Mech371 lab manual - Summary Analysis and Design of Control Systems PDF

Preview

Summary

Department of Mechanical & Industrial Engineering Concordia UniversityMECH 371 Analysis andDesign of Control SystemsLaboratory ManualW. Xie, H. Hong, T. Wen, G. Huard 1/9/Table of ContentsLab 1: Control System Introduction, Familiarization with Lab Equipmentand Instruments .....................

Description

Department of Mechanical & Industrial Engineering Concordia University

MECH 371 Analysis and Design of Control Systems

Laboratory Manual

W. Xie, H. Hong, T. Wen, G. Huard 1/9/2017

Table of Contents Lab 1: Control System Introduction, Familiarization with Lab Equipment and Instruments …………………….………………………………………………....7 Lab 2: Determination of DC Motor Dead-Band, Gain, Servo-Amplifier Gain,Torque/SpeedCharacteristic…….……………………………………...17 Lab 3: Time Response of Basic Closed-Loop System and Effect of Tachometer Feedback………………………………………………………………27 Lab 4: Frequency Response of Basic Closed-Loop DC Motor System……33 Lab 5: DC Motor Position Control with Cascade PID Compensation…….37 Lab 6: Time Response of Basic Closed-Loop Speed Control System and Effect of Torque Load………………………………………………………….…...42 Appendix A: Appendix B: Appendix C: Appendix D:

Connect Oscilloscope to MS Excel………………………………………………….43 Alternate method to get one shot wave form…………………………………44 How to get Time Constant using Cursor measurement……………………45 Summary of MS150 Data- DC Motor System …………..………………….46

Labs are scheduled on an alternative week basis (every two weeks). Therefore, formal lab reports must be submitted every two weeks during your lab period. Please submit your last lab report directly to your lab instructor at his/her office, one week after you have performed the lab. No late lab reports will be accepted.

1

General Laboratory Safety Rules Follow Relevant Instructions •

• •

Before attempting to install, commission or operate equipment, all relevant suppliers’/manufacturers’ instructions and local regulations should be understood and implemented. It is irresponsible and dangerous to misuse equipment or ignore instructions, regulations or warnings. Do not exceed specified maximum operating conditions (e.g. temperature, pressure, speed etc.).

Installation/Commissioning •

•

• • • • •

•

Use lifting table where possible to install heavy equipment. Where manual lifting is necessary beware of strained backs and crushed toes. Get help from an assistant if necessary. Wear safety shoes appropriate. Extreme care should be exercised to avoid damage to the equipment during handling and unpacking. When using slings to lift equipment, ensure that the slings are attached to structural framework and do not foul adjacent pipe work, glassware etc. Locate heavy equipment at low level. Equipment involving inflammable or corrosive liquids should be sited in a containment area or bund with a capacity 50% greater that the maximum equipment contents. Ensure that all services are compatible with equipment and that independent isolators are always provided and labeled. Use reliable connections in all instances, do not improvise. Ensure that all equipment is reliably grounded and connected to an electrical supply at the correct voltage. Potential hazards should always be the first consideration when deciding on a suitable location for equipment. Leave sufficient space between equipment and between walls and equipment. Ensure that equipment is commissioned and checked by a competent member of staff permitting students to operate it.

Operation • •

•

Ensure the students are fully aware of the potential hazards when operating equipment. Students should be supervised by a competent member of staff at all times when in the laboratory. No one should operate equipment alone. Do not leave equipment running unattended. Do not allow students to derive their own experimental procedures unless they are competent to do so.

Maintenance •

Badly maintained equipment is a potential hazard. Ensure that a competent member of staff is responsible for organizing maintenance and repairs on a planned basis. 2

•

Do not permit faulty equipment to be operated. Ensure that repairs are carried out competently and checked before students are permitted to operate the equipment.

Electricity • • •

•

Electricity is the most common cause of accidents in the laboratory. Ensure that all members of staff and students respect it. Ensure that the electrical supply has been disconnected from the equipment before attempting repairs or adjustments. Water and electricity are not compatible and can cause serious injury if they come into contact. Never operate portable electric appliances adjacent to equipment involving water unless some form of constraint or barrier is incorporated to prevent accidental contact. Always disconnect equipment from the electrical supply when not in use.

Avoiding Fires or Explosion • • • • • • •

Ensure that the laboratory is provided with adequate fire extinguishers appropriate to the potential hazards. Smoking must be forbidden. Notices should be displayed to enforce this. Beware since fine powders or dust can spontaneously ignite under certain conditions. Empty vessels having contained inflammable liquid can contain vapor and explode if ignited. Bulk quantities of inflammable liquids should be stored outside the laboratory in accordance with local regulations. Storage tanks on equipment should not be overfilled. All spillages should be immediately cleaned up, carefully disposing of any contaminated cloths etc. Beware of slippery floors. When liquids giving off inflammable vapors are handled in the laboratory, the area should be properly ventilated. Students should not be allowed to prepare mixtures for analysis or other purposes without competent supervision.

Handling Poisons, Corrosive or Toxic Materials •

• • •

Certain liquids essential to the operation of equipment, for example, mercury, are poisonous or can give off poisonous vapors. Wear appropriate protective clothing when handling such substances. Do not allow food to be brought into or consumed in the laboratory. Never use chemical beakers as drinking vessels Smoking must be forbidden. Notices should be displayed to enforce this. Poisons and very toxic materials must be kept in a locked cupboard or store and checked regularly. Use of such substances should be supervised.

Avoid Cuts and Burns •

Take care when handling sharp edged components. Do not exert undue force on glass or fragile items.

3

•

Hot surfaces cannot, in most cases, be totally shielded and can produce severe burns even when not visibly hot. Use common sense and think which parts of the equipment are likely to be hot.

Eye/Ear Protection • •

• •

Goggles must be worn whenever there is risk to the eyes. Risk may arise from powders, liquid splashes, vapors or splinters. Beware of debris from fast moving air streams. Never look directly at a strong source of light such as a laser or Xenon arc lamp. Ensure the equipment using such a source is positioned so that passers-by cannot accidentally view the source or reflected ray. Facilities for eye irrigation should always be available. Ear protectors must be worn when operating noisy equipment.

Clothing •

•

Suitable clothing should be worn in the laboratory. Loose garments can cause serious injury if caught in rotating machinery. Ties, rings on fingers etc. should be removed in these situations. Additional protective clothing should be available for all members of staff and students as appropriate.

Guards and Safety Devices • • • • •

Guards and safety devices are installed on equipment to protect the operator. The equipment must not be operated with such devices removed. Safety valves, cut-outs or other safety devices will have been set to protect the equipment. Interference with these devices may create a potential hazard. It is not possible to guard the operator against all contingencies. Use commons sense at all times when in the laboratory. Before staring a rotating machine, make sure staff are aware how to stop it in an emergency. Ensure that speed control devices are always set to zero before starting equipment.

First Aid • • •

If an accident does occur in the laboratory it is essential that first aid equipment is available and that the supervisor knows how to use it. A notice giving details of a proficient first-aider should be prominently displayed. A short list of the antidotes for the chemicals used in the particular laboratory should be prominently displayed.

4

Mr. Gilles Huard

8798

Standard lab safety must be followed in all laboratories • •

• • •

• • • •

First discuss your experiment regarding possible hazards or problems, with the demonstrator, or the MIE technical staff, or your professor. Do not work alone. Work with another person in a lab that has running machinery, machine tools, conveyors, hydraulics, lifting equipment, voltage hazards, or where chemicals are in use. Safety glasses must be worn in the vicinity of pneumatics, machine tools grinders, power saws, and drills. Users of lasers need special safety glasses for the particular wavelength of the laser. No equipment or machine may be operated by anyone unless they have received adequate instruction from a qualified instructor e.g. machine tools, hydraulics, chemicals, lasers, running machinery, robots. Undergraduate students may not use any machine or equipment unless a Department technical staff member Is present. Graduate students are the responsibility of their immediate academic supervisor. Workplace Hazardous Material training must be obtained before using chemicals or compressed gasses. Contact Dainius Juras tel: 848 3128 for training. All appropriate safety accessories (lab coats, safety glasses, gloves, etc.) must be used when handling chemicals. No open toe shoes are permitted in laboratories. No chemicals to be left unattended or unlabeled according to WHMIS. All chemicals must be stored properly. Long term unattended tests must be fail safe. When the university Is officially closed, you may not work in a lab unless your supervisor or a technical staff member is present. 5

• •

• •

No eating in laboratories. Major accidents and injuries must be reported at once to Security tel: 811, the Safety Officer (tel: 3128), the Professor (Supervisor) or the Department Administrator (tel: 7975} should then be informed. During working hours all minor accidents should be reported to the Safety Officer (tel: 3128), the Professor (Supervisor) or the Department Administrator (tel: 7975). An "Incident Report" must be filled out by the person involved, for all accidents and injuries.

LABORATORY RULES Considering the large number of students attending the labs and in order for the lab to operate properly, the students are asked to abide by the following rules: 1. 2. 3.

No smoking, eating, or drinking is permitted in the laboratory. No students are allowed access to the instruments of the other course. No equipment is allowed to be exchanged from one bench to another.

4.

Upon entering and when leaving the laboratory students should check equipment against the

5.

list posted at each station. All damaged or missing equipment and cables must be reported immediately to the

6. 7.

demonstrator. Failure to do so will result in students being charged for damages or losses. All data must be recorded in the laboratory paper and must be signed by the demonstrator. Laboratory demonstrators are not permitted to admit any students other than those on their

8.

class list. Any student who is more than 30 minutes late will not be permitted into the laboratory.

9.

Furthermore, repeated tardiness will not be tolerated. After your laboratory session is completed all components, connecting jumpers, and cables

must be returned to their respective places. 10. No students are allowed access to parts in the cabinets. Your laboratory demonstrator will provide you with all necessary parts.

6

Lab 1: Control System Introduction, Familiarization with Lab Equipment & Instruments Objectives To familiarization students with MS150 DC Motor Control Modules, instruments such as function generator and oscilloscope and to calibrate potentiometers, Op Amp and pre-amplifier.

Introduction The purpose of the laboratory is to acquaint the student with a practical classical feedback, control system [specifically an electromechanical angular position control system using a DC motor], and to become familiar with the measurement of basic performance parameters of the system, both in the time-domain and in the sinusoidal frequency domain. A position control system (rather than any other variable) is used in this lab not only because of its wide application (e.g. position control in robotic manipulators, setting of hydraulic/pneumatic valves in process-control systems, positioning of directional antennas in communication systems etc.) but also because important operational characteristics such as overshoot may be directly (visually) observed when the controlled variable is the 'position'. ฀฀฀฀

฀฀฀฀

150A

Ki 150H

−

฀฀฀฀

K1

Kp

150B top

150C

฀฀฀฀

฀฀฀฀ ฀฀+฀฀฀฀฀฀

฀฀฀฀

150D +150F

฀฀

฀฀฀฀

฀฀฀฀ 150X (Gear)

Ko 150K

Figure 1-1 Basic DC Motor Angular Position Control System Figure 1.1 is a basic angular position control system. An Input Potentiometer 150H (input position transducer) translates the desired angular position θd into a proportional voltage Vi. A Servoamplifier 150D which drives the motor and which, together with a DC motor in 150F, forms the 'servomotor'. The motor drives a mechanical load mainly consisting of a flywheel (representing a real load), through a Gear train (Gear box) in 150F which provides both amplification of the motor torque as well as speed reduction. 7

Oscilloscope

Function Generator

AU150B Top

OA150A

PS150E

AU150B Bot

PA150C

PID150Y

SA150D DCM150F

GT150X

LU150L IP150H

OP150K

Figure 1-2 MS150 DC Motor Control System An Output Potentiometer 150K (output position transducer) translates the angular position θo, of the flywheel shaft, into a proportional voltage Vo. The device called the “Reference Comparator” 150A compares the voltage Vo with the reference input voltage Vi, which represent s the desired posit ion of the fly wheel, and generates the difference between them: Ve = Vi –Vo, then the 8

voltage Ve will represent the 'error' between the desired position and the actual position. The reference comparator is therefore also called an 'error detector'. The 'error' signal Ve , can be adjusted by K1 150B, then amplified by a pre-amplifier 150C and subsequently by a poweramplifier 150D, is used to drive the motor in such a sense as to reduce the 'error' itself. A system such as the one just described (shown in Figure 1.1) is called a closed loop, negative-feedback position control system. The Modular DC Servotrainer MS150 used in the lab is designed to demonstrate the basic principles of a classical closed-loop negative feedback control system as shown in Figure 1-2: an electromechanical system using a DC motor which controls the angular-position of a shaft. The equipment consists of modular units for the motor, amplifiers etc., mounted on a baseplate. The various modules are positioned on a baseplate as shown above. Each station also includes a function generator and an Oscilloscope. Except for some main connections, interconnections between the various modules are made by the student, using banana-plug-ended patch cords which are provided in the laboratory. The power supply module 150E is permanently connected to the motortachometer module 150F and to the servo-amplifier module 150D. Terminals which provide a balanced +15/ 0 /-15 volt DC output are available on the power supply and servo-amp modules. A 3-wire harness is connected to distribute the ±15 volt supply to the operational amplifier, preamplifier and PID modules. The +15/ 0 /-15 supply voltages, available at terminals on the power supply module 150E, are also used to supply voltages to the Input & Output Potentiometers (150H & 150K) , which make up the "error channel". Power Supply PS150E provides the ±15 volt DC power supplies through two sets of sockets. These sockets are used to operate small amplifiers and provide reference voltage. The Ammeter is used for monitoring motor overload. The AC outputs are not used in our experiments. The front panel is shown in Figure 1-3.

Figure 1-3 Power Supply: PS150E

Potentiometers: showing in Figure 1-4. The module includes an Input Potentiometer IP150H (as an input position transducer), an Output Potentiometer OP150 K (output position transducer), and an Attenuator Unit AU150B containing two smaller potentiometers, which are used to adjust gains in the forward and feedback paths. The input and output pots are fitted with discs graduated (in degrees) on their shaft. However, the output pot can be rotated continuously over 360º, whereas the input pot has a limited rotation of about ± 150°. Both these 'angular position transducers' are normally supplied with +15 and –15 volts, so that their outputs can vary linearly from zero to almost either of these limits as their shafts are rotated in either direction from a central (zero) position. Normal operation is symmetrical about this zero position. Note that in the output pot, a zero-voltage transition also 9

occurs at the + or –180° position, hence requiring operation which ensures output angular displacements within these limits. Assuming that the total voltage applied across the output pot is 30 volts, and the rotation is 360°, the position-to-voltage transducer sensitivity K0 will be 30 / 360 ≈ 0.083 volt / deg., or approx. 4.8 volts/radian. The input and output potentiometers should be calibrated to obtain their sensitivity constants and/or to confirm whether Ki ≈ Ko. The pots in the Attenuator unit are provided with knobs and scale graduations from 0 to 10. These pots can be used as voltage dividers and to obtain the very small voltages.

A: Input Pot IP150H

B: Output Pot

OP150K

C: Attenuator AU150B

Figure 1-4 Potentiometers Operational Amplifier OA150A (Figure 1-5) is an op-amp normally connected as a unity-gain summing-inverter by means of the 3-position switch mounted on it. It is used as the angular-positionerror detector. Since the unit is a summing amplifier, the feedback signal polarity must be reversed with respect to the reference signal, in order that the output will represent the error. The unit has three summing input terminals, and the output is available at two (or three) output sockets. The unit also has a zero-set control and a selector switch, which selects the feedback (normally resistive) within the unit. The selector switch is normally switched to the leftmost position indicating resistive feedback with unity gain. The op-amp must be zeroed before use. {ZERO PROCEDURE: With no input applied (input terminals#1, #2, #3 connect to ground), the Zero-Set control knob should be carefully adjusted until the output #6 is zero volt Figure 1-5 Op-Amp OA150A mean.}

Experiment Procedure MS150 System is equipped with a DC motor, with a tachometer to measure angular velocity, turning potentiometer (designated as input pot and output pot ) to give and measure angular position, and power amplifier (also known as pre-amp and servo-amp) to drive the motor. The 10

command signal can be provided by the function generator or input pot, and the output of angular pos...