An adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system

Abstract

This invention proposes an adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system. This method enables flexible switching between closed-loop and open-loop, active and passive control modes, thereby allowing the auxiliary thrust unit to smoothly interact with external, variable, and uncertain resistance. It effectively avoids large speed fluctuations and force impacts, ensuring the reliability and safety of valve insertion, locking, and separation processes. This method also solves the problem of jamming during docking, locking, and separation of the active and passive refueling interfaces, which can lead to mission failure.

Description

Technical Field

[0001] This invention relates to an adaptive control method for an active-end auxiliary drive unit, applicable to on-orbit refueling systems. Background Technology

[0002] Under current satellite technology and usage patterns, propellant load is a primary factor affecting a satellite's on-orbit lifespan. As satellite functions expand and performance improves, payload weight increases. Limited by launch capacity and cost, the conflict between initial propellant load and on-orbit lifespan is becoming increasingly prominent. This urgently necessitates a shift from the current ground-based, single-fuel refueling model to a technological revolution that enables multiple on-orbit refueling of the propulsion system. A gas-liquid replenishment interface is used to achieve on-orbit propellant replenishment at the end of the lifespan of high-value satellites. The main function of this device is to connect and disconnect the sealed liquid and gas loop channels between the service satellite and the target satellite in orbit, enabling gas-liquid transfer between spacecraft and completing the on-orbit propellant replenishment mission for the recipient spacecraft.

[0003] Depending on the structure of the spacecraft's propulsion system tanks and the characteristics of the refueling process, there are various on-orbit refueling schemes, mainly including pressurized gas reuse, pressure multiplication, venting, and through-type refueling. For different refueling schemes, a sealed fluid transmission channel needs to be established in advance between the service satellite and the target satellite. This is achieved through a standardized gas-liquid refueling interface to connect, seal, and lock the active valve body on the service satellite with the passive valve body on the target satellite. In the through-type refueling scheme, two sealed channels, one for gas and one for liquid, are typically established simultaneously for each propellant to complete tasks such as fuel refueling and pressurized gas refueling respectively. Therefore, the standardized refueling interface has two valve bodies on both the active and passive ends, establishing two sealed fluid channels simultaneously during operation, offering both high versatility and reliability.

[0004] The active end interface is connected to the fuel tank via a hose. During refueling, the robotic arm grabs the active end of the refueling interface on the service satellite. Coarse docking between the active end and the passive end interface of the refueling interface is achieved through various optional solutions such as robotic arm joint angle information, robotic arm hand-eye camera and remote operation.

[0005] However, since the on-orbit connection is equivalent to a precise, sealed on-orbit assembly, with a single-sided gap of less than 0.05mm between the active and passive valve bodies, and significant sealing friction and self-locking valve spring resistance during docking, exceeding the driving torque and precision requirements of the robotic arm, the active end interface mechanism needs to implement passive compliant and auxiliary thrust functions. The compliant module primarily uses a spring and guide rail to achieve the following of the two rotational degrees of freedom. The auxiliary thrust module uses a brushless DC motor and planetary reducer to achieve rapid and reliable docking, locking, and separation of the active and passive valve bodies.

[0006] The basic procedure for in-orbit refueling is as follows:

[0007] 1) The active end of the robotic arm, guided by vision, utilizes the passive compliance characteristics of the compliant module to complete a rough docking with the passive end within a large tolerance range.

[0008] 2) Set the robotic arm to follow mode (i.e., the end of the robotic arm can be dragged freely), and start the auxiliary thrust unit at the same time. The rotation of the screw drives the active end to move towards the passive end. Finally, under error conditions, the two active end valve bodies can be self-corrected and adaptively inserted into the passive end valve body. In this process, it is necessary to overcome the spring resistance of the self-locking valve, the resistance of the O-ring friction pair, the dragging force of the robotic arm and hose, etc.

[0009] 3) When the limit switches on both sides of the active end are detected to be closed, it indicates that the valve body has been inserted into place, the motor stops rotating, and the active end and the passive section are in a locked state.

[0010] 4) After the valve body is connected, start on-orbit refueling and monitor the valve body insertion status in real time during the refueling process;

[0011] 5) After the gas-liquid replenishment is completed, the auxiliary thrust unit screw rotates in the opposite direction until the active end and the passive end are no longer in contact.

[0012] Because of position and attitude errors during the insertion of the active valve body into the passive valve body, and the interference of various external uncertainties such as spring resistance, friction and hose drag, the insertion process is prone to serious consequences such as insertion failure or even jamming and inability to be pulled out. Summary of the Invention

[0013] The technical problem to be solved by this invention is: the adaptive control method of the active-end auxiliary thrust unit proposed in this invention realizes flexible switching between closed-loop and open-loop, active and passive control modes, thereby enabling the auxiliary thrust unit to have the ability to smoothly interact with external changes and uncertain resistance, effectively avoiding large speed fluctuations and force impacts, ensuring the reliability and safety of valve body insertion, locking and separation processes, and solving the problem that the active and passive refueling interfaces are prone to jamming during docking, locking and separation processes, leading to mission failure.

[0014] The technical solution adopted in this invention is: an adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system, comprising:

[0015] When the active valve body enters the envelope of the passive valve body, the filling controller uses speed control mode to control the motor in the active auxiliary unit to rotate. The motor drives the screw and nut to rotate through a planetary reducer. After the nut contacts the passive nut seat, it is limited by rotation. The screw continues to rotate, driving the active end to move towards the passive end for insertion. During the rotation, the motor current is monitored in real time. When the motor winding current is detected to exceed the set value I... a At that time, the corresponding motor output torque is T. a =K t ×I a The refueling controller switches to follow-up control mode to control the motor, and saves and fixes the duty cycle of the current loop regulator output at the mode switching moment and outputs it to the power driver, completing the adjustment from closed-loop control to open-loop control. The motor speed is adjusted according to the external load: when the load increases, the motor speed decreases, the screw rotation speed decreases, and the active end valve body movement speed decreases; when the load decreases, the motor speed increases, the screw rotation speed increases, and the active end valve body movement speed increases. When the limit switch signal is detected, it indicates that the active end valve body is inserted in place, and the active end auxiliary drive unit stops working.

[0016] When the filling process is completed and the valve body separation is initiated, a constant thrust is applied in the opposite direction to the thrust applied when the active valve body is inserted into the passive valve body. The filling controller is set to torque control mode, and the motor is in current closed-loop control mode, rotating in reverse. When the thrust generated by the motor's reverse rotation exceeds the resistance, the valve body separation speed gradually increases, and the rotational speed n is monitored to satisfy |n≥n D When |+Δn, the active-end auxiliary drive unit switches to follow-up control mode; in follow-up control mode, the motor speed and the moving speed of the active-end valve body are dynamically adjusted according to the change in resistance: the active and passive valve bodies move as they separate from the passive-end valve body, and when the motor speed n is detected to satisfy |n≥n C When |+Δn, the filling controller switches to speed control mode until the active and passive ends finally lose contact and the active auxiliary drive unit stops working.

[0017] Among them, K t Let n be the torque constant of the brushless DC motor. D This is the motor speed setting value when switching from torque mode to follow-up mode during valve body separation; Δn is the switching speed threshold. C Δn is the motor speed setting value when switching from follow-up mode to speed mode after valve body separation, and Δn is the speed switching threshold.

[0018] Furthermore, in the servo control mode, the motor speed and torque satisfy the following relationship:

[0019]

[0020] Among them, Ka U is the pulse width modulation duty cycle parameter of the power driver at the switching point. dc K is the DC bus voltage of the three-phase power bridge. e K is the back electromotive force constant of the brushless DC motor. t Let be the torque constant of the brushless DC motor, R be the phase resistance of the brushless DC motor, n be the speed, and T be the torque constant of the brushless DC motor. e This refers to the torque.

[0021] Furthermore, the adaptive control method for the active-end auxiliary drive unit of the on-orbit refueling system further includes:

[0022] When the resistance increases abnormally during the insertion of the active valve body, the speed gradually decreases until the current reaches the protection current limiting threshold. The refueling controller then switches from follow-up control mode to torque control mode. The refueling controller controls the motor of the active auxiliary unit to operate at constant torque, with a constant driving force. If the external resistance is greater than the driving force, the active valve body continues to decelerate until it stalls and cannot be inserted into the passive valve body. At this point, the motor stops forward drive and switches to reverse separation mode. After separation, the position and attitude are readjusted for re-insertion. If the external resistance changes to be less than the driving force, the motor speed increases while maintaining a constant torque. When the speed n satisfies n≥n B When +Δn is reached, the refueling controller switches to follow-up control mode. When the limit switch signal is detected, it indicates that the insertion is in place, and the drive stops.

[0023] Where, n B This is the motor speed setpoint when switching from torque control mode to follow-up control mode, and Δn is the switching speed threshold.

[0024] Furthermore, the refueling controller is used to realize the power drive and control of the active-end auxiliary drive unit, including a power driver, an adaptive control unit, a speed loop regulator, a current loop regulator, a current sampling ADC, and a Hall interface;

[0025] The current sampling ADC collects the motor winding current and feeds back the current value;

[0026] The Hall interface module collects the Hall signal output by the motor, and obtains the motor's rotational speed and position through the rotational speed estimation unit and the rotational position estimation unit, respectively, and feeds the speed and position back to the adaptive control unit;

[0027] The adaptive control unit controls the duty cycle required by the power driver by controlling the speed loop regulator and the current loop regulator, thereby controlling the motor current and torque.

[0028] The refueling controller has three control modes: speed control mode, follow-up control mode, and torque control mode.

[0029] The speed control mode includes an outer speed loop and an inner current loop. The output value of the speed loop regulator is the setpoint of the current loop regulator. The adaptive control unit outputs the motor speed setpoint, which is subtracted from the speed feedback value to obtain the deviation. This deviation is then calculated by the speed loop regulator to obtain the current setpoint. The current setpoint is used as the input value of the current loop regulator. It is compared with the current feedback value sent by the current sampling ADC and then calculated by the current loop regulator to obtain the pulse width modulation duty cycle required by the power driver, thereby realizing the control of motor current and speed.

[0030] The torque control mode includes a current loop. The adaptive control unit controls the speed loop regulator to turn off, and the adaptive control unit directly outputs the current loop setpoint. After comparing it with the current feedback sent by the current sampling ADC, the current loop regulator calculates the pulse width modulation duty cycle required by the power driver, thereby realizing the control of motor current and torque.

[0031] The servo control mode is characterized by the direct output of the pulse width modulation duty cycle by the adaptive control unit. In this mode, the motor is in an open-loop control state, and the motor current and speed are determined by the combined effect of the given pulse width modulation duty cycle and the external load.

[0032] The advantages of this invention compared to the prior art are:

[0033] 1. The present invention adopts the active end auxiliary drive unit to realize the correction, insertion, locking and separation of the active end valve body and the passive end valve body of the filling system, which reduces the complexity and difficulty of the active and passive end docking process. This is significantly different from the scheme that relies entirely on the active compliant control of the robotic arm to realize the active and passive end docking.

[0034] 2. The active-end auxiliary drive unit of this invention adopts a drive control strategy that combines closed-loop control and on-off control, as well as active and passive control. This ensures that the valve body can autonomously and adaptively adjust the control mode during insertion to flexibly adapt to dynamic changes in external resistance. Simultaneously, a hysteresis switching method is used during locking and disengagement to ensure the smoothness of the mode switching process. This is significantly different from existing methods that use a single control mode.

[0035] 3. The technical method adopted in this invention fully considers the uncertainty and time-varying nature of the position and attitude changes during the docking process of the main and passive valve bodies, as well as the uncertainty and time-varying nature of the spring resistance, sealing ring friction resistance and drag resistance. Based on the changes in external resistance, the control mode and parameters are adaptively adjusted, so that the auxiliary thrust unit has the ability to smoothly interact with external changes and uncertain resistance, effectively avoiding large speed fluctuations and force impacts, and ensuring the reliability and safety of the locking and disengaging process.

[0036] 4. This invention employs an open-loop passive drive method at low speeds, automatically finding a stable point during dynamic force interaction. This solves the problem of poor rotational closed-loop control caused by inaccurate Hall signal speed measurement at low speeds, eliminates the problem of stalled integral desaturation in speed closed-loop control, and addresses the instability of the operating point in current closed-loop control. A hysteresis switching method is also used, resulting in smoother and more seamless mode switching. Attached Figure Description

[0037] Figure 1 This is a diagram showing the initial working state of the active-end auxiliary drive unit.

[0038] Figure 2 This is a control mode diagram of the active-end auxiliary drive unit in this invention;

[0039] Figure 3 This is a schematic diagram of the adaptive control process of the active-end auxiliary drive unit in this invention;

[0040] Figure 4 This is the adaptive control block diagram in this invention. Detailed Implementation

[0041] The present invention will be described in detail with reference to the accompanying drawings.

[0042] The active-end auxiliary drive unit includes a motor, a planetary gearbox, a screw, and a nut, wherein the motor is a brushless DC motor. When the brushless DC motor rotates, it drives the screw and nut to rotate after being reduced in speed by the planetary gearbox. If the nut is constrained by a limit switch, the screw acts like a screw, driving the entire active-end auxiliary drive unit to move.

[0043] like Figure 4 As shown, the refueling controller is used to realize the power drive and control of the active-end auxiliary drive unit, mainly including a motor power driver, an adaptive control unit, a speed loop regulator, and a current loop regulator. The current sampling ADC collects the motor winding current and feeds back the current value. The Hall interface module collects the Hall signal output by the motor, and obtains the motor rotation speed and position through the rotation speed estimation unit and the rotation position estimation unit, respectively, and feeds the speed and position back to the adaptive control unit.

[0044] The main control modes of the refueling controller include speed control, follow-up control and torque control modes.

[0045] The speed control mode consists of an outer speed loop and an inner current loop. The output of the speed loop regulator is the setpoint for the current loop. The adaptive control unit outputs the motor speed setpoint, which is subtracted from the speed feedback value to obtain the deviation. This deviation is then calculated by the speed loop regulator (usually a proportional-integral regulator) to obtain the current setpoint. This value serves as the input to the current loop. After being compared with the current feedback, it is calculated by the current loop regulator (usually a proportional-integral regulator) to obtain the pulse width modulation duty cycle required by the power driver, thereby achieving control of the motor current and speed.

[0046] The torque control mode consists of a separate current loop. The adaptive control unit controls the speed loop regulator to be turned off (constant output is 0), and the adaptive control unit directly outputs the current loop setpoint. After being compared with the current feedback, the current loop regulator (usually a proportional-integral regulator) calculates the pulse width modulation duty cycle required by the power driver, thereby realizing the control of motor current and torque.

[0047] In the follow-up control mode, the adaptive control unit directly outputs the pulse width modulation duty cycle, closing both the speed loop and the current loop. At this time, the motor is in an open-loop control state, that is, the motor current and speed are not regulated through the closed loop, but are determined by the combined effect of the given pulse width modulation duty cycle and the external load, which is a follow-up state.

[0048] The adaptive control method described in this invention is a refueling controller control mode and its adaptive control strategy designed based on the working characteristics and control objectives of the active auxiliary drive unit.

[0049] The initial operating state of the adaptive control of the active-end auxiliary drive unit is as follows: Figure 1 As shown, at this time, the active valve body enters the envelope of the passive valve body seat under the guidance and clamping device composed of spring and guide rail. Simultaneously, the nut of the active auxiliary drive unit enters the nut seat of the passive end. Starting from this point, the active auxiliary drive unit begins to work until the active valve body is safely and reliably inserted into the passive valve body. During the valve body docking process, there are positional and attitude errors, and it is also affected by various external factors such as spring resistance, friction, and hose dragging force. For example... Figure 3 As shown, the control modes (speed control, follow-up control, and torque control) of the active-end auxiliary drive unit are adaptively switched and adjusted according to the insertion and separation process of the active-end valve body.

[0050] Figure 3 This is a schematic diagram of the adaptive control process of the auxiliary drive unit in this invention, where the horizontal axis represents the torque T. e The vertical axis represents the rotational speed n.

[0051] The detailed control method is described below:

[0052] Step 1: As Figure 2 The active-end auxiliary drive unit operates in speed control mode, meaning the brushless DC motor rotates using closed-loop speed control. The screw after the planetary reducer drives the nut to rotate (the nut and screw are mounted via a helical transmission pair). When the nut hits the nut seat, it is limited in rotation. At this point, the screw continues to rotate, and the nut is locked in place. Under the tension of the thread, the entire active end moves towards the passive end for insertion, and the corresponding resistance gradually increases. Figure 3 In the constant speed region, the speed is given as n A The speed feedback is calculated using Hall signals, such as... Figure 4 As shown, both the speed loop and the current loop use proportional-integral controllers with anti-integral saturation, the speed command is given by the adaptive control unit, and the motor current is monitored in real time during rotation.

[0053] Step 2: As the depth of the active valve body into the passive valve body seat increases, the resistance gradually increases. When the motor winding current exceeds the set value I, the resistance continues. a (The corresponding motor output torque is T) a =K t ×I a When the active auxiliary drive unit switches to a follow-up control mode, the motor speed closed-loop control and current closed-loop control cease operation. The duty cycle of the current loop regulator output at the mode switch moment is saved and fixedly output to the power driver, thus completing the transition from closed-loop control to open-loop control. At this point, the motor speed will adaptively adjust according to changes in the external load. Figure 3 In the position follow-up zone, when the load increases, the motor speed decreases, the screw rotation speed decreases, and the moving speed of the active end valve body decreases. Conversely, when the load decreases, the motor speed increases, the screw rotation speed increases, and the moving speed of the active end valve body increases. During the follow-up process, the speed and torque satisfy the following relationship:

[0054]

[0055] In the formula, K a For the power driver pulse width modulation duty cycle (PWM) parameter at the switching point, U dc K is the DC bus voltage of the three-phase power bridge. e K is the back electromotive force constant of the brushless DC motor. t U is the torque constant of the brushless DC motor, R is the phase resistance of the brushless DC motor, and n is the speed. When switching to servo control mode, U... dc K e K t All are fixed values, K a This is an adjustable parameter.

[0056] As mentioned above, the process of continuously inserting the active valve body into the passive valve body is a self-correction process of the active valve body's position and attitude. The initial position and attitude error of the active valve body is uncertain and is also affected by the passive dragging resistance of the robotic arm end and the hose. The uncertain and constantly changing position and attitude error will cause the spring resistance, sealing ring friction resistance, and dragging resistance experienced by the valve body during insertion to exhibit significant uncertainty and time-varying characteristics.

[0057] Therefore, when the active-end auxiliary drive unit switches to follow-up control mode, the motor operating point is at Figure 3 Point AB in the diagram (the coordinates of point A are (T) a n A The coordinates of point B are (T) b n B The movement between the two ends is adaptively and passively adjusted by the motor speed and the speed at which the active end valve body inserts into the passive end in accordance with the real-time changes in the external load. During the dynamic process, it autonomously seeks the compliance and stability of the interaction with the external force. When the external resistance increases, it adaptively reduces the speed to cooperate with the self-correction process of the external compliance module and the position-attitude of the robotic arm. When the position and attitude error decreases and the external resistance decreases, it adaptively increases the speed to shorten the docking and locking time.

[0058] When the resistance increases abnormally during the insertion of the active valve body, and the rotation speed gradually decreases until the current reaches the protection current limiting threshold, the active auxiliary drive unit automatically switches from the follow-up control mode to the torque control mode. Figure 3 In the constant torque region, the current closed loop is given by the current limiting threshold, and the corresponding output torque is T. b At this point, there is a constant torque output (corresponding to a constant driving force), which prevents stall torque (T) from occurring. m The mechanism jams during output, leading to a serious malfunction where the valve body cannot be corrected or disengaged. (Corresponding...) Figure 3 In the context of B-B0 (the coordinates of point B0 are (T...),... b In the range of 0), if the external resistance is greater than the driving force, the active valve body will continuously decelerate until it stalls and cannot be inserted. At this time, it is necessary to stop the forward drive and switch to the reverse separation mode. After separation, the position and attitude should be readjusted and reinserted. If the external resistance changes to be less than the driving force, the operating point will be set according to B-B1 (the coordinates of point B1 are (T)). b n B The vehicle moves in the direction of +Δn)) and enters the follower zone when the rotation speed n satisfies the following formula (2). When the limit switch signal is detected, it indicates that the insertion is in place and the drive stops. Figure 3 n B This is the motor speed setpoint when switching from torque control mode to follow-up control mode, and Δn is the switching speed threshold.

[0059] n≥n B +Δn (2)

[0060] Step 4: When the valve body separates after the filling process is completed, a constant thrust opposite to that used during insertion is applied. The active auxiliary drive unit control mode is set to torque control mode, and the motor is in current closed-loop control mode, rotating in the opposite direction. The set current value is greater than the protection current threshold during insertion to ensure that friction, spring resistance, and other resistances can be overcome (the coordinates of point D are (T...). d ,n D The coordinates of point D1 are (T d ,n D +Δn)).

[0061]

[0062] The above formula is the expression for the screw thrust F, where T is the motor output torque and L is the screw lead.

[0063] When the thrust generated by the reverse rotation of the motor is greater than the resistance, the speed of valve body separation gradually increases. When the speed n is monitored to meet the following conditions (formula (4)), the active end auxiliary drive unit switches to follow-up control mode. Figure 3 n D Δn is the motor speed setting value when switching from torque mode to follow-up mode during valve body separation, and Δn is the switching speed threshold.

[0064] n≥n D |+Δn (4)

[0065] In the follow-up control mode, the motor speed and the moving speed of the active end valve body will be dynamically adjusted according to the change of resistance. If the active and passive valve bodies move as they separate from the passive end valve body, their resistance will decrease, causing the active and passive end valve bodies to separate further and faster. When the motor speed n is detected to meet the following conditions (formula (5)), the speed control mode is switched to continue until the active and passive ends finally separate from each other, the active end auxiliary drive unit stops working, and the entire filling process is completed. Figure 3 n C Δn is the motor speed setting value when switching from follow-up mode to speed mode after valve body separation, and Δn is the speed switching threshold.

[0066] n≥n C |+Δn (5)

[0067] The parts of this invention not described in detail are well-known to those skilled in the art.

Claims

1. An adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system, characterized in that, include: When the active valve body enters the envelope of the passive valve body, the filling controller uses speed control mode to control the motor in the active auxiliary unit to rotate. The motor drives the screw and nut to rotate through a planetary reducer. After the nut contacts the passive nut seat, it is limited by rotation. The screw continues to rotate, driving the active end to move towards the passive end for insertion. During the rotation, the motor current is monitored in real time. When the motor winding current is detected to exceed the set value I... a At that time, the corresponding motor output torque is T. a =K t ×I a The refueling controller switches to follow-up control mode to control the motor, and saves and fixes the duty cycle of the current loop regulator output at the mode switching moment and outputs it to the power driver, completing the adjustment from closed-loop control to open-loop control. The motor speed is adjusted according to the external load: when the load increases, the motor speed decreases, the screw rotation speed decreases, and the active end valve body movement speed decreases; when the load decreases, the motor speed increases, the screw rotation speed increases, and the active end valve body movement speed increases. When the limit switch signal is detected, it indicates that the active end valve body is inserted in place, and the active end auxiliary drive unit stops working. When the filling process is completed and the valve body separation is initiated, a constant thrust is applied in the opposite direction to the thrust applied when the active valve body is inserted into the passive valve body. The filling controller is set to torque control mode, and the motor is in current closed-loop control mode, rotating in reverse. When the thrust generated by the motor's reverse rotation exceeds the resistance, the valve body separation speed gradually increases, and the rotational speed n is monitored to satisfy |n|≥|n D When |+Δn, the active-end auxiliary drive unit switches to follow-up control mode; in follow-up control mode, the motor speed and the moving speed of the active-end valve body are dynamically adjusted according to the change in resistance: the active and passive valve bodies move as they separate from the passive-end valve body, and when the motor speed n is detected to satisfy |n|≥|n C When |+Δn, the filling controller switches to speed control mode until the active and passive ends finally lose contact and the active auxiliary drive unit stops working. Among them, K t Let n be the torque constant of the brushless DC motor. D This is the motor speed setting value when switching from torque mode to follow-up mode during valve body separation; Δn is the switching speed threshold. C Δn is the motor speed setting value when switching from follow-up mode to speed mode after valve body separation, and Δn is the speed switching threshold.

2. The adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system according to claim 1, characterized in that, In servo control mode, the motor speed and torque satisfy the following relationship: Among them, K a U is the pulse width modulation duty cycle parameter of the power driver at the switching point. dc K is the DC bus voltage of the three-phase power bridge. e K is the back electromotive force constant of the brushless DC motor. t Let be the torque constant of the brushless DC motor, R be the phase resistance of the brushless DC motor, n be the speed, and T be the torque constant of the brushless DC motor. e This refers to the torque.

3. The adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system according to claim 2, characterized in that, Also includes: When the resistance increases abnormally during the insertion of the active valve body, the speed gradually decreases until the current reaches the protection current limiting threshold. The refueling controller then switches from follow-up control mode to torque control mode. The refueling controller controls the motor of the active auxiliary unit to operate at constant torque, with a constant driving force. If the external resistance is greater than the driving force, the active valve body continues to decelerate until it stalls and cannot be inserted into the passive valve body. At this point, the motor stops forward drive and switches to reverse separation mode. After separation, the position and attitude are readjusted for re-insertion. If the external resistance changes to be less than the driving force, the motor speed increases while maintaining a constant torque. When the speed n satisfies n≥n B When +Δn is reached, the refueling controller switches to follow-up control mode. When the limit switch signal is detected, it indicates that the insertion is in place, and the drive stops. Where, n B This is the motor speed setpoint when switching from torque control mode to follow-up control mode, and Δn is the switching speed threshold.

4. The adaptive control method for the active-end auxiliary drive unit of an on-orbit refueling system according to claim 3, characterized in that, The refueling controller is used to realize the power drive and control of the active-end auxiliary drive unit, including a power driver, an adaptive control unit, a speed loop regulator, a current loop regulator, a current sampling ADC, and a Hall interface; The current sampling ADC collects the motor winding current and feeds back the current value; The Hall interface module collects the Hall signal output by the motor, and obtains the motor's rotational speed and position through the rotational speed estimation unit and the rotational position estimation unit, respectively, and feeds the speed and position back to the adaptive control unit; The adaptive control unit controls the duty cycle required by the power driver by controlling the speed loop regulator and the current loop regulator, thereby controlling the motor current and torque. The refueling controller has three control modes: speed control mode, follow-up control mode, and torque control mode.

5. The adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system according to claim 4, characterized in that, The speed control mode includes an outer speed loop and an inner current loop. The output value of the speed loop regulator is the setpoint of the current loop regulator. The adaptive control unit outputs the motor speed setpoint, which is subtracted from the speed feedback value to obtain the deviation. This deviation is then calculated by the speed loop regulator to obtain the current setpoint. The current setpoint is used as the input value of the current loop regulator. It is compared with the current feedback value sent by the current sampling ADC and then calculated by the current loop regulator to obtain the pulse width modulation duty cycle required by the power driver, thereby realizing the control of motor current and speed.

6. The adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system according to claim 4, characterized in that, The torque control mode includes a current loop. The adaptive control unit controls the speed loop regulator to turn off, and the adaptive control unit directly outputs the current loop setpoint. After comparing it with the current feedback sent by the current sampling ADC, the current loop regulator calculates the pulse width modulation duty cycle required by the power driver, thereby realizing the control of motor current and torque.

7. The adaptive control method for an active-end auxiliary drive unit in an on-orbit refueling system according to claim 4, characterized in that, The servo control mode is characterized by the direct output of the pulse width modulation duty cycle by the adaptive control unit. In this mode, the motor is in an open-loop control state, and the motor current and speed are determined by the combined effect of the given pulse width modulation duty cycle and the external load.

Images