Mars power decline ZEM / ZEV guidance method based on disturbance observation compensation

Abstract

The invention provides a Mars power descent ZEM / ZEV guidance method based on disturbance observation compensation, and the method comprises the steps: obtaining the three degrees of freedom of a target detector, and determining a control acceleration constraint condition according to the three degrees of freedom; according to the three degrees of freedom, determining an interference estimation value of the target detector by adopting a sliding mode interference observer; according to the interference estimation value, the three degrees of freedom and a control acceleration constraint condition, a ZEM / ZEV guidance law is adopted to determine the control acceleration of the disturbed observation target detector; according to the control acceleration, thrust provided by an engine of the target detector is determined through the three degrees of freedom, and then compensation guidance is executed on the target detector. The method has the beneficial effects that on the premise that fuel is kept to be approximately optimal, the descending precision, stability and safety of the Mars power descending section are improved.

Description

Technical Field

[0001] The present invention relates to the field of Mars powered descent guidance technology, and in particular to a Mars powered descent ZEM / ZEV guidance method, device, electronic equipment and storage medium based on interference observation compensation. Background Art

[0002] The process of precise soft landing on the surface of Mars mainly includes key stages such as atmospheric entry, parachute descent and powered descent. During the powered descent, the probe uses the reverse thrust engine to effectively decelerate in order to achieve a safe landing at the target point. Since the powered descent is the last key stage of the Mars probe landing process, it determines whether a precise soft landing can be successfully achieved.

[0003] When designing the guidance law for the powered descent, it is necessary to design the control acceleration so as to achieve a soft landing while minimizing fuel consumption. However, during the powered descent on Mars, the Mars surface wind, dust, and the uncertainty of the probe's own model may interfere with the process. If no corresponding compensation or adaptive adjustment is performed, the landing accuracy is likely to decrease.

[0004] The existing Mars powered descent guidance schemes for probes can be summarized into two categories: computational guidance and feedback guidance. Traditional computational guidance requires computers to perform a large number of calculations online and is not very robust; the trajectory can be planned offline and then tracked, but when the probe deviates too much from the expected trajectory, it may cause long-term trigger saturation, resulting in excessive fuel consumption and even the risk of damage. Summary of the invention

[0005] Aiming to solve at least one of the technical problems existing in the prior art, the present invention provides a Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, which improves the landing accuracy, stability and safety of the Mars powered descent stage while keeping the fuel approximately optimal.

[0006] One aspect of the present invention provides a Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, comprising:

[0007] Acquire three degrees of freedom of the target detector, and determine control acceleration constraint conditions according to the three degrees of freedom;

[0008] Determining a disturbance estimate of the target detector using a sliding mode disturbance observer according to the three degrees of freedom;

[0009] Determine the control acceleration of the target detector observed by the interference using the ZEM / ZEV guidance law according to the interference estimation value, three degrees of freedom and control acceleration constraints;

[0010] According to the control acceleration, the thrust provided by the engine of the target probe is determined through the three degrees of freedom, and then compensation guidance is performed on the target probe.

[0011] According to the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, the three degrees of freedom of the target probe are obtained, and the control acceleration constraint conditions are determined according to the three degrees of freedom, including:

[0012] The dynamic equations of the three degrees of freedom are:

[0013]

[0014] Where r = [r x ,r y ,r z ] T , v=[v x ,v y ,v z ] T , a=[a x ,a y ,a z ] T are the position vector, velocity vector and control acceleration vector provided by thrust, x, y, z are the spatial coordinates of the landing point of the target probe, g = [0, 0, g] T is the gravitational acceleration on Mars, d = [d x ,d y ,d z ] T is the interference acceleration vector, which represents the interference, m is the mass of the target detector, and F = [F x ,F y ,F z ] T is the engine thrust vector, is the thrust value, c p =I sp g e is the engine exhaust velocity, I sp is the specific impulse, g e is the acceleration due to Earth’s gravity;

[0015] According to the landing time of the target probe, the control acceleration constraint condition is determined as:

[0016] v(t f )=v f , r(t f )=r f

[0017] Among them, t f For landing time.

[0018] According to the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, the interference estimation value of the target detector is determined by using a sliding mode interference observer according to the three degrees of freedom, including:

[0019] The sliding mode disturbance observer is:

[0020]

[0021] where λ≥d imax , d imax is the upper bound of the absolute value of the interference, η∈(0,1), α1 and α2 are positive constants to be determined, T c is the predetermined time for the velocity error to converge, i represents x, y, z, i.e. the landing position of the target detector, is the interference observation vector The component of is the interference estimation vector, and δ is the saturation function thickness;

[0022] According to the landing point position, determine the saturation function thickness δ and the predetermined time T for the velocity error to converge. c , α1, α2 and η, and, according to the upper limit of the disturbance acceleration d imax Determine λ, where α1, α2 and η are the sliding mode disturbance observer parameters;

[0023] Determine the disturbance observation vector according to the velocity vector of the three degrees of freedom and the sliding mode disturbance observer The interference observation vector This is the interference estimate.

[0024] According to the Mars powered descent ZEM / ZEV guidance method based on disturbance observation compensation, the sliding mode disturbance observer is used to calculate the time T of the Mars powered descent ZEM / ZEV. c Converges to |s i |<δ as a constraint.

[0025] According to the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, the ZEM / ZEV guidance law is used to determine the control acceleration of the target probe obtained by compensation after interference observation according to the interference estimation value, three degrees of freedom and control acceleration constraints, including:

[0026] The control acceleration of the target detector obtained by compensation is:

[0027]

[0028] Where a is the control acceleration, t go For the remaining time, is the interference observation value, where ZEM is the zero control miss distance, ZEV is the zero control velocity deviation, and ZEV=v f -(v+t go g), where ZEM and ZEV represent the differences between the expected position and expected velocity and the predicted position and predicted velocity of the target detector after the current time when no additional control is applied.

[0029] According to the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, the thrust provided by the engine of the target probe is determined by the three degrees of freedom according to the control acceleration, and then the target probe is subjected to compensation guidance, including:

[0030] According to the disturbance observation value through ZEM / ZEV guidance law The three degrees of freedom are used to compensate for the interference d, determine the thrust required to be provided by the transmitter of the target detector at the current time, and perform the

[0031] The real-time position and velocity of the target probe are monitored and compensated for until the target probe reaches the spatial coordinates of the landing point.

[0032] According to the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, the ZEM / ZEV guidance law takes reaching the landing point and soft landing as constraints, wherein soft landing means that the control acceleration is 0 during landing, that is, r(t f )=0,v(t f )=0.

[0033] Another aspect of the present invention provides a Mars powered descent ZEM / ZEV guidance device based on interference observation compensation, comprising:

[0034] The first module is used to obtain the three degrees of freedom of the target detector and determine the control acceleration constraint conditions according to the three degrees of freedom;

[0035] A second module is used to determine the interference estimation value of the target detector using a sliding mode interference observer according to the three degrees of freedom;

[0036] The third module is used to determine the control acceleration of the target detector observed by the interference using the ZEM / ZEV guidance law according to the interference estimation value, three degrees of freedom and control acceleration constraints;

[0037] The fourth module is used to determine the thrust provided by the engine of the target probe through the three degrees of freedom according to the control acceleration, and then perform compensation guidance on the target probe.

[0038] Another aspect of an embodiment of the present invention provides an electronic device, including a processor and a memory;

[0039] The memory is used to store programs;

[0040] The processor executes the program to implement the method described above.

[0041] The embodiment of the present invention also discloses a computer program product or a computer program, which includes a computer instruction stored in a computer-readable storage medium. A processor of a computer device can read the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes the method described above.

[0042] The beneficial effects of the present invention are: the ZEM / ZEV guidance law is compensated based on the interference observer, the amount of calculation is less than that of the prior art, the system resource consumption during guidance is reduced, the stability of the system after compensation can be guaranteed, and the safety of the detector is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the trajectory of the powered descent phase of the Mars probe according to an embodiment of the present invention.

[0044] Figure 2 It is a schematic diagram of the ZEM / ZEV guidance process of Mars powered descent based on interference observation compensation in an embodiment of the present invention.

[0045] Figure 3 It is a structural diagram of a detector guidance system with an interference observer according to an embodiment of the present invention.

[0046] Figure 4a , 4b is a diagram of the estimation results of the sliding mode observer under step interference and triangular wave interference in an embodiment of the present invention.

[0047] Figure 5a , 5b is a diagram of simulation results of the classic ZEM / ZEV guidance law of an embodiment of the present invention.

[0048] Figure 6a , 6b, 6c, and 6d are schematic diagrams of simulation of the ZEM / ZEV guidance law based on interference observation compensation according to an embodiment of the present invention.

[0049] Figure 7 It is a schematic diagram of a Mars powered descent ZEM / ZEV guidance device based on interference observation compensation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. In the subsequent description, the use of suffixes such as "module", "component" or "unit" used to represent elements is only for the purpose of facilitating the description of the present invention, and has no specific meaning in itself. Therefore, "module", "component" or "unit" can be used in a mixed manner. "First", "second" and the like are only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the order of the indicated technical features. In this subsequent description, the continuous numbering of the method steps is for the convenience of review and understanding. In combination with the overall technical solution of the present invention and the logical relationship between the various steps, adjusting the implementation order between the steps will not affect the technical effect achieved by the technical solution of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0051] Please refer to Table 1 for explanation of some parameters of the embodiments of the present invention.

[0052] Table 1 Parameter explanation reference table

[0053]

[0054]

[0055] The variable symbol has a 0 in the lower right corner, indicating the initial value; the variable symbol has an f in the lower right corner, indicating the terminal value. f represent the detector positions at the initial and terminal moments respectively.

[0056] refer to Figure 1 , Figure 1 Schematic diagram of the trajectory of the powered descent phase of the Mars probe according to an embodiment of the present invention. During the powered descent phase of Mars, the probe uses a control acceleration provided by the reverse thrust engine to effectively decelerate, so as to achieve precise control of soft landing at a predetermined point. By adjusting the control acceleration a, the flight trajectory of the probe can meet different safety requirements.

[0057] In some embodiments, since the landing process of the probe lasts for a very short time, a very high accuracy can be achieved even without using a complex gravity field model; and the relative distance between the lander and the surface of Mars does not change much, so the gravitational acceleration can be regarded as a constant, usually -3.711400m / s2.

[0058] refer to Figure 2 ,in Figure 21 is a schematic diagram of a ZEM / ZEV guidance process for Mars powered descent based on interference observation compensation according to an embodiment of the present invention, which includes but is not limited to steps S100 to S400:

[0059] S100, acquiring three degrees of freedom of the target detector, and determining control acceleration constraint conditions according to the three degrees of freedom.

[0060] In some embodiments, the probe is considered as a point mass and the rotation of Mars is ignored. Then the three-degree-of-freedom dynamic equation of the probe is:

[0061]

[0062] Where r = [r x ,r y ,r z ] T , v=[v x ,v y ,v z ] T , a=[a x ,a y ,a z ] T are the position vector, velocity vector and control acceleration vector provided by thrust, x, y, z are the spatial coordinates of the landing point of the target probe, g = [0, 0, g] T is the gravitational acceleration on Mars, d = [d x ,d y ,d z ] T is the interference acceleration vector, which represents the interference, m is the mass of the target detector, and F = [F x ,F y ,F z ] T is the engine thrust vector, is the thrust value, c p =I sp g e is the engine exhaust velocity, I sp is the specific impulse, g e is the acceleration due to Earth's gravity.

[0063] It can be understood that the designed control acceleration needs to satisfy v(t f )=v f , r(t f )=r f , t f For landing time.

[0064] S200, using a sliding mode disturbance observer to determine a disturbance estimate of the target detector based on the three degrees of freedom. In some embodiments, the sliding mode disturbance observer is as follows

[0065]

[0066] In the formula, the subscript i represents x, y, and z (the same notation is used in the following text), The interference observation vector Component, λ≥d imax , d imax is the upper bound of the absolute value of the interference, η∈(0,1), α1 and α2 are positive constants to be determined, T c It is the expected time for the velocity error to converge.

[0067] In some embodiments, the saturation function thickness δ and the predetermined time T for the velocity error to converge are determined according to the landing point position. c , α1, α2 and η, and, according to the upper limit of the disturbance acceleration d imax Determine λ, where α1, α2 and η are the parameters of the sliding mode disturbance observer; determine the disturbance observation vector according to the velocity vector of the three degrees of freedom and the sliding mode disturbance observer The interference observation vector This is the interference estimate.

[0068] It can be understood that η∈(0,1) in the sliding mode disturbance observer is a parameter for nonlinear adjustment of the speed error, and α1 and α2 are linear gains after nonlinear adjustment of the error. η, α1, and α2 together determine the predetermined time T c .

[0069] If η and T are determined first c , then α1 and α2 can be calculated according to Make a selection

[0070] In some embodiments, the sliding mode disturbance observer design process includes:

[0071] (1) The designed sliding mode disturbance observer can ensure Scheduled time T c Converges to |s i |<δ.

[0072] The designed sliding mode variables are:

[0073]

[0074] Taking the derivative with respect to time we get:

[0075] , when |s|≥δ, select the Lyapunov function:

[0076]

[0077] Taking the derivative with respect to time we get:

[0078]

[0079] Select α1 and α2 so that but

[0080]

[0081] Convert differential inequalities to differential equations:

[0082]

[0083] Calculate the stabilization time:

[0084]

[0085] Visible system scheduled time T c Converges to |s i |<δ.

[0086] (2) When |s i |<δ, When bounded, The index approaches The regions represented by in Indicates d i The nth-order time derivative of , which has the same meaning as other parameters.

[0087] Select the following Lyapunov function:

[0088]

[0089] Taking the derivative with respect to time we get:

[0090]

[0091] Pick but:

[0092]

[0093] when Right now hour, visible When bounded, The index approaches Represented area.

[0094] It can be understood that from the above analysis, the designed sliding mode observer can estimate the external interference within a predetermined time, thereby improving the accuracy of interference estimation.

[0095] S300, based on the interference estimation value, three degrees of freedom and control acceleration constraints, the ZEM / ZEV guidance law is used to determine the control acceleration of the interference observed target detector.

[0096] In some embodiments, the control acceleration of the disturbed observed target detector (the control acceleration of the compensated target detector) is determined as:

[0097]

[0098] Where a is the control acceleration, t go For the remaining time, is the interference observation value, where ZEM is the zero control miss distance, ZEV is the zero control velocity deviation, and ZEV=v f -(v+t go g), where ZEM and ZEV represent the differences between the expected position and expected velocity and the predicted position and predicted velocity of the target detector after the current time when no additional control is applied.

[0099] In some embodiments, the performance indicators of the ZEM / ZEV guidance law are as follows:

[0100]

[0101] The three-degree-of-freedom dynamic equations and the following boundary conditions must be met:

[0102] r(t0)=r0,r(t f )=r f ,v(t0)=v0,v(t f )=v f

[0103] Among them, t f is the flight time, r0, v0, r f and v f They are initial position, initial velocity, target position and target velocity. The Hamiltonian function is defined as:

[0104]

[0105] Among them, p r and p v are the co-state vectors related to position and velocity respectively. The final optimal control law is:

[0106]

[0107] ZEM and ZEV represent the difference between the desired final position and velocity and the predicted final position and velocity if no additional control is applied after the current time. The expressions for ZEM and ZEV are as follows:

[0108]

[0109] ZEV=v f -(v+t go g)

[0110] The ZEM / ZEV guidance law is obtained from the expressions of ZEM and ZEV:

[0111]

[0112] Under the ZEM / ZEV guidance law, the fuel can be approximately optimal, but the ZEM / ZEV guidance law does not take interference into account when it is designed. For the ZEM / ZEV guidance law, after being disturbed by external factors:

[0113]

[0114] Therefore, it is necessary to observe the interference and then offset it, and then compensate the ZEM / ZEV guidance law to ensure the stability of the system. First, the compensated ZEM / ZEV guidance law is clarified, and the actual control acceleration is in the following form:

[0115]

[0116] analyze:

[0117] (1) First, analyze the effectiveness of the guidance law. Applying the control acceleration shown in the form of control acceleration, the system can eventually reach the target point and achieve a soft landing, that is, r(t f )=0,v(t f )=0.

[0118] For the following function:

[0119]

[0120] Taking the derivative with respect to time we get:

[0121]

[0122] Solve the equation:

[0123]

[0124] get:

[0125]

[0126] Among them, C is a constant determined by the initial value. As time goes by, t go →0, then but Bounded, r i →0, v i →0, r(t f )=0,v(t f )=0.

[0127] (2) Next, the stability of the system is analyzed. The system is stable by using the disturbance observation form shown in the sliding mode disturbance observer formula and the control acceleration shown in the actual control acceleration formula.

[0128] Proof: Choose the following Lyapunov function:

[0129]

[0130] Taking the derivative with respect to time we get:

[0131]

[0132] It can be seen that the V3 index approaches a neighborhood of V3 = 0 which decreases with time, so

[0133] Solve the equation:

[0134]

[0135] get:

[0136]

[0137] Among them, C2 is a constant determined by the initial value, indicating that r i Bounded and r i →0,v i →0, the system is stable. Based on the above analysis, we can know the effectiveness and robustness of the designed guidance law.

[0138] S400, according to the control acceleration, the thrust provided by the engine of the target probe is determined through three degrees of freedom, and then compensation guidance is performed on the target probe.

[0139] In some embodiments, reference Figure 3 The structure diagram of the detector guidance system with a disturbance observer is shown in FIG. The position and velocity information of the detector are substituted into the actual control acceleration formula, and the disturbance estimation value is substituted into the control acceleration, and then the thrust that the engine should provide is obtained by using the three-degree-of-freedom dynamic equation. After implementing the guidance scheme based on disturbance observation compensation, the following is obtained: Figure 3 The guidance system structure shown.

[0140] In some embodiments, the Mars environment and probe model parameters used in the simulation are shown in Table 2. Since the horizontal and vertical directions do not interfere with each other during guidance, and the vertical direction involves whether to hit the ground, the interference in the embodiment of the present invention is only taken as an example in the vertical direction. The interference form and parameters are shown in Table 3, and the sliding mode observer parameters are shown in Table 4.

[0141] Table 2 Basic parameters of Mars environment and probe model

[0142] parameter Value unit parameter Value unit g [0；0；-3.711400] <![CDATA[m / s -2 ]]> <![CDATA[r0]]> <![CDATA[[r x0 ;0;1500]]]> m <![CDATA[m0]]> 1905 kg <![CDATA[v0]]> [100；0；-75] m / s <![CDATA[c p ]]> 2000 m / s <![CDATA[r f ]]> [0；0；0] m <![CDATA[t f ]]> 55 s <![CDATA[v f ]]> [0；0；0] m / s

[0143] Table 3 Interference forms and parameters

[0144]

[0145] Table 4 Sliding mode observer parameters

[0146] parameter Value unit η 0.3 - <![CDATA[T c ]]> 0.05 s <![CDATA[α1]]> 150 - <![CDATA[α2]]> 150 - δ 0.0005 m / s λ 2 <![CDATA[m / s 2 ]]>

[0147] In some embodiments, the simulation conditions are as follows:

[0148] (1)r x0 =2000(m), d=d1, verify the estimation performance of sliding mode disturbance observer;

[0149] (2)r x0 =2000(m), d=d2, verify the estimation performance of sliding mode disturbance observer;

[0150] (3)r x0 =-500, 0, 500, 1000, 1500, 2000, d = d3, using the classic ZEM / ZEV guidance law simulation;

[0151] (4)r x0 =-500, 0, 500, 1000, 1500, 2000, d = d3, the proposed ZEM / ZEV guidance law based on interference observation compensation is used for simulation; the termination condition of the simulation is t>t f -0.01s.

[0152] Simulation results: The simulation results corresponding to working condition 1 and working condition 2 are plotted on Figure 4a and Figure 4b , the simulation results corresponding to working condition 3 are plotted on Figure 5a and Figure 5b , Figure 6a , Figure 6b , Figure 6c and Figure 6d This is the simulation result corresponding to working condition 4.

[0153] Figure 4a represents the step disturbance simulation result, Figure 4bRepresents the simulation result of triangle wave interference, Figure 4a and Figure 4b It can be seen that the designed sliding mode disturbance observer can quickly track the upper step signal within 0.01 seconds, showing a faster tracking speed; at the same time, when tracking the triangular wave signal, it shows a very small tracking error. Therefore, the designed sliding mode observer can meet the application requirements in terms of performance. In summary, the sliding mode disturbance observer used in the embodiment of the present invention to compensate the ZEM / ZEV guidance law is reliable.

[0154] Figure 5a It represents the simulation results before the interference compensation of the classic ZEM / ZEV guidance law. Figure 5b It represents the simulation diagram of the actual control acceleration change of the z-axis before the interference compensation of the classic ZEM / ZEV guidance law. As can be seen from Figure 5, before the interference compensation is performed, the probe will hit the surface of Mars midway, and the control acceleration will have a negative value in the later stage, which violates the thrust angle constraint;

[0155] Depend on Figure 6a , Figure 6b , Figure 6c and Figure 6d It can be seen that the sliding mode observer error is less than 0.003m / s under complex fast-changing interference. 2 , which is suitable for compensation. If the disturbance observer compensation designed in the embodiment of the present invention is added to the guidance framework, the probe can avoid collision with the surface of Mars and control the acceleration normally.

[0156] The above results indicate that the sliding mode observer designed in the embodiment of the present invention can effectively perform active interference compensation, so that the probe can fly according to the trajectory designed by ZEM / ZEV, achieve near-optimal fuel efficiency, successfully complete the established mission, realize precise soft landing, and ensure the safe operation of the probe.

[0157] The embodiment of the present invention innovatively proposes a ZEM / ZEV guidance method based on interference observation compensation. The method compensates the ZEM / ZEV guidance law based on the interference observer. The resulting guidance scheme has the advantages of small computational complexity, approximate fuel optimization, practicality and effectiveness, and can ensure the stability of the system after compensation, improve the safety of the detector, and expand the practical application effect and value of the ZEM / ZEV guidance law.

[0158] Figure 7 1 is a diagram of a ZEM / ZEV guidance analysis device for Mars powered descent based on interference observation compensation according to an embodiment of the present invention. The device includes a first module 710 , a second module 720 , a third module 730 and a fourth module 740 .

[0159] Among them, the first module is used to obtain the three degrees of freedom of the target detector and determine the control acceleration constraints based on the three degrees of freedom; the second module is used to determine the interference estimation value of the target detector based on the three degrees of freedom by using the sliding mode interference observer; the third module is used to determine the control acceleration of the target detector after interference observation by using the ZEM / ZEV guidance law based on the interference estimation value, three degrees of freedom and the control acceleration constraints; the fourth module is used to determine the thrust provided by the engine of the target detector through the three degrees of freedom based on the control acceleration, and then perform compensatory guidance on the target detector.

[0160] Exemplarily, with the cooperation of the first module, the second module, the third module and the fourth module in the device, the embodiment device can implement any of the aforementioned Mars powered descent ZEM / ZEV guidance methods based on interference observation compensation, that is, obtaining the three degrees of freedom of the target probe, and determining the control acceleration constraint conditions according to the three degrees of freedom; according to the three degrees of freedom, using the sliding mode interference observer to determine the interference estimation value of the target probe; according to the interference estimation value, the three degrees of freedom and the control acceleration constraint conditions, using the ZEM / ZEV guidance law to determine the control acceleration of the target probe after interference observation; according to the control acceleration, the thrust provided by the engine of the target probe is determined through the three degrees of freedom, and then the target probe is performed with compensation guidance. The beneficial effects of the present invention are: using the interference observer to compensate the ZEM / ZEV guidance law, the amount of calculation is relatively small compared to the prior art, which reduces the system resource consumption during guidance, and can ensure the stability of the system after compensation, thereby improving the safety of the probe.

[0161] An embodiment of the present invention further provides an electronic device, the electronic device comprising a processor and a memory;

[0162] The memory stores a program;

[0163] The processor executes a program to perform the aforementioned Mars powered descent ZEM / ZEV guidance method based on interference observation compensation; the electronic device has the function of carrying and running the software system for Mars powered descent ZEM / ZEV guidance based on interference observation compensation provided by an embodiment of the present invention, for example, a personal computer, a minicomputer, a main frame, a workstation, a network or distributed computing environment, a separate or integrated computer platform, or communicating with a charged particle tool or other imaging device, etc.

[0164] An embodiment of the present invention further provides a computer-readable storage medium, wherein the storage medium stores a program, and the program is executed by a processor to implement the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation as described above.

[0165] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part for which is described as a larger operation is performed independently.

[0166] The embodiment of the present invention also discloses a computer program product or a computer program, which includes a computer instruction stored in a computer-readable storage medium. A processor of a computer device can read the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes the aforementioned Mars powered descent ZEM / ZEV guidance method based on interference observation compensation.

[0167] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features described may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in separate physical devices or software modules. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present invention. More specifically, in view of the properties, functions, and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional skills of the engineer. Therefore, those skilled in the art can implement the present invention set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0168] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program codes.

[0169] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0170] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0171] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0172] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0173] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0174] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A Mars powered descent ZEM / ZEV guidance method based on interference observation compensation, characterized in that: include: Acquire three degrees of freedom of the target detector, and determine control acceleration constraint conditions according to the three degrees of freedom; Determining a disturbance estimate of the target detector using a sliding mode disturbance observer according to the three degrees of freedom; Determine the control acceleration of the target detector observed by the interference using the ZEM / ZEV guidance law according to the interference estimation value, three degrees of freedom and control acceleration constraints; According to the control acceleration, the thrust provided by the engine of the target probe is determined through the three degrees of freedom, and then compensation guidance is performed on the target probe.

2. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 1 is characterized in that: The step of acquiring three degrees of freedom of the target detector and determining the control acceleration constraint condition according to the three degrees of freedom includes: The dynamic equations of the three degrees of freedom are: Where r = [r x ,r y ,r z ] T , v=[v x ,v y ,v z ] T , a=[a x ,a y ,a z ] T are the position vector, velocity vector and control acceleration vector provided by thrust, x, y, z are the spatial coordinates of the landing point of the target probe, g = [0, 0, g] T is the gravitational acceleration on Mars, d = [d x ,d y ,d z ] T is the interference acceleration vector, which represents the interference, m is the mass of the target detector, and F = [F x ,F y ,F z ] T is the engine thrust vector, is the thrust value, c p =I sp g e is the engine exhaust velocity, I sp is the specific impulse, g e is the acceleration due to Earth’s gravity; According to the landing time of the target probe, the control acceleration constraint condition is determined as: v(t f )=v f ,r(t f )=r f Among them, t f For landing time.

3. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 2 is characterized in that: Determining the interference estimation value of the target detector by using a sliding mode interference observer according to the three degrees of freedom includes: The sliding mode disturbance observer is: where λ≥d imax , d imax is the upper bound of the absolute value of the interference, η∈(0,1), α1 and α2 are positive constants to be determined, T c is the predetermined time for the velocity error to converge, i represents x, y, z, i.e. the landing position of the target detector, is the interference observation vector The component of the interference estimation vector is δ, which is the saturation function thickness. According to the landing point position, the saturation function thickness δ and the predetermined time T for the velocity error to converge are determined. c , α1, α2 and η, and, according to the upper limit of the disturbance acceleration d imax Determine λ, where α1, α2 and η are the sliding mode disturbance observer parameters; Determine the disturbance observation vector according to the velocity vector of the three degrees of freedom and the sliding mode disturbance observer The interference observation vector This is the interference estimate.

4. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 3 is characterized in that: The sliding mode disturbance observer is c Converges to |s i |<δ as a constraint.

5. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 3 is characterized in that: The method of using the ZEM / ZEV guidance law to determine the control acceleration of the target detector obtained by compensation after interference observation according to the interference estimation value, three degrees of freedom and control acceleration constraint conditions includes: The control acceleration of the target detector obtained by compensation is: Where a is the control acceleration, t go For the remaining time, is the interference observation value, where ZEM is the zero control miss distance, ZEV is the zero control velocity deviation, and ZEV=v f -(v+t go g), where ZEM and ZEV represent the differences between the expected position and expected velocity and the predicted position and predicted velocity of the target detector after the current time when no additional control is applied.

6. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 5 is characterized in that: The method of determining the thrust provided by the engine of the target probe through the three degrees of freedom according to the control acceleration, and then performing compensation guidance on the target probe, comprises: According to the disturbance observation value through ZEM / ZEV guidance law The three degrees of freedom are used to compensate for the interference d, determine the thrust required to be provided by the transmitter of the target detector at the current time, and perform the The real-time position and velocity of the target probe are monitored and compensated for until the target probe reaches the spatial coordinates of the landing point.

7. The Mars powered descent ZEM / ZEV guidance method based on interference observation compensation according to claim 5, characterized in that: The ZEM / ZEV guidance law takes reaching the landing point and soft landing as constraints, where soft landing means that the control acceleration is 0 during landing, that is, r(t f )=0,v(t f )=0.

8. A Mars powered descent ZEM / ZEV guidance device based on interference observation compensation, characterized in that: include: The first module is used to obtain the three degrees of freedom of the target detector and determine the control acceleration constraint conditions according to the three degrees of freedom; A second module is used to determine the interference estimation value of the target detector using a sliding mode interference observer according to the three degrees of freedom; The third module is used to determine the control acceleration of the target detector observed by the interference using the ZEM / ZEV guidance law according to the interference estimation value, three degrees of freedom and control acceleration constraints; The fourth module is used to determine the thrust provided by the engine of the target probe through the three degrees of freedom according to the control acceleration, and then perform compensation guidance on the target probe.

9. An electronic device, characterized in that: including a processor and a memory; The memory is used to store programs; The processor executes the program to implement the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: The storage medium stores a program, and the program is executed by a processor to implement the Mars powered descent ZEM / ZEV guidance method based on interference observation compensation as described in any one of claims 1-7.

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