Advanced Manufacturing Industrial Robots.ppt

1、Advanced Manufacturing Industrial Robots,Dr. L. K. Gaafar,This presentation uses information from: http:/www.glue.umd.edu/aksamuel/academic/Viewgraph_files/frame.htm,“A robot is a programmable, multifunction manipulator designed to move material, parts, tools, or special devices through variable pro

2、grammed motions for the performance of a variety of tasks” Robot Institute of America,Industrial Robots Definition,A robot is a programmable arm simulator,Motivation for using robots to perform task which would otherwise be performed by humans. Safety Efficiency Reliability Worker Redeployment Cost

3、reduction,The Advent of Industrial Robots, Arm or Manipulator End effectors Drive Mechanism Controller Custom features: e.g. sensors and transducers,Main Components of Industrial Robots,Arm or Manipulator, The main anthropomorphic element of a robot. In most cases the degrees of freedom depends on t

4、he arm The work volume or reach mostly depends on the functionality of the Arm,End Effectors,Grippers Mechanical Grippers Suction cups or vacuum cups Magnetized grippers Hooks Scoops (to carry fluids),Device attached to the robots wrist to perform a specific task,Tools Spot Welding gun Arc Welding t

5、ools Spray painting gun Drilling Spindle Grinders, Wire brushes Heating torches,End Effectors,Device attached to the robots wrist to perform a specific task,Sensors in robotics,Types of sensors : Tactile sensors (touch sensors, force sensors, tactile array sensors) Proximity and range sensors (optic

6、al 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 co

7、ntrol 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,Cartesian,Cylindrical,Polar (S

8、pherical),Jointed Arm,Physical Configuration,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,Programming Robots, Material Handling/Palletizing Machine Loading/Unloadi

9、ng Arc/Spot Welding Water jet/Laser cutting Spray Coating Gluing/Sealing Investment casting Processing operations Assembly Inspection,Applications, Size of the working envelope Precision of movement Control resolution Accuracy Repeatability Lifting capability Number of robot axes Speed of movement m

10、aximum speed acceleration/deceleration time,Motion control path control velocity control Types of drive motors hydraulic electric pneumatic,Performance Specifications of Industrial Robots,Determined by Physical configurations Size Number of axes The robot mounted position (overhead gantry, wall- mou

11、nted, floor mounted, on tracks) Limits of arm and joint configurations The addition of an end-effector can move or offset the entire work volume,Work Volume,Spatial region within which the end of the robots wrist can be manipulated,Depends on the position control system, feedback measurement, and me

12、chanical accuracy,Spatial Resolution,Smallest increment of motion at the wrist end that can be controlled by the robot, One half of the distance between two adjacent resolution points Affected by mechanical Inaccuracies Manufacturers dont provide the accuracy (hard to control),Accuracy,Capability to

13、 position the wrist at a target point in the work volume, Repeatability errors form a random variable. Mechanical inaccuracies in arm, wrist components Larger robots have less precise repeatability values,Repeatability,Ability to position back to a point that was previously taught, The lifting capab

14、ility provided by manufacturer doesnt 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,Weight Carrying Capacity,Acceleration/deceleration times are crucial for cycle time. Determined

15、by Weight of the object Distance moved Precision with which object must be positioned,Speed of Movement,Speed with which the robot can manipulate the end effector, Path control - how accurately a robot traces a given path (critical for gluing, painting, welding applications); Velocity control - how

16、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).,Motion Control,

17、 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 mainten

18、ance,Type of Drive System,Robot Location and Workspace,q1,q2,x,y,L1,L2,(x, y),Location:,Workspace:,Positioning:,2-link polar robot,Robot Applications (Configurations/Characteristics),SCARA Robot (Selective Compliance Assembly Robot Arm),Characteristics: Repeatability: 0.025mm (high) No. of axes: min

19、 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 (Con

20、figurations/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: 100

21、0mm/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 Robot,Characteristics: Repeatability: 0.1-0.

22、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, paint

23、ing, 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 u

24、nit 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

25、 (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 lin

26、ear 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., Simple Repetitive operations. Cycle times g

27、reater 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.,What to Automate,Robot Implementation Planning,Identify Objectives (Benefits) Increase productivity Reduce lab

28、or 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 chan

29、ges or process changes,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.,Robot Implementation Planning,Fixed versus Flexible Automation,