SU1339488A1 - Servo system with limited angle of turn of output shaft - Google Patents

Abstract

The invention relates to astro-technology and can be used to control the angle of rotation of optical telescopes and antennas of radio telescopes. The aim of the invention is to expand the area of the working angles of the system and reduce the time for the system to exit from the end positions to the working area. This goal is achieved due to the fact that at the moment the system reaches the stops, the limit switches of the limit switch block are activated and a signal is generated at its output that switches the regulator to dynamic braking mode, for example, by closing the motor winding to the dynamic braking resistor. In addition, a resistor in the field of the excitation winding is shunted with a key that is triggered by the presence of a signal at the output of the limit switch block and by the difference between the rotation speed of the motor and zero, thereby boosting the excitation flow of the electric motor. 2 Il. W ATS |) 4 00 00

Description

ten

20

11339488

The invention relates to automation and can be used when controlling the angular position of various objects.

The purpose of the invention is to expand the range of allowable angles of rotation of the output shaft of the system and decrease. The output system output shaft from the end positions to the operating position.

FIG. 1 is a schematic diagram of the system; in fig. 2 - oh, an embodiment.

The tracking system contains a control unit 1, an executive electric motor 2, a position sensor 3, a limit switch unit 4, a speed sensor 5, a detector 6, a comparator 7, element 8, a key 9, a control resistor 10, a winding 11, a measur 12, a source 13 supply voltage, unit 14, reference voltage source 15, error meter 16, control signal generator 17, power amplifier 18, threshold unit 19, load 20, switch 21, diode 22.

As keys 9 and 21, any inertia-free keys can be used. The control signal generator implements any control law.

The system works as follows.

When the load 20 moves in the working zone of the system, the key 9 is open, since the input And element 8, controlling the operation of the key. 9 ,, only the output signal of the speed sensor 5 through the detector 6 and the comparator 7 is received. The detector 6, together with the comparator 7, whose reference voltage level is zero, function as a threshold unit 19 generating a signal about the presence of system speed, regardless of its value and directions. In this case, the excitation winding 11 of the additional electric motor 2 is connected to the power supply source 13 through the adjusting resistor 10, the value of which is selected so that the nominal excitation current flows through the excitation winding 11. The output signal of the speed sensor 5 o. Is simultaneously supplied to the third information input of the control unit 1 to ensure the stable operation of the system.

l h and nn h x m 15 I t l m 25 century. l

thirty

35

40

45

50

55 to

0

0

When the system approaches the end positions, the limit switches of the block 4 limit switches are triggered and the signal from the output of block 4 is fed to the control input of control block 1, putting the system into dynamic braking mode, for example, by closing the main winding of the executive motor 2 to resis. dynamic braking torus or output impedance of power amplifier 18 and, moreover, to the second, the input of the IW element. In this case, element 5 and 8 generates a signal that is fed to the control input of the switch 9. The latter closes and shunts the adjusting resistor. 10, connecting the excitation winding 11 of the executive electric motor 2 directly to the power supply source 13, thereby forcing the current (flow into the building excitation) in the excitation winding 11. Since the torque developed by the direct current electric motor 2 is proportional to the excitation flow (excitation current), its braking torque, and therefore the braking angle of the system, which is inversely proportional to the torque of the executive electric motor 2, will decrease. At the end of the braking process and stopping the system E in the final position, the signal at the output of the speed sensor 5 is zero. In the result, the signal at the output of the element And 8 disappears, the key 9 opens and again connects the excitation winding 11 to Sources of supply voltage 13 via adjusting resistor 10, thus providing normal GTEM, excitation actuator motor 2.

0

five

0

When the system leaves the end position in the working area, the control unit 1 switches off the dynamic braking mode. A voltage appears on the bark 12 of the actuating motor 2, and it will begin to rotate towards the exit to the working zone. At the same time, speed sensor 5 starts to rotate, and a signal appears at the output of the comparator 7, which is fed to the first input of the element E.8 Since in the final position the block of 4 limit switches is triggered, a signal is also present at the second input of the AND 8 element. Element And 8 is triggered, and Si1 nal - from its output pos31

blunt to the input of the key 9, the latter closes, shunts the adjusting resistor 10 and reconnects the actuator winding 11

motor 2 directly to the power supply source 13, thereby forcing the excitation flow of the executive motor 2. The starting torque increases, and hardly increases, and accelerates the acceleration of the system, which provides a faster exit from the end position to the working area.

When the system leaves the limit switches, the signal from the output of the block 4 of the limit switches disappears, as a result the signal at the output of the element 8 disappears. The key 9 opens and connects the excitation winding 11 to the power supply source 13 through the resistor 10, ensuring that the most nominal excitation of the executive motor 2 when in the work area.

Consider the effect obtained when forcing the excitation of the executive motor 2 in the mode of dynamic braking. It is known that the time developed by the direct current electric motor 2 can be written in the form:

M K „(I,

(one)

where M is the moment of the electric motor 2; Kv is the proportionality coefficient depending on the design of the electric motor 2; .1 is the current in the corona circuit. On the other hand, the equation of equilibrium of moments on the shaft of the executive electric motor 2 without taking into account the moments of forces of static resistances has the form:

M I, 7Гd dt

(2)

where I is the total moment of inertia

kor 12 and the load, reduced to the shaft of the electric motor 2;

WITH - the angular velocity of the electric motor. 2

By neglecting the inductance of the core winding, which is usually small, the voltage equation in the core circuit of the executive motor 2 in the dynamic braking mode can be written:

- IR,

(3)

where K (d - the coefficient of back emf ;; R - total resistance

root chain.

Having determined from the equations (1) and (2) the current I in the crustal circuit, after substituting its expression in (3) and transformations, we obtain the equation describing the braking process of the system:

t „.“

dt

0

(BUT)

e-1

M -... V "

electromechanical constant of system time,

Integrating equation (4) in time twice at the initial t (0) 0; co (0) COO; ff (0) O, we obtain the expression for the braking angle of the system

i.

4 - e). (five)

0

five

0

five

Analysis of expression (5) with regard to expression T shows that the braking angle of the system is proportional to the electromechanical constant time of the system, which, in turn, is inversely proportional to the excitation flux of the executive electric motor 2 (the excitation current of the electric motor 2). Thus, a forcing, for example, the excitation flow of the executive electric motor 2, can reduce the coasting angle of the system by half and significantly expand the working area of the system.

Assuming that the acceleration of the actuator motor 2 when the system exits from the end / position to the working zone is carried out by a constant moment, the time for the system to reach the working zone can be calculated by the formula

where 6 is acceleration acceleration.

Then, when the excitation flow of the actuator motor 2 is doubled, the time it takes for the system to reach its final position in the working area will also be halved.

Thus, in the proposed servo system, the automatic excitation of the executive motor 2 is provided.

51339488

braking the system at the end positions and at the time of exit from the end positions with the aim of its moment in these modes, the increase in the moment of the performer electric motor 2 in the mode of braking deceleration leads to

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braking, which allows limit switches to be positioned closer to the limit position (mechanical stops), i.e. expand the working area of the system. Increasing the torque of the electric motor 2 in the mode of outputting the system from the end positions to the working zone allows increasing the acceleration of the acceleration of the system, which reduces the time taken for the system to exit from the end position to the working zone.

Claims (1)

Invention Formula A tracking system with a limited angle of rotation of the output shaft, containing a detector connected by an output to an information input of a comparator connected by a reference input to an output of a source of reference voltage, and an output to a first input of an And element connected by an output to a control input of a key, a setting connected by an output with the first input of the meter five 0 Q five 0 of the mismatch connected by the second input to the output of the position sensor, and the output to the first input of the control signal generator connected to the second input of the power amplifier connected to the root winding of the electric motor, the excitation winding of which is connected by one output to the first input to the output of the speed sensor and output the first output of the voltage source, and the other output through the adjusting resistor to the second output of the voltage source, the shaft of the executive electric The motor is the output shaft of the system and is kinematically connected with the load and the shafts of the position sensor and the speed sensor, which is aimed at expanding the range of permissible angles of rotation of the output shaft of the system and reducing the time for the output shaft end positions in the working area, a limit switch block is inserted, kinematically connected to the output shaft of the system and connected electrically to the second inputs of the power amplifier and element I, the input of the detector is connected to the output of the speed sensor, and the pins of the key are connected to the pins of the adjusting resistor. Fi8.2 Editor V. Petrash Compiled by G.Nefedov .fl44biK Proofreader C, Order 4216/35 Circulation 863 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 : Production and printing company, Uzhgorod, st. Project, 4