Robot Applications by renata.vivien

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									       Advanced Manufacturing
            Industrial Robots
                         Dr. L. K. Gaafar




This presentation uses information from:
http://www.glue.umd.edu/~aksamuel/academic/Viewgraph_files/frame.htm
          Industrial Robots Definition
         A robot is a programmable arm simulator


“A robot is a programmable, multifunction manipulator
designed to move material, parts, tools, or special devices
through variable programmed motions for the performance of
a variety of tasks”
                                  Robot Institute of America
          The Advent of Industrial Robots

Motivation for using robots to perform task which would otherwise
be performed by humans.

• Safety
• Efficiency
• Reliability
• Worker Redeployment
• Cost reduction
     Main Components of Industrial Robots


– Arm or Manipulator
– End effectors
– Drive Mechanism
– Controller
– Custom features: e.g. sensors and transducers
               Arm or Manipulator

• The main anthropomorphic element of a robot.
• In most cases the degrees of freedom depends on the arm
• The work volume or reach mostly depends on the functionality
of the Arm
                  End Effectors
 Device attached to the robot’s wrist to perform a specific task




Grippers
– Mechanical Grippers
– Suction cups or vacuum cups
– Magnetized grippers
– Hooks
– Scoops (to carry fluids)
                      End Effectors
     Device attached to the robot’s wrist to perform a specific task



Tools
– Spot Welding gun
– Arc Welding tools
– Spray painting gun
– Drilling Spindle
– Grinders, Wire brushes
– Heating torches
                        Sensors in robotics

Types of sensors :
– Tactile sensors (touch sensors, force sensors, tactile array sensors)
– Proximity and range sensors (optical sensors, acoustical sensors,
electromagnetic sensors)
– Miscellaneous sensors (transducers and sensors which sense variables
such temperature, pressure, fluid flow, thermocouples, voice sensors)
– Machine vision systems
                      Sensors in robotics
Uses of sensors:
– Safety monitoring
– Interlocks in work cell control
– Part inspection for quality control
– Determining positions and related information about objects
                     Sensors in robotics

Desirable features of sensors:
Accuracy
Operation range
Speed of response
Calibration
Reliability
Cost and ease of operation
            Physical Configuration
                               Cylindrical
Cartesian
         Physical Configuration


Polar (Spherical)          Jointed Arm
           Programming Robots

•Manual
     Cams, stops etc
•Walkthrough (Lead-through)
      Manually move the arm, record to memory


• Manual teaching
      Teach pendant


• Off-line programming
        Similar to NC part programming
        VAL, RAPT
                        Applications

• Material Handling/Palletizing
• Machine Loading/Unloading
• Arc/Spot Welding
• Water jet/Laser cutting
• Spray Coating
• Gluing/Sealing
• Investment casting
• Processing operations
• Assembly
• Inspection
Performance Specifications of Industrial Robots

• Size of the working envelope           •Motion control
• Precision of movement                        – path control
       – Control resolution                    – velocity control
       – Accuracy                        •Types of drive motors
       – Repeatability                         – hydraulic
•Lifting capability                            – electric
                                               – pneumatic
•Number of robot axes
•Speed of movement
      – maximum speed
      – acceleration/deceleration time
                       Work Volume
Spatial region within which
the end of the robot’s wrist
can be manipulated



Determined by
      – Physical configurations
      – Size
      – Number of axes
      – The robot mounted position (overhead gantry, wall-
              mounted, floor mounted, on tracks)
      – Limits of arm and joint configurations
      – The addition of an end-effector can move or offset the
              entire work volume
                  Spatial Resolution
Smallest increment of motion at the wrist end that can be controlled by
                              the robot


Depends on the position control system, feedback measurement,
and mechanical accuracy
                          Accuracy
Capability to position the wrist at a target point in the work volume


 • One half of the distance between two adjacent
        resolution points
 • Affected by mechanical Inaccuracies
 • Manufacturers don’t provide the accuracy (hard to          control)
                      Repeatability
 Ability to position back to a point that was previously taught

• Repeatability errors form a random variable.
• Mechanical inaccuracies in arm, wrist components
• Larger robots have less precise repeatability values
             Weight Carrying Capacity

• The lifting capability provided by manufacturer doesn’t include the
        weight of the end effector
• Usual Range 2.5lb-2000lb
• Condition to be satisfied:
Load Capability > Total Wt. of workpiece +Wt. of end effector + Safety range
                     Speed of Movement
        Speed with which the robot can manipulate the end effector


•Acceleration/deceleration times are crucial for cycle time.
•Determined by
        – Weight of the object
        – Distance moved
        – Precision with which object must be positioned
                      Motion Control

• Path control - how accurately a robot traces a given path (critical for
gluing, painting, welding applications);
• Velocity control - how well the velocity is controlled (critical for
gluing, painting applications)
• Types of control path:
- point to point control (used in assembly, palletizing, machine
loading); - continuous path control/walkthrough (paint spraying,
welding).
- controlled path (paint spraying, welding).
            Type of Drive System
• Hydraulic
– High strength and high speed
– Large robots, Takes floor space
– Mechanical Simplicity
– Used usually for heavy payloads
• Electric Motor (Servo/Stepper)
– High accuracy and repeatability   – Low cost
– Less floor space                  – Easy maintenance
• Pneumatic
– Smaller units, quick assembly
– High cycle rate                   – Easy maintenance
            Robot Location and Workspace
                    2-link polar robot
                                         y
Location:


                                                   q2   L2   (x, y)
Workspace:
                                              L1
                                         q1
                                                               x
Positioning:
 Robot Applications (Configurations/Characteristics)
SCARA Robot
                        Characteristics:
(Selective Compliance
                        •Repeatability: < 0.025mm (high)
Assembly Robot Arm)
                        •No. of axes: min 4 axes
                        • Vertical motions smoother, quicker,
                        precise (due to dedicated vertical axis)
                        • Good vertical rigidity, high compliance in
                        the horizontal plane.
                        •Working envelope: range < 1000mm
                        •Payload:10-100 kg
                        •Speed: fast 1000-5000mm/s


                        Applications:
                        •Precision, high-speed, light assembly
 Robot Applications (Configurations/Characteristics)
Cylindrical Coordinate Robot Characteristics:
                                •Wide range of sizes
                                •Repeatability: vary 0.1-0.5mm
                                •No. of axes: min 3 arm axes (2 linear)
                                •Working envelope: typically large (vertical
                                stroke as long as radial stroke)
                                • The structure is not compact.
                                •Payload: 5 - 250kg
                                •Speed: 1000mm/s, average
                                •Cost: inexpensive for their size and
                                payload
Applications:
•Small robots: precision small assembly tasks
•Large robots: material handling, machine loading/unloading.
 Robot Applications (Configurations/Characteristics)
Vertical Articulated Arm         Characteristics:
Robot                            •Repeatability: 0.1-0.5mm (large sizes not
                                 adequate for precision assembly)
                                 •No. of axes: 3 rotary arm-axes, 2-3
                                 additional wrist axis (excellent wrist
                                 articulation)
                                 •Working envelope: large relative to the
                                 size, Structure compact, but not so rigid
                                 •Payload: 5-130kg
                                 •Tool tip speed: fast 2000mm/s




Applications: Welding, painting, sealing, deburring, and material handling
 Robot Applications (Configurations/Characteristics)
Spherical Coordinate Robot      Characteristics:
                                •Repeatability: poor 0.5-1mm
                                •No. of axes: 3 arm-axes (1 linear radial), 1
                                -2 additional wrist-axes.
                                •Working envelope: large vertical envelope
                                relative to the unit size
                                •Payload: 5-100 kg
                                •Speed: low (linear motions are not smooth
                                and accurate- require coordination of
                                multiple axes)




Applications: Material handling, spot welding, machine loading
 Robot Applications (Configurations/Characteristics)
Cartesian Coordinate Robot       Characteristics:
                                 •Repeatability: high (0.015-0.1)
                                 •No. of axes: 3 linear arm-axis,
                                 •Working envelope:relative large
                                 •Payload:5- 100kg
                                 •Speed: fast




Applications: Precise assembly, arc welding, gluing, material handling
   Robot Applications (Configurations/Characteristics)
 Gantry Robot                      Characteristics:
                                   •Repeatability: 0.1-1mm
                                   •No. of axes: 3 linear traverse-axes, 1-3
                                   additional wrist axes
                                   •Working envelope: very large
                                   •Payload: vary function of size, support
                                   very heavy 10-1000kg
                                   •Speed: low for large masses




Applications:
Handling very large parts, moving material on long distances, welding, gluing.
                What to Automate

• Simple Repetitive operations.
• Cycle times greater than 5s.
• Parts can be delivered in proper locations/orientation.
• Part weight is suitable.
• One or two persons can be replaced in 24 hr period.
• Setups and changeovers are not frequent.
       Robot Implementation Planning


Identify Objectives (Benefits)
• Increase productivity
• Reduce labor cost
• Reduce cycle time
• Eliminate undesired jobs
• Safety reasons: protect from exposure to hazardous conditions
• Increase product quality
       Robot Implementation Planning

•Consider Drawbacks
• The impact upon the workers
• The impact upon production schedule and maintenance
• Questions of potential model changes or process changes
       Robot Implementation Planning
              Fixed versus Flexible Automation
Fixed automation:
Expensive
Can become obsolete early (dedicated for a single task)
Large inventories
Difficulties in commissioning and high maintenance costs
Faster and more accurate
Flexible (robot) automation:
Reprogrammable for different tasks
Quick to commission
Easy to maintain
Cheaper to design.

								
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