A High-Reliability and Power-Saving Focusing Locking and Unlocking Control Method

Abstract

A high-reliability and power-saving focus locking and unlocking control method uses two control branches to energize a single phase of a focus motor to achieve motor locking before satellite launch and orbit insertion and unlocking before imaging. The first control branch is a combination of a camera controller and a power drive circuit, and the second control branch is a focus locking and unlocking circuit. Before the satellite is launched and inserted into orbit, the first control branch is not powered on, and the single-phase coil of the focus motor is grounded and conducted through the second control branch to achieve focus motor locking. After the satellite is launched and inserted into orbit, the second control branch operates, the single-phase coil of the focus motor is no longer grounded, and at the same time the first control branch is powered on, and the first control branch controls the focus motor according to the usage requirements to complete focusing. The present invention can prevent the focal plane from shifting due to vibration, shock, etc. during satellite launch, and at the same time reduce the circuit power consumption and potential electromagnetic radiation impact during launch.

Description

Technical Field

[0001] The present invention belongs to the technical field of focus control for space remote sensing cameras, and relates to a control method for focus locking and unlocking of a space camera. Background Art

[0002] The focus control technology for space remote sensing cameras is mainly applied to the adjustment of the focal plane position or the lens of the camera during the satellite launch process and in space, so as to achieve the purpose of clear imaging.

[0003] In order to prevent the focusing mechanism from generating relative displacement due to the vibration of the rocket during the satellite launch process, generally during the satellite launch process, it is necessary to perform locking control on the focusing mechanism. After the satellite is in orbit, first perform unlocking control on the focusing mechanism, and then perform operations such as command focusing and automatic focusing to cooperate with the imaging task.

[0004] The key to the design of the focus locking function for aerospace use is high reliability, low power consumption, good electromagnetic compatibility, and light weight. At present, the focus locking function of the space remote sensing camera focusing mechanism is mainly realized by electromagnetic locking, motor holding torque locking, and increasing the friction between the lead screw and nut in the focusing mechanism. The method of increasing the friction between the lead screw and nut of the focusing mechanism requires the friction force to be designed in an accurate range, which not only ensures no relative movement during the launch process but also ensures reliable focusing after the spacecraft is in orbit. Due to the complex vibration and shock conditions during the launch process, which also involve the unlocking explosion of pyrotechnics and the impact of satellite-rocket separation, there may be deviations in simulation and estimation. In such a high-reliability application scenario in aerospace, it is generally not used alone, but is used as an auxiliary design to complete the locking and unlocking functions. Electromagnetic locking requires adding a locking device and a control circuit for controlling the locking device in the focusing mechanism, resulting in more product weight and power consumption. Therefore, most current designs achieve the focus locking function through the motor holding torque.

[0005] As Figure 1 shown, during the satellite launch period, both the controller and the power drive circuit work. The power drive circuit is controlled by the camera controller to energize the single-phase (A-phase) of the motor to achieve motor locking and thus the focal plane locking function. After the satellite is in orbit, the motor is driven to the optimal focal plane position according to the imaging requirements. This solution requires the controller and the power drive circuit to be powered on during the satellite launch period. The controller, as the control computer of the aerospace camera, has functions such as power supply and distribution, bus communication, satellite process control, command sending, telemetry acquisition, and focus control, generally with relatively high power consumption and complex electromagnetic radiation conditions. During the satellite launch phase, it is powered by a battery, and it is required that the device power consumption be as low as possible. Since the controller has no other power-on requirements except for the focus locking function, powering on the entire controller only for the focus locking function will cause waste of resources. Moreover, during the satellite launch phase, there are also requirements for the electromagnetic interface of the rocket to the satellite, and there is a risk of electromagnetic compatibility exceeding the standard when the controller is powered on. Summary of the Invention

[0006] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, providing a highly reliable and low-power focusing lock control method, which is applicable to locking the focusing motor during the launch of a space camera and unlocking the motor after it is in orbit. While preventing the focal plane from shifting due to vibration, shock, etc., it reduces the power consumption during launch and the potential impact of electromagnetic radiation.

[0007] The technical solution of the present invention is: a highly reliable and power-saving focusing lock and unlock control method, which uses two control branches to energize a single phase of the focusing motor to achieve motor locking before the satellite is launched into orbit and unlocking before imaging. Among them, the first control branch is a combination of a camera controller and a power drive circuit, and the second control branch is a focusing lock and unlock circuit; before the satellite is launched into orbit, the first control branch is not powered on, and the single-phase coil of the focusing motor is grounded and conducted through the second control branch to achieve focusing motor locking; after the satellite is launched into orbit, the second control branch acts, the single-phase coil of the focusing motor is no longer grounded, and at the same time the first control branch is powered on, and the first control branch controls the focusing motor according to the usage requirements to complete focusing.

[0008] The described focusing lock and unlock circuit is implemented by a magnetic latching relay, and one state of the magnetic latching relay switch can ground the single-phase coil of the focusing motor.

[0009] The described focusing lock and unlock circuit includes 2 magnetic latching relays with two sets of contacts each. The 2 sets of contacts within a single magnetic latching relay act simultaneously, the 2 sets of contacts within a single magnetic latching relay are in parallel, and the two magnetic latching relays are in series; the positions of the four sets of contacts correspond to two working states of locking and unlocking. The locking working state is that the single-phase coil of the focusing motor is grounded, forming a path from the focusing power supply to the single-phase coil of the focusing motor to the return line of the focusing power supply; the unlocking working state is that the single-phase coil of the focusing motor is no longer grounded through the magnetic latching relay, but the motor rotation is controlled according to instructions or a predetermined process to achieve the focusing function.

[0010] The magnetic latching relay contacts are also provided with contacts for generating telemetry signals. The telemetry signal corresponding to the unlocking working state is a high level representing the voltage of the focusing power supply, and the telemetry signal corresponding to the locking working state is a low level.

[0011] The advantages of the present invention compared with the prior art are as follows:

[0012] (1) The present invention introduces a focus lock / unlock circuit to complete the function of locking the motor by energizing a single phase (phase A) of the motor, thereby achieving the focus plane locking function. During the satellite launch process, the controller and the power drive circuit are not powered on, and the introduced focus lock / unlock circuit uses a magnetic latching relay to achieve the focus lock / unlock function. The magnetic latching relay only requires power supply during the switching moment and does not require power supply to maintain at other times, greatly saving satellite energy and reducing electromagnetic radiation;

[0013] (2) The focus lock / unlock circuit introduced in the present invention, through the redundant design of the magnetic latching relay, the two sets of contacts in a single relay are connected in parallel, and two relays are connected in series to reliably achieve the focus lock / unlock function. When a single set of contacts fails to open, the locking function will not fail, or when a single relay fails and cannot be unlocked, it will not affect the unlocking function after the satellite is in orbit, avoiding the functional failure caused by a single fault, and no manual intervention is required to reduce the fault handling time and improve the reliability of locking and unlocking;

[0014] (3) By adopting the method of the present invention, the telemetry of the lock / unlock state can be increased, and the product state can be more intuitively understood, which is helpful for state judgment; at the same time, the modification to the original design is small, the modification risk is small, and it does not affect the normal focusing function after the satellite is in orbit. Description of the Drawings

[0015] Figure 1 is the schematic diagram of the composition principle of the existing focus lock and unlock drive circuit;

[0016] Figure 2 is the optimized focus lock and unlock control schematic diagram of the present invention;

[0017] Figure 3 is the implementation diagram of the focus lock and unlock circuit of the present invention (locking state);

[0018] Figure 4 is the implementation diagram of the focus lock and unlock circuit of the present invention (unlocking state);

[0019] Figure 5 is the schematic diagram of the present invention to solve the failure of a single relay;

[0020] Figure 6 is the schematic diagram of the present invention to solve the abnormal disconnection fault of the contact; Detailed Embodiment

[0021] As Figure 2 shown, it is the control schematic diagram of the focus lock and control method of the present invention. Relative to Figure 1, this design method additionally adds a set of focus locking and unlocking circuits, which enables the controller and power drive circuit to be completely powered off during transmission. Only through the designed focus locking and unlocking circuits can the single-phase (phase A) of the motor be powered on to lock the motor, thereby achieving the focus plane locking function.

[0022] As can be seen from Figure 2 , in addition to the original control function of the controller + power drive circuit for the phase A coil of the focus adjustment motor, a focus locking and unlocking circuit control is additionally added. The combination of the controller + power drive circuit is only used to drive the focus adjustment motor after the satellite is in orbit and is not powered on or used during satellite launch. During satellite launch, the focus adjustment motor is locked by controlling the grounding conduction of the phase A coil of the focus adjustment motor through the focus locking and unlocking circuit (mainly composed of a magnetic latching relay). After the satellite is in orbit, the focus locking and unlocking circuit is controlled to release the phase A of the motor, enabling it to be controlled by the combination of the controller + power drive circuit to achieve the focus adjustment function.

[0023] As Figure 3 shown, before satellite launch, connect the contacts 1-1 and 1-3 of relay 1 and relay 2, and connect the contacts 2-1 and 2-3. At this time, a loop of the focus adjustment power supply, the phase A of the motor, the relay, and the focus adjustment power supply return line is formed, and the current flow is as shown by the dotted line in the figure. Since there is current flowing through the phase A of the motor, the motor generates a greater holding torque to achieve the focus plane locking function. At this time, the lock / unlock telemetry voltage V is the voltage division of the focus adjustment power supply voltage for R1 and R2, and the upper-level system can judge the focus plane locking state by collecting this telemetry voltage. During this process, other parts of the single unit, including the motor power drive part, are not powered on and do not participate in motor control.

[0024] Figure 4 This is a schematic diagram when the camera needs to adjust the focus after the satellite is in orbit. At this time, control the relay coil to connect the contacts 1-1 and 1-2 of relay 1 and relay 2, and connect the contacts 2-1 and 2-2. The phase A coil of the motor is no longer connected to the focus adjustment power return line through the relay, but is controlled by the single-unit power drive part. The single-unit power drive circuit can control the rotation of the focus adjustment motor according to instructions or a predetermined strategy to complete the camera focus adjustment function. At this time, the lock / unlock telemetry signal is connected to the focus adjustment power supply return line, and the voltage is 0V. The upper-level system can judge whether the motor is unlocked through this telemetry.

[0025] The use of two double-contact relays to achieve the focus lock and unlock function is to improve the reliability of the design. Since spacecraft products generally do not have maintainability and are costly with a great impact after failure, it is necessary to analyze the failure modes of the products and take targeted measures. This design mainly aims at the failure modes that the relay cannot be controlled due to the relay coil failure and the abnormal disconnection of the relay contacts caused by the vibration during the launch process. The relay coil failure will cause the relay to not respond to the command and the contacts to maintain their original state. This design uses a series mode of two relays. Even if one of the two relays can respond to the command and disconnect the contacts (such as Figure 5 , this figure shows the failure of relay 2), no current loop as shown in Figure 3 will be generated, thus completing the unlocking action. The single-machine power drive part can also complete the control of the motor. The lock / unlock telemetry voltage V is 0V, which is the unlock state and can accurately reflect the actual lock / unlock state. The vibration during satellite launch and the impact during pyrotechnic device unlocking may both cause the abnormal disconnection of the relay contacts. This failure mainly occurs during launch and will affect the motor locking function. The use of double-contact relays can effectively avoid the impact caused by this failure. As shown in Figure 6 , the contact 1-1 of relay 2 is abnormally connected to contact 1-2, resulting in the disconnection of the upper half branch of the current. Since the double-contact parallel mode is adopted, the lower half branch can still complete the locking function. The lock / unlock telemetry voltage V is the focus power supply voltage and can still effectively characterize the motor locking state.

[0026] At present, the invention has completed the design, production and testing. The application model has completed the in-orbit verification of the satellite, and the product performance is good, and the circuit function meets the usage requirements.

[0027] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A high-reliability and power-saving focusing lock and unlock control method, characterized in that: Two control branches are used to energize the single-phase focusing motor to achieve motor locking before satellite launch and unlocking before imaging. The first control branch is a combination of a camera controller and a power drive circuit, and the second control branch is a focusing lock / unlock circuit. Before the satellite is launched into orbit, the first control branch is not powered on, and the single-phase coil of the focusing motor is grounded and conducted through the second control branch to achieve focusing motor locking. After the satellite is launched into orbit, the second control branch operates, the single-phase coil of the focusing motor is no longer grounded, and at the same time, the first control branch is powered on. The first control branch controls the focusing motor according to the usage requirements to complete focusing. The described focusing lock / unlock circuit is implemented using a magnetic latching relay. One state of the magnetic latching relay switch grounds the single-phase coil of the focusing motor. The described focusing lock / unlock circuit includes two magnetic latching relays with two sets of contacts each. The two sets of contacts within a single magnetic latching relay operate simultaneously, and the two sets of contacts within a single magnetic latching relay are in parallel. The two magnetic latching relays are in series. The positions of the four sets of contacts correspond to two working states of locking and unlocking. The locking working state is that the single-phase coil of the focusing motor is grounded, forming a path from the focusing power supply to the single-phase coil of the focusing motor to the focusing power supply return line. The unlocking working state is that the single-phase coil of the focusing motor is no longer grounded through the magnetic latching relay, but instead, the motor is controlled to rotate according to instructions or a predetermined process to achieve the focusing function.

2. The high-reliability and power-saving focusing lock and unlock control method according to claim 1, characterized in that: A contact for generating a telemetry signal is also provided on the magnetic latching relay contact. The telemetry signal corresponding to the unlocking working state is a high level representing the voltage of the focusing power supply, and the telemetry signal corresponding to the locking working state is a low level.

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