Mitsubishi MELSEC-F Training Manual
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Mitsubishi MELSEC-F Training Manual

Mitsubishi MELSEC-F Training Manual

Positioning control
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Positioning Control
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  • Page 1 Positioning Control Training Manual...
  • Page 2 Positioning Control Cautions on Safety Make sure to read the manuals and pay careful attention to safety when designing a system. In practice, pay attention to the following contents and handle any products or demonstration units correctly. Cautions on practice DANGER •...
  • Page 3 Positioning Control Positioning Control Manual number : JY992D89901 Manual revision : A Date : July 2000...
  • Page 4 Positioning Control...
  • Page 5 Positioning Control FAX BACK Mitsubishi has a world wide reputation for its efforts in continually developing and pushing back the frontiers of industrial automation. What is sometimes overlooked by the user is the care and attention to detail that is taken with the documentation. However,to continue this process of improvement, the comments of the Mitsubishi users are always welcomed.
  • Page 6 Positioning Control...
  • Page 7 Introduction This manual describes basic operation for those who learn positioning control for the first time, the aim being so that they can get training using demonstration units of Mitsubishi FA equipment. The following relevant manuals are available and should be referred to...
  • Page 8 Positioning Control...

  • Page 9: Table Of Contents

    Positioning Control Contents 1. The World of Positioning Control............1-1 1.1 Welcome to the new world! ................. 1-1 1.2 Diversified actuators .................... 1-2 1.3 Positioning method type ..................1-4 2. Positioning by AC Servo System............2-1 2.1 When an AC servo system is introduced............. 2-1 2.2 Examples of AC servo systems ................
  • Page 10 Positioning Control Contents viii...
  • Page 11 Positioning Control The World of Positioning Control 1 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 13: Welcome To The New World

    Positioning Control The World of Positioning Control 1 The World of Positioning Control Welcome to the new world! The positioning controller, together with the programmable controller, personal computer and operator interface, is one of the four main units of FA (factory automation). Among them, the positioning controller is important as the basis of FA, and regarded as the center of the mechatronics field in which many senior engineers have been playing active parts.

  • Page 14: Diversified Actuators

    Positioning Control The World of Positioning Control 1 Diversified actuators • A power source which moves an element in a system is called actuator. A unit which detects a position of a work piece or moving part is called sensor. •...
  • Page 15 Positioning Control The World of Positioning Control 1 Stepping motor • Positioning mechanism is simple. • If load is heavy, motor may step out and displacement can occur. • Motor capacity is small. • Precision is poor at high speed. DC servo system •...

  • Page 16: Positioning Method Type

    Positioning Control The World of Positioning Control 1 Positioning method type 1) There are three types of positioning method Control method Description Schematic drawing Two limit switches are provided in places where a Moving part systems moving part Ball screw passes.
  • Page 17 Positioning Control The World of Positioning Control 1 2) Positioning method and stop precision < Limit switch method > Velocity - When automatically stopping a moving part driven by a motor, stop the motor by a position signal, detected by a limit switch Coasting distance (in general conditions, turn on the brake at...
  • Page 18 Positioning Control The World of Positioning Control 1 < Pulse count method > - When a pulse encoder is attached to a moving part, and the motor speed is controlled by a number steps while the pulse number is counted, the movement quantity per pulse is determined in accordance with the relationship between the pulse number generated by one rotation of the encoder, and the movement quantity of the moving part (workpiece) realized by one rotation of the motor.

  • Page 19: Positioning By Ac Servo System

    Positioning Control Positioning by AC Servo System 2 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 21: When An Ac Servo System Is Introduced

    Positioning Control Positioning by AC Servo System 2 Positioning by AC Servo System When an AC servo system is introduced • Positioning can be performed by many diversified methods. Recently, AC servo methods which offer many advantages are often introduced. •...
  • Page 22 Positioning Control Positioning by AC Servo System 2 In the latest AC servo systems, conventional weak points have been improved as follows. - Though the latest systems are completely digital, they are equipped with parameters in conformance to diversified mechanical specifications and electrical specifications so that simple setting is possible.

  • Page 23: Examples Of Ac Servo Systems

    Positioning Control Positioning by AC Servo System 2 Examples of AC servo systems • Positioning indicates the operation to move an element, such as a workpiece or tool (drill or cutter) from a certain position (point) to another target position (point) and stop it with high efficiency and high precision.
  • Page 24 Positioning Control Positioning by AC Servo System 2 Index table The position of the circular table is indexed. The index position is set on the outside (digital switch) or the inside (program). Shortcut drive is performed depending on the index position. Lifter moving-up/down As negative load is applied on the servo motor in positioning of the lifter in the...

  • Page 25: Components Of Positioning Control And Their Roles

    Positioning Control Components of Positioning Control and Their Roles 3 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...
  • Page 27 Positioning Control Components of Positioning Control and Their Roles 3 Components of Positioning Control and Their Roles Positioning control requires a number of components such as a positioning controller, servo amplifier, servo motor and drive mechanism. This section describes the role of each component.
  • Page 28 Positioning Control Components of Positioning Control and Their Roles 3 AC power Position controller supply • Outputs the positioning speed and the movement quantity in command pulses to the servo amplifier. • Transfers signals between the programmable controller. • Controls return to the zero point. Power board •...
  • Page 29 Positioning Control Components of Positioning Control and Their Roles 3 Servo motor • Dedicated to high speed response optimal to positioning control, has large start torque, large maximum torque and wide variable speed range 1/1 or more (1/1,000 to 1/5,000). When a moving element goes beyond a limit switch (LS), the motor stops.

  • Page 30: Positioning Controller

    Positioning Control Components of Positioning Control and Their Roles 3 Positioning controller As the positioning controller gives position commands to the servo amplifier, positioning programs should be created, and parameters defined. The contents related to programs and parameters are described below. 3.1.1 Command pulse and feed quantity There are the following three types of command pulse output modes.

  • Page 31: Setting The Acceleration/Deceleration Time

    Positioning Control Components of Positioning Control and Their Roles 3 3.1.3 Setting the acceleration/deceleration time • When the start command is given, acceleration, operation at constant speed and deceleration are performed for positioning. Set the acceleration time and the deceleration time in the parameters.

  • Page 32: Zero Point Return Function

    Positioning Control Components of Positioning Control and Their Roles 3 3.1.5 Zero point return function • There are two types of servo motor encoders, incremental type (pulse count method) and absolute type (absolute position detection method). • Incremental type is constructed so that the current value stored in the position controller does not increase or decrease, even if the workpiece stop position changes by some reason while the power is turned off, therefore the positioning address is not assured.

  • Page 33: Servo Amplifier And Servo Motor

    Positioning Control Components of Positioning Control and Their Roles 3 Servo amplifier and servo motor The servo amplifier controls the movement quantity and the speed in accordance with commands given by the positioning controller. The servo motor transmits rotation to the drive mechanism after receiving a signal from the servo amplifier.

  • Page 34: Regenerative Brake Function

    Positioning Control Components of Positioning Control and Their Roles 3 3.2.4 Regenerative brake function • During deceleration, because the servo motor rotates by the load inertia of the drive mechanism, it functions as a generator and electric power returns to the servo amplifier. The regenerative resistor absorbs this electric power, and functions as a brake (called a regenerative brake.) •...

  • Page 35: Drive Mechanism

    Positioning Control Components of Positioning Control and Their Roles 3 Drive mechanism The drive mechanism converts the rotation motion of the servo motor into the reciprocating or vertical motion through a speed reducer, timing belt, ball screw, etc. to move the machine. 3.3.1 Concept of drive system movement quantity 1) Representative positioning system using AC servo motor...
  • Page 36 Positioning Control Components of Positioning Control and Their Roles 3 2) Examples of calculation equations a) Movement quantity per rotation of motor (mm/rev) Movement × quantity per Lead of ball screw (mm/rev) Speed reduction ratio rotation of motor b) Number of rotations of motor (rev/min.) (The maximum number of rotations is realized during quick feed.) Number of Rated number of...

  • Page 37: Setting The Target Position

    Positioning Control Components of Positioning Control and Their Roles 3 3.3.2 Setting the target position In positioning control, the target position can be set by the following two methods. (Available command units are "mm", "inch", "degree" or "pulse".) 1) Absolute method In this method, a point (absolute address) is specified for positioning while the zero point is regarded as the reference.
  • Page 38 Positioning Control Components of Positioning Control and Their Roles 3 3-12...
  • Page 39 Positioning Control Advanced Positioning 4 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 41: Advanced Positioning

    Positioning Control Advanced Positioning 4 Advanced Positioning Interpolation control The interpolation function controls two or more axes alternately or simultaneously. Linear interpolation and circular interpolation are usually offered. < Linear interpolation > < 2-axis linear interpolation > End point - Linear interpolation controls two or more axes so that the start point and axis the end point (target position) are...
  • Page 42 Positioning Control Advanced Positioning 4 < Circular interpolation > < Circular interpolation when an auxiliary point is specified > - Circular interpolation controls two or Auxiliary End point more axes so that the start point and line axis the end point (target position) are connected with circular arc.

  • Page 43: Other Controls

    Positioning Control Advanced Positioning 4 Other controls In some models, controls in accordance with diversified special needs such as speed control, position follow-up control and three-dimensional interpolation control shown below are available. < Speed control > - After movement starts from the start p o i n t , i t t h e n c o n t i n u e s a t t h e s p e c i f i e d s p e e d u n t i l t h e s t o p Start point...
  • Page 44 Positioning Control Advanced Positioning 4 < Speed changeover control > Y axis - From the start point which is the mm/min point current stop address, positioning 5000 mm/min control is performed to the end point 1000 address while the speed changes at mm/min speed changeover points.
  • Page 45 Positioning Control Advanced Positioning 4 < Position follow-up control > Y axis - If the end point address is changed while a positioning control movement is being executed, positioning is Change Original c o n t r o ll e d t o t h e n e w e n d p o in t point end point address.
  • Page 46 Positioning Control Advanced Positioning 4...
  • Page 47 Positioning Control Actual Positioning 5 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 49: Actual Positioning

    The demonstration items required for the basic setup are as follows; -20GM F2-422 CAB0 Communications cable FX-232AW(C) Converter FX-232 CAB-1 Communications cable Personal computer FX-PCS-VPS\Win software FX-422CAB0 FX-232AW(C) F2-232CAB-1 MITSUBISHI POWER AUTO READY MELSEC FX -10GM START ERROR STOP CPU-E...

  • Page 50: Operation Of The Demonstration Equipment

    Positioning Control Actual Positioning 5 Operation of the demonstration equipment Source the required demonstration equipment, and setup as in section 5.1. If a plotter is being used refer to the operations manual for the particular unit and setup accordingly. Throughout this example it is assumed that you will have read and understood both the FX 20GM Hardware / Programming manual (JY992D77801) and the FX-PCS-VPS/Win-E softtware manual (JY992D86801) or you will have then close at hand for reference.

  • Page 51: Program Example

    Positioning Control Actual Positioning 5 5.2.1 Program example The program below demonstrates basic positioning using the FX -20GM. As this program is designed to be used without a mechanical plotter, the electrical zero point is used for reference. Many programs can be stored in a GM unit at one time.

  • Page 52: Writing The Program

    Positioning Control Actual Positioning 5 5.2.2 Writing the program Using FX-PCS-VPS\Win-E, re-create the flow chart program shown in section 5.2.1. If assistance is required in the operation of the software, please refer to the Software manual JY992D86801. When opening a new file in VPS, choose ‘FX(2N)/E-20GM with simultaneous 2 axis’ The example program is designed to utilize the real time monitor function of VPS software.

  • Page 53: Parameters

    Positioning Control Actual Positioning 5 5.2.3 Parameters In addition to the preparation of a positioning program, diversified parameters should be set in the FX -20GM. In this example, only a few parameters need be set. If a plotting table is used, the parameters should be set in accordance with its mechanism.
  • Page 54 Positioning Control Actual Positioning 5 As we will not be connecting any mechanical hardware to the FX2N-20GM, the limit switch and DOG switch settings do not require setting. We do how ever need to reduce the Creep speed and the Zero return speed. All of the parameter settings on this screen window can be left as their default values, they are already optimized for our program.

  • Page 55: Operation

    Positioning Control Actual Positioning 5 5.2.4 Operation Now that your program has been written, check the communication cables between the FX 20GM and PC, then download your program to the FX -20GM. Make sure that the GM unit is in ‘MANU’ mode before download, or it will be impossible to communicate. In VPS, start the Monitor mode by clicking the Monitor icon on the tool bar, shown below.
  • Page 56 Positioning Control Actual Positioning 5 The next step, it to switch the FX -20GM to ‘AUTO’ mode, so that the program can be executed. Finally, on the Monitor screen click on either the X or Y axis start buttons. It does not matter which one, as both will start the program.
  • Page 57 Positioning Control Product Line up 6 The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 59: Product Line Up

    Positioning Control Product Line up 6 Product Line up We are offering diversified position controllers, servo amplifiers and servo motors. You can select desired units in accordance with your system and application. For the derails, refer to the catalog of each product. Position controller 1) Outline of position controller models In the position controller, the positioning function is built in or extended.
  • Page 60 Positioning Control Product Line up 6 Model name/ Positioning language Outline unit name A171UHCPU (512 I/O points): 4-axis control Language dedicated to servo system A172SHCPU (512 I/O points): [4-, 32-axis independent control, 2- to 4- 8-axis control axis linear interpolation control, 2-axis cir- A171SH A173UHCPU (2,048 I/O cular interpolation control, speed control,...
  • Page 61 Positioning Control Product Line up 6 1) When and which position controller? In addition to the PLC series, take into account the following contents to determine the position controller to be used. a) Determine the position controller to be used in accordance with the number of controlled axes (motors).
  • Page 62 Positioning Control Product Line up 6 b) Determine the position controller to be used in accordance with the output pulse frequency. However, the pulse frequency actually used inside the servo amplifier can be increased by electronic gearing. 100kp/sec When the required command pulse is 100 kpps or less -1PG, FX Series PLC 200kp/sec...

  • Page 63: Servo Amplifier

    Positioning Control Product Line up 6 Servo amplifier 1) Outline of serve amplifier models Model name Outline • DC 24V • Size is extremely small, and capacity is small. MR-J2-Jr Series • Applicable to 10 to 30 w. • Used for semiconductor manufacturing unit and small robots. •...
  • Page 64 Positioning Control Product Line up 6 2) When and which servo amplifier? In addition to the series, take into account the following contents to determine the servo amplifier to be used. a) Determine the servo amplifier to be used in accordance with the rated output of the servo motor.

  • Page 65: Servo Motor

    Positioning Control Product Line up 6 Servo motor Servo motors are classified into series in accordance with the application, the outside dimensions and the motor inertia moment. In each series, models of different output capacity are lined up. Motor model Rated Rated name...
  • Page 66 Positioning Control Product Line up 6 Motor model Rated Rated name rotation output Features Application (encoder speed capacity resolution) (r/min.) Low inertia and medium capacity (compatible with speed HC-RF reducer). • Frequent carrier unit (16384P/rev) 3000 1kW to 5kW Optimal to frequent operation •...
  • Page 67 Positioning Control Tentative Selection of Motor Capacity A The World of Positioning Control Positioning by AC Servo System Components of Positioning Control and Their Roles Advanced Positioning Actual Positioning Product Line up Appendix A: Tentative Selection of Motor Capacity...

  • Page 69: A-1: Tentative Selection Of Motor Capacity

    Positioning Control Appendix A: A-1: Tentative Selection of Motor Capacity Temporarily select the motor capacity at first while taking into account the following two points, and determine the model. • The rated torque of the motor should be larger than the effective torque. •...

  • Page 70: A-1-1: Motor Effective Torque

    Positioning Control A-1-1: Motor effective torque When the motor effective torque obtained by the calculation below does not exceed the rated torque (100%) of the servo motor specifications, it is suitable. If the obtained effective torque exceeds 100%, increase the motor capacity and perform the calculation again.
  • Page 71 Positioning Control 2) The torque during constant speed is the torque required to move the load at the constant speed. Motor torque during constant speed = Load torque 3) The torque during deceleration is the torque required for deceleration and stop. Torque during deceleration = Torque to decelerate load inertia moment + Load torque 4) How to obtain the cycle time The representative machine operation pattern consists of acceleration, constant speed,...

  • Page 72: A-1-2: Load Inertia Moment

    Positioning Control 5) Machine load torque (TL) The rotation force required to move or cut an object is called load torque. During operation at constant speed, the motor is outputting the torque balancing this load torque. • The calculation equation to obtain the load torque varies depending on the motion type (horizontal, rotation or vertical).
  • Page 73 Under no circumstances will Mitsubishi Electric be liable or responsible for any consequential damage that may arise as a result of the installation, use and/or programming of the products associated with this manual. All examples and diagrams shown in this manual are intended as an aid to understanding the text, not to guarantee operation.
  • Page 74 HEAD OFFICE: MITSUBISHI DENKI BLDG MARUNOUCHI TOKYO 100-8310 TELEX: J24532 CABLE MELCO TOKYO HIMEJI WORKS: 840, CHIYODA CHO, HIMEJI, JAPAN Effective July. 2000 Specifications are subject JY992D89901A to change without notice. (MEE0007)

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