A small satellite twelve-thruster force couple type attitude and orbit coupling control system and method

Abstract

The application relates to the technical field of space robots, and provides a small-satellite twelve-thruster force-couple type attitude-orbit coupling control system which comprises a satellite body, first to twelfth thrusters T1-T12 and a controller. T1-T8 constitute an attitude-orbit coupling thruster group, four groups of force-couple type force coupling units C1-C4 are formed according to the positions which are central symmetrical about a coordinate origin and the opposite directions of the thrust forces. The directions of the unit thrust forces of the thrusters in T1-T8 are determined according to the installation position coordinates of the thrusters according to a unified rule, so that the directions of the thrust forces of the thrusters have a corresponding relationship which is central symmetrical about the coordinate origin. When two thrusters in the same force-couple type force coupling unit are fired with equal thrust forces, the resultant force is zero and a control torque which does not change with the position of the satellite gravity center is generated. The controller is configured to combine two groups of force-couple type force coupling units in C1-C4 to generate positive or negative control torques around the X axis, the Y axis and the Z axis. T9-T12 constitute a +X direction orbit-changing acceleration and deceleration thruster group.

Description

Technical Field

[0001] This invention relates to the technical field of space robots, and more particularly to a twelve-thrust couple-type attitude-orbit coupling control system and method for small satellites. It is applied to the attitude control, orbit control, and micro-propulsion systems of small satellites and other space robots. Specifically, it employs a twelve-thrust attitude-orbit coupling control technology scheme that uses four sets of couple-type coupling units (T1 to T8) to achieve six-directional attitude control torque, and uses T9 to T12 to enhance the ±X-direction orbital change acceleration and deceleration capabilities. Background Technology

[0002] U-class small satellites and small space robots are typically subject to strict constraints from factors such as the overall satellite envelope size, mass limits, space constraints for gas supply piping, and onboard energy supply conditions, resulting in extremely limited design margins. Therefore, they must simultaneously perform both attitude control and orbit control within a very compact installation space. In conventional technical solutions, flywheels are suitable for continuous, high-precision attitude adjustment, providing stable and controllable torque output; while thrusters not only generate the thrust required for orbit control but can also be used to unload the angular momentum accumulated by the flywheel or actively supplement attitude control torque. In recent years, with the continuous expansion of small satellite mission requirements, higher demands have been placed on high-precision control during rapid orbital maneuvers, formation flying, and rendezvous and docking. The functional positioning of thruster arrays has gradually evolved from a single orbital propulsion means or an independent attitude control actuator to a coupled control system integrating attitude and orbit.

[0003] However, the commonly used eight-thrust or twelve-thrust layout schemes in existing technologies usually require comprehensive compromises and trade-offs between the control force output capability in the three axes, the control torque output capability in the three axes, and the effective thrust magnitude in the main orbit change direction, making it difficult to balance the performance of all aspects. Specifically, if the orientation of the eight attitude-orbit coupled thrusters results in the control torque component in a certain axis being always zero, then the control in that direction can only rely on the flywheel or other additional actuators, and it is impossible for the thruster array to independently generate control torque in both positive and negative directions, thereby weakening the system's autonomous control capability under flywheel failure or flywheel saturation conditions. On the other hand, if the paired couple relationship between the thrusters is deliberately disrupted in order to obtain rolling torque, then when the satellite's center of gravity changes due to propellant consumption, the ignition combination is very likely to generate undesirable additional resultant force or additional torque, thereby affecting the control accuracy of attitude and orbit.

[0004] Furthermore, in a typical layout where most of the satellite's internal volume is occupied by cold gas cylinders, propellant consumption will cause the satellite's center of gravity to shift in the X, Y, and Z directions. Since the action line of the orbit-changing thruster deviates from the actual center of gravity, it will inevitably generate residual torque in the pitch or yaw direction, further exacerbating the complexity of attitude and orbit coupling control.

[0005] Therefore, it is urgent to propose a method that can clearly define the force coupling structure of the four sets of force couples from T1 to T8 while keeping them unchanged. , , The ignition combination of control torques in each axis and the twelve-thrust layout scheme that can real-time redistribute the control quantities of each thruster according to changes in the satellite's center of gravity are used to address the aforementioned shortcomings in the existing technology. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a small satellite twelve-thrust couple-type attitude and orbit coupling control system and method. The goal is to achieve a couple-type coupling configuration where eight attitude and orbit coupling thrusters maintain central symmetry and opposite directions within the finite outer envelope of the small satellite. Simultaneously, these eight thrusters generate three-axis positive and negative control torques, and an additional four thrusters enhance the acceleration and deceleration capabilities in the ±X directions.

[0007] The above-mentioned objective of this invention is achieved through the following technical solutions: A small satellite twelve-thrust couple attitude and orbit coupling control system includes a satellite body, first thrusters T1 to twelfth thrusters T12, and a controller. The outer envelope dimensions of the satellite body along the X, Y, and Z directions are a, b, and c, respectively, with the geometric center of the satellite body as the coordinate origin. T1 to T8 constitute the attitude-track coupling thruster group, and according to the positions of the pairs of centrally symmetrical about the coordinate origin and the opposite thrust action directions, they form four sets of couple-type force coupling units C1 to C4. The direction of the unit thrust of each thruster in T1 to T8 is determined according to the coordinates of its installation position in accordance with a unified rule, so that the thrust direction of each thruster has a symmetrical correspondence about the origin of the coordinate system. When the two thrusters in the same couple unit ignite with equal thrust, the resultant force is zero and a control torque that does not change with the position of the satellite's center of gravity is generated. The controller is configured to generate positive or negative control torques around the X-axis, Y-axis and Z-axis respectively by combining two sets of couple-type coupling units from C1 to C4. T9 to T12 constitute the ±X direction orbital change acceleration and deceleration thruster group.

[0008] Furthermore, when any of the thrusters T1 to T8 The installation position vector relative to the geometric center is At that time, the direction of its unit thrust is:

[0009] in, , , The first The coordinate components of the installation position of the thruster in the X, Y, and Z axes. The roll bias coefficient and , This is the unit direction vector of the thrust acting on the satellite body.

[0010] Furthermore, let A = a / 2, B = b / 2, C = c / 2, where A, B, and C are the half-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively. The installation positions of T1 to T8 are as follows: T1 is located at (+A,+B,+C); T2 is located at (-A,-B,-C); T3 is located at (+A,+B,-C); T4 is located at (-A,-B,+C); T5 is located at (+A,-B,+C); T6 is located at (-A,+B,-C); T7 is located at (+A,-B,-C); T8 is located at (-A,+B,+C). The thrust direction of each thruster is calculated using the formula for the unit thrust direction.

[0011] Furthermore, C1 is composed of T1 and T2, C2 is composed of T3 and T4, C3 is composed of T5 and T6, and C4 is composed of T7 and T8; for any couple-type force coupling unit The installation position vectors of the two thrusters are opposites of each other, and the directions of their thrust are opposites of each other.

[0012] Furthermore, T1, T3, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T2, T4, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T4, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T1, T3, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T3, T6, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T1, T4, T5 and T8 ignite simultaneously with equal thrust to generate Track control force; in , , The track control forces are respectively along the X-axis, Y-axis, and Z-axis. When the origin of the coordinate system is taken as the torque reference point, the non-target axial force components and the three-axis torque components of each ignition combination cancel each other out.

[0013] Furthermore, C1 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C3 ignite simultaneously with equal thrust to produce Controlling torque, C1 and C3 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C3 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C1 and C2 ignite simultaneously with equal thrust to produce Control torque; where , , These are the control torques around the X-axis, Y-axis, and Z-axis, respectively, and the non-target axis torque components in each combination cancel each other out.

[0014] Furthermore, T9 is located in And the direction of the thrust is T10 is located And the direction of the thrust is T11 is located And the direction of the thrust is T12 is located And the direction of the thrust is Where A, B, and C are the semi-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively, and the projections of T9 to T12 in the YZ plane form a cross shape; The controller has a fixed thrust control mode and a continuously adjustable thrust control mode. In the fixed thrust control mode, the equivalent thrust is adjusted by the ignition pulse width, duty cycle or number of ignitions. In the continuously adjustable thrust control mode, each thruster is continuously adjustable from 1mN, with an adjustment granularity of 1mN and not exceeding its rated thrust. The roll offset coefficient κ is 0.7 to 0.9, so that the roll control torque about the X-axis is less than the pitch control torque about the Y-axis and the yaw control torque about the Z-axis and remains non-zero; The six-row, eight-column control matrix formed by T1 to T8 has a rank of 6 and contains a zero generalized force bias vector with all positive components, enabling T1 to T8 to generate thrust through continuous thrust or time-averaged thrust under non-negative thrust constraints. , , , , and This enables the system to perform six-degree-of-freedom attitude-orbit coupling control solely by the thruster, even when the flywheel is not installed or is unavailable.

[0015] A method for controlling the attitude and orbit of a small satellite using a torque-coupled attitude and orbit coupling control system as described above is applied to a twelve-thrust system including the satellite body, the first thruster T1 to the twelfth thruster T12, and a controller. T1 to T8 are arranged in pairs with symmetrical installation positions and opposite thrust directions to form four sets of torque-coupled units C1 to C4. T9 and T10 act along the +X direction, and T11 and T12 act along the -X direction. The method includes: S1: Obtain the desired six-dimensional generalized force, current satellite center of gravity, and thruster status; S2: Establish a control matrix based on the installation positions of T1 to T12, the direction of thrust, and the current center of gravity of the satellite; S3: Determine if there is a need for a +X or -X direction orbit change; S4: When the track change requirement exists, T9 and T10 or T11 and T12 shall be allocated preferentially respectively; S5: Calculate the residual six-dimensional generalized force after deducting the generalized force generated by the orbital acceleration and deceleration thruster assembly; S6: Based on the force couple combination allocation of C1 to C4 , and ; S7: Jointly distribute the triaxial force components of T1 to T8 and perform amplitude limiting or quantization; S8: Outputs ignition control commands for twelve thrusters.

[0016] Furthermore, in the fixed thrust control mode, the ignition duty cycle is used as a continuous equivalent control variable for control allocation and then converted into a pulse sequence; in the continuously adjustable thrust control mode, the obtained thrust command is quantized with a granularity of 1mN, and the residual generalized force is recalculated after quantization.

[0017] Furthermore, when the satellite's center of gravity shifts due to propellant consumption, the lever arm in the control matrix is ​​updated; the residual pitch and yaw moments caused by the center of gravity shift between T9 and T10 or between T11 and T12 are compensated by C1 to C4, while the pure couple moments generated by C1 to C4 during constant thrust ignition are not changed due to the center of gravity shift.

[0018] Compared with the prior art, the present invention has at least one of the following beneficial effects: (1) T1 to T8 are not ordinary corner-mounted oblique units, but are set up as four sets of centrally symmetrical, opposite-direction force couple units. When the two thrusters in the same force couple unit ignite with equal thrust, the resultant force is zero, and the control torque generated does not change with the position of the satellite's center of gravity. This characteristic fundamentally eliminates the influence of the center of gravity drift caused by propellant consumption on the pure torque output of the force couple unit itself, eliminating the need for additional torque compensation for the center of gravity shift, and significantly simplifying the design complexity of the control system.

[0019] (2) By setting the roll bias coefficient and The unified direction cosine rule ensures that while maintaining the central symmetry of the thrust direction of each thruster, the rolling torque component around the X-axis is no longer zero, making the rolling control component, which was originally zero when κ=1, controllable. Furthermore, by combining two sets of four force couple units ignited simultaneously with equal thrust, positive or negative pure control torques around the X, Y, and Z axes are generated respectively. , , Furthermore, the non-target axial torque components in each combination cancel each other out.

[0020] (3) The rank of the six-row, eight-column control matrix formed by T1 to T8 is 6, and there exists a zero generalized force bias vector with all positive components. This allows the three-axis positive and negative orbital control forces to be covered simultaneously by continuous thrust or time-averaged thrust, under the physical constraint that the thruster can only output unidirectional thrust. , , and three-axis positive and negative attitude control torque , , Even when the flywheel is not set or is unavailable, all six degrees of freedom control variables can still be independently completed by the thruster to achieve complete six-degree-of-freedom attitude-orbit coupling control.

[0021] (4) T9 to T12 are arranged with a cross-shaped edge in the YZ plane, which effectively enhances the acceleration and deceleration capability of orbit change in the ±X direction. When the satellite's center of gravity shifts, the residual pitching moment and yaw moment generated by the paired ignition of T9 and T10 or T11 and T12 are compensated by C1 to C4. The pure couple moment generated by C1 to C4 during constant thrust ignition does not change due to the shift of the center of gravity, ensuring that the attitude is not disturbed during the orbit change process. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the overall layout, YZ plane projection and XY plane projection of the twelve thrusters of the present invention. The three-dimensional overall layout marks the origin of the satellite's geometric center O, and each projection is marked T1 to T12. The thrust components perpendicular to the projection plane and pointing out of and into the paper are represented by dot formula symbols and cross formula symbols, respectively. Figure 2 This is a diagram showing the relationship between the four sets of couple-type force coupling units (T1 to T8) and the six-axis control torque combination of the present invention. Figure 3 This is a flowchart of the twelve-thruster control and allocation method of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0025] In this invention, T1 to T8 form four sets of centrally symmetrical, oppositely oriented force couple units in eight corner regions; the positions are... At that time, the direction of the unit thrust is ,in When the same couple ignites with equal thrust, the resultant force is zero, and the torque is independent of the center of gravity; the four couples combined in pairs produce pure torque. , , The eight-thrust control matrix is ​​full rank, allowing for six-degree-of-freedom control even without a flywheel or when the flywheel is unavailable, relying solely on the thrusters. T9 and T10 are located on the -X side and act along the +X direction, while T11 and T12 are located on the +X side and act along the -X direction. Their projection onto the YZ plane forms a cross shape, enhancing ±X orbital acceleration and deceleration. The controller updates the control matrix and allocates the main thrust and residual generalized force based on the current center of gravity. This invention effectively solves the problem of small satellites struggling to achieve both efficient attitude control and orbital maneuvering under limited thrust quantity and unidirectional thrust constraints. It significantly improves six-degree-of-freedom attitude-orbit coupling control capabilities, thrust allocation flexibility, and orbital efficiency, providing hardware configuration and control foundation support for the on-orbit dexterity of small satellites and space robots.

[0026] The following is an illustration through specific examples: First Embodiment like Figure 1 As shown, this embodiment provides a small satellite twelve-thrust couple attitude and orbit coupling control system, including a satellite body, a first thruster T1 to a twelfth thruster T12, and a controller. The outer envelope dimensions of the satellite body along the X, Y, and Z directions are a, b, and c, respectively, with the geometric center of the satellite body as the coordinate origin. T1 to T8 constitute the attitude and orbit coupling thruster group. According to the positions of the pairs of centrally symmetrical about the origin of the coordinate system and the opposite thrust action directions, four sets of couple-type couple units C1 to C4 are formed. T1 to T8 are set at the eight corner points of the satellite or their adjacent installation areas. The direction of the unit thrust of each thruster in T1 to T8 is determined according to the coordinates of its installation position in accordance with a unified rule, so that the thrust direction of each thruster has a symmetrical correspondence about the origin of the coordinate system. When the two thrusters in the same couple unit ignite with equal thrust, the resultant force is zero and a control torque that does not change with the position of the satellite's center of gravity is generated. The controller is configured to generate positive or negative control torques around the X-axis, Y-axis and Z-axis respectively by combining two sets of couple-type coupling units from C1 to C4. T9 to T12 constitute the ±X direction orbital change acceleration and deceleration thruster group.

[0027] Furthermore, when any of the thrusters T1 to T8 The installation position vector relative to the geometric center is At that time, the direction of its unit thrust is:

[0028] in, , , The first The coordinate components of the installation position of the thruster in the X, Y, and Z axes. The roll bias coefficient and , This is the unit direction vector of the thrust acting on the satellite body.

[0029] The jet direction is opposite to the direction of the thrust. The present invention differs from the case where the roll component is zero by making the roll component zero. The non-zero rolling torque is retained even when it is less than 1; When the value is close to 1, the roll capability is weaker than the pitch and yaw capabilities, which meets the mission requirements that are mainly based on pitch and yaw.

[0030] Same couple The installation positions and orientations of the two inner thrusters meet the requirements. , When two thrusters ignite with the same thrust u, their resultant force... and about the current focus Resultant torque They are respectively:

[0031]

[0032] The resultant force of the thrust ignition by the couple is zero, and the current center of gravity is... The components are strictly offset. Therefore, the change in center of gravity caused by propellant consumption will not change the pure control torque generated by the couple itself, which is the basis for the T1 to T8 couple settings to adapt to changes in center of gravity.

[0033] Furthermore, let A = a / 2, B = b / 2, C = c / 2, where A, B, and C are the half-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively. The installation positions of T1 to T8 are as follows: T1 is located at (+A,+B,+C); T2 is located at (-A,-B,-C); T3 is located at (+A,+B,-C); T4 is located at (-A,-B,+C); T5 is located at (+A,-B,+C); T6 is located at (-A,+B,-C); T7 is located at (+A,-B,-C); T8 is located at (-A,+B,+C). The thrust direction of each thruster is calculated using the formula for the unit thrust direction.

[0034] Furthermore, C1 is composed of T1 and T2, C2 is composed of T3 and T4, C3 is composed of T5 and T6, and C4 is composed of T7 and T8; for any couple-type force coupling unit The installation position vectors of the two thrusters are opposites of each other, and the directions of their thrust are opposites of each other.

[0035] Furthermore, T1, T3, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T2, T4, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T4, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T1, T3, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T3, T6, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T1, T4, T5 and T8 ignite simultaneously with equal thrust to generate Track control force; in , , The track control forces are respectively along the X-axis, Y-axis, and Z-axis. When the origin of the coordinate system is taken as the torque reference point, the non-target axial force components and the three-axis torque components of each ignition combination cancel each other out.

[0036] Furthermore, C1 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C3 ignite simultaneously with equal thrust to produce Controlling torque, C1 and C3 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C3 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C1 and C2 ignite simultaneously with equal thrust to produce Control torque; where , , These are the control torques around the X-axis, Y-axis, and Z-axis, respectively, and the non-target axis torque components in each combination cancel each other out.

[0037] Furthermore, T9 is located in And the direction of the thrust is T10 is located And the direction of the thrust is T11 is located And the direction of the thrust is T12 is located And the direction of the thrust is Where A, B, and C are the semi-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively, and the projections of T9 to T12 in the YZ plane form a cross shape; The controller has a fixed thrust control mode and a continuously adjustable thrust control mode. In the fixed thrust control mode, the equivalent thrust is adjusted by the ignition pulse width, duty cycle or number of ignitions. In the continuously adjustable thrust control mode, each thruster is continuously adjustable from 1mN, with an adjustment granularity of 1mN and not exceeding its rated thrust. The roll offset coefficient κ is 0.7 to 0.9, preferably 0.8, so that the roll control torque about the X-axis is less than the pitch control torque about the Y-axis and the yaw control torque about the Z-axis and remains non-zero; The six-row, eight-column control matrix formed by T1 to T8 has a rank of 6 and contains a zero generalized force bias vector with all positive components, enabling T1 to T8 to generate thrust through continuous thrust or time-averaged thrust under non-negative thrust constraints. , , , , and This enables the system to perform six-degree-of-freedom attitude-orbit coupling control solely by the thruster, even when the flywheel is not installed or is unavailable.

[0038] In this embodiment, let A = a / 2, B = b / 2, and C = c / 2. The amplitudes of the three moments of the four sets of couples are:

[0039]

[0040]

[0041] The torque signs of the four sets of couples are as follows: , , , When any two sets of couples are ignited simultaneously with equal thrust, the two non-target axis components cancel each other out, thus forming pure single-axis positive and negative control torques.

[0042] Table 1. Symbolic installation coordinates and thrust direction of the twelve thrusters

[0043] In Table 1, the origin O is located at the geometric center of the satellite. The directions of T1 to T8 are all the direction of unit thrust, and the installation coordinates and thrust directions of the two thrusters in each group of C1 to C4 are opposites of each other; the thrust directions of T9 to T12 are along the +X or -X direction, respectively.

[0044] Table 2 Typical Couple Combinations for Six-Directional Control Torques

[0045] Table 2 This represents the maximum thrust of a single unit from T1 to T8. The roll moment formula contains a factor. Therefore, it can be passed This results in relatively weak roll control capability but maintains a non-zero value; pitch and yaw moments are respectively determined by... The product of terms and geometric dimensions is enhanced.

[0046] In addition to the six-directional control torque, T1 to T8 can also generate the four equal thrust combinations shown in the table below. , and Orbit control force. When the satellite's geometric center O is used as the torque reference point, the selected thruster ignites with the same thrust u, and the three-axis torque cancels out the two non-target axis force components; the fixed thrust mode uses the same duty cycle, and the continuously adjustable mode uses the same thrust command.

[0047] Table 3 Typical constant thrust combinations for six-axis orbital control forces

[0048] The formula for the maximum resultant force in Table 3 is directly derived from the direction cosines of T1 to T8. When the geometric center O is taken as a reference, the resultant force on the non-target axis and the resultant moment on all three axes are zero; when the current center of gravity is offset relative to O... At that time, the residual torque generated by the resultant force of the track control is The controller compensates by updating the control matrix and superimposing the C1-C4 couple combination.

[0049] For the six degrees of freedom controllability of T1 to T8, the generalized force column vector corresponding to the unit thrust of a single thruster is defined as:

[0050]

[0051] When the geometric center is taken as the torque reference point, the pure couple columns can be obtained by performing sum and difference transformations on the vectors of each group of relative thrusters. and triaxial force direction column A direction matrix consisting of four independent direction vectors. The rank is 3, and the moment matrix is ​​composed of four couple vectors. The rank of is 3, therefore:

[0052] Moving the torque reference point from the geometric center to the current center of gravity is equivalent to performing a reversible torque translation transformation on the generalized force, without changing the matrix rank. Furthermore, the sum of the four sets of couple vectors is zero, therefore... ,and All components are positive. As can be seen from the full row rank and the positive null space vector, any sufficiently small signed six-dimensional generalized force command can be converted into a non-negative thrust command by superimposing control increments on a common bias; in fixed thrust mode, time averaging can be achieved using duty cycle, and in continuously adjustable mode, it can be directly quantized.

[0053] T9 to T12 are used to enhance thrust in the ±X direction. T9 and T10 are located at the upper and lower edges of the -X side and act along the +X direction, while T11 and T12 are located at the front and rear edges of the +X side and act along the -X direction. If the rated thrust of each of T9 to T12 is 200 mN, when T9 and T10 or T11 and T12 ignite simultaneously at full thrust, the resultant force in the X direction is 0.4 N; for a satellite with a mass of 5 kg, the corresponding acceleration is 0.08 N / m². .

[0054]

[0055] When the current center of gravity is At that time, the residual torque of the center of gravity shift generated by the paired ignition of T9 and T10 is 2u , 2u The residual torque generated by the paired ignition of T11 and T12 is 2u , 2u After updating the control matrix, the controller calls C1 to C4 for compensation. If , If the torque is no more than 30 mm and the thrust of a single engine is 0.2 N, then the single residual moment component will not exceed 0.012 N·m, which is less than the example capability of the above pitch and yaw combination.

[0056] Second Embodiment This embodiment provides a small satellite twelve-thrust couple attitude-orbit coupling control method executed using the aforementioned small satellite twelve-thrust couple attitude-orbit coupling control system. It is applied to a twelve-thrust system including the satellite body, the first thruster T1 to the twelfth thruster T12, and a controller. T1 to T8 are arranged in paired, centrally symmetrical installation positions and opposite thrust directions to form four sets of couple-type coupling units C1 to C4. T9 and T10 act along the +X direction, and T11 and T12 act along the -X direction. The method includes: S1: Obtain the desired six-dimensional generalized force, current satellite center of gravity, and thruster status; S2: Establish a control matrix based on the installation positions of T1 to T12, the direction of thrust, and the current center of gravity of the satellite; S3: Determine if there is a need for a +X or -X direction trajectory change; S4: When the track change requirement exists, T9 and T10 or T11 and T12 shall be allocated preferentially respectively; S5: Calculate the residual six-dimensional generalized force after deducting the generalized force generated by the orbital acceleration and deceleration thruster assembly; S6: Based on the force couple combination allocation of C1 to C4 , and ; S7: Jointly distribute the triaxial force components of T1 to T8 and perform amplitude limiting or quantization; S8: Outputs ignition control commands for twelve thrusters.

[0057] Furthermore, in the fixed thrust control mode, the ignition duty cycle is used as a continuous equivalent control variable for control allocation and then converted into a pulse sequence; in the continuously adjustable thrust control mode, the obtained thrust command is quantized with a granularity of 1mN, and the residual generalized force is recalculated after quantization.

[0058] Furthermore, when the satellite's center of gravity shifts due to propellant consumption, the lever arm in the control matrix is ​​updated; the residual pitch and yaw moments caused by the center of gravity shift between T9 and T10 or between T11 and T12 are compensated by C1 to C4, while the pure couple moments generated by C1 to C4 during constant thrust ignition are not changed due to the center of gravity shift.

[0059] Third Embodiment In the embodiments of this application, the inventive points of the present invention are further illustrated by specific examples. First, the spatial layout of the twelve thrusters is described, followed by the six-directional control torque formed by T1 to T8, the control distribution process, and the adaptation methods under conditions of center of gravity change and thruster failure. The specific dimensions, masses, and thrust values ​​in the embodiments are used to illustrate preferred feasible implementations and are not intended to limit the scope of protection defined by the claims.

[0060] Figure 1 This is a schematic diagram of the overall layout of the twelve thrusters provided in an embodiment of this application. Figure 1 As shown, the outer envelopes of the satellite body in the X, Y, and Z directions are represented by a, b, and c, respectively, and the geometric center of the satellite is marked as the origin O=(0,0,0). In the YZ plane projection, the dot formula symbol represents the thrust component outside the paper in the +X direction, and the cross formula symbol represents the thrust component inside the paper in the -X direction; in the XY plane projection, the dot formula symbol represents the thrust component outside the paper in the +Z direction, and the cross formula symbol represents the thrust component inside the paper in the -Z direction. In the XY plane projection, T6, T8, and T9 are located together at (-a / 2, +b / 2), and T2, T4, and T10 are located together at (-a / 2, -b / 2). Coincident positions are represented by concentric dots and squares; diagonal arrows extending from the same point represent the planar thrust components of T1 to T8, and horizontal arrows represent the +X thrust of T9 or T10.

[0061] For example, , , The entire satellite has a mass of 5 kg, and its initial center of gravity is located approximately 20–30 mm from the geometric center along the -X direction. T1–T8 are installed at the eight corner points or their adjacent areas, while T9–T12 are installed at the four edges. The rated thrust of each unit of T1–T8 is 50 mN, and the rated thrust of each unit of T9–T12 is 200 mN.

[0062] Table 4 Thrust Coordinates, Direction Cosines, and Grouping

[0063] In Table 4, the unit thrust direction for T1 to T8, i.e., the unit direction vector with a modulus of 1, is determined by the thrust direction cosine. It was determined uniformly. b= When κ=0.8, the absolute values ​​of the direction cosines are 0.5454, 0.6545, and 0.5236, respectively. The direction cosines of the relative corner points are all reversed, thus forming four sets of couple-type force-coupled elements, C1 to C4.

[0064] Table 3 shows the specific configurations for achieving six-directional orbital control forces from T1 to T8: Call T1, T3, T5, and T7. Call T2, T4, T6, and T8; Call T2, T4, T5, and T7. Call T1, T3, T6, and T8; Call T2, T3, T6, and T7. Call T1, T4, T5, and T8. In each combination, the four thrusters operate with the same thrust or duty cycle. With the geometric center O as a reference, the two non-target axial force components and the three-axis torque components cancel each other out. When the center of gravity deviates from O, the controller updates the control matrix according to the current center of gravity and calls C1 to C4 to compensate for the residual torque generated by the resultant force of the track control.

[0065] Figure 2 The diagram shows the relationship between the T1 to T8 couples and the six-directional control torque combination provided in the embodiments of this application. Figure 2 As shown, when only pure roll torque is needed, the equal thrust relationship within any couple is not changed. Instead, two couples with the same roll sign and opposite pitch and yaw signs are called simultaneously. Call C1 and C4, Call C2 and C3. Using the same method, Call C1 and C3, Call C2 and C4, Call C3 and C4, Call C1 and C2. Therefore, T1 to T8 can independently generate non-zero values ​​without relying on the flywheel. Control torque; although the rolling torque capability may be less than the pitch and yaw torque capabilities, it is not cancelled.

[0066] Under the numerical conditions of this embodiment, =50mN and L=0.229m. Substituting the above parameters into the formulas in Tables 2 and 3, we obtain the maximum torque and the maximum resultant force in six directions.

[0067] Table 5 Maximum Force and Maximum Torque in Six Directions of Example 1

[0068] The values ​​in Table 5 correspond to the simultaneous ignition of the four selected T1 to T8 thrusters at 50mN. In the fixed thrust mode, the average time value can be adjusted proportionally according to the common duty cycle, and in the continuously adjustable mode, it can be adjusted proportionally according to the common thrust command.

[0069] When the target contains multiple axial moments, the above six basic combinations can be superimposed according to the desired amplitude, and then the thruster commands can be solved by weighted least squares or quadratic programming with upper and lower limits. The weights can prioritize pitch and yaw errors over roll errors and limit the thrust of a single thruster to no more than its rated thrust.

[0070]

[0071] Figure 3 A flowchart illustrating the control and allocation process for twelve thrusters provided in this application embodiment. Figure 3 As shown, the controller acquires the desired six-dimensional generalized force. Current focus First, based on satellite quality and thruster health status, establish a twelve-thrust control matrix. If a +X orbit change is required, prioritize allocating the same or approximately the same thrust to T9 and T10; if a -X orbit change is required, prioritize allocating the same or approximately the same thrust to T11 and T12. After deducting the generalized force already generated by the orbit change group, the residual force and torque are allocated to T1 through T8.

[0072] In the fixed thrust control mode, the solver outputs the target duty cycle for each control cycle and converts it into a rated thrust pulse; the rated thrust for T1 to T8 is 50 mN, and the rated thrust for T9 to T12 is 200 mN. In the continuously adjustable thrust control mode, each thruster is continuously adjustable starting from 1 mN and quantized in 1 mN granularity. After quantization, the residual generalized force is recalculated and compensated in the next control cycle.

[0073] Furthermore, the controller deletes the control matrix column corresponding to the failed thruster based on the thruster's health status and resolves the problem. If the remaining matrix cannot maintain all six degrees of freedom control, it is reassigned according to the task priority of pitch, yaw, main thrust for trajectory changes, roll, and secondary translational forces. Under normal conditions, the constant thrust pure couples of C1 to C4 are unaffected by changes in the center of gravity; changes in the center of gravity only alter the additional torque of the non-zero resultant ignition combination and the trajectory change combination of T9 to T12, which is updated in real time. They received compensation.

[0074] A computer-readable storage medium stores computer code that, when executed, performs the methods described above. Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. This program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0075] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A small satellite twelve-thrust couple attitude and orbit coupling control system, comprising a satellite body, a first thruster T1 to a twelfth thruster T12, and a controller, wherein the outer envelope dimensions of the satellite body along the X, Y, and Z directions are a, b, and c, respectively, and the geometric center of the satellite body is taken as the origin of the coordinate system, characterized in that: T1 to T8 constitute the attitude-track coupling thruster group, and according to the positions of the pairs of centrally symmetrical about the coordinate origin and the opposite thrust action directions, they form four sets of couple-type force coupling units C1 to C4. The direction of the unit thrust of each thruster in T1 to T8 is determined according to the coordinates of its installation position in accordance with a unified rule, so that the thrust direction of each thruster has a symmetrical correspondence about the origin of the coordinate system. When the two thrusters in the same couple unit ignite with equal thrust, the resultant force is zero and a control torque that does not change with the position of the satellite's center of gravity is generated. The controller is configured to generate positive or negative control torques around the X-axis, Y-axis and Z-axis respectively by combining two sets of couple-type coupling units from C1 to C4. T9 to T12 constitute the ±X direction orbital change acceleration and deceleration thruster group.

2. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 1, characterized in that, When any of the thrusters T1 to T8 The installation position vector relative to the geometric center is At that time, the direction of its unit thrust is: in, , , The first The coordinate components of the installation position of the thruster in the X, Y, and Z axes. The roll bias coefficient and , This is the unit direction vector of the thrust acting on the satellite body.

3. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 2, characterized in that, Let A = a / 2, B = b / 2, C = c / 2, where A, B, and C are the half-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively. The installation positions of T1 to T8 are as follows: T1 is located at (+A,+B,+C); T2 is located at (-A,-B,-C); T3 is located at (+A,+B,-C); T4 is located at (-A,-B,+C); T5 is located at (+A,-B,+C); T6 is located at (-A,+B,-C); T7 is located at (+A,-B,-C); T8 is located at (-A,+B,+C). The thrust direction of each thruster is calculated using the formula for the unit thrust direction.

4. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 3, characterized in that, C1 is composed of T1 and T2, C2 is composed of T3 and T4, C3 is composed of T5 and T6, and C4 is composed of T7 and T8; for any couple-type force coupling unit The installation position vectors of the two thrusters are opposites of each other, and the directions of their thrust are opposites of each other.

5. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 3, characterized in that, T1, T3, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T2, T4, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T4, T5, and T7 ignite simultaneously with equal thrust to produce Orbital control force; T1, T3, T6 and T8 ignite simultaneously with equal thrust to generate Track control force; T2, T3, T6, and T7 ignite simultaneously with equal thrust to produce Track control force; T1, T4, T5, and T8 ignite simultaneously with equal thrust to produce Track control force; in , , The track control forces are respectively along the X-axis, Y-axis, and Z-axis. When the origin of the coordinate system is taken as the torque reference point, the non-target axial force components and the three-axis torque components of each ignition combination cancel each other out.

6. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 5, characterized in that, C1 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C3 ignite simultaneously with equal thrust to produce Controlling torque, C1 and C3 ignite simultaneously with equal thrust to produce Controlling the torque, C2 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C3 and C4 ignite simultaneously with equal thrust to produce Controlling the torque, C1 and C2 ignite simultaneously with equal thrust to produce Control torque; where , , These are the control torques around the X-axis, Y-axis, and Z-axis, respectively, and the non-target axis torque components in each combination cancel each other out.

7. The small satellite twelve-thrust couple attitude and orbit coupling control system according to claim 1, characterized in that, T9 is located And the direction of the thrust is T10 is located And the direction of the thrust is T11 is located And the direction of the thrust is T12 is located And the direction of the thrust is Where A, B, and C are the semi-envelope dimensions of the satellite body in the X, Y, and Z directions, respectively, and the projections of T9 to T12 in the YZ plane form a cross shape; The controller has a fixed thrust control mode and a continuously adjustable thrust control mode. In the fixed thrust control mode, the equivalent thrust is adjusted by the ignition pulse width, duty cycle or number of ignitions. In the continuously adjustable thrust control mode, each thruster is continuously adjustable from 1mN, with an adjustment granularity of 1mN and not exceeding its rated thrust. The roll offset coefficient κ is 0.7 to 0.9, so that the roll control torque about the X-axis is less than the pitch control torque about the Y-axis and the yaw control torque about the Z-axis and remains non-zero; The six-row, eight-column control matrix formed by T1 to T8 has a rank of 6 and contains a zero generalized force bias vector with all positive components, enabling T1 to T8 to generate thrust through continuous thrust or time-averaged thrust under non-negative thrust constraints. , , , , and This enables the system to perform six-degree-of-freedom attitude-orbit coupling control solely by the thruster, even when the flywheel is not installed or is unavailable.

8. A method for controlling the attitude and orbit coupling of a small satellite using a 12-thrust couple-type control system as described in any one of claims 1-7, applied to a 12-thrust system including the satellite body, first thrusters T1 to twelfth thrusters T12, and a controller, characterized in that... T1 to T8 are installed in pairs with central symmetry and opposite thrust directions to form four sets of couple-type force coupling units C1 to C4. T9 and T10 act along the +X direction, and T11 and T12 act along the -X direction. The method includes: S1: Obtain the desired six-dimensional generalized force, current satellite center of gravity, and thruster status; S2: Establish a control matrix based on the installation positions of T1 to T12, the direction of thrust, and the current center of gravity of the satellite; S3: Determine if there is a need for a +X or -X direction orbit change; S4: When the track change requirement exists, T9 and T10 or T11 and T12 shall be allocated preferentially respectively; S5: Calculate the residual six-dimensional generalized force after deducting the generalized force generated by the orbital acceleration and deceleration thruster assembly; S6: Based on the force couple combination allocation of C1 to C4 , and ; S7: Jointly distribute the triaxial force components of T1 to T8 and perform amplitude limiting or quantization; S8: Outputs ignition control commands for twelve thrusters.

9. The small satellite twelve-thrust couple attitude and orbit coupling control method according to claim 8, characterized in that, In the fixed thrust control mode, the ignition duty cycle is used as a continuous equivalent control variable for control allocation and then converted into a pulse sequence. In the continuously adjustable thrust control mode, the obtained thrust command is quantized with a granularity of 1mN, and the residual generalized force is recalculated after quantization.

10. The small satellite twelve-thrust couple attitude and orbit coupling control method according to claim 8, characterized in that, When the satellite's center of gravity shifts due to propellant consumption, the lever arm in the control matrix is ​​updated; the residual pitch and yaw moments caused by the center of gravity shift between T9 and T10 or between T11 and T12 are compensated by C1 to C4, while the pure couple moments generated by C1 to C4 during constant thrust ignition are not changed by the center of gravity shift.

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