Løsning til skriftlig eksamen i emnet SESM3401 Styring
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1. ET ET DO Figur 4 e Input EN enable boolean starts or triggers the timer e Input PT preset time time is the elapsed time or time delay before the timer output Q is set to ON The time format is a special data format used to represent time In Figure the PT value is 1 minute 10 second 25 milliseconds e Output Q output boolean is the timer output It gets value ON when the elapsed time is larger than the preset time e Output ET elapsed time time is the continuously running time Figure 5 shows a timing diagram which shows the behaviour of the timer along a time axis The timer operates as follows 1Q means output The ideal symbol O for output is not used since it is too easily misinterpreted as zero ON 1 EN OFF 0 A O Iml0s25ms ET ed St Os ON 1 Q oFF 0 Time I to ti t2 t3 t4 e a a Elapsed time is Elapsed time is PT 1m10s25ms less than PT Figur 5 e The timer starts when the input x0 at the EN input goes from OFF to ON As the timer starts the ET output increases continuously from the initial value of 0 seconds In this example the ET time value is stored in the data register DO which is a general register or memory cell where a value can be stored for use in subsequent programming expressions e When the ET time has become larger than the PT preset time value the boolean output Q is set to ON In this example the value of Q is stored in memory2. H gskolen i Buskerud L sning til skriftlig eksamen i emnet SESM3401 Styring av mekatroniske systemer Eksamensdato Mandag 8 desember 2008 Varighet 3 timer Vekt 70 Hjelpemidler Ingen trykte eller h ndskrevne hjelpemidler Kalkulator ikke tillatt Kontakt under eksamen 1 am Finn Haugen telefon 97019215 Hvis du mener at det i en oppgave mangler forutsetninger for l sning skal du selv definere disse forutsetningene slik at du allikevel kan l se oppgaven 1 15 vekt i dette oppgavesettet Den logiske funksjonen y x AND 73 OR z3 1 kan realiseres med ladderdiagram som vist i figur 1 og med xi x2 y Figur 1 funksjonsblokkdiagram som vist i figur 2 Xi amp X2 O y X3 Figur 2 2 15 Se figur 3 3 15 Fra kompendiet A timer function is similar to a clock which is started triggered by a starting signal changing value from OFF to ON When a preset time has elapsed the timer output is set to ON Set Reset Out Figur 3 As an example a timer can be used to implement a time delayed start of a motor Another example is to control the ON time of a heater PLCs have a number of different timers in their functions library Figure 4 shows an example of a timer The example can be found in a user s manual of the GX IEC Developer programming tool of Mitsubishi PLCs The timer parameters are as follows Inputs Outputs y Timer1 x0 EN Q MO T 1m10s25ms
3. cell MO which is a general memory cell where a boolean value can be stored for use in subsequent programming expressions e If EN goes from ON to OFF ET is reset to zero 4 15 Transferfunksjonen for motor med sensor prosessen er K 2 Ts 1 2 H s der K og T har kjente verdier Det er spesifisert at reguleringssystemets responstid Tc skal v re omtrent lik T F r da ihht Skogestads tabell T T 1 Kr kG KT K 8 x T min T 1 447 min T 1 447 T 4 5 25 Sekvesiell styring av en batch prosess fra kompendiet benyttet i emnet Figure 6 shows a simple batch process The tank Figur 6 A batch process to be controlled by sequential control is filled with water The water is then heated and stirred and finally the heated water is discharged from the tank The control signals are e u valve in boolean i e having value TRUE or FALSE or ON or OFF e u valve out boolean e u motor boolean e u_heat continuous having any value between 0 and 100 The motor is assumed to ensure homogenuous thermal conditions in the water in the tank The measurements are e Temperature T of the water in the tank e Level h of the water in the tank In the exam you are asked to draw a state diagram of the control system The state diagram will be identical to the SFC Sequential Function Chart shown in Figure 7 E g the states are SO S1 etc The actions are A0 1 AO 2 etc The trans
4. itions are TO_1 T1_ 2 etc Actions AO 1 u_valve_in OFF AO 2 u_valve_out OFF AO 3 u motor OFF AO 4 PID auto OFF Transition TO 1 Start Batch Button TRUE S1 A1 1 u valve in ON Filling T1_2 Level gt Level High S2 A2_1 u_valve_in OFF Heat Stirr A2_2 u_motor ON A2_3 PID_auto ON A2_4 Timer_Enable ON T2_3 Timer_Value gt 10000s s3 Emptying A3_1 u_valve_out ON A3 2 u_motor OFF T3 4 Level lt Level Low S4 A4 1 u valve out OFF Pause A4 2 PID auto OFF T4 5 Finish Button ON T4 1 Restart Button ON S5 End Figur 7 6 5 Posisjonen er den tidsintegrerte av hastigheten I s planet uttrykkes tidsintegrasjon med divisjon med s Transferfunksjonen fra p draget u til posisjonen x blir da K 5 Ts 1 s 5 7 10 HIL simulering Fysisk reguleringsutstyr kalt ECU Electronic Control Unit regulerer en simulert prosess HIL simulering kan v re nyttig for testing og oppl ring
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