JP2019191822A - Swivel base control device and setting method for the same - Google Patents

Abstract

To provide a swivel base control device and setting method for the same to control the turning drive of a swivel base via a negative feedback loop, which enables more flexible control according to the temperature.SOLUTION: A control device 20 controls a turning drive of a swivel base 10 through a negative feedback loop. A transfer function GC is a transfer function obtained by combining a first transfer function G1 related to the control device 20 and a second transfer function G2 related to the swivel base 10. The first transfer function G1 is set so as to suppress changes due to temperature in the combined transfer function GC.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for a swivel base and a setting method thereof, and more particularly, to a control device for controlling the swivel drive of a swivel base via a negative feedback loop.

  A swivel for swiveling the mounted object is used, for example, to swivel a surveillance camera in accordance with a subject to be photographed. The swivel base is used in various environments and needs to cope with a wide temperature range of, for example, -20 ° C to + 45 ° C.

FIG. 5 is an example of a block diagram relating to control of a conventional swivel base. Controller is an example P controller, proportional control revolving base of the swivel drive with a gain K _p. Here, when the bearing used for the swivel mechanism of the swivel includes grease, the wide temperature range becomes a problem. Since the viscosity of grease changes depending on the temperature, the swivel base is easy to move at high temperatures and difficult to move at low temperatures. Therefore, if the control gain is reduced in accordance with the high temperature environment, the turning speed may be excessively slow in the low temperature environment, and if the control gain is increased in accordance with the low temperature environment, the swing table may be vibrated due to overshoot. There is.

  An example of control for dealing with a wide temperature range is described in Patent Document 1.

JP 2009-52339 A

  However, the conventional technique has a problem that it is difficult to perform flexible control according to the temperature.

  For example, in Patent Document 1, only two-stage control, that is, control at a high temperature and control at a low temperature, can be performed, and flexibility is limited.

  The present invention has been made to solve such problems, and in a control device for controlling the turning drive of the swivel base via a negative feedback loop and its setting method, more flexible control according to the temperature is possible. The purpose is to provide what to do.

The control device according to the present invention is a control device that controls the turning drive of the turntable via a negative feedback loop,
The first transfer function suppresses a change in temperature of the combined transfer function with respect to the transfer function obtained by combining the first transfer function related to the control device and the second transfer function related to the swivel base. Is set.
According to a particular aspect,
The first transfer function includes a differential element having a gain;
The first transfer function is set so that the gain changes according to temperature.
According to a particular aspect,
The second transfer function includes a first-order lag element having a time constant;
The first transfer function is set so that the combined transfer function is only a proportional element.
According to a particular aspect, the first transfer function is set to suppress a change in temperature in the combined transfer function within a range of −20 ° C. to + 45 ° C.
According to a specific aspect, the swivel base is capable of swiveling about a plurality of swivel axes, the control device has the first transfer function that is different for each swivel axis, and the swivel base is different for each swivel axis. Has a second transfer function.
The program according to the present invention causes a computer to function as the above-described control device.
Further, the control device setting method according to the present invention is a control device setting method for controlling the turning drive of the swivel base via a negative feedback loop,
The first transfer function related to the control device is variable, and the second transfer function related to the swivel is measurable.
The setting method is as follows:
Determining the second transfer function at a plurality of temperatures;
Setting the first transfer function to suppress a change due to temperature in the combined transfer function with respect to the transfer function combining the first transfer function and the second transfer function;
Is provided.
According to a particular aspect,
The first transfer function includes a differential element having a gain;
The second transfer function includes a first-order lag element having a time constant,
The first transfer function is set so that the gain changes according to temperature, so that the combined transfer function is only a proportional element regardless of temperature.

  Since the control device and its setting method according to the present invention suppress the temperature change in the transfer function, more flexible control according to the temperature is realized.

It is a figure which shows the example of a structure of the turntable which concerns on Embodiment 1 of this invention. It is an example of the block diagram which concerns on control of the turntable of FIG. 2 is an example of measurement results of the operation of the swivel of FIG. 1 at various temperatures. It is an example plot of the time constant of the swivel of FIG. 1 against temperature. It is an example of the block diagram which concerns on the control of the conventional swivel.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an example of the configuration of a swivel base 10 according to Embodiment 1 of the present invention. The swivel base 10 has at least one swivel axis, and is provided so as to be rotatable or turnable around the swivel axis. In the example of FIG. 1, the swivel base 10 has an azimuth axis A and an elevation angle axis E as swivel axes, and can be swiveled by being driven around two axes. A specific configuration for rotationally driving the swivel base 10 is not particularly shown, but can be appropriately realized using a servo motor and other components.

  FIG. 2 is an example of a block diagram relating to the control of the swivel base 10. In relation to the swivel base 10, a control device 20 that controls the swivel drive of the swivel base 10 is provided. The control device 20 may be provided inside the swivel base 10 or may be provided outside the swivel base 10 so as to be communicable with the swivel base 10.

  The control device 20 has a configuration as a known computer, and includes a calculation unit that performs processing such as calculation and a storage unit that stores information. The control device 20 can be configured as a known PD control device or PID control device, for example. The storage unit of the control device 20 may store a program (not shown). This program may cause the computer to function as the control device 20.

  As shown in FIG. 2, a negative feedback loop (feedback loop) is used for controlling the swivel base 10. This loop takes the command angle as input and outputs the actual turning angle (also referred to as rotational position or angular position) of the swivel base 10. The actual turning angle of the turntable 10 can be detected using a known angle sensor 30 or the like.

  As described above, the control device 20 controls the turning drive of the turntable 10 through the negative feedback loop. Although FIG. 2 relates to a single turning axis, a similar loop can be provided for each turning axis. For example, the control device 20 controls the azimuth angle of the swivel base 10 based on the command azimuth angle with respect to the swivel base 10 and the actual azimuth angle of the swivel base 10, the command elevation angle with respect to the swivel base 10, and the swivel base 10. The elevation angle of the turntable 10 is controlled based on the actual elevation angle.

The transfer function G1 (first transfer function) related to the control device 20 can be set variably. In the present embodiment, G1 is configured as follows, and thereby the control device 20 is set.
G1 = K _p + K _{D (t)} s
In the equation, the coefficient of the first-order complex angular frequency s is KD _(t) . That is, G1 includes a differential element having a gain KD _(t) . K _{D (t)} is a function of temperature and represents a temperature characteristic related to control by the control device 20. In particular, in the present embodiment, G1 is composed only of the sum of the proportional element _Kp and the differential element KD _(t) s.

In the present embodiment, the following is assumed as the transfer function G2 (second transfer function) related to the swivel base 10.
G2 = K _M / (T _{M (t)} s + 1)
In the equation, T _{M (t)} is a function of temperature and represents a temperature characteristic related to the turning of the swivel base 10. In the equation of G2, the coefficient of the first-order complex angular frequency s included in the denominator is T _{M (t)} . That is, G2 includes a first-order lag element having a time constant T _{M (t)} . Also, particularly in this embodiment, G2 is composed of only a first-order lag element having a gain K _M and the time constant _{T M (t).}

  Although G2 differs depending on the configuration of the swivel base 10 or the like, those skilled in the art can specifically specify G2 in advance based on a known technique. For example, an example where G2 can be measured is shown below.

First, the transfer function G1 of the control unit 20 only the proportional element _{K p} (and ie _{K D (t) = 0)} , to measure the operation of the swivel base 10 at a plurality of temperatures. For example, first, the response when the temperature of the swivel base 10 is maintained at a low temperature (for example, −20 ° C.) and the command angle is given as a step function is measured. This is repeated for other temperatures (eg, 0 ° C., + 20 ° C., + 45 ° C., etc.).

  FIG. 3 is an example of the result of such a measurement. The rise is slow at −20 ° C., and rises faster as the temperature rises. As in the case of + 45 ° C., there may be a case where overshoot occurs or a case where vibration occurs.

  Next, for each temperature measurement result, a transfer function that matches the measurement result is determined. For example, when the transfer function is represented by a first-order lag element of K / (Ts + 1), a set of values of the gain K and the time constant T that are well suited to the measurement result is determined. Then, after determining the values of the gain K and the time constant T for each temperature, G2 representing these as a function of temperature is determined. A device and algorithm for determining such a transfer function can be appropriately designed by those skilled in the art based on known techniques. For example, known system identification software (for example, Matlab) may be used.

  Assuming that G2 includes a first-order lag element, a method for determining a specific G2 based on the values of the gain K and the time constant T for each temperature is performed by a person skilled in the art by any method based on a known technique. An example is shown below. In this example, it is assumed that G2 is represented only by the first-order lag element.

FIG. 4 is a plot example of the time constant T with respect to temperature. In this example, the gain K for all the temperature is assumed to be the same value K _M. Select the function that best approximates the value of the time constant at each temperature. For example, T _{M (t)} may be obtained as a straight line passing through the vicinity of each point using a least square method or the like. In this way, T _{M (t)} = T ₀ -Ct. Here, T ₀ is a time constant at a predetermined reference temperature (for example, 0 ° C.), and C is a slope (however, C> 0) representing the rate of change of the time constant with temperature.

  In this way, it is possible to determine the specific shape of G2. The above is an example in which G2 is represented by only the first-order lag element. However, even when G2 is a function of another form (for example, when it includes a time delay element or a second-order lag element) The trader can specify G2 as appropriate.

In such a control system, if the control device 20 uses G1 that is fixed regardless of the temperature, T _{M (t)} is large at low temperatures, which may cause the swivel 10 to turn slowly. _{Since M (t)} is small, there is a possibility that vibration occurs in the turning of the turntable 10. Such a problem may occur in the conventional configuration.

In order to explain the operation of the present invention, a transfer function obtained by combining G1 and G2 is referred to as a transfer function GC. That is, it can be expressed as follows.
GC = G1 · G2 = (K _p + K _{D (t)} s) · K _M / (T _{M (t)} s + 1)

  In the present embodiment, G1 is set so as to suppress a change due to temperature in GC (that is, the whole including G1 and G2). Here, since the specific content of G2 is specified including its temperature-dependent characteristics as described above, a person skilled in the art can easily specify an appropriate G1 and set the control device 20 based on this. Can do.

For example, in the example of FIG. 2, G1 can be configured such that the gain K _{D (t)} of the differential element changes according to the temperature. As a specific example,
_{K D (t) = K p} T M (t)
It is good. If you do this,
GC = G1 ・ G2
= (K _p + K _{D (t)} s) · K _M / (T _{M (t)} s + 1)
_{= (K p + K p T} M (t) s) · K M / (T M (t) s + 1)
= _K p · _{K M}
And TM _(t) is erased. Since K _p and K _M is a constant independent of temperature, GC becomes a form that does not depend on temperature. In particular, in this case, the complex angular frequency s is eliminated, and it can be said that G1 is configured such that GC is only a proportional element regardless of temperature.

  As described above, the control device 20 and the setting method thereof according to the first embodiment of the present invention suppress the temperature change in the combined transfer function GC, so that more flexible control according to the temperature is realized. For example, relatively quick turning is possible even in a low temperature environment, and overshoot and vibration are suppressed even in a high temperature environment.

In the first embodiment, the following modifications can be made.
It need not be completely erased the _{T M (t)} from the _GC, even _{if T M (t)} remains in the GC, suppress the effect of change corresponding to the temperature of _{T M (t)} in GC It is sufficient that G1 is set so as to. It is easy for those skilled in the art to configure such G1.

Moreover, the change according to the temperature of TM _(t) does not need to be considered about the whole temperature range, and may be considered only for a specific temperature range. For example, G1 may be set so as to suppress changes due to temperature in GC within a range of −20 ° C. to + 45 ° C. Such an effect in the temperature range is useful in an ordinary swivel base.

Further, “change due to temperature” in the GC may be evaluated based on, for example, a predetermined reference temperature. For example, the response (actual turning angle of the swivel base 10 ₎ when _{KD (t) is set} to 0 at the reference temperature is set as the reference response, and KD _{( t)} may be configured.

  The transfer function of the angle sensor 30 is not particularly considered, but may be appropriately taken into account. An ideal sensor (having a transfer function equal to 1) may be assumed, or a sensor having a more realistic transfer function may be assumed.

  The control system in FIG. 2 can be configured for each turning axis. In this case, the contents of the transfer functions G1 and G2 may be the same for all the turning axes, or may be different for each turning axis.

  10 turntable, 20 control device (computer), A azimuth axis (turning axis), E elevation axis (turning axis), G1 first transfer function, G2 first transfer function, GC coupled transfer function.

Claims (8)

A control device for controlling the turning drive of the turntable via a negative feedback loop,
The first transfer function suppresses a change in temperature of the combined transfer function with respect to the transfer function obtained by combining the first transfer function related to the control device and the second transfer function related to the swivel base. Control device to be set. The first transfer function includes a differential element having a gain;
The first transfer function is set so that the gain changes according to temperature.
The control device according to claim 1. The second transfer function includes a first-order lag element having a time constant;
The first transfer function is set so that the combined transfer function is only a proportional element.
The control device according to claim 2.   The control according to any one of claims 1 to 3, wherein the first transfer function is set so as to suppress a temperature change in the combined transfer function within a range of -20 ° C to + 45 ° C. apparatus.   The swivel can swivel about a plurality of swivel axes, the control device has the first transfer function that is different for each swivel axis, and the swivel has the second transfer function that is different for each swivel axis. The control apparatus as described in any one of Claims 1-4.   The program which functions a computer as a control apparatus as described in any one of Claims 1-5. A control device setting method for controlling the turning drive of a turntable via a negative feedback loop,
The first transfer function related to the control device is variable, and the second transfer function related to the swivel is measurable.
The setting method is as follows:
Determining the second transfer function at a plurality of temperatures;
Setting the first transfer function with respect to a transfer function obtained by combining the first transfer function and the second transfer function so as to suppress a change due to temperature in the combined transfer function;
A setting method comprising: The first transfer function includes a differential element having a gain;
The second transfer function includes a first-order lag element having a time constant;
The first transfer function is set so that the gain changes according to temperature, so that the combined transfer function is only a proportional element regardless of temperature.
The setting method according to claim 7.

Images