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WORKING AND PROGRAMMING OF KUKA ROBOT

  1. 1. i WORKING AND PROGRAMMING OF KUKA ROBOT A project work report submitted to MANIPAL UNIVERSITY For partial fulfillment of the requirement for the Award of the Degree of BACHELOR OF ENGINEERING in MECHANICAL AND MANUFACTURING ENGINEERING by SHAHID FAIZEE SAMRAT SUR Under the Guidance of Dr. N. Yagnesh Sharma Professor, Department of Mechanical & Manufacturing Engineering DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING MANIPAL INSTITUTE OF TECHNOLOGY (A constituent Institute of MANIPAL UNIVERSITY) MANIPAL - 576 104, KARNATAKA, INDIA
  2. 2. ii MANIPAL INSTITUTE OF TECHNOLOGY (A constituent Institute of MANIPAL UNIVERSITY ) MANIPAL - 576 104 . DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING CERTIFICATE This is to certify that project work titled “WORKING AND PROGRAMMING OF KUKA ROBOT” is a bonafied work of SHAHID FAIZEE SAMRAT SUR 080929282 080929014 carried out in partial fulfillment of the requirements for awarding the degree of Bachelor of Engineering in Mechanical discipline in Manipal Institute of Technology under MANIPAL University, Manipal during the academic year 2008-2009. Mr. Pravin Y. Koli Manager HED- Electronics Cell External Guide Dr. N.Yagnesh Sharma Professor & Head Dept. of Mechanical & Manufacturing Engineering
  3. 3. iii ACKNOWLEDGEMENT Written words have an unfortunate tendency to degenerate genuine gratitude into a formality. However it is the only way to record one's feelings permanently. I was bestowed with the golden opportunity to undergo my summer training at Larsen & Toubro Limited, Powai, and hence take this opportunity to express my heartfelt thanks to all those who have been associated with my training. I express my special thanks to Mr. Pravin Koli, HED- Electronics Cell, I gained experience and knowledge about the importance of work culture and planning, which is one of the best of the establishment; I had the privilege of working in the Electronic Cell, HED during my summer training. I had exposure to: Knowledge about computer & various packages, which are used in an organization for its efficient function. Achieving goals and targets by proper planning & time management. The importance of communication skill especially when having a group discussion. I express my heartfelt gratitude to Mr. Rishi Shahani. For providing me with endless support and encouragement in all my endeavors at every moment during my training. This acknowledgement is really incomplete if I would fail to express my sincere thanks to Ms. Kirti Uchil, placement department, L&T for giving the opportunity of working in the Production Engineering. Last but not the least I thank all my fellow Trainees for their Co- operation and support. SHAHID FAIZEE SAMRAT SUR Mentor
  4. 4. iv TABLE OF CONTENT CHAPTER PARTICULARS PAGE. NOS. CERTIFICATE ii ACKNOLWEDGEMENT iii TABLE OF CONTENT iv INTRODUCTION v-vi 1.0 THE ROBOT SYSTEM 1 1.1 ROBOT SYSTEM BASICS 1 1.1.1 Components of a complete KUKA robot system 1 1.1.2 KUKA Control Panel (KCP) 1 1.1.3 Mechanical construction of a KUKA robot 1 1.1.4 Axis designation of a KUKA robot 2 1.2 SYSTEM OVERVIEW 3 1.2.1 KR C2 control for max. 7 axes 3 1.2.2 USER GROUPS 4 1.3 ENERGY SUPPLY 5 1.3.1 KUKA energy supply systems – series 2000 robot 5 1.3.2 Energy supply systems – Adjusting the protectors 5 1.3.3 KUKA robot controller (KRC) 5 1.3.4 Performance features of KUKA Robot Controller (KRC) 6 2.0 COORDINATE SYSTMES 7 2.1 OPERATION OF KUKA ROBOT PANEL (KCP) 7 2.1.1 Operator control elements 7 2.1.2 Mode table 7 2.1.3 Types of Keys 8 2.2 COORDINATE SYSTEM OF ROBOTS 9 2.3 JOGGING AXIS SPECIFIC 9 2.4 WORLD COORDINATE SYSTEM 9 2.4.1 Assignment of the angles of rotation in Cartesian coordinate 9 2.4.2 Dominant axis activated 10 2.4.3 Dominant axis not activated 10 2.4.4 TOOL Coordinate system 10 2.4.5 BASE Coordinate system 10 3.0 SETUP 12 3.1 MASTERING 12 3.1.1 Why is Mastering carried out 12 3.1.2 Mastering Equipments 12 3.1.3 Reasons for Re mastering 12 3.1.4 Mastering with the EMT 13 3.1.5 Preparation for EMT Mastering 13 3.1.6 What Happen in during tool calibration 14 3.2 METHODS OF TOOL CALIBRATION 14 3.2.1 Methods of measurement of the TCP 14 3.2.2 Methods of the measurement of the orientation 15
  5. 5. v 3.3 TOOL PAYLOAD 16 3.3.1 Loads on the robot 16 3.3.2 Playload data 16 3.3.3 Supplementary load on the robot 16 3.4 BASE CALIBRATION 17 3.4.1 Base Calibration 17 3.4.2 The “3-point” method 17 4.0 APPLICATION OF KUKA ROBOT 18 4.1 KUKA.LaserCut 18 4.2 KUKA.LaserWeld 18 4.3 KUKA.GlueTech 19 4.4 KUKA.ArcTech 19 4.5 KUKA.PalletTech 19 4.6 KUKA Milling 8 kW 20 4.6.1 KUKA Milling 8 kW – Scope of Supply 20 5.0 CAN A CAR SEAT WTHSTAND CONDITIONS AT THE NORTH POLE? 21 6.0 AC SERVO MOTOR 23 6.1 WHAT IS SERVO? 23 6.2 TYPES OF SERVO MOTORS 24 6.3 PRINCIPLE OF OPERATION OF A.C. SERVO MOTOR 24 6.4 WORKING OF A.C. SERVO MOTOR 25 6.5 APPLICATIONS OF A.C. SERVO MOTOR 25 6.5.1 Commercial Application 25 6.5.2 Industrial Application 25 7.0 PROGRAMMING OF KUKA ROBOT 26 7.1 Motion Programming 26 7.2 BCO Run 26 7.2.1 Part 1 26 7.2.2 Part 2 26 7.2.3 Part 3 27 7.3 LIN (Linear) - Motion 27 7.3.1 Programming a LIN motion 27 7.3.2 Orientation Control 28 7.4 CIRC (Circular) - Motion 28 7.4.1 Programming a CIRC motion 28 7.4.2 Orientation Control 29 7.4.3 360 degree full circle 29 7.5 Approximation of a motion 30 7.5.1 PTP motion with approximate positioning 30 7.5.2 LIN & CIRC motion with approximate positioning 30 REFERENCES 31
  6. 6. vi INTRODUCTION KUKA Robots come with a control panel that has a display resolution of 640 x 480 pixels and an integrated mouse, with which the manipulator is moved, positions are saved (TouchUp), or where modules, functions, data lists, etc. are created and modified. To manually control the axles the enabling switch on the back of the control panel (the KCP, or KUKAControlPanel) must be activated (today only with a panic function). The connection to the controller is a VGA interface and a CAN-bus. A rugged computer located in the control cabinet communicates with the robot system via an MFC card. Control signals between the manipulator and the controls are transferred using the so-called DSE-RDW connection. The DSE card is in the control cabinet, the RDW card in the robot socket. Controls for the old KRC1 types used Windows 95 to run VxWorks-based software. Peripheral equipment includes a CD-ROM and a disk drive; Ethernet, Profibus, Interbus, Devicenet and ASI sockets are also available. Controls for the newer KRC2 type use the Windows XP operating system. Systems contain a CD-ROM drive and USB ports, Ethernet connection and feature optional connections for Profibus, Interbus, DeviceNet and Profinet. Most robots come in the orange or black, the former featuring prominently as a corporate color. KUKA's industrial robots product range:[3] KUKA´s industrial robots Kinematic Type Number of Axis Significance Payload Range articulated robot 6 axis handling robots 5 to 1000 kg articulated robot 6 axis arc welding robots 5 to 16 kg articulated robot 6 axis spot welding robots 100 to 240 kg articulated robot 6 axis shelf-mounted robots, top loader robots for machine loading and unloading 6 to 210 kg
  7. 7. vii articulated robot 6 axis stainless steel robot for food processing, IP67 15 kg articulated robot 6 axis cleanroom robots 16 to 500 kg articulated robot 6 axis heat resistant robots for foundry industry 16 to 500 kg articulated robot 6 axis painting robots, ATEX-compliant robots for operating in explosive atmospheres 16 kg articulated robot 6 axis heat resistant robots for foundry industry 16 to 500 kg articulated robot 4 axis palletizers for bag and box palletizing and depalletizing 40 to 1300 kg[4] SCARA robot 4 axis handling robots for pick and place, handling and packaging operations 5 to 10 kg gantry robot 6 axis portal robot for machine tending and material handling tasks for distances of up to 20 m 30 to 60 kg KUKA Robot application examples KUKA industrial robots are used in material handling, loading and unloading of machines, palletizing, spot and arc welding. KUKA Robots have also appeared in various Hollywood Films. In the James Bond film Die Another Day, in a scene depicting an ice palace in Iceland, the NSA agent Jinx (Halle Berry) is threatened by laser-wielding robots. In the Ron Howard directed film The Da Vinci Code, a KUKA robot hands Tom Hanks’ character Robert Langdon a container containing a cryptex. In 2001 KUKA developed the Robocoaster, which is the world’s first passenger-carrying industrial robot. The ride uses roller-coaster-style seats attached to robotic arms and provides a roller coaster-like motion sequence to its two passengers through a series of programmable maneuvers. There is also the possibility that riders themselves can program the motions of their ride. In 2007 KUKA introduced a simulator, based on the Robocoaster.[5] KUKA´s Robocoaster is an amusement ride based on industrial robotics technology.
  8. 8. 1 CHAPTER 1 THE ROBOT SYSTEM 1.1 ROBOT SYSTEM BASICS 1.1.1. Components of a complete KUKA robot system : KUKA robot (e.g. KR 180) KUKA control panel (KCP) KR C2 robot controller 1.1.2. KUKA Control Panel (KCP) : Following are the various parts of KCP and their functions: Keyswitch for mode selection Drives on/off switch Emergency stop button 6D mouse Numeric keypad Alphabetic keypad Cursor block with Enter key Large color graphic display Softkeys around the display Hardkeys for program and display control 1.1.3. Mechanical construction of a KUKA robot : Arm Wrist Counterbalancing system
  9. 9. 2 Link arm Rotating column Base frame NOTE: The modular design means that the number of robot assemblies, and thus the overall number of components, can be restricted. 1.1.4. Axis designation of a KUKA robot : It consists of following axis: Axis 1 Axis 2 Axis 3 Axis 4 Axis 5 Axis 6 NOTE: Axis 1, 2 and 3 are the main axis Axis 4, 5 and 6 are the wrist axis
  10. 10. 3 1.2 SYSTEM OVERVIEW 1.2.1 KR C2 control for max. 8 axes Control of the 6 robot axis KUKA CONTROL PANEL & KUKA ROBOT
  11. 11. 4 1.2.2 USER GROUPS Configuration of the robot controller (external axes, technology packages) Configuration of the robot system (field buses, vision system, etc.) User defined technology commands with UserTECH Start up task (mastering, tool calibration) Simple application programs (programming using incline forms, motion commands, technology commands, limit value checking, no syntax errors) Advanced programming using the KRL programming language Complete application programs (subprograms, interrupt programming, loops, program branches) Numeric motion programming
  12. 12. 5 1.3 ENERGY SUPPLY 1.3.1 KUKA energy supply systems – series 2000 robot 1.3.2 Energy supply systems – Adjusting the protectors There are protectors placed on the robot for protection. These protectors cannot be adjusted. If the protector has worn down to red inner, the protector must be exchanged. 1.3.3 KUKA Robot Controller (KR C) The KR C robot controller makes programming easier with its Microsoft Windows interface. It is expandable, can be integrated into networks via a bus, and contains ready-made software packages – all factors which point the way to the industrial automation of the future. 5 4 3 2 1 6 1 2 3 Interface A1 Integrate section of dress package A1-A3 Outlet on A2 4 External section – rotating column – dress package A1-A3 5 Interface A3 6 Dress package A3- A6
  13. 13. 6 1.3.4 Performance features of KUKA Robot Controller (KR C) Open, network-capable PC technology 2 free slots for external axes DeviceNet and Ethernet slots for common bus systems (e.g. INTERBUS, ROFIBUS, DeviceNet) provided as standard Motion profile function for optimal interaction between the individual robot motors and their velocity Floppy disk and CD-ROM drives for data backup Facilities such as remote diagnosis via the Internet Simple operation and programming via KUKA Control Panel (KCP) with Windows user interface Compact control cabinet Ergonomic KUKA Control Panel (KCP) .
  14. 14. 7 CHAPTER 2 COORDINATE SYSTEMS 2.1 OPERATION OF KUKA ROBOT PANEL (KCP) 2.1.1 Operator control elements Mode selector Drives ON Drives OFF E-STOP 2.1.2 Mode table Mode selector switch T1 T2 AUTOMATIC AUTOMATIC EXTERNAL Jogging using keys or Space Mouse 250 mm/s Enabling switch (dead man function) 250 mm/s Enabling switch (dead man function) Jogging not active Jogging not active Program execution 250 mm/s Enabling switch (dead man function) START key pressed Prog. Velocity Enabling switch (dead man function) START key pressed Prog. Velocity Drives ON START key pulse Prog. Velocity Drives ON External start HOV POV
  15. 15. 8 2.1.3 Types of Keys STOP key Program start forward key Program start backward Escape key Window selection key Softkeys ASCII alphabetic keypad NUM key SYM key SHIFT key ALT key RETURN key CURSOR key Menu keys Status keys
  16. 16. 9 2.2 Coordinate systems of the robots Axis-specific motion Each robot axis can be moved individually in a positive or negative direction. WORLD coordinate system Fixed rectangular coordinate system whose origin is located at the base of the robot. TOOL coordinate system Rectangular coordinate system, whose origin is located in the tool. BASE coordinate system Rectangular coordinate system which has its origin in the workpiece that is to be processed. 2.3 Jogging axis specific Each robot can be moved individually in a positive or negative direction. 2.4 WORLD Coordinate system Fixed rectangular coordinate system whose origin is located at the base of the robot. 2.4.1 Assignment of the angles of rotation in Cartesian coordinate Angle A Rotation about the Z axis Angle B Rotation about the Y axis Angle C Rotation about the X axis
  17. 17. 10 2.4.2 Dominant axis activated When this function is switched on, the coordinate axis with the greatest deflection of the mouse is moved. In this example only the Y axis is moved. 2.4.3 Dominant axis not activated The function allows a superposed motion. Depending on the setting of the degree of freedom, either 3 or 6 axes can be moved simultaneously. In this example, motion is possible in the X, Y and Z directions (the velocity depends on the deflection). 2.4.4 TOOL Coordinate system Rectangular coordinate system, whose origin is located in the tool. 2.4.5 BASE Coordinate system Rectangular Coordinate system which has its origin on the workpiece that is to be processed. + X A C B + Z + Y
  18. 18. 11 +Y + Z + X
  19. 19. 12 CHAPTER 3 SETUP 3.1 MASTERING 3.1.1 Why is Mastering carried out? When the robot is measured, the axes are moved into a defined mechanical position, the so called “mechanical zero position”. Once the robot in this mechanical zero position, the absolute encoder value for each axis is saved. NOTE : Only a mastered robot can move to programmed position and be moved using Cartesian coordinates; a mastered robot also knows the position of the software limit switches. 3.1.2 Mastering Equipments In order to move the robot to the mechanical zero position, a dial gauge or electronics or electronic measuring tool (EMT) is used. In EMT mastering, the axis is automatically moved by the robot controller to the mechanical zero position. If a dial gauge is being used, this must be carried out manually in axis- specific mode. 3.1.3 Reasons for Remastering The robot is to be mastered... Mastering is cancelled... ...after repairs (e.g. replacement of a drive motor or RDC) ...automatically on booting the system 1 ...after exchanging a gear unit ...manually by the operator ...when the robot has been moved without the controller (e.g. hand crank) ...automatically on booting the system 1 ...after an impact with a mechanical end stop at more than jog velocity (25 cm/s) ...manually by the operator ...after a collision involving tool or robot ...manually by the operator 1) If dispensaries are detected between the resolver data saved when shutting down the controller and the current position, all mastering data are deleted for safety reasons.
  20. 20. 13 `3.1.4 Mastering with the EMT 1) Only possible if the mastering is still valid (i.e. no change to the drive train e.g. replacement of a motor or parts, or following a collision, etc.) 3.1.5 Preparation for EMT mastering Move axes to pre-mastering position (frontsight and rearsight aligned) Move axes manually in axis-specific mode Each axis is mastered individually Start with axis 1 and move upward Always move axis from + to – Only in T1! Remove protective cap from gauge cartridge Mastering with the EMT Set mastering First mastering Teach offset Check mastering Master load with offset Master load without offset SET-UPMasteringLoss
  21. 21. 14 Attach EMT and connect signal cable (connection X32 on the junction box on the rotating column ) Three LEDs on the EMT 3.1.6 What happens in during tool calibration? The tool receives a user-defined Cartesian coordinate system with its origin at a reference point specified by the user. 3.2 Methods of tool calibration 1. Calculation of the TCP relative to the flange coordinate system 2. Definition of the rotation of the tool coordinate system from the flange coordinate system 3.2.1 Methods of measurement of the TCP 1. XYZ-4 point method In this method the TCP of the tool is moved to a reference point from four different directions The TCP of the tool is then calculated from the different flange positions and orientations - Error - Falling edge - Rising edge
  22. 22. 15 2. XYZ –reference method In the X Y Z –reference method the TCP data are determined by means of a comparison with a known point on the wrist flange. The unknown TCP can be calculated on the basis of the various positions and orientations of the robot flange and the dimensions of the known point. 3.2.2 Methods of the measurement of the orientation 1. The A B C – World 5D method In this method, the tool must be oriented parallel to the Z axis of the world coordinate system in the working direction. This calibration method is used if only the working direction (tool direction) of the tool is required for its positioning and manipulation (e.g. MIG/MAG welding laser or waterjet cutting). 2. The A B C – World 6D method In this method, the tool must be oriented in alignment with the world coordinate system. The axes of the tool coordinate system must be parallel to the axes of the world coordinate system. This method is used if the orientation of all three tool axes is required for positioning and manipulation (welding gun, gripper) 3. The A B C – 2-point method This method is used if an exact orientation of the three tool axes is required for positioning and manipulation, e.g. in case of vacuum grippers. Steps Involved: • First of all, the TCP (which has been calibrated beforehand) is moved to a known reference point • The TCP is now moved to a point on the negative X axis of the tool to be calibrated. The working direction of the tool is defined in this way. ▪ The tool is now moved so that the reference point is located with a positive Y value on the future XY plane of the tool.
  23. 23. 16 3.3. Tool Payload 3.3.1 Loads on the robot Each robot is designed for: A rated payload on the robot wrist with a specified load center distance a specified principal moment of inertia of the load a supplementary load on the robot (arm) With this rated payload, the robot executes motions in its entire work envelope with standard accelerations and velocities Note- “the maximum robot payload must not be exceeded!!” Max payload-1 6 kg Total load= Payload + Supplementary load = 46 kg max • If the robot is overload, the wear of the robot is increased. • This causes premature failures and reduces the service life of the robot. • Overloading the robot may even mean that the robot can no longer be operated safely. • If the static holding torque is exceeded, the robot can no longer be operated safely as the axes may slag! • Use of incorrect load data nullifies all warranty obligations on the part of KUKA Roboter GmbH. 3.3.2 Payload Data In order to optimize use of the available maximum moments of acceleration of the robot axes, it is necessary to enter the load data of the tool that is being used. CAUTION: The load data must be entered for every geometrically calibrated tool. 3.3.3 Supplementary load on the robot In addition to the load on the robot wrist, the robot can also move a load mounted on the arm, link arm or rotating column, using standard dynamic values.
  24. 24. 17 This can be a welding transformer or a terminal box with value modified, for example A value for the permissible supplementary load is specified by KUKA for each robot NOTE: The supplementary load must not be exceeded, as there is otherwise a risk of the axes sagging, as in the case of exceeding the permissible load on the wrist. Exceeding the permissible supplementary load generally increases wear and reduces the service life of the robot. 3.4 Base Calibration The work surface (pallet, clamping table, workpiece...) receives a user-defined Cartesian coordinate system with its origin at a reference point specified by the user. 3.4.1 Purpose of base calibration Jogging along the edges of the work surface or workpiece. Teaching Point- The taught point coordinate refers to the BASE coordinate origin Program Mode- If the BASE coordinate system is offset, the taught point move with it. Program Mode- It is possible to create several BASE coordinate systems. 3.4.2 The “3-point “ method 1. In the first step, the TCP of the reference tool is moved to the origin of the new BASE coordinate system. 2. In the second step, the TCP of the reference tool is moved to a point on the positive X axis of the new BASE coordinate system 3. In the third step, the TCP of the reference tool is moved to a point with a positive Y value on the XY plane of the new BASE coordinate system.
  25. 25. 18 CHAPTER 4 APPLICATIONS OF KUKA ROBOT 4.1 KUKA.LaserCut Technologies for laser cutting: once KUKA.Laser Cut has been set up, additional commands are available. These commands support the programmer in the creation of robot programs which use laser functions. Commands for switching the laser on and off, control of a distance sensor system, the setting of the gas pressure and the programming of simple geometric figures are 4.2 KUKA.LaserWeld KUKA.LaserWeld is a time-saving and easy-to-operate programming support package with a modular structure for laser welding with KUKA robots. User- friendly inline forms and parameter lists make for easy inputting, setting and modification of parameters. In addition to the functions for laser welding applications, KUKA.LaserWeld also contains an independent configuration program and various modules help you create applications. The integration of laser welding systems into the KUKA KR C2 robot controllers allows the programming of all important functions.
  26. 26. 19 4.3 KUKA.GlueTech KUKA.GlueTech packages are used for controlling a range of different dispensing controllers. Depending on the capabilities of the dispensing controller used, a range of ready-made functions is available, from simple opening and closing of the adhesive gun to checking the quantity of adhesive dispensed. To simplify operator control, these functions are offered to the programmer in dialog form. A configuration tool is provided for fast commissioning. This tool provides input masks, for example, for the configuration of any input/outputs or seam- specific parameters that may be required. 4.4 KUKA.ArcTech KUKA.ArcTech is a welding technology package for controlling power sources with program number control. This package has been specially developed for use with cooperating robots and enables the simultaneous operation of up to three robots that are in communication with one another. The package is further characterized by its high degree of operating convenience. The setup procedures are simplified by means of a configuration tool. Safe operation with the Shared Pendant is supported by the wide range of available operating and simulation modes for convenient teaching, and detailed, cause-specific messages including indication of the originator. The technology package is also available, with all its user-friendly features, to users of single applications. 4.5 KUKA.PalletTech Shortening the distance from application to program. The KUKA.PalletTech® intelligent palletizing software and the KUKA robot controller KR C2 ensure easy and efficient implementation of your application. As the second generation of the PC-based robot controller, the KR C2 offers you even more flexibility and power. It can be used to control an entire line, and can be integrated into higher-level structures via a field bus. Moreover, all of the standard interfaces for gripper, vision, and sensor systems are also provided. Programming is easy with the Windows user interface – and with the new "Icon Editor" program, which allows programming and operator control using an intuitive set of symbols.
  27. 27. 20 4.6 KUKA Milling 8 kW With the milling 8 kW application module, KUKA offers application-specific components and tools for deployment of a robot as a machine tool for milling tasks. Milling 8 kW is specially designed for machining tasks using an electrically-driven spindle with a rated power of 8 kW. It is used particularly with lightweight materials such as plastic, wood or rigid foamed material. From the HsC spindle and its controller to the special milling software, the application module has everything you need for the quick and easy setup of a robot as a powerful milling unit. 4.6.1 KUKA Milling 8 kW – Scope of Supply Technology cabinet with integrated spindle controller frequency inverter), pneumatic air supply and safety PLC Air and water supply for the spindle HSC electrically-driven spindle, high-speed cutting spindle with rated power 8 kW Mounting kit for the spindle on the robot flange HMI milling Robot software
  28. 28. 21 CHAPTER 5 CAN A CAR SEAT WITHSTAND CONDITIONS AT THE NORTH POLE? Starting point / Task definition Can a car seat withstand conditions at the North Pole? Car seats have to withstand a lot. The weight of the driver, for example, his movement while waiting impatiently at a red light, or extracting a wallet from his back trouser pocket.... Furthermore, cars are being driven all over the world. Some are parked in the blazing sun of Arizona, while others are stationed in the frozen conditions of Siberia. What materials can withstand such conditions? To find out the answer, car manufacturers must subject their seats to rigorous load testing – at all conceivable temperatures. Yet there is indeed a prime candidate for this job: the KUKA KR 210-2 robot. This robot has already taken up its first position at Volvo in Sweden. Volvo has been testing the durability of car seats for a long time now. Car seats were previously tested using a pneumatic seat tester. This system, however, could only place a two-dimensional load on the seats. It merely carried out either horizontal or vertical motions. Volvo went looking for a flexible system in which all conceivable climatic conditions and the full range of motions of a vehicle occupant could be simulated. Implementation / Solution The manufacturer’s high quality standards led to the company investing in a state-of-the- art system that allowed it not only to subject the seats to extreme climatic conditions, but also to provide authentic simulation of the motions of a wide range of different vehicle occupants. A KUKA robot fitted with a special protective suit and located in a climatic chamber imitates the motions of a human driver, thereby testing the durability of the seats. The KR 210-2 works day and night at varying temperatures. Five seats are set up around the robot in the climatic chamber. The robot executes the preprogrammed motions in sequence, holding a padded dummy shaped to mimic the human from.
  29. 29. 22 System components / Scope of supply Force/torque sensors enable it to reproduce human movements. It can be flexibly programmed and has a high degree of repeatability. The measuring system provides six measurement dimensions for forces and torques and ensures absolute accuracy. This provides the user with data about the actual forces being exerted on the contact surface between the dummy and the seat. The robot motions are also regularly adjusted in relation to the wear on the test object. To adapt the overall system to a new seat, it is merely necessary to redefine the base coordinate system. The robot and climatic chamber are controlled externally from a main computer. The robot is contained in its own climatic unit, being clothed in a fabric suit. Cool air is blown in at three points. The temperature around the robot is thus maintained at a constant 20 °C. Results / Success The robot treats all seats equally. It is also flexibly programmable. It is therefore possible to subject all test objects to the same loading. A standard program is generally executed. If, however, a new seat is introduced part way through a test series, the robot notes the arrival of this “newcomer” and knows exactly which test cycles are still required for this seat. A test phase can last up to ten weeks. This yields results for five seat types. With the old test system, it took four weeks to test just a single seat.
  30. 30. 23 CHAPTER 6 A.C. SERVO MOTOR 6.1 WHAT IS A SERVO? This is not easily defined nor self-explanatory since a servomechanism, or servo drive, does not apply to any particular device. It is a term which applies to a function or a task. The function, or task, of a servo can be described as follows. A command signal which is issued from the user's interface panel comes into the servo's "positioning controller". The positioning controllers the device which stores information about various jobs or tasks. It has been programmed to activate the motor/load, i.e. change speed/position. The signal then passes into the servo control or "amplifier" section. The servo control takes this low power level signal and increases, or amplifies the power up to appropriate levels to actually result in movement of the servo motor/load. These low power level signals must be amplified: Higher voltage levels are needed to rotate the servo motor at appropriate higher speeds and higher current levels are required to provide torque to move heavier loads. This power is supplied to the servo control (amplifier) from the "power supply" which simply converts sac power into the required DC level. It also supplies any low level voltage required for operation of integrated circuits. As power is applied onto the servo motor, the load begins to move . . . speed and position changes. As the load moves, so does some other "device" move. This other "device" is a tachometer, resolver or encoder (providing a signal which is "sent back" to the controller). This "feedback" signal is informing the positioning controller whether the motor is doing the proper job. The positioning controller looks at this feedback signal and determines if the load is being moved properly by the servo motor; and, if not, then the controller makes appropriate corrections. For example, assume the command signal was to drive the load at 1000 rpm. For some reason it is actually rotating at 900 rpm. The feedback signal will inform the controller that the speed is 900rpm. The controller then compares the command signal (desired speed) of 1000 rpm and the feedback signal (actual speed) of 900 rpm and notes an error. The controller then outputs a signal to apply more voltage onto the servo motor to increase speed until the feedback signal equals the command signal, i.e. there is no error. Therefore, a servo involves several devices. It is a system of devices for controlling some item (load). The item (load) which is controlled (regulated) can
  31. 31. 24 be controlled in any manner, i.e. position, direction, speed. The speed or position is controlled in relation to reference (command signal), as long as the proper feedback device (error detection device) is used. The feedback and command signals are compared, and the corrections made. Thus, the definition of a servo system is, that it consists of several devices which control or regulate speed/position of a load. 6.2 Types of Servo Motors There are two types of servo motors--AC and DC. AC servos can handle higher current surges and tend to be used in industrial machinery. DC servos are not designed for high current surges. Generally speaking, DC motors are less expensive than their AC counterparts. 6.3 Principle of operation of A.C. Servo Motor AC Motors are the first choice for constant speed applications and where large starting torque is not required. They are available in three or single phase. The smaller motors are for household applications and they are made for single phase operation. For industrial application, AC motors are available from a fraction to a hundred horse power output. The principle of operation is that the rotor is made of laminated steel. And bars of conducting material such as aluminum and copper are buried in the motor which are short circuited at both ends. The stator is made of laminated steel with properly designed slots. In the slots a well designed number of windings is located which is connected to the power supply. The power supply generates a rotating magnetic field. When the motor is connected to the power supply, a voltage is induced in the bars located in the rotor which causes a current flow through them. As a result of the current, an electromotive torque is developed which accelerates the motor. As the speed increases the induced voltage reduces because the rotor approaches the synchronous speed. At the synchronous speed, the torque becomes zero. Therefore, AC motors always rotate at a speed lower than the synchronous speed. The synchronous speed is determined by the frequency of the power supply and number of poles in the stator.
  32. 32. 25 6.4 Working of A.C. Servo Motor A servo motor operates on the principal of "proportional control." This means the motor will only run as hard as necessary to accomplish the task at hand. If the shaft needs to turn a great deal, the motor will run at full speed. If the movement is small, the motor will run more slowly. A control wire sends coded signals to the shaft using "pulse coded modulation." With pulse-coded modulation, the shaft knows to move to achieve a certain angle, based on the duration of the pulse sent via the control wire. A 1.5 millisecond pulse will make the motor turn to the 90-degree position. Shorter than 1.5 moves it to 0 degrees, and longer will turn it to 180 degrees. 6.5 Applications of A.C. Servo Motor 6.5.1 Commercial Application A.C. Servo Motors for Toy Enthusiasts A.C. Servo motors can be found in radio-controlled toy cars. Servos are used in radio-controlled airplanes to position the rudders, in radio- controlled cars to move the wheels and in other remote-controlled toys like puppets. 6.5.2 Industrial Application In food services and pharmaceuticals, the tools are designed to be used in harsher environments, where the potential for corrosion is high due to being washed at high pressures and temperatures repeatedly to maintain strict hygiene standards.
  33. 33. 26 CHAPTER 7 PROGRAMMING OF KUKA ROBOT 7.1 Motion Programming 1) Axis-specific motions * PTP (point-to-point): The tool is moved along the quickest path to an end point. 2) Path-related motions * LIN (Linear): The tool is guided at a defined velocity along a straight line. * CIRC (Circular): The tool is guided at a defined velocity along a circular path. 7.1.1 PTP – Motion 7.2 BCO Run 7.2.1 Part 1 For the purpose of ensuring that the robot position corresponds to the coordinates of the current program point, a so called BCO run (Block Coincidence) is executed. This is carried out at reduced velocity. The robot is moved to the coordinates of the motion block in which the block pointer is situated. 7.2.2 Part 2 This is done : After a program reset by means of a BCO run to the home position After block selection to the coordinates of the point at which the block pointer is situated PTP CONT Vel = 100 % PDAT2
  34. 34. 27 After selection of the “CELL” program before the Automatic External Mode can be started. After a new program has been selected After jogging in programming mode After modifying a command NOTE: A HOME run is recommended for both the first and final motions as this represents an unambiguously defined uncritical position. 7.2.3 Part 3 1. This is done by holding down the Start key after selecting the program. 2. The robot moves automatically at reduced velocity 3. Once the robot has reached the programmed path, the program can be continued by pressing the Start key again. NOTE: A BCO run always take place by the direct route from the current position to the destination position. It is therefore important to make sure that there are no obstacles on this path in order to avoid damage to components, tools or the robot! CAUTION: No BCO run is carried out in Automatic External Mode! 7.3 LIN (Linear) – Motion The TCP is moved along a straight line to the end point. 7.3.1 Programming a LIN motion LIN CONT Vel = 2 m/s PDAT2P1
  35. 35. 28 7.3.2 Orientation Control Standard – During the path motion, the orientation of the tool changes continuously from the start position to the end position. This is achieved by rotating and pivoting the tool direction. Wrist PTP – During the path motion, the orientation of the tool changes continuously from the start position to the end position. This is done by linear transformation (axis- specific motion) of the wrist angles. The problem of the wrist singularities can be avoided using thisoption as there is no orientation control by rotating and pivoting he tool direction. Constant – The orientation remains constant during the CP motion. he programmed orientation is disregarded for the end point and that of the start point is used. 7.4 CIRC (Circular) – Motion The TCP is moved along an arc to the end point. Here, the TCP or workpiece reference point moves to the end point along an arc. The path is defined using start, auxiliary and end points. The end point of a motion instruction serves as the start point for the subsequent motion. NOTE: The orientation of the TCP is not taken into consideration at the auxiliary point and is not relevant for the teaching of coordinates. 7.4.1 Programming a CIRC motion P1 CONT Vel. = 2 m/sCIRC CPDAT1
  36. 36. 29 7.4.2 Orientation Control Standard – During the path motion, the orientation of the tool changes continuously from the start position to the end position. This is achieved by rotating and pivoting the tool direction. Wrist PTP – During the path motion, the orientation of the tool changes continuously from the start position to the end position. This is done by linear transformation (axis- specific motion) of the wrist angles. The problem of the wrist singularities can be avoided using this option as there is no orientation control by rotating and pivoting the tool direction. Constant – The orientation remains constant during the CP motion. The programmed orientation is disregarded for the end point and that of the start point is used. 7.4.3 360 degree full circle The full circle should be made of at least two segments. INI PTP HOME .... LINE P1 LINE P2 CIRC P3 P4; P3 is AUX; P4 is END CIRC P3 P2; P5 is AUX; P2 is END LIN P1 .... PTP HOME END
  37. 37. 30 7.5 Approximation of a motion During approximate positioning, the robot does not move exactly to each programmed position, nor is it broken completely. ADVANTAGE: Reduce wear Improved cycle times 7.5.1 PTP motion with approximate positioning The value of “Approximation distance” specifies the size of the approximate positioning range. The page cannot be set, nor is it predictable. 7.5.2 LIN & CIRC motion with approximate positioning The value entered for “Approximation distance” specifies the distance from the end point and the point at which the approximation motion commences. The result path is note an arc. The same applies to the following CIRC command.
  38. 38. 31 REFERENCES 1. SEMINAR WORKBOOK OF BASIC ROBOT PROGRAMMING for KUKA System Software V5.x PROGRAMMER 2. SEMINAR WORKBOOK OF ADVANCED ROBOT PROGRAMMING for KUKA System Software V5.x PROGRAMMER 3. www.wikipedia.com 4. www.kuka.com 5. www.kuka-robotics.com

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