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feedback MS150 Getting Started

Modular servo workshop
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  • Page 2 MS150 Modular Servo Workshop Getting Started 33-008-1M5 Feedback Feedback Instruments Ltd, Park Road, Crowborough, E. Sussex, TN6 2QR, UK. Telephone: +44 (0) 1892 653322, Fax: +44 (0) 1892 663719. email: feedback@fdbk.co.uk World Wide Web Homepage: http://www.fbk.com Manual: 33-008-1M5 Ed02 991116 Printed in England by Fl Ltd, Crowborough Feedback Part No.
  • Page 3 Notes...
  • Page 4 While we provide the fullest possible user information relating to the proper use of this equipment, if there is any doubt whatsoever about any aspect, the user should contact the Product Safety Officer at Feedback Instruments Limited, Crowborough. This equipment should not be used by inexperienced users unless they are under supervision.
  • Page 5 Should this equipment be used outside the classroom, laboratory study area or similar such place for which it is designed and sold then Feedback Instruments Ltd hereby states that conformity with the protection requirements of the European Community Electromagnetic Compatibility Directive (89/336/EEC) may be invalidated and could lead to prosecution.

  • Page 6: Table Of Contents

    3.3. Stopping procedure MENU DESCRIPTION 4.1. Tools 4.2. Design and identification 4.3. Models and experiments 4-16 FIRST EXAMPLES 5.1. Example 1. Closed-loop control system with state feedback gains 5.2. Example 2. Ziegler-Nichols method for designing PID controller 33-008-1M5 TOC 1...
  • Page 7 MODULAR SERVO Contents Getting Started CONNECTING THE PC AND THE SERVO 6.1. PCL-812PG acquisition board: 6.2. Switch settings - 16 bit board 6.3. Jumper Settings 6.4. Switch SW1 settings for 8 bit full length PCL - 812 board 6.5. Installation of PCL-812 Board TOC 2 33-008-1M5...

  • Page 8: Introduction And Description

    INTRODUCTION AND DESCRIPTION The Modular Servo Workshop (MSW) is an open-architecture software environment for real-time control experiments using the Feedback © digital servomechanism. The main concept of the Modular Servo Workshop was to create a rapid and direct path from control system design to hardware implementation.

  • Page 9: Knowledge Level Required

    Getting Started 1.1.1. Knowledge Level Required The manual assumes that the user has a basic experience with one of the Feedback digital servomechanisms, with MATLAB 5 & Simulink from MathWorks Inc, and with the Microsoft Windows 95 or NT operating System. More experience in control is required for experiments described in the ADVANCED TEACHING manual.

  • Page 10: Principal System Interconnections And Software Operation

    CHAPTER 1 MODULAR SERVO Getting Started Introduction and Description 1.2. Principal system interconnections and software operation The control system applied for the servomechanism is given in a block diagram form in Figure 1-1. auxiliary clock internal excitation source DC motor controller external excitation...
  • Page 11 The Modular Servo Toolbox , using MATLAB matrix functions, provides the functions specialised for real-time control of the Feedback digital servomechanism. It is the general assumption that the toolbox is an open system. This approach by its nature forces the basic functions of the toolbox to be in the user domain.
  • Page 12 CHAPTER 1 MODULAR SERVO Getting Started Introduction and Description The collection of the toolbox functions can divided into two main categories: • Real-Time Kernel communication functions, • Real-Time Kernel configuration functions. The toolbox functions and MATLAB functions can be used at different application levels. In this manual the following convention is used: •...
  • Page 13 CHAPTER 1 MODULAR SERVO Introduction Getting Started Notes 33-008-1M5...

  • Page 14: Model And Control Algorithms

    CHAPTER 2 MODULAR SERVO Getting Started Model And Control Algorithms MODEL AND CONTROL ALGORITHMS In this section a brief review of the embedded control algorithms is given. For a detailed description of control algorithms refer to the Advanced Teaching Manual ( 33-008-4M5 ). The design process for the controllers listed below was performed assuming a linear model of the DC motor in the form of two first-order linear differential equations.

  • Page 15: Pid Control

    K 1 ,K 2 are controller gains. The LQ optimal feedback gain vector K = [K ] can be calculated in such a way that the feedback law u = -K ε ; where ε = [ ε , ε ] minimises the cost function: ∞...

  • Page 16: Time - Optimal Control

    MODULAR SERVO Getting Started Model And Control Algorithms Another selection of state-feedback gains is based on 'dead-beat' principle. The feedback gain vector K = [K ] is calculated in such a way that eigenvalues of the state matrix of the discrete closed-loop system are equal to zero:...
  • Page 17 CHAPTER 2 MODULAR SERVO Model And Control Algorithms Getting Started Notes 33-008-1M5...

  • Page 18: Starting , Testing And Stopping Procedures

    Perform all connections as described in Section 6 of this manual. They will ensure correct communications between Computer – Advantech PCL812PG i/o board – 33-301 Analogue Interface unit and the rest of modular servo MS150 units. Ensure that the Attenuator Unit AU150B has the top gain-pot set to a value around 8 and the Pre-Amplifier Unit PA 150C has the pot to ‘zero set’.

  • Page 19: Testing And Troubleshooting

    CHAPTER 3 MODULAR SERVO Starting, Testing and Stopping Procedures Getting Started • double click on the Set base address button. This set the base address of the i/o card. • If the address of your data acquisition board agrees with the default value then accept it, otherwise type the proper address.
  • Page 20 CHAPTER 3 MODULAR SERVO Getting Started Starting, Testing and Stopping Procedures Figure 3-2: Basic test window • set the position of the OP150K manually to 70 degrees anticlockwise. If this is not set to 70 degrees, the Basic Test program will not provide results similar to the ones shown in Fig.
  • Page 21 Free some memory in your Windows system (e.g. close unused applications) Cannot open es_par.ini file. Create the file named es_par.ini . using the Base address is set to zero. Windows Notepad program or copy this file from the CD-ROM into your MATLAB\FEEDBACK subdirectory. 33-008-1M5...

  • Page 22: Stopping Procedure

    CHAPTER 3 MODULAR SERVO Getting Started Starting, Testing and Stopping Procedures 3.3. Stopping procedure Any practical can be stopped at any time. Double click the Stop Practical button in the Main Control Window . If you wish to interrupt the visualisation process for any time click once on the Pause item in the Simulation menu (located on the top menu bar of the screen) 33-008-1M5...
  • Page 23 CHAPTER 3 MODULAR SERVO Starting, Testing and Stopping Procedures Getting Started Notes 33-008-1M5...

  • Page 24: Menu Description

    CHAPTER 4 MODULAR SERVO Getting Started Menu Description MENU DESCRIPTION The Main Control Window shown in Figure 3-1 contains three groups of menu buttons: • TOOLS • DESIGN & IDENTIFICATION • MODELS & EXPERIMENTS Generally, the Main Control Window was developed for application level 2. However, some of the windows activated by buttons from the TOOLS group can support the experiments performed from application level 1, e.g.
  • Page 25 CHAPTER 4 MODULAR SERVO Menu Description Getting Started Using this tool you can collect and plot real-time data. This tool allows you to: • set sample time, • read contents of the data acquisition buffer, • clear buffer and collect data for 10 seconds, •...
  • Page 26 CHAPTER 4 MODULAR SERVO Getting Started Menu Description The reason for not being able to monitor the plant while the simulation is running from Simulink is that the display and data transfer conflict between the two applications, However the real-time control is still running when the display process is paused. 4) Stop practical - stops the actual control task, 5) Reset Encoder - sets encoder to zero for actual position of the servo, 6) Calibration of 33-301 –...
  • Page 27 CHAPTER 4 MODULAR SERVO Menu Description Getting Started Table 4.1 Item Description Signal source or sink voltage of the signal connected to the analogue input 150K output channel A/D1 of the Analogue Control Interface expressed pot. in [V] voltage of the signal connected to the analogue input 150X Tacho channel A/D2 of the Analogue Control Interface expressed in [V]...
  • Page 28 CHAPTER 4 MODULAR SERVO Getting Started Menu Description In the example shown in Figure 4-2 the data source is defined as follows: Channel 1- angle expressed in [deg] - signal connected to the A/D1 input channel of the Analogue Control Interface, Channel 2 - angle expressed in [deg] measured from the incremental encoder sensor, Channel 3 - angular velocity from tachogenerator connected to the A/D2 input channel of the Analogue Control Interface expressed in [deg/sec],...
  • Page 29 CHAPTER 4 MODULAR SERVO Menu Description Getting Started If an arbitrary algorithm is running and this window is then opened, then the algorithm is marked (the black dot) with the current active values of parameters. If none of algorithms are running then the UNRECOGNISED button is marked without any visible parameters. You can select the type of the algorithm by clicking the PID, LQ or Time optimal radio- button.
  • Page 30 CHAPTER 4 MODULAR SERVO Getting Started Menu Description 9) Set parameters of internal excitation source - opens the window to set the shape and parameters of the signals from the internal excitation generator (Figure 4-4). Figure 4-4: Set parameters of internal excitation source window Here you can set parameters of the internal excitation source.
  • Page 31 CHAPTER 4 MODULAR SERVO Menu Description Getting Started The signals generated by the internal excitation source are interpreted as a control input if the system is in the open-loop mode, or as a reference signal if the system is in the closed-loop mode.

  • Page 32: Design And Identification

    CHAPTER 4 MODULAR SERVO Getting Started Menu Description 4.2. Design and identification The respective buttons in the group DESIGN & IDENTIFICATION of the Main Control Window perform the following tasks: 1) Static characteristic of the DC motor - performs an experiment to measure the static characteristic of the DC motor ( rotation vs.
  • Page 33 CHAPTER 4 MODULAR SERVO Menu Description Getting Started The Message Window in the bottom gives you auxiliary messages. Figure 4-6 shows an example of measured characteristics. 2) Time domain identification - opens the window to start identification on the base of a step system response (Figure 4-7).
  • Page 34 CHAPTER 4 MODULAR SERVO Getting Started Menu Description V2Vel identification starts experiment of V2Velocity coefficient identification [see the Reference Manual – 33-008-2M5], Simulation starts simulation for fixed K and T Surface Method fits a smooth function of two variables to the real response and calculates the optimum K and T Save data...
  • Page 35 4) Closed-loop system design and simulation - opens the window shown in Figure 4-9. This simulation window allows you to display step response of the linear, closed-loop system with feedback gains from position and velocity. You can design parameters for discrete or continuous LQ and "deadbeat" controllers.
  • Page 36 - model gain, Time constant Ts - model time constant, Sampling time T0 - setting of the sampling time for discrete version calculations, K1, K2 - position and velocity feedback gains, Reference input -reference step input, Discrete or Continuous - start simulation in discrete or continuous mode,...
  • Page 37 Menu Description Getting Started LQ controller design (discrete mode) Clicking the LQ continuous or LQ discrete button calculates the optimal feedback gain matrix K such that the feedback law u = -Kx minimises the cost function (discrete case): ∑ J(u) (n)Qx(n)
  • Page 38 CHAPTER 4 MODULAR SERVO Getting Started Menu Description 5) Ziegler Nichols method - opens the window for PID controller design (Figure 4-10). Figure 4-10: Ziegler - Nichols method window This window allows the calculation of the transfer function of the open-loop system step response using second order curve fitting.

  • Page 39: Models And Experiments

    3) State feedback closed-loop system opens the Simulink model to start real time experiments for a closed-loop system with state feedback. This model can be used for experiments with LQ or deadbeat controllers, 4) Time optimal opens the Simulink model to start real time experiments for a closed-loop system with time optimal controller.
  • Page 40 CHAPTER 4 MODULAR SERVO Getting Started Menu Description Figure 4-11: PID controller window After double clicking the Real Time Task block you can set the following parameters (Figure 4-12): Figure 4-12: Real Time Task window 33-008-1M5 4-17...
  • Page 41 CHAPTER 4 MODULAR SERVO Menu Description Getting Started • Sampling time defines sampling period during the experiment, • PID controller parameters, • Downsampling ratio - this parameter decreases the rate of output data flow from the output of Real Time Task. For example, if downsampling ratio is equal to 10, for each 10 samples only one is transferred to the output of the block , •...

  • Page 42: First Examples

    In this section two examples are presented. The first one uses Modular Servo Toolbox functions directly, the second shows how to use menu. 5.1. Example 1. Closed-loop control system with state feedback gains (application level 1). We wish to design a closed-loop system having no oscillations. An illustration is provided in the M.file - mservo1.m.

  • Page 43: Example 2. Ziegler-Nichols Method For Designing Pid Controller

    CHAPTER 5 MODULAR SERVO Menu Description Getting Started 5.2. Example 2. Ziegler-Nichols method for designing PID controller (application level 2). After double-clicking Ziegler-Nichols method button in the Main Control Window (Figure 3-1) the screen presented in Figure 4-10 appears. Assume, that the model parameters are correctly identified, using the “Time Domain Identification toolbox”...
  • Page 44 CHAPTER 5 MODULAR SERVO Getting Started Menu Description We conclude that this PID controller can properly control the servo system. Figure 5-3: Simulation results (discrete version) The values of Kr, Ki and Kd calculated by the Ziegler-Nichols method could then be used to optimally control the digital servo using a PID control algorithm.
  • Page 45 CHAPTER 5 MODULAR SERVO Menu Description Getting Started Click Simulation/Start in the window from Figure 4-11. The results of the experiment are shown in Figure 5-5. Figure 5-5: Results of the PID control experiment Again we may conclude that the controller is effective. 33-008-1M5...
  • Page 46 CHAPTER 6 MODULAR SERVO Getting Started Connecting the PC and the Servo CONNECTING THE PC AND THE SERVO EQUIPMENT REQUIREMENTS - the following equipment is required: Modular Servo system - Feedback part numbers OA150A Operational Amplifier AU150B Attenuator PA150C Pre-Amplifier...
  • Page 47 CHAPTER 6 MODULAR SERVO Connecting the PC and the Servo Getting Started 6.1. PCL-812PG acquisition board: Analogue I/O CN1 Digital Out Digital In Analogue I/O CN2 6 7 8 Figure 6-1: Switches and Jumpers of PCL-812 board 6.2. Switch settings - 16 bit board (PCL 812PG) Switch SW1 controls the base address for I/O transfer (switches 1-6), and the CPU wait states (Switches 7-8).
  • Page 48 CHAPTER 6 MODULAR SERVO Getting Started Connecting the PC and the Servo Set the base address on the PCL-812PG board (switch SW1). The factory default base address is 220(HEX) 6.3. Jumper Settings The Jumpers on the PCL-812PG board should be set in the positions indicated below. JP1 - Trigger Source Selection JP2 - Counter Input Clock Selection JP3, JP4 - D/A Reference Selection...
  • Page 49 CHAPTER 6 MODULAR SERVO Connecting the PC and the Servo Getting Started None of the other settings need to be changed . 6.4. Switch SW1 settings for 8 bit full length PCL - 812 board I/O Address Range (hex SW1 Switch position and decimal) 200-20F (512-527 Dec) 210-21F (528-543 Dec)
  • Page 50 CHAPTER 6 MODULAR SERVO Getting Started Connecting the PC and the Servo See Figure 6-2. Two slots are required at the rear of the PC - one for the two 20 way analogue port sockets, and one for the 40 way socket at the end of the wide ribbon cable for the digital ports.
  • Page 51 Run the tuning program - click Calibration 33-301 button in the Main Control Window and follow the screen instructions. Note: it is necessary to tune the Analogue Control Unit because the electronic circuits in the MS150 are not identical in all copies. After calibration close Windows and turn off the computer. Make general patching: θ...
  • Page 52 +15V Cable to PC OP150K Output i/p 2 o/p 4 Potentiometer Set s/w to NORMAL +15V IP150H Input Potentiometer AU150B Narrow Ribbon -15V Attenuator Unit Cable to PC Figure 6-5 33-301 Analogue MS150 Modular Servo Control Interface connections diagram 33-008-1M5...
  • Page 53 CHAPTER 6 MODULAR SERVO Modular Servo - Layout and Connections Getting Started Notes 33-008-1M5...

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