: Military

Robot Fields: Service

Robot Fields: Exploration

Robot Fields: Manufacturing

MANUFACTURING Robot Definition (4 distinctions)

A robot is an automatically controlled, reprogrammable, multipurpose, manipulative machine with several reprogrammable axis, which may be either fixed in place or mobile for use in industrial automation applications.

Industrial Robot Applications (1st distinction)

AKA Multi-functional / Multipurpose

May perform many operations such as welding, bending, moving, breaking, etc.

Robot Applications: Loading/Unloading

Robot Applications: Loading/Unloading

Robot Applications: Arc Welding

Robot Applications: Arc Welding

Robot Applications: Plasma Arc Welding

Robot Applications: Spot Welding

Robot Applications: Testing/Inspection

Robot Applications: Grinding / Deburring

Robot Applications: Pick and Place / Palletizing

Robot Applications: Plasma Arc Cutting

Robot Applications: Plasma Arc Cutting

Robot Applications: Plasma Arc Cutting

Robot Applications : Spray Painting

Robot Applications: Spray Painting

Robot Applications: Adhesive Application

Robot Applications: Assembly

Other Common Robot Applications:

Deflashing Measuring Waterjet Cutting

Manufacturing Robots are Reprogrammable: (2nd distinction)

1. Robot’s motion is controlled by written program, on or off-line

2. The program may be modified change motion

Robotic Controller:1. Central processing unit (CPU)-

microprocessor, performs calculations

2. Memory- stores data, regulates computation time

3. I/O devices- keyboard, outside computer, teach pendant, recorders, printers, screen

4. Software- AML, RAIL, Karel, APT, VAL, VAL2

Teaching Robots – Accomplished through:

Teach pendants

Teach terminals

Controller front panels

Teaching Activities:1. Robot power-up and preparation for

programming

2. Entry and editing of programs

3. Program Compilation (error check and post processing)

4. Program execution

*NOTE: not a sequence of steps for all robots

Programming Methods

On-line – realtime connection of programming manipulator movements (downtime associated. Robot cannot produce value during on-line programming. However, what you see is what you get.

Off-line- no physical connection of programmer with manipulator. Downtime minimized.

Offline ProgrammingUtilized feature of Simulation software

Allows cell to continue operations during programming

Check for trouble areas and Suggest optimum path, tools (with simulation)

Upload existing programs to be evaluated/changed (while robot is operating)

Allows complex tool paths to be programmed easily (particularly with simulation)

Minimize joint wear

Very little time needed to refine operation

Three Types of Programming:

1. Simulation

2. Structured Languages

3. Manual real-time or lead through

1) Robot Programming : GUI/Simulation

Simulation Tasks

Offline Programming (OLP)

Robot Evaluation and Set-up

Ergonomics

Safety

Demonstration

Simulation: Evaluation and Set-Up

Test “What-If” scenariosChanges in robot positionSelection of robot modelPart entry/movement/exit in cellConveyor positioningCell layout interferences with plant layout

All can be modeled and virtually “Walked Through” using simulation.

Simulation: Ergonomics & Safety

Eliminates need for Programmer to be in work envelope during programmingEvaluate Machine-Human interactionsOperator/Laborer can be modeled along with equipmentSafety features can be testedCell and safety devices can be viewed from all angles before the actual building of the cell

2) Robot Programming : Structured Languages

Typically offline programming

Multiple scenarios can be scripted in very little time (for testing)

Complex routines are made possible

Typical capability with many of today’s simulation softwares.

Robot Programming : Structured Languages

3) Robot Programming : Manual Real-time (online)

AKA Lead-Through Programming

On-line programming – dedicated link between operator and manipulator

Limited capability in testing multiple scenarios

Robot Programming : Manual Real-time

Why do we have robots?1. Robots can work in hazardous

environments

2. Robots can work 24 hours/day, 7 days/week

3. Robots can handle repetitious tasks (Repeatable)

4. Robots can work in sterile environments eliminating any risk of contamination

Why do we have robots?

5. Robots can be more precise than humans in some applications

6. Reprogrammable (flexible)

7. Variable sizes

8. Fast

9. Low hourly cost to operate

Problems with robots:

1. Limited applications (movement restrictions) – limited capability

2. Can be costly (end-effectors, ROI)

3. Payload restrictions

4. Programming can take time

5. Repeatability can be lacking for some robots

6. Must be continuously maintained

Robot System1. Robot Arm(s)2. Hardware- power supply and controller

(communication interface which monitors and operates the equipment and sensors)

3. Equipment, devices, and sensors required for the robot to perform its task (electrical and fluid support systems)

4. The end-effector(s) – tooling performing work, grippers

5. Software- language used to communicate action of the manipulator

Manipulator Power Sources:

Control through electric-drive motors, pneumatic / hydraulic actuators.

End-Effector:AKA End-of-arm tooling

Describes tooling (welders, adhesive applicators, hooking mechanisms)

Gripper- open and closing mechanism designed to grasp parts, most grippers activated by compressed air (pneumatics)

Terms:Accuracy- degree to which a robot arm is able to move to a specific position, Robot accuracy is usually one or two magnitudes greater than the arms repeatability.

Repeatability- Repeatability is the degree to which a robot system is able to return to a specific point, the best in terms of repeatability on assembly robots is within .0005 inches.

Terms:Work Envelope- Space which the robot gripper can move

Axis numbering- method used to describe the axes of motion of a robot when programming (base to end-effector)

Coordinate systems- XYZ, ABC, number of coordinates required to define a point is determined by the number of degrees of freedom present on the robot

Terms:Degree of freedom- [typical industrial robots have four to seven degrees of freedom] each axis has a degree of freedom within the work envelope

Duty cycle- the ratio of run time to the total operational time that a robot can continuously work with the rated payload at rated conditions (e.g., speed, acceleration, and temperature) without overheating or degrading the robot specifications

Terms:

Payload- load capacity of a robotPayload = Tooling Weight [EOA] + Part

WeightRated payloadMaximum payload