Docking control method and system of space docking mechanism and readable storage medium

Abstract

The application provides a docking control method and system of a spatial docking mechanism and a readable storage medium. The method comprises a docking control process and an unlocking control process. The docking control process comprises: presetting a maximum rotation limit of a motor according to a transmission parameter of the docking mechanism; a controller controls the motor to rotate in a first direction to drive the docking mechanism to perform a docking action; whether the docking mechanism reaches a docking completion position is detected by a docking completion sensor; when any of the following conditions is met, the controller sends a stop command to the motor: condition one: the docking completion sensor is triggered; condition two: the actual rotation of the motor reaches the maximum rotation limit; the unlocking control process comprises: the controller controls the motor to rotate in a second direction to drive the docking mechanism to perform an unlocking action, and whether the locking mechanism reaches an unlocking completion position is detected by a plurality of parallel unlocking completion sensors; when any of the unlocking completion sensors is triggered, a stop command is sent.

Description

Technical Field

[0001] This application relates primarily to the field of space docking control technology, and in particular to a docking control method, system, and readable storage medium for a space docking mechanism. Background Technology

[0002] With the rapid development of aerospace technology, the demand for tasks such as on-orbit assembly and on-orbit maintenance is increasing. The space docking mechanism is the foundation for realizing the above-mentioned key technologies. The success of docking directly determines the success or failure of the mission. Its docking control logic is like the "brain" of the space docking mechanism, and the rationality of the control logic is a key factor in determining the success or failure of docking.

[0003] Currently, existing control schemes for space docking mechanisms have the following shortcomings: Existing schemes often rely solely on "sensor triggering upon docking completion" as the only condition for motor shutdown. If the sensor fails or the signal is lost, the motor will continue to rotate, causing the ball screw to disengage and the mechanism to be damaged. Furthermore, when power is restored after a sudden power outage, the controller cannot determine the current position of the mechanism, resulting in a loss of reference for position control. In addition, existing control methods either only describe the normal docking and unlocking process or only passively shut down after a fault occurs, lacking a systematic fault handling process for abnormal conditions such as sudden power outages, incomplete connections after docking, or jamming.

[0004] Therefore, there is an urgent need for a docking control logic and method that is simple in logic, reliable in control, and capable of handling sudden failures, so as to ensure the reliability of the docking and unlocking process of the docking mechanism. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a docking control method, system and readable storage medium for a space docking mechanism, which solves the technical problem that existing docking control schemes rely on single or limited detection and protection means, which can easily lead to docking failure or mechanism damage when a single fault occurs, such as sensor failure, position loss or abnormal working conditions, and the overall control reliability is insufficient.

[0006] To address the aforementioned technical problems, this application provides a docking control method for a space docking mechanism, including a docking control process and an unlocking control process. The docking control process includes: presetting a maximum rotation limit for the motor based on the transmission parameters of the docking mechanism; the controller controlling the motor to rotate along a first direction, driving the docking mechanism to perform a docking action; detecting whether the docking mechanism has reached the docking completion position using a docking completion sensor; and the controller sending a stop command to the motor when any of the following conditions are met: condition one: the docking completion sensor is triggered; condition two: the actual rotation number of the motor reaches the maximum rotation limit. The unlocking control process includes: the controller controlling the motor to rotate along a second direction, driving the docking mechanism to perform an unlocking action, the second direction being opposite to the first direction; detecting whether the locking mechanism has reached the unlocking completion position using multiple parallel unlocking completion sensors; and the controller sending a stop command to the motor when any of the unlocking completion sensors is triggered. The unlocking control process and the docking control process employ an asymmetric control strategy, and in the unlocking control process, the stop command is not sent to the motor when the actual rotation number of the motor reaches the maximum rotation limit.

[0007] In some embodiments, the maximum number of rotations of the motor is the sum of the theoretical number of rotations required for docking and the number of rotations allowed as a margin.

[0008] In some embodiments, a fault handling process is also included, which includes: when power is restored after a sudden power outage, the controller controls the motor to rotate in the second direction; multiple unlocking completion sensors connected in parallel detect whether the locking mechanism has reached the unlocking completion position; when any of the unlocking completion sensors is triggered, the controller sends a stop command to the motor and sets the actual number of rotations of the motor to zero, thus completing the position calibration.

[0009] In some embodiments, a fault handling process is further included, the fault handling process including: after the docking completion sensor is triggered, if the controller receives a continue docking instruction, the controller controls the motor to continue rotating a first predetermined number of revolutions in the first direction; and / or, after the unlocking completion sensor is triggered, if the controller receives a continue unlocking instruction, the controller controls the motor to continue rotating a first predetermined number of revolutions in the second direction.

[0010] In some embodiments, during the docking control process, at the docking initiation stage, a docking start sensor detects whether the passive end of the docking mechanism has been sent to a predetermined docking start position; when the docking start sensor is triggered, the controller determines whether the continuous triggering time of the docking start sensor has reached a set duration threshold; when the continuous triggering time reaches the set duration threshold, the controller controls the motor to rotate along the first direction.

[0011] In some embodiments, a step loss detection and protection process is further included, which includes: setting a Hall position sensor at the tail end of the motor, the Hall position sensor being used to record the actual number of rotations of the motor; the controller comparing the actual number of rotations of the motor with the number of command pulses, and when the two are inconsistent, determining that the motor has lost step, and the controller sending a stop command to the motor.

[0012] In some embodiments, a current detection process is further included, which includes: monitoring the current of the motor; when the current of the motor is detected to exceed a preset overcurrent threshold, the controller controls the motor to stop; when the current of the motor is detected to exceed a preset stall current threshold for a preset time and the motor position feedback does not change, the controller determines that there is a stall fault, controls the motor to rotate a second predetermined number of revolutions in a second direction, and then sends a stop command to the motor, wherein the second direction is opposite to the first direction.

[0013] To address the aforementioned technical problems, this application provides a docking control system for a space docking mechanism, comprising: The sensor assembly includes a docking start sensor, a docking completion sensor, and multiple parallel-connected unlock completion sensors; A Hall position sensor, located at the tail end of the motor, is used to record the actual number of rotations of the motor. The controller is connected to the sensor assembly and the Hall position sensor signal. The controller performs the method as described in this application.

[0014] To address the aforementioned technical problems, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described in this application.

[0015] Compared with the prior art, this application has the following advantages: The docking control method, system, and readable storage medium of the space docking mechanism disclosed in this application, in its docking control process, preset a maximum motor rotation limit based on the transmission parameters of the docking mechanism. During the docking action driven by the motor along the first direction, the docking completion sensor triggering and the actual number of motor rotations reaching the maximum rotation limit are used as two independent shutdown conditions. An OR logic is used for judgment, and shutdown is triggered when either condition is met, realizing dual-redundant shutdown protection combining sensor triggering and rotation limit. When the docking completion sensor fails to trigger due to a fault, the rotation limit acts independently as a safety backup, forcing the motor to stop when it reaches the preset maximum number of rotations. This fundamentally solves the technical problems in the prior art where the failure of a single positioning sensor leads to continuous motor rotation, ball screw disengagement, and mechanism damage. It significantly improves the success rate and safety of on-orbit docking missions of lightweight space docking mechanisms. At the same time, this control logic does not require additional complex calculations and hardware resources, making it suitable for resource-constrained lightweight space docking mechanisms.

[0016] Secondly, this application employs an asymmetric control strategy for both the unlocking and docking control processes. This asymmetric strategy is a specialized design tailored to the resource-constrained characteristics of lightweight space docking mechanisms. Given the strict limitations on the computing, storage, and power consumption of the controller in these mechanisms, and considering that the physical limits in the unlocking direction are sufficient to prevent overtravel damage, the rotation limit logic is proactively removed. This simplifies the control process, reducing system complexity and potential failure sources, aligning with the fundamental principle of "simpler is more reliable" in aerospace high-reliability design. In short, the asymmetric strategy is a targeted design based on a comprehensive consideration of the physical limitations in the unlocking direction and the resource constraints of the lightweight platform. Attached Figure Description

[0017] The accompanying drawings are included to provide a further understanding of this application. They are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application.

[0018] Figure 1 This is an architecture diagram of the docking control system of the space docking mechanism in this application.

[0019] Figure 2 This is a schematic diagram of the docking control process in the docking control method of this application.

[0020] Figure 3 This is a schematic diagram of the unlocking control process in the docking control method of this application.

[0021] Figure 4 This is a schematic diagram illustrating the location marking under sudden power outage conditions in the fault handling process of this application.

[0022] Figure 5This is a schematic diagram illustrating the continued operation after the fault handling process in this application has been completed.

[0023] Figure 6 This is a schematic diagram of the trigger duration determination process for the start of docking in the docking control method of this application.

[0024] Figure 7 This is a schematic diagram of the out-of-step detection and protection process in the docking control method of this application.

[0025] Figure 8 This is a schematic diagram of the current detection process in the docking control method of this application.

[0026] Figure 9 This is a schematic diagram of an optimized embodiment of the docking control process in the docking control method of this application.

[0027] Figure 10 This is a schematic diagram of an optimized embodiment of the unlocking control process in the docking control method of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0029] This application provides a docking control method, system, and computer-readable storage medium for a space docking mechanism. The aim is to improve the reliability of the docking and unlocking process of the docking mechanism by using a dual-redundant shutdown mechanism that combines sensor triggering and rotation limit, a dual-parallel redundant design of the unlocking completion sensor and power-off position calibration, a systematic fault handling process, and out-of-step detection and current detection protection.

[0030] This application provides a docking control system for a space docking mechanism. The space docking mechanism is the controlled object of the docking control system of this application. In one embodiment, the space docking mechanism includes a motor, a ball screw transmission mechanism, and a locking mechanism. The ball screw transmission mechanism converts the rotational motion of the motor into linear motion, driving the central rod to extend or retract, thereby realizing the docking and unlocking actions of the docking mechanism. The locking mechanism is used to achieve a rigid connection after the two spacecraft have docked. When the central rod pulls the active end and the passive end closer to a predetermined position, the locking mechanism actuates, locking the two spacecraft together.

[0031] like Figure 1As shown, the docking control system 100 includes a sensor assembly, a Hall position sensor 2, and a controller 3. The sensor assembly includes, but is not limited to, a docking start sensor 11, a docking completion sensor 12, and multiple parallel-connected unlock completion sensors 13.

[0032] The docking start sensor is used to detect whether the passive end of the docking mechanism has been sent to the predetermined docking start position; the docking completion sensor is used to detect whether the docking mechanism has reached the docking completion position; and the unlocking completion sensor is used to detect whether the locking mechanism has reached the unlocking completion position.

[0033] The Hall position sensor is located at the tail end of the motor and is used to record the actual number of rotations of the motor in real time.

[0034] The controller is connected to the sensor assembly and the Hall position sensor signal respectively. It is used to receive the detection signals of each sensor and the rotation signal of the Hall position sensor, and send drive commands or stop commands to the motor according to the preset control logic.

[0035] The above embodiments provide a detailed description of the hardware architecture and components of the docking control system provided in this application. The following will combine... Figures 2 to 7 This application provides a detailed description of the specific control logic for each process in the docking control method provided, including the docking control process, unlocking control process, fault handling process, out-of-step detection and protection process, and current detection process. The controller achieves docking, unlocking, and fault handling control of the docking mechanism by executing the following process steps.

[0036] like Figure 1 As shown, the docking control method for the space docking mechanism provided in this application includes a docking control process. The docking control process includes: Step S101: Based on the transmission parameters of the docking mechanism, preset the maximum number of rotations limit of the motor.

[0037] In one embodiment, the controller pre-stores transmission parameters of the docking mechanism, including but not limited to the transmission ratio i, the ball screw lead P, and the fixed stroke L from the initial docking position to the completed docking position. The controller calculates the theoretical number of motor rotations n according to the following formula:

[0038] The maximum number of rotations of the motor is N, which is a margin of safety added to the theoretical number of rotations. That is, N = n + k, where k is the margin of safety.

[0039] In one embodiment, k = 5. Assuming the theoretical number of rotations calculated based on the transmission ratio and ball screw lead is 100 rotations, the maximum rotation limit is preset to 105 rotations. This 5-rotation margin ensures that the sensor triggers the shutdown first after docking is completed under normal operating conditions, and also provides reliable limit protection in case of sensor failure. This avoids accidental shutdown due to insufficient margin causing the sensor to reach the rotation limit before triggering, or excessive margin causing excessive motor over-rotation and mechanism damage after sensor failure.

[0040] Step S102: The controller controls the motor to rotate in the first direction, driving the docking mechanism to perform the docking action.

[0041] The controller sends a start command to the motor, controlling the motor to rotate along a first direction, driving the docking mechanism to perform the docking action. In this embodiment, the first direction is the direction in which the active end of the docking mechanism extends towards the passive end. When the motor rotates along the first direction, the ball screw transmission mechanism converts the rotational motion of the motor into linear motion, driving the center rod to extend, and the active end gradually approaches the passive end.

[0042] Step S103: The docking completion sensor detects whether the docking mechanism has reached the docking completion position.

[0043] During the docking process, the controller uses a docking completion sensor to detect in real time whether the docking mechanism has reached the docking completion position. The docking completion sensor is set at a predetermined position on the docking mechanism body. When the active end and the passive end reach the predetermined docking position, the docking completion sensor is triggered and outputs a trigger signal to the controller.

[0044] Step S104: The controller sends a stop command to the motor when any of the following conditions are met: Condition 1: Sensor triggering upon docking completion; Condition 2: The actual number of rotations of the motor reaches the maximum rotation limit.

[0045] In abnormal situations, such as when the docking completion sensor malfunctions (damage, broken signal line, etc.) and fails to trigger normally, the motor will not stop due to condition one, but will continue to rotate. The controller records the actual number of rotations of the motor in real time through the Hall position sensor and compares the actual number of rotations with the preset maximum number of rotations limit. When the actual number of rotations of the motor reaches the maximum number of rotations limit, the controller forcibly sends a stop command to the motor to prevent the motor from over-rotating, which could cause the ball screw to disengage or the mechanism to be damaged.

[0046] The aforementioned dual-condition shutdown mechanism employs "OR logic." Shutdown is triggered when either of the two conditions is met, achieving dual redundancy protection for sensor triggering and rotation limit, significantly improving the reliability of the docking process.

[0047] like Figure 3 As shown, the docking control method provided in this application embodiment also includes an unlocking control process, which specifically includes the following steps: Step S201: The controller controls the motor to rotate in the second direction, driving the docking mechanism to perform the unlocking action. The second direction is opposite to the first direction.

[0048] In one embodiment, the controller sends a start command to the motor, controlling the motor to rotate in a second direction, driving the docking mechanism to perform an unlocking action. In this embodiment, the first direction is the direction in which the central rod extends, and the second direction is the direction in which the central rod retracts. When the motor rotates in the second direction, the ball screw transmission mechanism drives the central rod to retract, the locking mechanism disengages, and the two spacecraft separate.

[0049] Step S202: Detect whether the locking mechanism has reached the unlocking completion position using multiple unlocking completion sensors connected in parallel.

[0050] During the unlocking process, the controller uses multiple parallel-connected unlocking completion sensors to detect in real time whether the locking mechanism has reached the unlocking completion position. In this embodiment, the unlocking completion sensors adopt a dual-parallel redundant design, that is, two unlocking completion sensors are connected in parallel on the docking mechanism body to detect whether the locking mechanism has reached the unlocking position. The signals of the two unlocking completion sensors are logically ORed. When either sensor is triggered, the controller receives a valid completion signal.

[0051] The technical advantages of the dual parallel redundancy design are as follows: During the normal unlocking process, a stop signal can be sent as soon as either unlocking sensor is triggered, avoiding the failure of a single sensor that would result in no trigger signal and motor stall; When power is restored after a sudden power outage, the controller can reliably calibrate the current position of the mechanism by reading the signal status of the two parallel unlocking sensors, avoiding the loss of the zero point of the position (see the "Position Calibration under Sudden Power Outage" process below for details).

[0052] Step S203: When any unlocking complete sensor is triggered, the controller sends a stop command to the motor.

[0053] The motor stops after receiving the stop command, and the unlocking is complete.

[0054] In one embodiment, the unlocking control process and the docking control process employ an asymmetric control strategy. Specifically, in the unlocking control process, a stop command is not sent to the motor when the actual number of rotations reaches the maximum rotation limit. In other words, the unlocking control process controls the motor to stop only through the trigger signals of multiple unlocking completion sensors connected in parallel, without setting a rotation limit stop condition.

[0055] This asymmetric strategy is a specialized design adopted to address the resource constraints of lightweight space docking mechanisms. Its design is based on the following: After unlocking, the locking mechanism is completely released, and the central rod retracts to the mechanical hard limit at the end of the ball screw's stroke. At this point, the nut is against the limit end face, and even if the motor continues to rotate, it cannot move forward further; the motor is in an idling state and will not cause substantial damage to the mechanism. Simultaneously, the signals from the two unlocking completion sensors are logically in an "OR" relationship, meaning that when either sensor is triggered, the controller receives a valid positioning signal, avoiding the situation where a single sensor failure would prevent normal operation and improving reliability. Adding a rotation limit function would require additional rotation limit parameters, comparison logic, and threshold judgment steps. Under the strict limitations of computing resources, storage resources, and power consumption of the lightweight space docking mechanism controller, these additional logical steps would introduce additional potential failure points. Therefore, given that the physical limit in the unlocking direction can already prevent damage from overtravel, the rotation limit logic is proactively removed. By simplifying the control flow, system complexity is reduced, and potential failure sources are decreased, consistent with the fundamental principle of "simpler is more reliable" in aerospace high-reliability design. In other words, the asymmetric strategy is not a simple "risk trade-off", but a targeted design based on a comprehensive consideration of the physical limitations of the unlocking direction and the resource constraints of the small platform.

[0056] like Figure 4 As shown, the docking control method provided in this application embodiment also includes a fault handling process, which includes a position calibration sub-process under sudden power failure, specifically including the following steps: Step S301: When power is restored after a sudden power outage, the controller controls the motor to rotate in the second direction.

[0057] During normal operation, the actual number of motor rotations is continuously maintained by a counter in the controller software (accumulated or decremented based on the pulse signal from the Hall position sensor). In the event of a sudden power outage, the controller loses power, the counter's value is lost, and upon power restoration, the controller cannot determine the motor's current position, thus requiring recalibration.

[0058] In this embodiment, the second direction is the direction in which the central rod retracts and the locking mechanism is released. As the motor rotates along the second direction, the locking mechanism gradually moves towards the unlocked position.

[0059] Step S302: Detect whether the locking mechanism has reached the unlocking completion position by using multiple unlocking completion sensors connected in parallel.

[0060] Step S303: When any unlocking completion sensor is triggered, the controller sends a stop command to the motor and sets the actual number of rotations of the motor to zero, thus completing the position calibration.

[0061] When any unlock completion sensor is triggered, it indicates that the locking mechanism has reached the known unlock completion position. At this time, the controller sends a stop command to the motor and resets the actual number of motor rotations to zero. "Resetting to zero" means that, using the unlock completion position as a reference, the counter recording the actual number of motor rotations in the controller software is reset to zero, and the position coordinate system is re-established. Afterward, the controller can re-accumulate the actual number of motor rotations from zero based on the pulse signal from the Hall position sensor, thus restoring the position control mode to its effective state.

[0062] The technical effect of the above position calibration process is that when power is restored after a sudden power outage, the controller recalibrates the current position with the unlocked position as the reference point, which solves the problem of position reference loss after power failure and enables subsequent position control to proceed normally.

[0063] like Figure 5 As shown, the docking control method provided in this application embodiment also includes a fault handling process, which includes a sub-process of continuing action after the target is reached, specifically including the following steps: Step S401: After the sensor is triggered upon completion of docking, if the controller receives a command to continue docking, the controller controls the motor to continue rotating a first predetermined number of revolutions in the first direction.

[0064] This "continue to work after reaching the target depth" sub-process is used to address the following scenarios: when the docking depth is not reached due to component deformation, temperature changes, or other reasons, or when electrical or optical connectors have poor contact and cannot effectively conduct electricity, the above problems can be resolved by continuing docking to a certain depth. The "continue to dock" command can be sent uplink from the ground telemetry and control system, or it can be generated autonomously by the spaceborne computer based on preset criteria.

[0065] Step S402: After the sensor is triggered upon unlocking, if the controller receives a command to continue unlocking, the controller controls the motor to continue rotating a first predetermined number of revolutions in the second direction.

[0066] This "continue to act after reaching the target position" sub-process is used to handle the following scenario: when the locking mechanism is stuck or not fully separated due to part deformation, lubrication changes, or other reasons, the stuck state is released by continuing to unlock to a certain depth. The continue unlocking command can be sent uplink from the ground telemetry and control system, or it can be generated autonomously by the spaceborne computer based on preset criteria.

[0067] It should be noted that steps S401 and S402 can be executed independently or in combination. That is: in scenarios where docking continues after docking is completed, only step S401 can be executed; in scenarios where unlocking continues after unlocking is completed, only step S402 can be executed; in scenarios where two types of faults need to be handled simultaneously, both steps can be executed.

[0068] The first predetermined number of revolutions is a pre-set small rotation amount (e.g., 1 to 5 revolutions), which differs from the theoretical number of revolutions or the maximum limit of revolutions in the normal docking / unlocking stroke. The "continue action after reaching the position" function is a compensatory action performed within a limited range after the normal stroke has been completed. Its rotation amount is much smaller than the rotation amount of the normal stroke, so it will not cause overtravel damage to the mechanism.

[0069] like Figure 6 As shown, in the initial docking phase, the docking control method provided in this application embodiment further includes the following steps: Step S501: Detect whether the passive end has been sent to the predetermined docking start position by using the docking start sensor.

[0070] During the initial docking phase, the robotic arm grasps the passive end of the docking mechanism and moves it to the predetermined docking start position of the active end. A docking start sensor is mounted on the docking mechanism body to detect whether the passive end has reached the predetermined docking start position. When the passive end reaches this position, the docking start sensor is triggered and outputs a trigger signal to the controller.

[0071] Step S502: Determine whether the continuous triggering time of the docking start sensor has reached the set duration threshold.

[0072] Step S503: Start the motor after the continuous triggering time reaches the threshold.

[0073] When the controller receives the trigger signal from the docking start sensor, it does not immediately start the motor. Instead, it further determines whether the continuous triggering time of the sensor has reached a set duration threshold. Only after the continuous triggering time of the docking start sensor reaches the set duration threshold does the controller control the motor to rotate in the first direction, officially starting the docking operation.

[0074] This is because during the initial docking phase, as the robotic arm grasps the passive end and guides it into the active end, it operates in impedance control mode. Impedance control allows the robotic arm to exhibit compliance as it approaches the target position, adapting to the contact forces between the docking mechanisms. However, it also results in a dynamic adjustment process at the end of the robotic arm before final positioning. During this process, the mechanical guiding structures of the passive and active ends interact, gradually eliminating the robotic arm's pose error through contact forces. Because the passive end may experience multiple momentary contacts near the predetermined docking start position during this adjustment, the docking start sensor may be briefly triggered. If the motor is started immediately at this point, the docking action will begin before the passive end is stably positioned, potentially leading to misalignment between the center rod and the docking hole on the passive end, causing risks such as tooth breakage or partial docking. Therefore, when the controller receives the trigger signal from the docking start sensor, it does not immediately start the motor. Instead, it determines whether the sensor's continuous triggering time has reached a set duration threshold (e.g., 5 seconds). The purpose of setting the duration threshold is to ensure that the passive end has completed pose error elimination and is stably positioned at the predetermined docking start position, rather than triggering the start during momentary contact in the robotic arm's impedance adjustment process. Only when the continuous triggering time reaches the set duration threshold will the controller control the motor to rotate in the first direction and officially start the docking action.

[0075] like Figure 7 As shown, the docking control method provided in this application embodiment also includes a loss-of-synchronization detection and protection process, specifically including the following steps: Step S601: Record the actual number of rotations of the motor in real time using a Hall position sensor.

[0076] A Hall position sensor is installed at the tail end of the motor to record the actual number of rotations of the motor in real time.

[0077] Specifically, the Hall position sensor generates pulse signals in real time by detecting changes in the magnetic field of the motor rotor. The Hall position sensor outputs one pulse for every fixed angle the motor rotates. The controller accumulates and counts the received pulses to obtain the actual number of rotations of the motor in real time.

[0078] Step S602: The controller compares the actual number of rotations of the motor with the number of command pulses.

[0079] The command pulse count is the expected number of rotations calculated by the controller based on the total number of command pulses issued. The control principle of a stepper motor is: for each command pulse issued by the controller, the motor rotates by a fixed step angle. Therefore, the command pulse count = total number of command pulses issued by the controller / number of pulses required per motor rotation. This value represents the theoretical number of rotations the controller expects the motor to rotate.

[0080] The comparison between the actual number of rotations (Hall position sensor feedback) and the number of command pulses (controller's expected value) forms a comparison between the "expected value" and the "actual value." This is the basic logic of step loss detection.

[0081] Step S603: When the actual number of rotations of the motor is inconsistent with the number of command pulses, the controller determines that the motor has lost synchronization and sends a stop command to the motor.

[0082] When the actual number of motor rotations differs from the command pulse count, it indicates that the mechanism has jammed, causing the motor to lose synchronization. The controller immediately sends a stop command to the motor to protect the safety of the entire mechanism, while simultaneously recording and reporting the fault information. Task managers can prepare to restart the docking process by adjusting docking parameters (such as reducing docking speed or acceleration) or taking other measures. Before restarting docking, the controller resets the actual number of motor rotations to zero, using the current jammed position as the new position reference.

[0083] like Figure 8 As shown, the docking control method provided in this application embodiment also includes a current detection process, specifically including the following steps: Step S701: Monitor the motor current.

[0084] Step S702: When the current of the motor is detected to exceed the preset overcurrent threshold, the controller controls the motor to stop.

[0085] When the motor current exceeds the preset overcurrent threshold, the controller determines it as an overcurrent fault and immediately sends a stop command to the motor. Overcurrent faults may be caused by motor short circuits, drive circuit failures, or severe jamming of the mechanism. Timely disconnection of the drive can prevent motor burnout or damage to the drive circuit.

[0086] Step S703: When the current of the motor exceeds the preset stall current threshold and continues for a preset time, and there is no change in the motor position feedback, the controller determines that there is a stall fault, controls the motor to rotate a second predetermined number of revolutions in the second direction, and then sends a stop command to the motor. The second direction is opposite to the first direction.

[0087] In some embodiments, the determination of a stall fault requires the simultaneous fulfillment of three conditions: first, the current exceeds a preset stall current threshold (e.g., 120% to 150% of the rated current); second, the overcurrent condition lasts for a preset time (e.g., 0.5 to 2 seconds); and third, there is no change in the motor position feedback (the Hall position sensor shows that the actual number of rotations has not increased).

[0088] When all three conditions are met simultaneously, it indicates that the motor is energized but stuck and unable to rotate, which is a stall fault, not a momentary current spike or normal load change. After determining it to be a stall fault, the controller controls the motor to rotate a second predetermined number of revolutions in the second direction and then sends a stop command to the motor. The second direction is opposite to the first direction. The second predetermined number of revolutions is a small rotation amount (e.g., 1 / 4 revolution to 1 revolution) used to attempt to release the jam by reverse micro-motion. Unlike the first predetermined number of revolutions in step S401 ("continue docking"), the second predetermined number of revolutions is a trial-and-error action in fault handling, and its rotation amount is usually less than the first predetermined number of revolutions. If the jam is released after reverse micro-motion, the system can return to normal operation; if the jam persists after reverse micro-motion, the preset number of attempts can be repeated or the fault can be reported for further handling.

[0089] Based on the above basic docking control process, the docking control process of this application will be described in detail below with reference to a more specific embodiment. For example... Figure 9 As shown, in one embodiment, the docking control process specifically includes the following steps: Step S801: The spacecraft computer sends a start docking command to the controller and configures control parameters, including a threshold for the sensor trigger duration of the docking start.

[0090] In one embodiment, the control parameters include, but are not limited to: docking speed, docking acceleration, motor current limit, and docking start sensor trigger duration threshold.

[0091] Generally, setting a higher docking speed, higher docking acceleration, and higher motor current reduces docking time and improves docking efficiency. The trigger duration threshold for the docking initiation sensor can be set to 5 seconds. This is primarily because during the process of the robotic arm delivering the passive end to the active end, the robotic arm may experience momentary contact under impedance control, causing the docking initiation sensor to be triggered instantaneously. If the motor starts immediately at this time, it may lead to tooth breakage or incomplete docking. By setting the trigger duration threshold, these momentary false signals can be filtered out, ensuring that the docking process only starts after the passive end is stably positioned. It should be noted that the specific values ​​of the above parameters can be dynamically configured by the spacecraft computer according to mission requirements, or they can be pre-stored in the controller.

[0092] Step S802: The robotic arm grasps the passive end and feeds it into the active end.

[0093] The robotic arm grasps the passive end of the docking mechanism and delivers it to the predetermined docking starting position of the active end. During the delivery process, under the impedance control of the robotic arm, the mechanical guiding structure of the passive end of the docking mechanism interacts with the mechanical guiding structure of the active end to eliminate the positional error of the robotic arm and to initially align the passive end and the active end.

[0094] The impedance control of the robotic arm is a force / position hybrid control strategy. Its basic principle is that when the end effector of the robotic arm is subjected to an external force, the compliance of the robotic arm is adjusted to adapt to the external environment. In this embodiment, the robotic arm, under impedance control, sends the passive end into the active end. Even if there is a certain positional deviation, the mechanical guiding structure can guide the passive end to the correct position through contact force.

[0095] Step S803: Determine that the docking start sensor is triggered and the duration reaches the duration threshold.

[0096] The controller monitors the trigger status of the docking start sensor in real time. When the docking start sensor is triggered, the controller starts timing and determines whether the continuous triggering time of the sensor has reached a set duration threshold. If the continuous triggering time reaches the set duration threshold, it indicates that the passive end has been stably positioned, and the process proceeds to step S804. If the continuous triggering time does not reach the set duration threshold, it indicates that there may be a momentary contact spurious signal or that the passive end has not yet been stably positioned, and the controller continues to wait, repeating the feeding action of step S802 if necessary.

[0097] The purpose of this step is to prevent the docking start sensor from being mistakenly triggered and the motor from starting prematurely due to instantaneous contact during the elimination of robot arm pose error, thus avoiding the risk of tooth breakage or partial docking.

[0098] Step S804: The motor rotates in the first direction to begin docking.

[0099] Once the continuous triggering time of the docking start sensor reaches the set duration threshold, the controller controls the motor to rotate in the first direction, driving the center rod to extend and officially starting the docking operation.

[0100] Step S805: During the docking process, the controller also determines in real time whether the actual number of rotations of the motor is consistent with the number of command pulses. If they are consistent, it means that the motor is running normally and the docking action is proceeding as expected, proceeding to step S806; if they are inconsistent, it means that the motor has lost synchronization, usually due to the mechanism jamming causing a sharp increase in resistance torque, proceeding to step S808.

[0101] Specifically, the controller compares the actual number of rotations fed back by the Hall position sensor with the number of command pulses calculated based on the total number of command pulses. When motor step loss is detected, the controller immediately sends a stop command to the motor to protect the safety of the entire mechanism. At the same time, the controller records and reports the fault information, and task managers can restart the docking by adjusting docking parameters (such as reducing docking speed, reducing acceleration, etc.) or taking other measures.

[0102] This out-of-step detection mechanism operates in real time during the docking process (not just after docking is completed). Its function is to detect abnormalities and stop the action midway through the docking process, thus avoiding more serious damage caused by continuous driving while the mechanism is stuck.

[0103] Step S806: Determine whether the docking completion sensor has been triggered.

[0104] As the motor rotates in the first direction, the controller monitors the trigger status of the docking completion sensor in real time.

[0105] If the docking completion sensor is triggered, it indicates that the docking mechanism has reached the docking completion position. The controller immediately sends a stop command to the motor, the motor stops rotating, and the docking is complete.

[0106] If the docking completion sensor is not triggered, it indicates that the docking mechanism has not yet reached the docking completion position, and proceed to step S807.

[0107] Step S807: Determine whether the maximum number of rotations limit in position control mode has been reached.

[0108] If the docking completion sensor is not triggered, the controller further determines whether the actual number of rotations of the motor has reached the preset maximum rotation limit. If the actual number of rotations of the motor has reached the maximum rotation limit, the controller will forcibly send a stop command to the motor even if the docking completion sensor is not triggered, the motor will stop, and the docking will be completed.

[0109] Step S808: The motor stops, the controller records the fault information and reports it. The task manager can restart the docking by adjusting the docking parameters (such as reducing the docking speed, reducing the acceleration, etc.) or by taking other measures.

[0110] The rationale for this step is that the motor's actual number of rotations reaching the maximum limit means the center rod has extended to the preset safety limit position. In this situation, even if the docking completion sensor fails to trigger due to a malfunction, the mechanism has already reached the safety boundary near the completion position. Continuing to rotate may cause the ball screw to disengage or the mechanism to be damaged, therefore a forced shutdown is necessary.

[0111] If the actual number of rotations of the motor does not reach the maximum number of rotations limit, it indicates that the docking has not been completed and is still within the safe travel range. Return to step S804, and the motor continues to rotate in the first direction to continue the docking operation.

[0112] The docking control process disclosed in the above optimized embodiments has the following beneficial effects: By judging the continuous triggering duration of the docking start sensor, false signals generated by instantaneous contact during the impedance control of the robotic arm are filtered out, avoiding the risk of tooth breakage and partial docking caused by motor mis-start. During the execution of the docking action, the actual number of motor rotations and the number of command pulses are compared in real time, enabling timely detection of mechanism jamming and shutdown protection midway through the docking stroke, preventing more serious damage caused by continued drive in a jammed state. Upon completion of docking, the system is triggered to stop when either the docking completion sensor triggers or the actual number of motor rotations reaches the maximum limit, solving the technical problem of motor over-rotation and mechanism damage caused by the failure of a single sensor.

[0113] Based on the above basic unlocking control process, the unlocking control process of this application will be described in detail below with reference to a more specific embodiment. For example... Figure 10 As shown, in one embodiment, the unlocking control process specifically includes the following steps: Step S901: The spacecraft computer sends a start unlocking command to the controller and configures the parameters.

[0114] In some embodiments, control parameters include, but are not limited to, unlocking speed, unlocking acceleration, and motor current limit. Generally, setting a larger unlocking speed, larger unlocking acceleration, and larger motor current reduces unlocking time and improves unlocking efficiency. The specific values ​​of these parameters can be dynamically configured by the spacecraft computer according to mission requirements, or they can be pre-stored in the controller.

[0115] Step S902: The controller controls the motor to rotate in the second direction to perform the unlocking action.

[0116] The controller sends a start command to the motor, controlling the motor to rotate in a second direction, driving the docking mechanism to perform an unlocking action. The second direction is opposite to the first direction. In this embodiment, the first direction is the direction in which the center rod extends to achieve docking, and the second direction is the direction in which the center rod retracts to achieve unlocking. When the motor rotates in the second direction, the ball screw transmission mechanism converts the motor's rotational motion into linear motion, driving the center rod to retract, gradually loosening the locking mechanism, and realizing the separation of the two spacecraft.

[0117] Step S903: During the unlocking process, the controller also checks in real time whether the actual number of rotations of the motor matches the number of command pulses. If they match, it indicates that the motor is operating normally and the unlocking action is performed as expected, proceeding to step S904; if they do not match, it indicates that the motor has lost synchronization, usually due to a sharp increase in resistance torque caused by mechanism jamming, proceeding to step S906.

[0118] Step S904: Detect whether the locking mechanism has reached the unlocking completion position using multiple unlocking completion sensors connected in parallel.

[0119] In this embodiment, the unlocking completion sensor adopts a dual parallel redundant design, meaning two unlocking completion sensors are connected in parallel at the unlocking position detection location on the docking mechanism body to detect whether the locking mechanism has reached the unlocking position. The two unlocking completion sensors are structurally mounted near the same detection location and operate independently. Each unlocking completion sensor can independently detect whether the locking mechanism has reached the unlocking position and output a trigger signal. The signal lines of the two sensors are connected to two input ports of the controller respectively, without affecting each other.

[0120] Step S905: When any unlocking completion sensor is triggered, the controller sends a stop command to the motor, the motor stops rotating, and the unlocking is complete.

[0121] Step S906: The controller records the fault information and reports it. The motor stops. The task manager can restart the unlocking process by adjusting the docking parameters (such as reducing the unlocking speed, reducing the unlocking acceleration, etc.) or by taking other measures.

[0122] When either of the two parallel-connected unlocking sensors is triggered, the controller receives a valid arrival signal and immediately sends a stop command to the motor, causing the motor to stop and the unlocking to be completed.

[0123] It is worth noting that the aforementioned dual-parallel redundant unlocking completion sensors, in addition to triggering the shutdown during the normal unlocking process, also perform position calibration after a sudden power outage, achieving functional reuse of hardware resources. Specifically, upon power restoration after a sudden power outage, the controller needs to calibrate the current mechanism position by reading the signal states of the two parallel unlocking completion sensors. Because the two sensors are connected in parallel, even if the state of one sensor is uncertain after a power outage, the other sensor can still provide a reliable position signal, ensuring accurate position calibration. This dual-function reuse design reduces the need for additional hardware, achieving high reliability within limited volume and weight constraints for lightweight space docking mechanisms.

[0124] In one embodiment, this application also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the docking control method described in any of the above embodiments. The computer-readable storage medium may be a non-transient storage medium such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), flash memory, a solid-state drive (SSD), a magnetic disk, or an optical disk. The storage medium may be located in the spacecraft's controller or may be located independently.

[0125] The docking control method, system, and computer-readable storage medium for the space docking mechanism provided in this application can be applied to aerospace mission scenarios such as on-orbit assembly and on-orbit maintenance. Its control logic is simple and efficient, suitable for resource-constrained environments of lightweight space docking mechanisms. Its dual-redundant shutdown mechanism, dual-parallel redundancy design, systematic fault handling process, out-of-step detection, and current detection protection, among other reliability designs, can effectively cope with various abnormal operating conditions that may occur in aerospace missions, and have significant industrial practical value.

[0126] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0127] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

[0129] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0130] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A docking control method for a space docking mechanism, characterized in that, This includes the docking control process and the unlocking control process; The docking control process includes: presetting a maximum motor rotation limit based on the transmission parameters of the docking mechanism; controlling the motor to rotate in a first direction to drive the docking mechanism to perform the docking action; detecting whether the docking mechanism has reached the docking completion position using a docking completion sensor; and sending a stop command to the motor when any of the following conditions are met: Condition 1: The docking is completed and the sensor is triggered; Condition 2: The actual number of rotations of the motor reaches the maximum number of rotations limit; The unlocking control process includes: the controller controlling the motor to rotate in a second direction, driving the docking mechanism to perform an unlocking action, the second direction being opposite to the first direction; detecting whether the locking mechanism has reached the unlocking completion position through multiple parallel unlocking completion sensors; when any of the unlocking completion sensors is triggered, the controller sends a stop command to the motor; the unlocking control process and the docking control process adopt an asymmetric control strategy, in which the stop command is not sent to the motor when the actual number of rotations of the motor reaches the maximum number of rotations limit.

2. The method as described in claim 1, characterized in that, The maximum number of rotations of the motor is the sum of the theoretical number of rotations required for docking and the number of rotations allowed as a margin.

3. The method as described in claim 1, characterized in that, It also includes a fault handling process, which includes: When power is restored after a sudden power outage, the controller controls the motor to rotate in the second direction; Multiple parallel-connected sensors detect whether the locking mechanism has reached the unlocking completion position. When any of the unlocking completion sensors are triggered, the controller sends a stop command to the motor and sets the actual number of rotations of the motor to zero, thus completing the position calibration.

4. The method as described in claim 1, characterized in that, It also includes a fault handling process, which includes: After the docking completion sensor is triggered, if the controller receives a command to continue docking, the controller controls the motor to continue rotating a first predetermined number of revolutions in the first direction; and / or, After the unlocking is completed and the sensor is triggered, if the controller receives a command to continue unlocking, the controller controls the motor to continue rotating a first predetermined number of revolutions in the second direction.

5. The method as described in claim 1, characterized in that, In the docking control process, at the docking start stage, the docking start sensor detects whether the passive end of the docking mechanism has been sent to the predetermined docking start position; when the docking start sensor is triggered, the controller determines whether the continuous triggering time of the docking start sensor has reached a set duration threshold. When the continuous triggering time reaches the set duration threshold, the controller controls the motor to rotate along the first direction.

6. The method as described in claim 1, characterized in that, It also includes a step-out detection and protection process, which includes: A Hall position sensor is installed at the tail end of the motor, and the Hall position sensor is used to record the actual number of rotations of the motor. The controller compares the actual number of rotations of the motor with the number of command pulses. When the two are inconsistent, it determines that the motor has lost synchronization, and the controller sends a stop command to the motor.

7. The method as described in claim 1, characterized in that, It also includes a current detection process, which includes: Monitor the motor current; When the current of the motor is detected to exceed a preset overcurrent threshold, the controller controls the motor to stop. When the current of the motor exceeds the preset stall current threshold and remains so for a preset time, and the motor position feedback shows no change, the controller determines that there is a stall fault. After controlling the motor to rotate a second predetermined number of revolutions in the second direction, the controller sends a stop command to the motor. The second direction is opposite to the first direction.

8. A docking control system for a space docking mechanism, characterized in that, include: The sensor assembly includes a docking start sensor, a docking completion sensor, and multiple parallel-connected unlock completion sensors; A Hall position sensor, located at the tail end of the motor, is used to record the actual number of rotations of the motor. The controller is connected to the sensor assembly and the Hall position sensor signal. The controller performs the method as described in any one of claims 1-7.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-7.

Images