附录英文资料及其译文CHAPTER 1 Basis of the automatic control1. 1. Out lineThis device is temperature control experimental device of temperature, lever, pressure , that are the most common control subject for water treatment plants, chemical factories and power plants.At the experiment of automatic control, it is very important to keep the balance of system. Automatic control system is composed of control subjects and to keep control device. Especially process control has many control subjects to keep self-balance, so the experimental results is conducted with balance condition.This experimental device experiments about the relation of input signal and output signal to keep the balance (System characteristics) at the cascade experiment and fixed command control, also experiments on dynamic characteristic (Balance condition without time variation),static characteristic (Balance condition considerating time variation).And you record the change of control amount which was input handling amount or establishment of characteristic experiment. These typical response can be thought step response . Y ou experiment optimum control experiment , fixing P . I. D constant of control device, relating this step response.2. Process controlProcess control keeps the balance of the system, automatically correcting toward deviation, and compares every variable to operating toward deviation, and compares every variable to operation condition of industrial process of flux, temperature, surface, pressure, etc with the established goal. Process control is decided into closed loop and Open loop control.3. Kinds of automatic controlControl is composed of detection (measurement), comparison, judgment, operation and manual control is done by man’s hand and automatic control is done by measure or adjuster or other machinery. At present, automatic control is taken at the many plants .Moreover , we cannot think plant control without automatic control.Kinds of automatic control is decided like below.Automatic control Open loop controlSequential controlClosed loop control Feedback control3-1 .Feed back controlFeed back control detects (measure) compares , judges ,operates ,automatically. And it measures the results every moment , and corrects automatically if there is any differential between the desired value (set value).Feed back control is one of the main process control .This is the control that detecting (measuring) the results (Control amount: tank water lever ) with differential transmitter, and comparing the value with the set water lever and correct the deviation(Opening operation flow control of the control value)Like the above, feed back control automatically does the movement of measurement(detection) comparison calculation modernfication. Feed back system has the element of doing these functions.At the diagram 3-1 block line diagram it is the closed loop and it transmitted the correcting signal of the opposition toward the process flow.Diagram 3—1 Block line diagram of feed back control corollaryBlock line diagram: Indicating the constructing element of control system in block , and connecting the line expressing the signal flow.Signal :The amount being used for transmit the information3-2.Feed forward controlFeed forward control is the control method doing necessary correct movement before the influence appears to the control system , when disturbance enters into the control system.At feed back control, it starts correct movement to erase the deviation after the influence by disturbance appears, so in case of sudden change of disturbance or set value, then control disorders transiently and arises many problems.Feed forward control breaks down this weak point.At feed forward control, results of the controller is not done feedback and becomes open-loop control, not being close-loop control. Accordingly, in case of feed back control, the relation between cause and effect of disturbance and the results of control must be understood well. That is ,relation of influence to the control amount toward load change, and operating amount needed to compensate it should be clear.But it is generally difficult. In many cases it is difficult that all the disturbance is detected, andto get the perfect process model in actual process.Moreover it is difficult to avoid constant deviation, so it is used combined with feed back control.3-3 Sequence controlSequence control processes the fixed process in advance step by step. This sequence control is used in neon signs, vending machines, or electric washing machines. On the other hand, it is needed in the producing process at chemical factory, automobile factory, conveyer, automatic warehouse as automation.3.4 Classification of control methodsProduction method by continuous process is employed, when scale of process industry gets bigger and larger production amount id requested.You need to make proper use of the control method on some different condition of operation. To classfy automatic control system is difficult strictly because their control system has correlation. But general method of cassification will be like below.4-1 Classification by desired valueAutomatic control Fixed command controlFollowing control Follow up controlProgram control4-1-1 Fixed command controlMost of the controls belong to this control when desired value is constant.4-1-2 Following command controlServo mechanism composed to follow the change belongs to this control when desired value changes optionally.4-1-3 Program controlIt is used for the control in which desired value changes according to fixed time schedule. Normally , it is well used to temp. Control of fever process of metal or batch process at the chemical industry.4-2. Classification by control methodAutomatic control Unity control loopRatio controlCascade control4-2-1 ratio controlIt is well used to flow control of 2 fluid when desired value keeps with other fluid (other amount) constantly.You compare and measure if special ratio keeps toward basic fluid (B), then maintain the ratio as the purpose.4-2-2 Cascade controlIt is the control method that more than 2 automatic control systems control by output of other control device. In short, control circuit is combined in series.You change the desired value of flow by output of flux adjuster. If you control the desired value of flow control to fix water level in water tank, then you can prevent the influence to the level such as main pressure change of flow itself.The purpose of cascade control method is to absorb disturbance at first control, also to make easy the next step control, and to progress the control on the whole.3.5 Control actionAt control action, movement to reduce control deviation, giving operating amount in accordance with a movement signal is called control action.The following is this classification.5-1 Continuous controlIt does constantly correct movement toward deviation with desired value,measuring continuously toward controlled variable change.5-1-1 Proportional actionIt is the movement that operating amount Y is in proportion to movement signal and deviation. Suppose you make deviation as e, gain as kp,3.6 Automatic control apparatusFollowing apparatus are necessary for each part, like a block diagram( See diagram 3-2) of feedback control.◇ Primary Detecting element◇ Final control element◇ Controlling means6-1 Primary Detecting elementThis is the part to take out necessary signals from controlling object , and transmit on control devece.(1)Expanding thermometer (Bimetal type)Bimetal is the joined two metal boards which have different thermal expansion coefficient. It curves by temp.change.(2)Pressure type thermometer ( Vapor pressure )You put vaporlizableliquied like propane or ether into thermal sensitivity part.These liquid has certain vapor pressure, by contact surface with gas, and it deflects the needle, by changing pressure measuring mechanism.(3)Resistance thermometerIt is well known that in thermometry resistor (Rt). Its resistance increases as electric resistance changes by temp. and temp. rises.You build a bridge with thermometry resistor, and when its resistance value changes by temp., unbalanced current generates at the bridge. From this, you will know the temperature.(4) Thermoelectric thermometer (Thermocouple)Zeebesk effect is employed. You connect different kinds of metal. And make one connecting point temp.(Thermometry contact point) higher than another connecting point (Standard contact point) . Then thermoelectromotive force is generated between both connecting points.(5) Radiant thermometerSolid emits radiant energy in proportion to the square of four of absolute temp., like Stefan-Boltzmann’s formula.(6) Thermocouple and thermometry resistorDetecting part (Temp.sensor) of temp.control experimental device (SPC-201) is mostly used in industrial tem.measurement.And it employs thermocouple and thermometry resistor with which you can measure in high accuracy and easily.6-2. Final control element ( Control valve)Control valve receives output of adjuster and converts it into process variable Control valve isthe element to feedback to the process. So decides valve specifications. Understanding each controlled objects.6-2-1 Control valve feature(1) Flow feature( Proper feature)Relation of lift of control valve. That is , valve operation signal, with flux is called flow feature,equal percentage feature and on-off feature represent.1、near feature2、queral percentage feature3、On-off feature①Linear featureValve opening degree and flow are in proportion. Accordingly, flux changes 10% linearly,as opening degree changes 10%.②Equal percentage featureFlow increasing modulus becomes constant toward unit change of valve lift . Suppose there is flow increasing modulus at 10%, toward n% change of lift. Then flow will be.When 10 L/min weighting is 10*0.1=1 L/minWhen 50 L/min weighting is 50*0.1=1 L/minWhen 90 L/min weighting is 90*0.1=1 L/minEven if the same n% lift change, flow change is small, if flow is small. And it becomes big if flow is big. So, it has fine adjustment feature over wide flow range.③ On-off featureFlow soon reaches to the max.value, when a valve shift starts to move. It is usually used for 2-positioning control.It is called on-off feature or quick open feature.7.Relation of PID value and disturbance and control response toward setting change.Collect the relationship of PID value and control response toward disturbance, from experimental results, acquired at experiments.(1)proportional (P) action effect••••••••••••To increase proportional gain•To decrease off set amount (In case of no-integral action)•To become oscillative ,and be hunting condition•To get shouter the period of oscillation(2)Integral (I) action resultsFollowing things are conducted in aexperiment ,changed only integral time T I and shortening T I.•To lose off set amount•The first mountain gets smaller•To become oscillative. Amplitude damping ratio gets bigger to finally exhale•Returning time initially to setting value is shortened.(3)Differential (D) action effectFollowing thing is conducted in aexperiment ,changing only differential time and making T D longer.•Off set amount does not change (In case of no-integral action)•The first mountain gets smaller•Oscillation i s restrained. Amplitude damping ratio gets smaller. But ,if differential time is too long ,it becomes oscillative again.•Oscillaion period is shortened.8. P.I.D adjustment procedureYou shall understand PID feature and nature from experiments you did ,however, have difficulty in finding true value ,despite the adjustment .(1)Adjust P-I-D in order. Make step change toward desirable value, changing each constant.Then confirm and record the results.(2)Change proportional (P) band from large number to small number. Stop it when measuringvalue causes hunting.(3)Change integral time (T I) from large number to small number, too. Stop it when measuringvalue causes hunting, and bring a little back larger.(4)Change differential time (T D) from small number to large number. Stop it when measuringvalue causes hunting, and bring a little back smaller.(5)When you wish to shorten setting time, make P much smaller, and check the change ofmeasuring value.9. Optimum adjustmentTo arrange the control purpose based on the former experiments.(1)When you change desirable value, make measuring value and desirable value agree, as soonas possible. (Desirable value change, step response)(2)If measuring value deviates from desirable value, owing to changes of surrounded conditiontemporarily, put it back as soon as possible. (Disturbance response)As for (1) , time passage to make them agree is the problem. Measuring value change on PID value, in case of desirable value change, will be normally like diagram 9-1.At this diagram, temporarily it gets over desirable value. This is called overshoot. To decrease this over amount, and to shorted time to settle down measuring value (Setting time) do not normally coexist. In short, adjusting not to get over makes the setting time longer.Also, control process may have some trouble, if you shorten the setting time, ignoring over amount. On the other hand, it may be better to reach the desirable value sooner in spite of over amount. So, establishing guideline of overshoot, and you have and adjusting method, making time minimum within the range. It is called optimum adjustment, to adjust PID constant.自动控制基础1、提纲这套设备是用来测量温度、流量、液位、压力的实验设备中的温度的设备。