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COntrol System tutorials academic year 2017
Typology: Essays (university)
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resistor, inductor, and capacitor of an electrical circuit. These are respectively known as hydraulic resistor ( R , attributable to friction and turbulence internal to the fluid), hydraulic inertor ( I , attributable to mass of fluid in flow - which is never zero !), and hydraulic capacitor ( C , attributable to storage and compression). Consider the pressure sensor shown in Fig. P1 , which is used to obtain a measurement Ps of a source pressure PP , both relative to a low sump pressure P 0. What is the transfer function between the actual and sensed pressure values? Let the fluid flow in the pipe be given by Q , as shown.
1 IC $ s^2 + RC $ s + 1
modulated for pressure using a valve, the flow Q (^) v through which is a nonlinear function of the pressure differential across it, given by
where A is the valve cross section area controlled by a servomechanism. Obtain the nonlinear equation that determines pressure PS in presence of effective resistance R and capacitance C. Linearise the equation about a set point given by pressure PS 0 and valve opening A 0. P (^) S ( s ) A ( s ) =^
Cs + 0.5 KA 0 $ [ P (^) S 0 ā P 0 ]ā0.
of a system, is in the shape of a conducting disk, across which a magnetic field of uniform flux density B is applied (Fig. P3 ). With the rotary system shaft driven at torque T
(radius r D ) and the shaft surface (radius r s ). The electrical
section for one type of electromechanical actuator that is used in large steam flow systems. It consists of a coil of 500 turns around a soft iron plunger of radius 2cm, and an air gap annulus of 0.5mm around it. The plunger has mass M , and is supported by a spring of
0
Ps R I
0
S
S R
1 R A ( )
ε
rs
rD
(500 turns)
(mass M) (constant K)
2 cm
0.5mm air gap
5cm x
constant K. The position of the plunger beyond the coil is given by a variable x ( t ), which in the rest position shown in the figure, has a value x 0. If the electromagnetic force on the plunger by a DC current i ( t ) in the coil is given by ½ i^2 ( t ).d L ( x )/d x , and if this tends to draw the plunger inwards towards a minimum reluctance position, obtain the nonlinear system dynamic equation of this actuator. Linearise the equation about x 0 and current i 0 , and obtain the transfer function for small valve opening in response to small current.
6332 i 0 (0.05 + x 0 ) 2
$ Ms^2 + K +
6332 i 02 (0.05 + x 0 ) 3
ā 1
functions a and c , together with feedback transfer functions b , d , and e. Obtain the sensitivity transfer functions of the system with respect to each of the feedback blocks. ab (1 ā cd ) (1 ā ab )(1 ā cd ) (^) ā eac ,^
cd (1 ā ab ) (1 ā ab )(1 ā cd ) (^) ā eac ,^
eac (1 ā ab )(1 ā cd ) (^) ā eac
comfortable by incorporating appropriate tires, shock absorbers, and leaf springs in a vehicle configuration. However one parameter that they never can freeze on is the weight of the passenger s !! That remains arbitrary, and hence the objective of this analysis.
The model in Fig. P6 represents the dynamics of one wheel of a four-wheeler automobile. M 1 is roughly ¼ the mass of the automobile (with the questionable weight of passengers included !). K 1 and D 1 respectively represent the leaf spring and shock absorber associated with a single wheel. M 2 is the mass of the wheel, and K 2 represents the tire stiffness. Obtain the transfer function of X 1 ( s )/ X ( s ) - which represents the effect of the bumpiness of the terrain on the passenger - and most important of all, its sensitivity to M 1.
S (^) M^ G ( 1 s )^ = ā M 1 s^2 ( M 2 s^2 + D 1 s + K 1 + K 2 ) ( M 1 s^2 + D 1 s + K 1 )( M 2 s^2 + D 1 s + K 1 + K 2 ) (^) ā ( D 1 s + K 1 ) 2
a c
b d
e
R s ( )^ Y s ( )
P
x
x 2
x 1