JP2001211692A - Camera platform controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera platform controller capable of attaining reduction in the number of parts and cost by using a stepping motor as a motor for panning and tilting the camera platform in a remote control camera platform system, and using the stepping motor satisfactorily in the remote control camera platform system by controlling the rotational speed of the stepping motor for preventing out-of-step by means of a compensating signal, even if a speed control signal for commanding panning speed and tilting speed cannot be received temporarily because of a communication error or the like. SOLUTION: The stepping motor is used for a pan motor 38 (and tilt motor 40) of the camera platform 10. A motor drive circuit 36 controls a pan motor 38 based on a speed control signal upon receipt of the speed control signal for commanding the panning speed from a camera platform controller 12, and decelerates the pan motor 38 based on the rate of a change within a limit of no out-of-step when the speed control signal cannot be received, thereby preventing the pan motor 38 from being out of control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head control device and, more particularly, to a speed control signal transmitted from a head controller by communication to a rotation speed of a stepping motor for panning or tilting a camera supported on the head. The present invention relates to a camera platform control device that performs control based on a camera.

[0002]

2. Description of the Related Art Conventionally, a camera platform that supports a camera and pans and tilts the camera by driving a motor;
2. Description of the Related Art There is known a remote control pan head system including a pan head and a pan head controller that controls a camera via a communication line or the like.

The pan head controller includes pan head panning,
A joystick for tilting operation is provided, and when this joystick is operated back and forth and left and right, a speed control signal for commanding the panning speed and tilting speed according to the operation direction and operation amount is transmitted to the camera platform. Based on this, a panning and tilting motor mounted on the camera platform is driven. Servo motors are generally used for the panning and tilting motors.

[0004]

By the way, there is generally known a stepping motor which rotates to a rotation angle proportional to the number of pulses of an input pulse signal, stops, and rotates at a rotation speed proportional to the pulse frequency. Since the stepping motor can be used in an open loop, the use of the stepping motor is advantageous in that the circuit configuration of the control system is simpler, the number of parts is smaller, and the cost is lower than the use of the servomotor. However, conventionally, there has been a problem in using the stepping motor in the above-described remote control pan head system. That is, when a stepping motor is used as a motor for panning and tilting, for example, when a speed control signal of a panning speed or a tilting speed transmitted from the pan head controller to the pan head is temporarily lost due to a communication error or the like, The motor control circuit of the stepping motor stops outputting the pulse train to the stepping motor. At this time, the stepping motor suddenly stops the rotation by the pulse train applied up to that time, which may cause a step-out and an uncontrollable state may occur.

The present invention has been made in view of such circumstances, and in a remote control head system, a stepping motor is used as a motor for panning and tilting of the head to reduce the number of parts and cost. In addition, even if a speed control signal for commanding a panning speed or a tilting speed cannot be received temporarily due to a communication error or the like, a pan head control device that can ensure normal operation of the stepping motor without step-out is obtained. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for controlling a stepping motor for panning or tilting a camera supported on a camera platform by transmitting a speed transmitted from a camera platform controller by communication. By outputting a pulse train with a pulse cycle according to the control signal,
In the camera platform control device that controls the rotation speed of the stepping motor, when controlling the rotation speed of the stepping motor based on the speed control signal, if the speed control signal cannot be received, the stepping motor is controlled. It is characterized in that the rotation speed is reduced at a rate of change within a limit that does not cause loss of synchronism.

According to the present invention, if the speed control signal from the pan head controller cannot be received due to a communication error or the like, the rotation speed of the stepping motor is reduced at a rate of change within a limit not to lose synchronization. Even when a signal cannot be received, step-out is prevented, and normal operation of the stepping motor can be ensured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a pan head control device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a remote control pan head system to which the present invention is applied. The remote control head system shown in FIG. 1 includes a remote control head 10 (hereinafter, simply referred to as a head 10) and a head controller 12. The camera platform 10 includes a housing 14 that houses a television camera (hereinafter simply referred to as a camera), and a camera platform body 16 that pans and tilts the housing 14. A transparent protective glass 18 is provided on the front surface of the housing 14, and a camera housed in the housing 14 captures an image outside the housing 14 through the protective glass 18.

The housing 14 is supported by a tilt shaft (not shown) extending from the camera platform main body 16, and the tilt shaft is driven to rotate by a tilt motor built in the camera platform main body 16. The pan head main body 16 is supported by a pan shaft 19 fixed on a mounting table (not shown), and the pan head main body 16 is driven to rotate about the pan shaft 19 by a pan motor built in the pan head main body 16. Therefore, the head body 1
When the pan motor and the tilt motor built in 6 are driven, the camera housed in the housing 14 pans and tilts. A stepping motor is used as the pan motor and the tilt motor for the panning and the tilting, and the control thereof will be described later.

The camera platform controller 12 is connected to the camera platform 10 via a cable and a communication line such as a dedicated line or a public line, and transmits a control signal to the camera based on the operation of various operation members provided on the camera platform controller 12. The operation is transmitted to the platform 10 to control various operations of the camera platform 10 and the camera mounted on the camera platform 10. As shown in the plan view of FIG. 2, the pan head controller 12 is provided with an operation stick (joystick) 20, a focus knob 22, and a zoom knob 23. When the joy stick 20 is operated back and forth and right and left, the housing of the pan head 10 is provided. 14 (and the camera) can be panned and tilted, and the focus knob 2
2. When the zoom knob 23 is rotated, the housing 1
Focus adjustment and zoom adjustment of the camera No. 4 (lens device attached to the camera) can be performed. The pan head controller 12 is provided with switches based on various functions, but the description thereof will be omitted.

Next, control of the pan motor and the tilt motor of the camera platform 10 using a stepping motor will be described. FIG. 3 is a block diagram showing components related to the control of the pan motor and the tilt motor of the pan head 10 in the remote control pan head system. The CPU 30 of the pan head controller 12 shown in FIG. 3 detects the operation direction and the operation amount of the joystick 20 (see FIG. 2) at predetermined time intervals T by a digital signal via the A / D converter 31. A speed control signal for instructing a panning speed and a tilting speed based on the operation amount is output to the communication circuit 32. Hereinafter, a speed control signal for instructing a panning speed is referred to as a pan speed control signal, and a speed control signal for instructing a tilting speed is referred to as a tilt speed control signal. In particular, when these signals are not distinguished, they are simply referred to as a speed control signal.

The communication circuit 32 transmits the speed control signal output from the CPU 30 to the camera platform 10 via a communication line by serial communication.

The communication circuit 34 of the camera platform 10 receives the speed control signal transmitted from the camera platform controller 12 via a communication line, and supplies the received speed control signal to the motor control circuit 36.

The pan motor 38 and the tilt motor 40 of the camera platform 10 are both stepping motors that are pulse-controlled. The motor control circuit 36 controls these pan motors 38 based on the speed control signal received by the communication circuit 34.
And the rotation speed of the tilt motor 40 is controlled by a pulse signal. That is, upon receiving the pan speed control signal from the pan head controller 12, the motor control circuit 36 outputs a pulse train having a pulse frequency proportional to the panning speed commanded by the pan speed control signal to the pan motor 38.
As a result, the pan motor 38 rotates at a rotational speed proportional to the pulse frequency, and the camera of the camera platform 10 pans at the instructed panning speed. Similarly, when receiving the tilt speed control signal from the pan head controller 12, the motor control circuit 36 outputs a pulse train having a pulse frequency proportional to the tilting speed commanded by the tilt speed control signal to the tilt motor 40. . As a result, the tilt motor 40 rotates at a rotational speed proportional to the pulse frequency, and the head 1 is rotated at the commanded tilting speed.
Camera 0 tilts. Here, the pan motor 3
The use of the stepping motor for the tilt motor 8 and the tilt motor 40 allows the motor control circuit 36 to control the pan motor 38 and the tilt motor 40 in an open loop, thereby simplifying the circuit configuration.

The speed control signal also includes information on the magnitude and direction of the speed (rightward or leftward, upward or downward), and the rotation direction of the pan motor 38 and the tilt motor 40 depends on the direction of the speed control signal. Is controlled by the phase of the A-phase pulse train and the B-phase pulse train having the same pulse frequency, for example. However, the pulse frequencies of the A-phase pulse train and the B-phase pulse train are the same, and since the present invention mainly relates to the control of the pulse frequency, these A-phase and B-phase pulse trains will be described without distinction.

Next, the control contents of the motor control circuit 36 will be described in detail. Note that the pan motor 38 and the tilt motor 40 to be controlled by the motor control circuit 36 are controlled in exactly the same manner based on the pan speed control signal and the tilt speed control signal.
Only the control for is described. FIG. 4A is a graph showing an example of a pan speed control signal provided from the camera platform controller 12 to the motor control circuit 36.
The horizontal axis represents time, and the vertical axis represents the panning speed (or the rotation speed of the pan motor 38) specified by the pan speed control signal. As shown in the figure, the pan speed control signal indicates the magnitude of the panning speed to be instructed by the magnitude of the amplitude, and also indicates the panning direction (left-right direction) by the amplitude direction. Such a pan speed control signal is transmitted to the motor control circuit 36 not as an analog signal but as a digital signal, and is actually supplied to the motor control circuit 36 not continuously but as a digital value at predetermined time intervals T ( 4 (B) to 4 (C) described later).

When the motor control circuit 36 receives the pan speed control signal from the camera platform controller 12 at the above-described time intervals T, the panning speed at which the pan speed control signal instructs the pulse frequency of the pulse train to be output to the pan motor 38 at the time intervals T. To the pulse frequency corresponding (proportional) to
That is, the rotation speed of the pan motor 38 is changed according to the pulse frequency so that the pan speed control signal becomes the panning speed commanded. Note that a pulse frequency at which the pan speed control signal indicates the panning speed is hereinafter referred to as a pulse frequency based on the pan speed control signal.

However, as shown by a section X in FIG. 4A, when a situation occurs in which the motor control circuit 36 cannot temporarily receive the pan speed control signal due to a communication error or the like, The motor control circuit 36 does not stop the output of the pulse train to the pan motor 38 (sets the pulse frequency to 0), but gradually reduces the pulse frequency of the pulse train at a change rate within a limit that the pan motor 38 does not lose synchronism. A correction signal is output to the pan motor 38 to prevent the pan motor 38 from becoming uncontrollable due to step-out.

That is, as shown in FIG. 4B in which the vicinity of the section X is enlarged, the time t ₀ when the pan speed control signal is normally received.
After that, if the pan speed control signal cannot be received after a lapse of time T (time t ₀ + T), which should otherwise receive the next pan speed control signal (near time t _{0 in} FIG. 4B) 4 (C), which is an enlarged view of FIG. 4), the pulse frequency is sequentially reduced at intervals of time T at a rate of change within a limit at which the pan motor 38 does not lose synchronism. In the case described here, at time t ₀ + T
If the pan speed control signal cannot be received at this time, it is determined that the pan speed control signal has not been normally received, and the correction signal is output immediately. However, a predetermined time elapses after time t ₀ + T. If the pan speed control signal cannot be received after waiting for this, it may be determined that the pan speed control signal has not been normally received, and the correction signal may be output.

The pulse train (correction signal) output to the pan motor 38 by the processing when the pan speed control signal is not normally received, gradually attenuates the panning speed as indicated by the mark x in the section X in FIG. . Here, the stepping motor has a limit on the rotation speed that can be taken after a certain time according to the rotation speed due to its characteristics. If the limit is exceeded, a step-out phenomenon occurs, but the pan motor 38 does not step out. The change rate within the limit means a change rate of the pulse frequency (or the rotation speed of the pan motor 38) that does not exceed the limit.

On the other hand, the pan speed control signal can be normally received.
After disappearing, time t in FIG. ₁Bread as shown
When the speed control signal is received normally
Means that the motor control circuit 36 outputs a pulse to the pan motor 38
Immediately determine the pulse frequency of the train based on its pan speed control signal.
Instead of changing to a pulse frequency, the pan motor 38
The pulse frequency is set at the rate of change within the limit at which the
And outputs the increased or decreased correction signal, and outputs the correction signal
Pulse frequency based on the pan speed control signal
Change it to approach the number. This makes bread
The pulse train (correction signal) output to the motor 38 is shown in FIG.
Time t₁Thereafter, as indicated by the cross mark, the panning speed
Panning speed based on pan speed control signal
Approach the degree. Then, at time t in FIG._TwoAs shown
The pulse frequency of the correction signal (pan by the correction signal)
Pulse speed based on the pan speed control signal
(Panning speed commanded by pan speed control signal)
Then, after that, the pattern based on the pan speed control signal
The pulse train of the loose frequency is output to the pan motor 38.

When the correction signal is being output, the pulse frequency of the pulse train output to the pan motor 38 is changed at intervals of time T at a rate of change within a limit at which the pan motor 38 does not step out (that is, the pulse frequency is changed). Is changed, a pulse train is output at fixed time intervals during the time T)
However, the present invention is not limited to this, and the pulse frequency (interval between pulse trains) may be continuously changed at a change rate within a limit at which the pan motor 38 does not step out.

As described above, even when the pan speed control signal cannot be received due to a communication error or the like, an unexpected situation in which the pan motor 38 loses synchronism can be properly prevented. In this case, a stepping motor can be used.

FIG. 5 is a flowchart showing a processing procedure of the motor control circuit 36. First, the motor control circuit 36 communicates with the pan head controller 12 via the communication circuit 34.
(Step S)
10). Then, after a predetermined time T (time T is a time interval at which the pan speed control signal is transmitted) elapses (step S12), it is determined whether the pan speed control signal has been normally received during this time. (Step S14). It should be noted that whether or not the predetermined time T has elapsed in step S12 is measured by a timer, and the timer measures the predetermined time T, and if YES is determined in step S12, the timer is reset (the determination in step S22 below). In the same way). If YES is determined in step S14, a pulse train having a pulse frequency based on the pan speed control signal is output to the pan motor 38, and the pan head 10 is driven at the panning speed commanded by the pan speed control signal.
Is driven (step S16). Then, the process returns to step S10, and the same process is repeated at a cycle of the predetermined time T.

On the other hand, in step S14, N
O, that is, when it is determined that the pan speed control signal has not been normally received due to a communication error or the like, the correction signal in which the pulse frequency of the pulse train is reduced at a rate of change within the limit at which the pan motor 38 does not step out as described above. Output to the pan motor 38, the rotation speed of the pan motor 38 is reduced, and the panning speed is reduced (step S18). Subsequently, the reception of the pan speed control signal is started in the same manner as in steps S10 to S14 (step S20), and a predetermined time T elapses (step S22). It is determined whether or not it has been received (step S24). Thereby, when it is determined as NO,
The processing from step S18 is repeatedly executed at a cycle of the predetermined time T, and the rotation speed of the pan motor 38 is further reduced at a rate of change within a limit at which no step-out occurs, thereby reducing the panning speed. If the rotation of the pan motor 38 has stopped, only the processing from step S20 to step S24 is repeated.

On the other hand, in step S24, YES
That is, when it is determined that the communication is normal and the pan speed control signal has been normally received, the pulse frequency of the pulse train to the pan motor 38 (the pulse frequency of the correction signal) and the pulse frequency based on the pan speed control signal at the present time are one. It is determined whether or not they match (step S26). When the determination is NO, the pulse frequency of the correction signal is changed at a rate of change that does not cause the pan motor 38 to step out so that the pulse frequency of the correction signal to the pan motor 38 approaches the pulse frequency based on the pan speed control signal, The correction signal is sent to the pan motor 3
8 (step S28). Thereby, the panning speed is accelerated or decelerated to approach the panning speed commanded by the pan speed control signal. Then, the processing from step S20 is repeatedly executed at a cycle of a predetermined time T.

By repeating the processing from step S22 to step S30, the pulse frequency of the correction signal gradually approaches the pulse frequency based on the pan speed control signal. In step S26, YES, that is, the pulse frequency of the correction signal becomes If it is determined that the pulse frequency matches the pulse frequency based on the speed control signal, the process proceeds to step S16.
Then, a pulse train having a pulse frequency based on the pan speed control signal is output to the pan motor 38, and thereafter, the control returns to the normal control of the pan motor 38.

Although the control of the rotation speed of the pan motor 38 has been described above, the control of the rotation speed of the tilt motor 40 is performed in exactly the same manner.

In the above-described embodiment, the control of the stepping motor used as the pan motor 38 and the tilt motor 40 of the camera platform 10 has been described. However, the present invention is not limited to this. The same applies to the control of the stepping motor used.

[0031]

As described above, according to the pan head control apparatus of the present invention, when the speed control signal from the pan head controller cannot be received due to a communication error or the like, the rotational speed of the stepping motor is not lost. The stepping motor is decelerated at the rate of change within the range, so that even when the speed control signal cannot be received, the step-out is prevented and the normal operation of the stepping motor can be ensured. As a result, a stepping motor can be used as a motor for panning and tilting of the camera platform, and the cost can be reduced by reducing the number of parts.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a remote control pan head system to which the present invention is applied.

FIG. 2 is a plan view showing an operation member of the camera platform controller.

FIG. 3 is a block diagram showing components related to control of a pan motor and a tilt motor of the pan head in the remote control pan head system;

4A is a diagram illustrating an example of a pan speed control signal, and FIGS. 4B and 4C are enlarged views of a main part of FIG. 4A;

FIG. 5 is a flowchart illustrating a processing procedure of a motor control circuit;

[Explanation of symbols]

10 head, 12 head controller, 20 joystick, 30 CPU, 32, 34 communication circuit, 36
... Motor control circuit, 38 ... Pan motor, 40 ... Tilt motor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02P 8/14 H04N 5/225 C H04N 5/222 5/232 B 5/225 7/18 E 5/232 H02P 8/00 R 7/18 304A F term (Reference) 2H105 AA12 5C022 AB62 AB65 AC27 AC33 AC69 AC74 AC78 5C054 AA01 AA05 CF01 CF05 CG05 DA08 EA01 FF02 5H209 AA15 BB09 CC05 DD11 GG04 HH15 5H580 AA10 BB06 FA02

Claims (3)

[Claims] 1. A pulse train having a pulse cycle corresponding to a speed control signal transmitted by communication from a pan head controller to a stepping motor that pans or tilts a camera supported by the pan head,
In the camera platform control device for controlling the rotation speed of the stepping motor, when controlling the rotation speed of the stepping motor based on the speed control signal, if the speed control signal can no longer be received, A head control device, wherein the rotation speed is reduced at a rate of change within a limit that does not cause loss of synchronism. 2. If the speed control signal is received again after the speed control signal cannot be received, the speed control of the stepping motor is accelerated or decelerated within a limit not to lose synchronization. The pan head control device according to claim 1, wherein the rotation speed is made to coincide with the rotation speed corresponding to the signal. 3. The change rate within the limit at which no step-out occurs, which is a change rate of the rotation speed that can be obtained after a certain time with respect to the current rotation speed due to the characteristics of the stepping motor. 1 pan head controller.