Camera platform apparatus, method for controlling camera platform apparatus, and storage medium

Abstract

An error in the reference position due to backlash cannot be reduced.SOLUTION: A camera platform apparatus for changing an image capturing direction of an image capturing unit configured to capture an image of a subject, the camera platform apparatus comprising: a driving source configured to output a driving force; and a deceleration mechanism configured to decelerate the driving force of the driving source, wherein the driving force decelerated by the deceleration mechanism is transmitted to the driving source, An output shaft position detection unit that detects an output shaft position which is a position of the output shaft, and a control unit that controls the drive source, wherein the control unit determines, as a reference position for controlling the position of the drive source, the output shaft position acquired after the drive source is driven by a removal movement amount in a removal direction which is a direction in which backlash generated by the speed reduction mechanism is removed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a pan head device, a control method for a pan head device, and a program. [Background technology]

[0002] A known pan head device houses an imaging device used for monitoring, video distribution, and the like, and includes a pan drive unit that rotates the imaging device horizontally and a tilt drive unit that rotates the imaging device vertically, thereby controlling the imaging range. In such a pan head device, a reference position is set, and the positions of the pan drive unit and the tilt drive unit are controlled based on the reference position. For example, when the pan head device controls the position based on an absolute value encoder, the reference position is determined by acquiring the value of the absolute value encoder.

[0003] To obtain the required torque output, the pan drive unit and tilt drive unit may rotate the output shaft from the motor shaft via a reduction mechanism. The reduction mechanism has multiple gears. Backlash, which is a gap between the multiple gears to allow smooth rotation, is provided. This backlash causes an error in the reference position and is a cause of position control errors.

[0004] For example, Patent Document 1 discloses a method for controlling the drive of a television camera based on the output of a position detector provided in the drive unit, in which the amount of deviation between a specified position and an actual position is calculated and the drive is controlled by adjusting the amount of deviation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-247504 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the prior art disclosed in the above-mentioned Patent Document 1 describes drive control based on the calculated deviation amount, but does not describe setting a reference position. Therefore, the technology in Patent Document 1 cannot be applied to a device that controls drive based on a reference position, and cannot reduce errors in the reference position due to backlash.

[0007] Therefore, the present invention provides a technique that can reduce errors in the reference position due to backlash in a camera platform device. [Means for solving the problem]

[0008] In order to solve this problem, for example, the camera platform device of the present invention has the following configuration: A camera platform device for changing the shooting direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means determines the output shaft position obtained after driving the drive source a removal movement amount in a removal direction that removes backlash generated by the reduction mechanism as a reference position for controlling the position of the drive source. [Effects of the Invention]

[0009] According to the present invention, it is possible to reduce errors in the reference position due to backlash in the camera platform device. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram illustrating the overall configuration of a control system of the camera platform device according to the embodiment. [Figure 2]1A and 1B are a plan view and a side view of a camera platform device according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating a drive transmission system of a drive unit according to the embodiment. [Figure 4] 5A and 5B are diagrams illustrating the relationship between the motor control position and the output shaft position of the drive unit of the camera platform device according to the embodiment. [Figure 5] FIG. 4 is a flowchart showing a reference position determination process of the camera platform device according to the first embodiment. [Figure 6] FIG. 10 is a flowchart showing a reference position determination process of the camera platform device according to the second embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a movement amount table according to the second embodiment. [Figure 8] FIG. 11 is a flowchart showing a reference position determination process of the camera platform device according to the third embodiment. [Figure 9] FIG. 10 is a flowchart showing a reference position determination process of the camera platform device according to the fourth embodiment. [Figure 10] 10A and 10B are diagrams illustrating the relationship between the motor control position and the output shaft position of the drive unit of an example of a pan head device. [Figure 11] FIG. 2 is a block diagram showing the hardware configuration of a system control unit. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] (First embodiment) 1 is a diagram illustrating the overall configuration of a control system of a camera platform device 1000 according to an embodiment of the present invention. The overall configuration of the camera platform device 1000 will be described with reference to FIG.

[0013] The camera platform device 1000 holds an imaging device 2000 that captures an image of a subject, and changes the imaging direction, including the pan direction and tilt direction, of the imaging device 2000. The camera platform device 1000 is connected to the imaging device 2000 and a client device 3000. The camera platform device 1000 includes a pan driver 1004, a tilt driver 1005, a system controller 1006, and a communication unit 1007.

[0014] The pan driving unit 1004 performs a panning operation of the camera platform device 1000. The panning operation is an operation of rotating the imaging device 2000 in the left-right direction (i.e., the horizontal direction) around a vertical axis. The pan driving unit 1004 is communicably connected to the system control unit 1006 so as to be able to send and receive signals such as rotation instructions. The pan driving unit 1004 realizes panning using a mechanism that performs the panning operation, such as an actuator such as a brushless DC motor, and an encoder that detects the pan position. In this embodiment, the pan driving unit 1004 is built into either a bottom case 1101 or a turntable 1102, which will be described later.

[0015] The tilt driver 1005 performs a tilt operation of the camera platform device 1000. The tilt operation is an operation of rotating the imaging device 2000 up and down (i.e., vertically) around a horizontal axis extending left and right. The tilt driver 1005 is communicatively connected to the system controller 1006 so as to be able to send and receive signals such as rotation instructions. The tilt driver 1005 realizes tilt drive using a mechanism that performs the tilt operation, such as an actuator such as a brushless DC motor, and an encoder that detects the tilt position. In this embodiment, the tilt driver 1005 is built into either a camera head support 1103 or a camera head 1104, which will be described later.

[0016] The system control unit 1006 is responsible for overall control of the camera platform device 1000. The system control unit 1006 includes a processor such as a CPU (Central Processing Unit). The system control unit 1006 is connected to a client device 3000, which is an information processing device (also called a computer), via a communication unit 1007 so as to be able to send and receive signals. The system control unit 1006 controls the camera platform device 1000 by exchanging signals including commands and responses with the client device 3000. That is, the system control unit 1006 receives commands sent from the client device 3000, analyzes the acquired commands, and executes processing according to the commands. The system control unit 1006 then transmits responses to the commands to the client device 3000. For example, the system control unit 1006 controls the imaging device 2000 based on instructions from commands related to camera control. The system control unit 1006 controls the pan driving unit 1004 and the tilt driving unit 1005 based on instructions from commands related to pan and tilt control to rotate the shooting direction of the imaging device 2000 in the pan direction and tilt direction. The system control unit 1006 receives image data, which is data of an image generated by the imaging device 2000 capturing an image of a subject. The system control unit 1006 transmits the received image data to the client device 3000 via the communication unit 1007. The term "image" may include still images, moving images, video, and data thereof. The system control unit 1006 is equipped with a nonvolatile memory, and stores and registers various data such as preset positions, which will be described later.

[0017] The communication unit 1007 is connected to the client device 3000 via a network, serial communication, etc., and transmits and receives signals to and from the client device 3000. The communication unit 1007 receives commands related to pan / tilt control and camera control from the client device 3000. The communication unit 1007 transmits responses from the system control unit 1006 to the client device 3000. The communication unit 1007 transmits image data received from the imaging device 2000 to the client device 3000.

[0018] The imaging device 2000 includes a lens, an imaging element, and a control circuit. The imaging device 2000 receives light from a subject that is imaged by an imaging optical system including a lens, and converts the optical image of the subject into an electrical signal through photoelectric conversion. The imaging device 2000 generates image data by performing image processing such as development, compression, and encoding on the photoelectrically converted electrical signal. The imaging device 2000 includes an optical zoom control mechanism that can change the imaging angle of view. The imaging device 2000 includes a focus control mechanism that can adjust the focus of the captured image. The imaging device 2000 is connected to the camera platform device 1000. Based on instructions from the client device 3000 acquired from the camera platform device 1000, the imaging device 2000 adjusts the imaging angle of view through zoom control and the focus of the captured image through focus. The imaging device 2000 transmits the generated image data to the camera platform device 1000. As a result, the image data is transmitted to the client device 3000 via the camera platform device 1000 .

[0019] 11 is a block diagram showing the hardware configuration of the system control unit 1006. The system control unit 1006 is, for example, a computer. The system control unit 1006 has a processor 1191, a memory 1192, a storage 1193, an input IF 1195, an output IF 1196, and a bus 1197. The processor 1191, the memory 1192, the storage 1193, the input IF 1195, and the output IF 1196 are connected via the bus 1197 so as to be able to transmit and receive information to and from each other.

[0020] The processor 1191 is an arithmetic processing device, such as a CPU (Central Processing Unit). The system control unit 1006 may include other processors, such as an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), or a QPU (Quantum Processing Unit), instead of or in addition to the CPU. The processor 1191 implements various functions and executes various processes by reading programs stored in the storage 1193 and expanding the programs in the memory 1192. For example, the processor 1191 executes each step of the reference position determination process, which will be described later, by reading a computer program. Some or all of the steps of the reference position determination process may be executed by one or more circuits, such as an ASIC (Application Specific Integrated Circuit) and an FPGA (Field Programmable Gate Array).

[0021] The memory 1192 is a high-speed readable / writable storage device such as a RAM (Random Access Memory). The memory 1192 functions as a work area when the processor 1191 executes a program. The memory 1192 temporarily stores the program and parameters necessary for executing the program. For example, in the reference position determination process, the memory 1192 stores the detected motor control position, output shaft position, and reference position as a processing result.

[0022] The storage 1193 is a non-volatile storage device such as a hard disk drive (HDD) or a solid state drive (SSD), etc. The storage 1193 holds programs, parameters required for executing the programs, and results of executing the programs even when power is not supplied.

[0023] The input IF 1195 is an interface for receiving information input from an input device, such as a mouse, a keyboard, or a touch panel.

[0024] The output IF 1196 is an interface for outputting information such as processing results to a display device such as a display.

[0025] Next, with reference to FIG. 2, the mechanical configuration of the camera platform device 1000 will be described in detail. FIG. 2 is a plan view and a side view of the camera platform device 1000 according to an embodiment. FIG. 2(a) is a plan view of the mechanical mechanism of the camera platform device 1000 viewed from above the vertical axis. FIG. 2(b) is a side view of the camera platform device 1000. As shown in FIG. 2, the camera platform device 1000 has a bottom case 1101, a turntable 1102, a camera head support 1103, and a camera head 1104. In this embodiment, the imaging device 2000 is built into the camera head 1104. In this embodiment, the pan drive unit 1004 is built into either the bottom case 1101 or the turntable 1102, which will be described later.

[0026] The bottom case 1101 functions as a base for the entire camera platform device 1000, including the pan drive unit 1004 and tilt drive unit 1005. The bottom case 1101 is disposed below the turntable 1102.

[0027] The turntable 1102 carries a camera head support 1103 (described later) and rotates about a vertical axis to drive the turntable in the panning direction, i.e., to pan the camera platform device 1000. The turntable 1102 can rotate in the panning direction from -175 degrees to +175 degrees.

[0028] That is, the mechanism, actuator, and encoder that perform the panning operation of the pan driving unit 1004 are built into either the bottom case 1101 or the turntable 1102. This allows the pan driving unit 1004 to rotate the imaging device 2000 in the pan direction from −175 degrees to +175 degrees. In this embodiment, the pan driving unit 1004 is built into either the bottom case 1101 or the turntable 1102, but may have another configuration. For example, the pan driving unit 1004 may not be built into either the bottom case 1101 or the turntable 1102, but may be arranged in another member.

[0029] The camera head support pillar 1103 extends vertically and is a support pillar that supports the camera head 1104, which will be described later. The camera head support pillar 1103 is disposed on the central axis of the turntable 1102. The camera head support pillar 1103 holds the camera head 1104 on the side opposite the turntable 1102 (here, the upper end).

[0030] The camera head 1104 is hollow. The camera head 1104 houses the imaging device 2000. The camera head 1104 is disposed at the upper end of a camera head support 1103. The camera head 1104 is driven in the tilt direction, that is, performs the tilt operation of the camera platform device 1000, around an axis perpendicular to the vertical axis as the central axis. The camera head 1104 can rotate from -45 degrees diagonally downward and forward to +90 degrees upward, with the horizontal direction being 0 degrees.

[0031] That is, the mechanism, actuator, and encoder that perform the tilt operation of tilt drive unit 1005 are built into either camera head support 1103 or camera head 1104. This allows tilt drive unit 1005 to rotate imaging device 2000 from a downward forward angle of −45 degrees to an upward angle of +90 degrees.

[0032] In addition, in this embodiment, tilt driving unit 1005 is built into either camera head support 1103 or camera head 1104, but may have other configurations. For example, tilt driving unit 1005 may not be built into either camera head support 1103 or camera head 1104, but may be disposed in another member.

[0033] In this way, the camera platform device 1000 of this embodiment can change the imaging direction by rotating the camera head 1104 in the pan direction and tilt direction, allowing the imaging device 2000 to capture an image. Note that the driving ranges of the pan direction and tilt direction of this embodiment are merely examples and are not limited to these. For example, the driving ranges of the pan direction and tilt direction may be configured to allow endless rotation.

[0034] 3 is a diagram illustrating the drive transmission system of the pan driver 1004 and the tilt driver 1005. The configuration of the internal drive transmission system of the pan driver 1004 and the tilt driver 1005 will be described with reference to FIG. 3. The pan driver 1004 and the tilt driver 1005 have roughly the same configuration. The pan driver 1004 and the tilt driver 1005 each have a motor 1201, a motor shaft encoder 1202, a reduction mechanism 1203, an output shaft 1204, and an output shaft encoder 1205.

[0035] The motor 1201 outputs a driving force as a rotational driving force and functions as a driving source for the pan driving unit 1004 and the tilt driving unit 1005. The rotation of the motor 1201 rotates an output shaft 1204, which is a rotation shaft for panning or tilting, via a speed reducing mechanism 1203. As a result, the motor 1201 rotates the imaging device 2000 in either the pan direction or the tilt direction. The motor 1201 may be, for example, a brushless DC motor.

[0036] The motor shaft encoder 1202 is provided on the motor shaft. The motor shaft encoder 1202 may be an incremental encoder or the like. The motor shaft encoder 1202 functions as a position detector that detects the position of the motor shaft (also called the motor control position). The motor shaft encoder 1202 outputs information on the detected motor shaft position to the processor 1191 of the system control unit 1006. The motor shaft encoder 1202 is an example of a drive control position detection means.

[0037] The speed reducing mechanism 1203 is made up of multiple stages of gears and belts, etc. The speed reducing mechanism 1203 reduces the rotation speed of the motor 1201, that is, reduces the driving force, and outputs the required torque to the output shaft 1204.

[0038] The output shaft 1204 is connected to the speed reducer 1203. Therefore, the driving force from the motor 1201, which has been reduced in speed via the speed reducer 1203, is transmitted to the output shaft 1204, and the output shaft 1204 outputs the transmitted rotational drive. As a result, the output shaft 1204 rotates the camera head 1104 in the pan direction or tilt direction, thereby changing the shooting direction of the imaging device 2000.

[0039] The output shaft encoder 1205 is provided on the output shaft 1204. The output shaft encoder 1205 may be an absolute value encoder or the like. The output shaft encoder 1205 functions as a position detector that detects the positions of the output shafts (also referred to as output shaft positions) of the pan driver 1004 and the tilt driver 1005. The output shaft encoder 1205 outputs information on the detected output shaft position to the processor 1191 of the system control unit 1006. The output shaft encoder 1205 is an example of an output shaft position detection means.

[0040] Here, a brushless DC motor has been described as an example of the motor 1201 serving as the drive source, but the motor 1201 is not limited to this and other types of actuators may be used. Also, while the configuration has been shown in which an incremental encoder is used as the motor shaft position detector and an absolute encoder is used as the output shaft position detector, this is not limiting and other types of position detectors may be used. Also, the configuration has been shown in which the position of the output shaft 1204 is directly detected using the output shaft encoder 1205 provided on the output shaft 1204, but this is not limiting. An encoder may be provided on a rotating shaft that rotates from the output shaft 1204 via the reduction gear mechanism 1203, and the encoder may be used to indirectly detect the position on the output shaft 1204.

[0041] The processor 1191 of the system control unit 1006 of the camera platform device 1000 of this embodiment registers, in the storage 1193, preset information that associates the position of the pan driver 1004, the position of the tilt driver 1005, the zoom control position of the imaging device 2000, and a preset number. Alternatively, the processor 1191 may register preset information that associates at least one of the position of the pan driver 1004, the position of the tilt driver 1005, and the zoom control position with a preset number. Furthermore, the processor 1191 may register preset information that includes image quality settings and the like in addition to the position of the pan driver 1004, the position of the tilt driver 1005, and the zoom control position.

[0042] Here, the camera platform device 1000 is configured so that the pan driver 1004 and tilt driver 1005 can be remotely controlled via a network and a dedicated line. Therefore, for example, when the processor 1191 receives a predetermined command and a registered preset number from a remote operator, it calls up preset information associated with the preset number. Based on the preset information, the processor 1191 controls the pan driver 1004, tilt driver 1005, and other components to execute a preset function that moves them to a preset position. Furthermore, the system control unit 1006 instructs the pan driver 1004 and tilt driver 1005 to move to the preset position within a predetermined time, thereby realizing a function called "shot" that coordinates and controls the pan and tilt movement times.

[0043] Figure 4 is a diagram illustrating the relationship between the motor control position and output shaft position of the drive unit of the camera head device 1000 of this embodiment. In Figure 4, the horizontal axis represents time. The vertical axis represents the motor control position, i.e., the value of the motor shaft encoder 1202, and the output shaft position, i.e., the value of the output shaft encoder 1205. The solid line represents the movement trajectory LA of the motor control position detected by the motor shaft encoder 1202. The dotted line represents the movement trajectory LB of the output shaft position detected by the output shaft encoder 1205.

[0044] At time t0 shown in FIG. 4, backlash is relatively small. Therefore, if the system control unit 1006 reads the output shaft position, which is the value of the output shaft encoder 1205 at position me0 at time t0, and determines that output shaft position as the reference position, an error will occur in the reference position, as described above. Therefore, the system control unit 1006 drives the motor 1201 in the removal direction by a small amount of movement (hereinafter also referred to as the removal movement amount) that is sufficient to remove the backlash. The removal direction may be a direction that removes or reduces the backlash. The removal movement amount sufficient to remove the backlash may be, for example, a movement amount greater than the maximum backlash. From time t0 to time t1 after driving starts, the output shaft 1204 does not rotate due to backlash. Therefore, the output shaft position detected by the output shaft encoder 1205 does not change and begins to change after time t1. At time t2, when the motor 1201 has been driven by a distance sufficient to remove the backlash, the system control unit 1006 reads the output shaft position detected by the output shaft encoder 1205 and determines the read position me1 as the reference position. The system control unit 1006 may also set the motor control position to position me1 as the reference position.

[0045] Thereafter, the system control unit 1006 uses the determined reference position to control the position of the motor 1201 based on the motor control position, causing the motor 1201 to reach position me2 at time t3. As a result, the output shaft position detected by the output shaft encoder 1205 reaches position oe2 at time t3, and the system control unit 1006 can reduce errors in the reference position due to backlash, regardless of the output shaft position when determining the reference position.

[0046] Fig. 5 is a flowchart showing the reference position determination process of the camera platform device 1000 of the first embodiment. The processor 1191 of the system control unit 1006 reads out a computer program stored in the storage 1193, loads the program and various data into the memory 1192, and executes the reference position determination process of this flowchart. When determining a reference position, the system control unit 1006 may execute the flowchart of Fig. 5 during initialization processing when the device is powered on, for example. For simplicity, this embodiment will explain the reference position determination process in the pan direction, but the reference position determination process in the tilt direction will also be performed using a similar flow.

[0047] In step S1001, the system control unit 1006 drives the motor 1201 of the pan drive unit 1004 by a removal movement amount in the removal direction. The removal direction may be a direction that removes or reduces backlash. For example, the system control unit 1006 may set the removal direction in consideration of the backlash-related characteristics of the speed reducer 1203 of the pan drive unit 1004, the influence of the weight of the camera head 1104 and other components, the movement direction before executing this process, and the like. The removal movement amount may be set based on the backlash as a movement amount sufficient to remove the backlash. Specifically, the removal movement amount may be preset to a value that adds an excess amount that takes into account variation based on design values ​​and actual measurement results, etc. If there is no difference in the amount of backlash removed depending on the direction, the system control unit 1006 may drive the motor 1201 in either direction. Here, the system control unit 1006 drives the motor 1201 by a removal movement amount of 1 degree in the positive direction, which is the removal direction.

[0048] In step S1002, the system control unit 1006 acquires the output shaft position from the output shaft encoder 1205 provided on the output shaft 1204 of the pan drive unit 1004, determines the acquired output shaft position as a reference position, and ends this process. Thereafter, the system control unit 1006 performs position control using the motor control position of the motor 1201 based on the determined reference position.

[0049] The system control unit 1006 also performs the tilt control of the camera platform device 1000 in the same manner as the pan control.

[0050] As described above, in the configuration in which the pan head device 1000 of the first embodiment determines the reference position for position control using the output shaft encoder 1205 of the output shaft 1204 of the pan drive unit 1004 and the tilt drive unit 1005, the motor 1201 of the pan drive unit 1004 and the tilt drive unit 1005 is driven in the removal direction by a removal movement amount sufficient to remove backlash, and then the reference position is determined, thereby making it possible to reduce errors in the reference position due to backlash. Furthermore, because the pan head device 1000 removes backlash by driving the motor 1201 in the removal direction by a removal movement amount, it is also possible to shorten the initialization processing time for processing to determine the reference position and reduce the processing load.

[0051] The pan head device 1000 of the first embodiment includes a brushless DC motor as the motor 1201 that is the drive source for the pan drive unit 1004 and the tilt drive unit 1005, and a motor shaft encoder 1202 that detects the motor control position of the motor 1201 on the motor shaft. Although the pan head device 1000 has been described as controlling the position of the motor 1201 using the motor control position detected by the motor shaft encoder 1202, the control method is not limited to this. For example, even in a configuration in which the pan head device 1000 uses a stepping motor as the drive source motor 1201 and the system control unit 1006 controls the motor control position using the number of steps and pulses of the stepping motor, the reference position may be determined using a method similar to that of the first embodiment.

[0052] (Second embodiment) Next, a method for appropriately controlling the elimination of backlash in accordance with the conditions of the second embodiment will be described with reference to Figures 6, 7, and 10. The same components as those in the first embodiment will be designated by the same reference numerals, and detailed descriptions thereof will be omitted, with the focus being on differences from the first embodiment. This method of omitting descriptions will also be used in the other embodiments described later.

[0053] In the first embodiment, a method for determining a reference position in which a uniform amount of movement for removing backlash is performed has been described. However, the method for determining a reference position is not limited to this. For example, the system control unit 1006 may change the amount of movement for removing backlash when determining a reference position depending on the position of the motor 1201 of the pan drive unit 1004. Furthermore, when the position of the motor 1201 of the tilt drive unit 1005 is 0 degrees, i.e., facing horizontally, backlash may be reduced due to the influence of the camera head 1104's own weight. In this case, movement for removing backlash is unnecessary. As such, the state of backlash may vary depending on the position of the motor 1201. Therefore, the system control unit 1006 may set the amount of movement for removing backlash depending on the output shaft positions of the motor 1201 of the tilt drive unit 1005 and the pan drive unit 1004 when determining a reference position.

[0054] Next, errors due to different backlashes will be described with reference to FIG.

[0055] FIG. 10 is a diagram illustrating the relationship between the motor control position and output shaft position of the drive unit of an example pan head device. FIG. 10(a) shows a state where the backlash is relatively small, and FIG. 10(b) shows a state where the backlash is relatively small. In FIG. 10, the horizontal axis is the time axis. The vertical axis shows the motor control position, i.e., the value of the motor shaft encoder 1202, and the output shaft position, i.e., the value of the output shaft encoder 1205. The solid line shows the movement trajectory LA of the motor shaft encoder 1202. The dotted line shows the movement trajectory LB of the output shaft encoder 1205.

[0056] At time t0 in FIG. 10(a), the system control unit 1006 reads the output shaft position detected by the output shaft encoder 1205 and determines a reference position. Based on the determined reference position, the system control unit 1006 sets the value of the motor shaft encoder 1202 to position me0. From there, the system control unit 1006 drives the motor 1201 to position me1 based on the motor control position. At this time, the motor control position detected by the motor shaft encoder 1202 changes linearly as shown by movement trajectory LA. Meanwhile, due to backlash in the reduction gear mechanism 1203, there is a period at the start of drive when the output shaft 1204 does not rotate even though the motor 1201 rotates. Specifically, the output shaft position detected by the output shaft encoder 1205 does not change from time t0 to time t1, as shown by movement trajectory LB, but begins to change after time t1, and then changes linearly thereafter. Then, at time t2, when the motor control position of the motor 1201 reaches position me1, the output shaft position detected by the output shaft encoder 1205 becomes position oe1, which is slightly short of position me1.

[0057] Similarly, in Figure 10(b), the system control unit 1006 reads the output shaft position detected by the output shaft encoder 1205 at time t0 to determine a reference position, and sets the value of the motor shaft encoder 1202 to position me0 based on the determined reference position. From there, the system control unit 1006 moves the motor 1201 to position me1. At this time, the motor control position of the motor shaft encoder 1202 and the output shaft position of the output shaft encoder 1205 follow a movement trajectory similar to that in Figure 10(a). Specifically, at the start of drive, there is a period during which the motor rotates but the output shaft does not rotate due to backlash in the reduction mechanism, that is, the period from time t0 to t1 during which the value of the output shaft encoder 1205 does not change. This period is slightly longer in Figure 10(b) than in Figure 10(a) because the backlash is relatively small. Furthermore, at time t2, when the motor 1201 reaches position me1, the position oe1 detected by the output shaft encoder 1205 is further short in Fig. 10(b) than in Fig. 10(a). In the states of Fig. 10(a) and Fig. 10(b), different errors occur in the stopping position at time t2 when the motor 1201 reaches position me1.

[0058] In this way, if the system control unit 1006 determines the reference position based on the output shaft position detected by the output shaft encoder 1205, an error will occur in the reference position depending on the position state of the fluctuation range of the backlash. Furthermore, if the system control unit 1006 performs position control of the motor 1201 based on the reference position under different backlash conditions, different errors will occur in the stop position.

[0059] Fig. 6 is a flowchart showing the reference position determination process of the camera platform device 1000 of the second embodiment. The processor 1191 of the system control unit 1006 reads out a computer program stored in the storage 1193, loads the program and various data into the memory 1192, and executes the reference position determination process of this flowchart. When determining a reference position, the system control unit 1006 may execute the flowchart of Fig. 6 during initialization processing when the device is powered on, for example. For simplicity, this embodiment will explain the reference position determination process in the pan direction, but the reference position determination process in the tilt direction will also be performed using a similar flow.

[0060] In step S 2001 , the system control unit 1006 acquires the output shaft position of the pan driving unit 1004 from the output shaft encoder 1205 .

[0061] In step S2002, the system control unit 1006 determines the removal movement amount for removing backlash based on the acquired output shaft position of the pan driving unit 1004 and on the movement amount table.

[0062] FIG. 7 is a diagram showing an example of a movement amount table. The movement amount table associates multiple ranges of the output axis position of the pan drive unit 1004 with removal movement amounts for removing backlash. The removal movement amounts in the movement amount table are, for example, sufficient movement amounts to remove backlash depending on the range of each output axis position of the pan drive unit 1004. The removal movement amounts are calculated based on design values ​​and actual measurement results of backlash, etc., and include an extra amount that takes backlash variation into account. In the movement amount table of FIG. 7, when the output axis position of the pan drive unit 1004 is between -175 degrees and -90 degrees, the removal movement amount is 0.5 degrees. When the output axis position of the pan drive unit 1004 is between -90 degrees and 90 degrees, the removal movement amount is 1.0 degrees. When the output axis position of the pan drive unit 1004 is between 90 degrees and 175 degrees, the removal movement amount is 0.7 degrees. In this movement amount table, the output shaft position of the pan drive unit 1004 is divided into three ranges, and a movement amount is associated with each range, but the number of divisions may be changed as appropriate.

[0063] If the relationship between the output shaft position of the pan driver 1004 and the amount of movement required to remove backlash can be expressed by a predetermined mathematical formula, the system control unit 1006 may calculate the amount of movement required to remove backlash using the formula rather than the movement amount table. Here, the system control unit 1006 sets the output shaft position of the pan driver 1004 acquired from the output shaft encoder 1205 to -100 degrees, and determines the amount of movement required to remove backlash to be 0.5 degrees based on the movement amount table.

[0064] In step S2003, the system control unit 1006 drives the motor 1201 of the pan drive unit 1004 in the removal direction by the removal movement amount determined based on the movement amount table. The system control unit 1006 may set the direction that removes or reduces backlash as the removal direction. In this example, the system control unit 1006 drives the motor 1201 in the positive direction by the 0.5 degrees set in step S2002.

[0065] In step S2004, the system control unit 1006 acquires the output shaft position from the output shaft encoder 1205 of the pan drive unit 1004, determines the acquired output shaft position as a reference position, and ends this process. Thereafter, the system control unit 1006 executes position control using the motor control position of the motor 1201 based on the determined reference position.

[0066] The camera platform device 1000 also performs the reference position determination process for tilt control in the same manner as for pan control.

[0067] The camera platform device 1000 of the second embodiment determines the reference position by removing backlash based on the amount of removal movement determined according to the position in the pan direction. As a result, the second embodiment can appropriately remove backlash and accurately determine the reference position even if the amount of backlash differs at multiple positions in the pan direction due to the tolerances of each component, assembly errors, etc.

[0068] (Third embodiment) Next, a method for appropriately controlling the elimination of backlash in accordance with the conditions of the third embodiment will be described with reference to Fig. 8. The same components as those in the above-described embodiment will be designated by the same reference numerals, and detailed descriptions thereof will be omitted. The following description will focus on the differences from the above-described embodiment. This method of omitting descriptions will also be applied to the other embodiments described below.

[0069] Although the second embodiment describes a method in which control for backlash removal is performed in a uniform sequence, this is not limiting. For example, the output shaft position of the pan drive unit 1004 may be near the limit position where it can be driven in the movement direction for backlash removal. In this case, the drive of the motor 1201 of the pan drive unit 1004 is limited to the limit position, and the pan drive unit 1004 cannot be driven sufficiently to remove the backlash. In this case, the system control unit 1006 first determines, based on the output shaft position, whether to drive the pan drive unit 1004 in the direction opposite to the backlash removal direction, i.e., the direction opposite to the limit position. Then, for example, if the output shaft position is within a predetermined range from the limit position, the system control unit 1006 may drive the motor 1201 in the direction opposite to the removal direction and then drive it in the removal direction for backlash removal to determine the reference position.

[0070] Fig. 8 is a flowchart showing the reference position determination process of the camera platform device 1000 of the third embodiment. The processor 1191 of the system control unit 1006 reads out a computer program stored in the storage 1193, loads the program and various data into the memory 1192, and executes the reference position determination process of this flowchart. When determining a reference position, the system control unit 1006 may execute the flowchart of Fig. 8 during initialization processing when the device is powered on, for example. For simplicity, this embodiment will explain the reference position determination process in the pan direction, but the reference position determination process in the tilt direction will also be performed using a similar flow.

[0071] In step S 3001 , the system control unit 1006 acquires the output shaft position of the pan driving unit 1004 from the output shaft encoder 1205 .

[0072] In step S3002, the system control unit 1006 determines whether the acquired output shaft position of the pan driver 1004 is close to the limit position in the removal direction for backlash removal. As described above, the limit position in the pan direction is 175 degrees in both the positive and negative directions. Here, the system control unit 1006 determines whether the removal direction for backlash removal is set to the positive direction and determines whether the output shaft position is close to the limit position in the positive direction. Specifically, the system control unit 1006 may determine whether the output shaft position is close to the limit position based on whether the output shaft position is within a predetermined position range, here, +174 degrees or greater. If the system control unit 1006 determines that the output shaft position is close to the limit position, the process proceeds to S3003. If the system control unit 1006 determines that the output shaft position is not close to the limit position, the process proceeds to S3004. For example, if the output shaft position is +174.8 degrees, the system control unit 1006 determines that the output shaft position is close to the limit position and proceeds to S3003.

[0073] In step S3003, the system control unit 1006 calculates the amount of movement and drives the motor 1201 of the pan drive unit 1004 by the calculated amount of movement in the direction opposite to the removal direction (here, the positive direction) for removing the backlash. Specifically, the system control unit 1006 drives the motor 1201 of the pan drive unit 1004 by the calculated amount of movement in the direction opposite to the limit position in the positive direction, i.e., in the negative direction. The system control unit 1006 calculates the amount of movement in the opposite direction by adding a predetermined amount of movement to the removal movement amount sufficient to remove the backlash. In other words, the amount of movement is greater than the removal movement amount. For example, as shown in the following equation, the system control unit 1006 adds 1.0 degree to 0.5 degrees, which is the removal movement amount sufficient for removing the backlash shown in FIG. 7, to calculate 1.5 degrees as the amount of movement in the opposite direction.

[0074] 0.5 + 1.0 = 1.5 degrees The system control unit 1006 drives the motor 1201 of the pan driving unit 1004 by 1.5 degrees, which is the calculated movement amount, in the negative direction.

[0075] In step S3004, the system control unit 1006 drives the motor 1201 of the pan drive unit 1004 in the removal direction by a removal movement amount. The removal direction here may be a direction approaching the limit position. The removal movement amount may be a movement amount sufficient to remove the backlash shown in the movement amount table of FIG. 7, for example, 0.5 degrees.

[0076] In step S3005, the system control unit 1006 acquires the output shaft position of the pan driver 1004 from the output shaft encoder 1205, determines the acquired output shaft position as the reference position, and ends this process. Thereafter, the system control unit 1006 performs position control of the motor control position of the motor 1201 based on the reference position determined here.

[0077] The tilt control of the camera platform device 1000 is also processed in the same manner as the pan control.

[0078] In the third embodiment, when the camera is at a limit position where a sufficient amount of movement to remove backlash cannot be ensured, the pan head device 1000 drives the motor 1201 of the pan drive unit 1004 in the direction opposite to the removal direction, and then drives it in the removal direction. This allows the camera to sufficiently remove backlash even at the limit position, and to accurately determine the reference position.

[0079] In the pan head device 1000 of the third embodiment, the movement amount for driving in the direction opposite to the removal direction is set to be larger than the removal movement amount that can sufficiently remove backlash. As a result, when driving the motor 1201 in the removal direction, the pan head device 1000 can drive the motor 1201 by the removal movement amount that can sufficiently remove backlash.

[0080] (Fourth embodiment) Next, a method for appropriately controlling the amount of backlash removal according to the conditions of the fourth embodiment will be described with reference to Fig. 9. The same components as those in the above-described embodiments will be designated by the same reference numerals, and detailed descriptions thereof will be omitted. The following description will focus on the differences from the above-described embodiments. This method of omitting descriptions will also be applied to the other embodiments described below.

[0081] In the first embodiment, a method for determining the reference position is described in which the removal direction of the motor 1201 for backlash removal is a uniform direction. However, the method for determining the reference position is not limited to this. For example, the installation orientation of the camera head device 1000 includes an upright state and an inverted state. The inverted state is, for example, a state in which the camera head device 1000 is installed upside down on a ceiling, a pole, or the like. Since the direction of the force due to the weight of the camera head 1104 varies depending on the installation orientation, the removal direction for backlash removal changes depending on the installation orientation. In such a case, the system control unit 1006 may set the removal direction for backlash removal based on the installation orientation of the camera head device 1000.

[0082] 9 is a flowchart showing the reference position determination process of the camera platform device 1000 of the fourth embodiment. The processor 1191 of the system control unit 1006 reads out a computer program stored in the storage 1193, loads the program and various data into the memory 1192, and executes the reference position determination process of this flowchart. When determining a reference position, the system control unit 1006 may execute the flowchart of FIG. 9 during initialization processing when the device is powered on, for example. For simplicity, this embodiment will explain the reference position determination process in the tilt direction, but the reference position determination process in the pan direction will also be performed using a similar flow.

[0083] In step S4001, the system control unit 1006 acquires information about the installation orientation of the pan head device 1000. The system control unit 1006 may receive information about whether the installation orientation of the pan head device 1000 is upright or inverted from the operator via an input device. Alternatively, the pan head device 1000 may be provided with a sensor that detects the direction of gravity, such as an acceleration sensor, and the system control unit 1006 may determine the installation orientation based on the acceleration value acquired from the acceleration sensor. Here, the installation orientation of the pan head device 1000 is assumed to be inverted.

[0084] In step S4002, the system control unit 1006 determines the removal direction of the motor 1201 of the tilt drive unit 1005 based on the installation attitude of the camera head device 1000. The removal direction is the direction that removes backlash in the tilt drive unit 1005 and is determined by the installation attitude. For example, when the camera head device 1000 is in an upright position, a force acts on the tilt drive unit 1005 in a downward direction, i.e., a negative direction, due to the influence of the weight of the camera head 1104. In this case, the system control unit 1006 determines the removal direction to be a positive direction. On the other hand, when the camera head device 1000 is in an inverted position, a force acts on the tilt drive unit 1005 in an upward direction, i.e., a positive direction. In this case, the system control unit 1006 determines the removal direction to be a negative direction. In this case, since the installation attitude is in an inverted position, the system control unit 1006 determines the removal direction to be a negative direction.

[0085] In step S4003, the system control unit 1006 drives the motor 1201 of the tilt drive unit 1005 by the removal movement amount in the removal direction determined in step S4002. The system control unit 1006 may determine the removal movement amount in the same manner as in the above-described embodiment. Here, the system control unit 1006 drives the motor 1201 by the removal movement amount of 0.5 degrees in the negative direction, which is the removal direction.

[0086] In step S4004, the system control unit 1006 acquires the output shaft position of the tilt drive unit 1005 from the output shaft encoder 1205. The system control unit 1006 sets the acquired output shaft position as the reference position and ends this process. Thereafter, the system control unit 1006 performs position control of the motor control position of the motor 1201 based on the determined reference position.

[0087] The pan control of the camera platform device 1000 is also processed in the same manner as the tilt control.

[0088] The pan / tilt head device 1000 of the fourth embodiment determines the removal direction in accordance with the installation posture of the pan / tilt head device 1000, drives the motor 1201 in the removal direction, removes backlash, and determines the reference position. This allows the pan / tilt head device 1000 to appropriately remove backlash and determine the reference position regardless of the set posture.

[0089] As described above, the camera platform device 1000 of each embodiment determines the reference position for position control using the output shaft encoder 1205 of the pan driver 1004 and the tilt driver 1005. In this configuration, the camera platform device 1000 determines the reference position after performing control for backlash removal using a more appropriate removal movement amount, removal direction, and control sequence based on the positions of the pan driver 1004 and the tilt driver 1005 and the installation attitude of the camera platform device 1000. This allows the camera platform device 1000 to reduce errors in the reference position due to backlash, and also shortens the initialization processing time and reduces the processing load for determining the reference position.

[0090] The above-described embodiments may be combined. When the embodiments are combined, a method for determining the reference position may be received from the operator.

[0091] In the above embodiment, an example has been described in which the imaging device 2000 and the pan head device 1000 are separate entities, but the configuration of the pan head device 1000 is not limited to this. For example, the pan head device may be configured integrally with the imaging device.

[0092] (Other Examples) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0093] The disclosure of this specification includes the following pan head device, pan head device control method, and program. (Item 1) A camera platform device for changing the shooting direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means determines the output shaft position acquired after driving the drive source by a removal movement amount in a removal direction that removes backlash generated by the reduction gear mechanism as a reference position for controlling the position of the drive source. A pan head device characterized by: (Item 2) a drive control position detection means for detecting a control position of the drive source; 2. The pan head device according to item 1, comprising: (Item 3) the drive source is a stepping motor, The control means uses the number of pulses of the stepping motor as a control position of the drive source. 2. The pan head device according to item 1, (Item 4) The control means The removal movement amount is determined based on the backlash of the reduction mechanism. 4. The pan head device according to any one of items 1 to 3, characterized in that: (Item 5) The control means The removal movement amount is determined based on the output shaft position, and the output shaft position obtained after driving the drive source by the removal movement amount is determined as the reference position. 5. The pan head device according to any one of items 1 to 4, characterized in that: (Item 6) The control means The removal movement amount is determined based on movement amounts associated with a plurality of ranges of the output shaft position. 6. The pan head device according to item 5, (Item 7) The control means Based on the position of the output shaft, it is determined whether or not the drive source is to be driven in a direction opposite to the removal direction, and the reference position is determined. 7. The pan head device according to any one of items 1 to 6, characterized in that: (Item 8) The control means If the output shaft position is within a predetermined range of positions, the drive source is driven in the reverse direction, and then driven in the removal direction, and the output shaft position obtained is determined as the reference position. 8. The pan head device according to item 7, (Item 9) The predetermined range of positions is a predetermined range from the limit position of the driving range of the driving source. 9. The pan head device according to item 8, (Item 10) The control means When the driving source is driven in the reverse direction, the driving source is driven in the reverse direction by a movement amount greater than the removal movement amount in the removal direction. 10. The pan head device according to any one of items 7 to 9, characterized in that: (Item 11) The control means The removal direction is determined based on the attitude of the camera head device, and the reference position is determined. 11. The pan head device according to any one of items 1 to 10, characterized in that: (Item 12) A camera platform device for changing the shooting direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; A control method for a camera platform device for changing the photographing direction of an imaging means for photographing a subject, comprising: The output shaft position acquired after driving the drive source by a removal movement amount in a removal direction that removes the backlash generated by the reduction mechanism is determined as a reference position for controlling the position of the drive source. A method for controlling a pan head device. (Item 13) A program for causing a computer to function as a control means for the camera platform device according to any one of items 1 to 11.

[0094] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0095] 1000: Pan head device; 2000: Imaging device; 1004: Pan drive unit; 1005: Tilt drive unit; 1006: System control unit; 1201: Motor; 1202: Motor shaft encoder; 1203: Reduction mechanism; 1204: Output shaft; 1205: Output shaft encoder.

Claims

1. A camera platform device for changing the photographing direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; Equipped with The control means determines the output shaft position acquired after driving the drive source by a removal movement amount in a removal direction that removes backlash generated by the reduction gear mechanism as a reference position for controlling the position of the drive source. A pan head device characterized by:

2. a drive control position detection means for detecting a control position of the drive source; 2. The pan head device according to claim 1, further comprising:

3. the drive source is a stepping motor, The control means uses the number of pulses of the stepping motor as a control position of the drive source.

2. The camera platform device according to claim 1.

4. The control means The removal movement amount is determined based on the backlash of the reduction mechanism.

2. The camera platform device according to claim 1.

5. The control means The removal movement amount is determined based on the output shaft position, and the output shaft position obtained after driving the drive source by the removal movement amount is determined as the reference position.

2. The camera platform device according to claim 1.

6. The control means The removal movement amount is determined based on movement amounts associated with a plurality of ranges of the output shaft position.

6. The camera platform device according to claim 5.

7. The control means Based on the position of the output shaft, it is determined whether or not the drive source is to be driven in a direction opposite to the removal direction, and the reference position is determined.

2. The camera platform device according to claim 1.

8. The control means If the output shaft position is within a predetermined range of positions, the drive source is driven in the reverse direction, and then driven in the removal direction, and the output shaft position obtained is determined as the reference position.

8. The camera platform device according to claim 7.

9. The predetermined range of positions is a predetermined range from the limit position of the driving range of the driving source.

9. The camera platform device according to claim 8.

10. The control means When the driving source is driven in the reverse direction, the driving source is driven in the reverse direction by a movement amount greater than the removal movement amount in the removal direction.

8. The camera platform device according to claim 7.

11. The control means The removal direction is determined based on the attitude of the camera head device, and the reference position is determined.

2. The camera platform device according to claim 1.

12. A camera platform device for changing the photographing direction of an imaging means for photographing a subject, a drive source that outputs a drive force; a speed reduction mechanism that reduces the driving force of the driving source; an output shaft connected to the reduction mechanism to which the reduced driving force is transmitted, the output shaft changing the imaging direction of the imaging means by the reduced driving force; an output shaft position detection means for detecting the position of the output shaft; a control means for controlling the driving source; A control method for a camera platform device for changing the photographing direction of an imaging means for photographing a subject, comprising: The output shaft position acquired after driving the drive source by a removal movement amount in a removal direction that removes the backlash generated by the reduction mechanism is determined as a reference position for controlling the position of the drive source. A method for controlling a pan head device.

13. A program for causing a computer to function as the control means for the camera platform device according to any one of claims 1 to 11.

Images