121 results about "Orbital control" patented technology

The invention relates to the technical field of spacecraft orbit control and space safety, and discloses a space debris orbit prediction and avoidance method, which comprises the following steps that: a ground computing center screens candidate targets and generates enhanced data packets for uploading; the spaceborne computer combines real-time navigation data to carry out geometric feature screening, and an instant high-risk target list is generated; controlling the star sensor to execute optical observation, and resolving an optical measurement relative orbit state by utilizing displacement superposition and Kalman filtering; selecting a high confidence coefficient or a conservative probability threshold according to the optical measurement state acquisition condition, and generating an avoidance instruction when the collision probability exceeds the limit; and the propulsion system responds to the instruction to execute avoidance, verifies the effect by confirming the semi-major axis variation and executes track recovery by selecting an aircraft. According to the method, the ground-air collaborative screening and shift superposition enhancement technology is adopted, the problems that the low-precision ephemeris false alarm rate is high and the detection capability of a satellite-borne sensor on a dark and weak target is insufficient are solved, and the accuracy of evasion decision making and the execution reliability are improved.

The present disclosure is a device and methods for satellite trajectory control and collision avoidance. Embodiments of the disclosure are comprised of a smart satellite device performing a process three steps. First, sensors collect data about the satellite's physical landing environment, passing information to satellite's database and processors. Second, the processors manipulate the information with a deep reinforcement learning program to produce instructions. Third, the instructions steer the satellite body by manipulating the satellite's panels for optimal trajectory and collision avoidance. The purpose for the present disclosure is to help solve the space debris problem.

The invention discloses a camera imaging control method and device for midnight sunlight avoidance, and belongs to the field of spacecraft attitude orbit control. The method comprises the steps of judging whether a satellite is currently in a midnight sunlight avoidance stage; when the satellite is not in the midnight sunlight avoidance stage, if the midnight sunlight avoidance condition is met, initializing to enter the midnight sunlight avoidance stage, and setting the satellite to quickly maneuver to a preset target avoidance trajectory; when the satellite is in the midnight sunlight avoidance stage, if the satellite receives an imaging instruction meeting the requirement, the satellite is maneuvered to an imaging point for imaging, and otherwise, the satellite is maintained to run on a target avoidance track; and when the satellite is in the imaging state of the midnight sunshine avoidance stage, if the satellite is in a sunshine receiving state, quickly maneuvering the satellite to the target avoidance track, otherwise, maintaining the imaging state of the satellite. According to the invention, the imaging safety of the camera during the midnight avoidance period can be realized, and the use efficiency of the camera load and the user experience are improved.

The invention discloses a satellite orbit control method based on a continuous time near-end strategy optimization reinforcement learning algorithm, and the method comprises the following steps: 1, determining an action, namely acceleration, taken by a satellite, and the execution time of the action based on the continuous time near-end strategy optimization reinforcement learning algorithm; and step 2, realizing satellite orbit control based on the action taken by the satellite and the execution time obtained in the step 1. The advanced near-end strategy optimization reinforcement learning algorithm (PPO) and the continuous time control framework are combined, a high-precision, stable and energy-efficiency-optimized satellite orbit control solution is provided, remarkable technical advancement and wide application prospects are achieved, and powerful technical support is provided for future space exploration and satellite operation.

The invention discloses a satellite constellation autonomous deployment method and system, belongs to the technical field of aerospace orbit control, and solves the problems of long deployment period, high personnel investment, slow collision avoidance response, increased orbit safety risk and the like caused by a traditional satellite deployment method. The method comprises the following steps: constructing a constellation network according to initial orbit parameters of a satellite and orbit injection time and orbit parameters of different stages; outputting an optimal deployment strategy of each stage of the constellation through a genetic algorithm; the right ascension of the ascending node and the phase are adjusted to a target position together while the height is deployed in place through a coupling equation, and ignition constraints are constructed; generating an orbital transfer plan according to the thrust and a satellite initial orbit needing to be deployed; an orbital transfer instruction is automatically generated according to the orbital transfer plan; according to on-orbit telemetering, the orbital transfer progress condition is judged, and strategy closed-loop adjustment is carried out; cooperative deployment of multi-orbit-plane satellites is achieved, and fuel and time cost are saved. The method is particularly suitable for multi-orbit-plane collaborative deployment and autonomous management of large-scale satellite constellations.

The application discloses a marine intelligent vertical transportation system and method, and belongs to the technical field of marine transportation. The rear end of the carrying platform is provided with a lifting platform, the bottom end of the lifting platform is provided with two supports for increasing supporting force, the rear end of the lifting platform and the two supports are movably connected with two lifting tracks, a control room is arranged on one side of the carrying platform, two scanning rods are arranged at the entrance of the front end of the carrying platform, and a weighing table and a push plate are arranged in the carrying platform. The application solves the problems of low efficiency, long response time, high safety risk and inability to realize intelligent management, and the overall transportation equipment and the control system are easy to integrate with other intelligent systems of the ship, thereby enhancing the convenience and real-time performance of management, realizing intelligent automatic identification and vertical transportation, improving transportation efficiency, and reducing human operation errors and delays while obtaining basic information of goods, thereby improving the safety of goods transportation.

The invention relates to a reflector satellite (1) comprising at least one curved reflecting surface (11), characterized in that it comprises at least one support structure (10) connected to at least four positioning and orientation systems (12) of the reflector satellite for achieving attitude and orbit control, said positioning and orientation systems comprising at least one propulsion system, said positioning and orientation systems being synchronized and arranged so as to allow orientation of the reflector satellite along at least two axes of rotation. A satellite assembly comprising a source satellite and a reflector satellite is also described. Abstract figure: Figure 1

This invention relates to the field of spacecraft orbit control technology, and particularly to a spacecraft approach control method based on the fusion of imitation learning and reinforcement learning. The method includes: S1: generating initial and target states, solving for the optimal fuel transfer trajectory offline using a direct method, and constructing an expert dataset; S2: based on the expert dataset, training a neural network controller through imitation learning to obtain a pre-trained model; S3: loading the weights of the pre-trained model, constructing a composite reward function, and training the policy network using a near-end policy optimization algorithm to obtain an optimized policy network model; S4: acquiring relative state data, optimizing the policy network model, and outputting the control quantity for the optimal fuel consumption trajectory transfer in real time. This invention rapidly masters an approximately optimal policy through imitation learning and surpasses the performance of expert data through reinforcement learning, completing control command solutions in milliseconds. It balances terminal control accuracy and fuel consumption optimization, offering advantages such as high solution efficiency, excellent control accuracy, and strong generalization ability.

The application discloses a method and device for orbit transfer control of a lunar spacecraft, and realizes orbit transfer of the spacecraft into a full-parameter target orbit. The method comprises the following steps: a three-impulse control strategy of a far-lunar maneuver, phase control and period control is designed; based on an orbit plane, an arch line and a perigee height, control time and omnidirectional control impulses for orbit transfer from an initial orbit to a first intermediate orbit are determined; based on an orbit phase, a first tangential impulse for orbit transfer from the first intermediate orbit to a second intermediate orbit is determined; and based on an orbit period, a second tangential impulse for orbit transfer from the second intermediate orbit to the target orbit is determined. The first tangential impulse and the second tangential impulse are taken as variables, and a far-lunar maneuver position vector deviation is taken as a fitness value, and a genetic optimization algorithm is used to solve initial values of the impulses. The method solves the problem of orbit control solution caused by nonlinear enhancement of orbit evolution under perturbation influence and complexity of omnidirectional impulse control parameters.

The present application relates to a kind of satellite load observation attitude control and data transmission, orbit control autonomous intelligent planning system and method, the system includes mission guide module, attitude control module, orbit control module and data transmission module;The attitude control module includes several thrusters for satellite attitude control, the orbit control module is used for satellite autonomous orbit control calculation, and carries out satellite orbit control, the data transmission module is used for satellite autonomous data transmission calculation, and satellite data is transmitted to ground;The mission guide module is in system control core, executes load observation task implementation strategy, according to priority reasonably arrange satellite's working time sequence, so that the satellite is intelligently switched between attitude control and data transmission to ground, orbit control, controls satellite autonomous intelligent operation in orbit.Autonomous intelligent planning, autonomous data transmission calculation, autonomous orbit control calculation are beneficial.

The application discloses a kind of distributed multi-curved surface array full airspace beam continuous control methods, comprising: setting satellite TT&C relay trigger event, trigger according to including satellite and TT&C station uplink and downlink state monitoring, orbit control instruction and pre-configured trigger instruction of switching condition;With satellite TT&C relay as the control core of random access node, utilize curved surface array tracking receiver state parameters and the partial satellite orbit information cached, based on TT&C relay trigger event, adaptively trigger curved surface array inter-beam switching process, ensure the continuous tracking of curved surface array to satellite.The present application can realize low-latency and low TT&C resource overhead distributed multi-curved surface array full airspace beam continuous control, support the low-latency TT&C relay demand of satellite in future large-scale constellation, realize on-demand switching without pre-planning, real-time capacity optimization, improve the adaptability to station network resources and the dynamic change of satellite motion state.

The invention relates to the technical field of satellite attitude and orbit control, in particular to a non-inductive coordination control method for quick zero passage of a momentum wheel under a redundant momentum wheel train. The method comprises the following steps: firstly, interpreting the change trend of the rotating speed of the momentum wheel according to the change condition of the rotating speed of the momentum wheel; secondly, judging the zero-crossing state of the momentum wheel according to the rotating speed change trend and the actually measured rotating speed of the momentum wheel; and finally, based on the characteristic of zero motion of the momentum wheel set, applying zero-crossing compensation torque to the momentum wheel in a zero-crossing state to enable the momentum wheel to quickly pass through a rotating speed zero-crossing interval, and applying reverse compensation torque to other momentum wheels to enable the resultant torque of the compensation torque of the momentum wheel set to be zero. The rotating speed of the momentum wheel quickly passes through a zero-crossing interval through a method of increasing zero-crossing compensation torque, and the influence of zero-crossing of the rotating speed of the momentum wheel on the satellite attitude control precision is reduced. The method can be popularized and applied to all satellites with zero-crossing momentum wheel rotating speed and high attitude control precision requirements.

This invention discloses a high-precision periodic orbit maintenance method based on maintenance point rolling optimization, relating to the field of spacecraft orbit control and orbit maintenance technology. Based on a high-precision ephemeris dynamics model, it constructs a maintenance point rolling prediction mechanism, a navigation and execution error model, and a least-squares orbit correction strategy under multi-path point constraints. This application uses the above method to achieve high-precision, low-energy-consumption, and highly robust long-term maintenance of a spacecraft's periodic orbit in a realistic multi-body perturbation environment.

The application discloses a non-cooperative target satellite rendezvous orbit design method based on active disturbance rejection control and belongs to the technical field of space orbit control. In order to solve the problem of modeling and simulation of relative motion between a mobile satellite and a target satellite under the condition that the parameters of the target satellite are unknown, the application calculates initial position and velocity components in the first geodetic coordinate system of the earth center according to prior orbit parameters of the mobile satellite and the target satellite; a dynamic and kinematic model of the mobile satellite and the target satellite is established; a state equation of relative motion between the mobile satellite and the target satellite is constructed by taking relative motion position, velocity and disturbance acceleration as independent variables; an extended state observer is adopted to estimate state variables; a mobile satellite orbit motion control model is established based on a proportional and differential control framework; and disturbance acceleration is compensated by adopting active disturbance rejection design to realize the rendezvous orbit design of the non-cooperative target satellite. The application does not need to accurately obtain orbit motion characteristics of the target satellite, and the method has strong adaptability.

A method, system, product, equipment, and storage medium for autonomous control of the satellite's semi-major axis based on energy constraints are disclosed. Belonging to the field of on-orbit satellite orbit control, this invention solves the problem that existing technologies rely on manual ground planning and command uploading, making it difficult to meet the needs of efficient autonomous orbit control for large-scale constellations. The method involves acquiring the satellite's real-time position and velocity, calculating the corresponding orbit control discrimination parameters, combining a bilateral semi-major axis threshold orbit control strategy to obtain the required orbit control quantities, acquiring the current solar phase angle and satellite orbit parameters, calculating the shadow area initiation phase, and the start time of control. Based on the required orbit control quantities and the energy constraints of a single orbit control operation, the planned orbit control duration parameters are calculated. The start time and planned orbit control duration parameters are used as orbit control execution parameters to achieve autonomous control of the satellite's semi-major axis.

The invention relates to an autonomous handling method suitable for orbit control faults of aircraft timing and fixed-point intersection, and belongs to the technical field of guidance control. An orbit control mode of aircraft autonomous timing and fixed-point intersection comprises element guidance and tail end correction. The method is characterized in that the following steps are executed in each control period in the orbit control process: S1, based on attitude information and a current orbit control execution state, autonomously judging whether the aircraft needs to be stopped and controlled, if so, autonomously executing orbit stopping and controlling processing, and after orbit stopping and controlling, adopting a corresponding attitude stabilization recovery measure according to an orbit stopping and controlling reason, and ending; s2, based on the attitude information orbit control execution state, autonomously judging whether the orbit control meets the condition of recovering the orbit control, if yes, entering step S3, and if not, entering step S3; otherwise, ending; and S3, according to different track control modes and track control stopping durations before control stopping, a track control strategy is determined in a corresponding fault recovery processing mode, and the track control strategy comprises the track control starting moment, the air injection direction and the execution speed increment needed by track control.

This invention relates to the field of remote sensing satellite orbit control technology, and discloses a satellite autonomous pipeline control method based on differential interferometric SAR imaging missions. The method includes: acquiring initial satellite orbit parameters; employing a multi-objective optimization algorithm for orbit optimization under a high-order gravity field; sampling and constructing a reference orbit point set; calculating orbit control deviations based on the actual orbit and the reference orbit; generating orbit control triggering rules and avoidance strategies through ground system simulation; executing orbit control strategy generation and control onboard system; and evaluating orbit control effectiveness and the evolution trend of orbit control deviations through the ground system. Existing technologies mainly rely on ground command injection, making it difficult for satellites to achieve efficient autonomous orbit control when performing heavy-orbit differential interferometric SAR imaging missions, and hindering the decoupling of orbit control and imaging tasks. This invention improves the efficiency and autonomy of orbit control, the execution efficiency of imaging missions, and the safety of on-orbit operation by constructing a closed-loop control system encompassing satellite-ground collaboration, strategy formulation, command execution, and effect evaluation.

The present application relates to a kind of low-orbit giant constellation networking orbit control strategy methods, comprising the following steps: S1: according to last group of orbit control ignition timing, GNSS telemetry and ground measured orbit data, constellation key parameter calibration and forecast are carried out;S2: according to the calibration result calculated in step S1 and nominal constellation configuration parameter, constellation networking stage is independently judged, and orbit control strategy is generated;S3: according to the control strategy generated in step S2, the constellation configuration evolution of a period of time in the future is calculated, and the control strategy is verified.The advantage is that it is suitable for the low-orbit giant constellation networking task configured with electric propulsion, and meets the existing giant constellation orbit control task demand.

The invention relates to the technical field of spacecraft orbit control and game decision, in particular to a reinforcement learning-based information waiting strategy forming method in an orbit pursuit scene, which comprises the following steps of: establishing a pulse round system game environment for describing relative movement of an orbit based on an orbit mechanical equation; based on the relative distance between the chasing party and the target, calculating the real-time observation confidence of the chasing party for observing the authenticity of the target, and updating the observation belief of the chasing party in real time by adopting Beta distribution; designing an expert strategy, and generating a state action database containing states and expert actions in a simulation environment; constructing a strategy network with an observation belief feature embedding layer, and pre-training the strategy network by using a state action database; and defining a reward function which aims at minimizing the capture time and contains distance penalty when the capture is not carried out, refining by maximizing a soft Q value of the sum of the reward and the strategy entropy, and finally outputting an optimal chasing party information waiting strategy with the high-entropy characteristic.

The invention discloses an electric propulsion satellite autonomous orbit control method based on solar wing constraint, which comprises the following steps: after receiving an orbit control task injected on the ground, determining whether the current energy meets the orbit control requirement or not, if so, calculating illumination condition polar plume avoidance, and if not, waiting for a storage battery to be charged until the orbit control requirement is met, and executing the step 2; the method comprises the steps of calculating illumination conditions and plume avoidance, generating an autonomous orbit control strategy based on a calculation result, performing orbit control on an electric propulsion satellite according to the autonomous orbit control strategy, determining whether an orbit control task is completed after at least one time of ignition and each time of ignition is finished, and if the orbit control task is not completed, performing orbit control on the electric propulsion satellite after current energy meets orbit control requirements. And the illumination condition and plume avoidance are calculated again, an autonomous orbit control strategy is generated, and orbit control is carried out until the orbit control task is completed. According to the method, solar wing constraints can be considered while autonomous orbit control is carried out on the electric propulsion satellite, and then the charging efficiency in the orbit control period is improved.

This invention discloses a camera imaging control method and apparatus for midnight sunlight avoidance, belonging to the field of spacecraft attitude and orbit control. The method includes: determining whether the satellite is currently in the midnight sunlight avoidance phase; if the satellite is not in the midnight sunlight avoidance phase, and the conditions for entering the midnight sunlight avoidance phase are met, then the satellite is initialized to enter the midnight sunlight avoidance phase, and the satellite is set to rapidly maneuver to a preset target avoidance trajectory; if the satellite is in the midnight sunlight avoidance phase, and the satellite receives a satisfactory imaging command, then the satellite is maneuvered to the imaging point for imaging; otherwise, the satellite remains on the target avoidance trajectory; if the satellite is in the imaging state during the midnight sunlight avoidance phase and is exposed to sunlight, then the satellite is rapidly maneuvered to the target avoidance trajectory; otherwise, the satellite's imaging state is maintained. This invention can ensure the imaging safety of the camera during midnight sunlight avoidance, improve the utilization efficiency of the camera payload, and enhance the user experience.

This utility model relates to a satellite electric propulsion system, addressing the problems of high cost, poor control precision, and low efficiency and reliability of existing chemical thrusters for micro and nanosatellites, as well as the issues of low efficiency and low reliability of resistance-heated thrusters. The system includes a propellant tank, a power supply and control module, a dual-path pressure regulation module, and a dual-thrust module. The propellant tank uses a full TC4 titanium alloy spherical structure to store liquid ammonia. The power supply and control module controls the high-voltage arc heating of the working fluid via a CAN bus. The dual-path pressure regulation module achieves redundant pressure reduction through solenoid valves, preheaters, and pressure reducing valves. The dual thrusters are arranged vertically at their centers of mass, providing mutual cold backup. This design reduces size and weight through modular integration, improves electrothermal conversion efficiency, orbit climbing mission success rate, and working fluid utilization efficiency, effectively solving the technical bottlenecks of existing propulsion systems and is suitable for high-precision orbit control of micro and nanosatellites.

The utility model relates to the technical field of track control, and discloses a track-based remote control device which comprises a rack, a lead screw is rotatably arranged in the rack, the lead screw is in threaded connection with a sliding table, the top end of the sliding table is provided with a bearing assembly for bearing an object, one end of the lead screw is fixedly provided with a clamping sleeve, and the other end of the lead screw is fixedly provided with a sliding block. A circular plate is connected into the clamping sleeve in a clamped mode, friction plates are fixedly arranged on the two sides of the circular plate, and a pressing plate for pressing the circular plate is fixedly arranged on one side of the clamping sleeve. Pressure can be applied to the circular plate through the pressing plate, friction force between the circular plate and the clamping sleeve and the pressing plate can be kept, the motor can be remotely controlled to work through the remote controller, torque transmission can be guaranteed through the friction force between the circular plate and the clamping sleeve and the pressing plate, the motor can drive the sliding table to move through the lead screw, and then the bearing assembly can move. And the circular plate and the clamping sleeve can play a role in overload protection.

The invention provides a ground hot test run checking method for a space orbit control engine, which is used for checking whether a product can reliably complete in-orbit flight or not, and is characterized by comprising the following steps of: 1, formulating an acceptance hot test run program and working conditions; 2, carrying out product acceptance hot test run; step 3, selecting a casual inspection hot test run product; 4, formulating a hot test run program and working conditions of the identification-grade service life assessment; step 5, carrying out identification-level service life examination hot test run on the casual inspection product; and step 6, evaluating whether the product passes the assessment. The method provided by the invention aims to identify the defects of the orbit control engine in advance through hot test run assessment, assess the adaptability of a product to a flight mission profile, and ensure that the long-life space orbit control engine works reliably in orbit.

The invention provides a satellite orbit control shutdown method, electronic equipment, a storage medium and a program product, and the method comprises the steps: determining an orbit control time length according to an orbit control data packet, and judging whether the orbit control time length is smaller than an orbit control time length threshold value or not; under the condition that the orbit control time length is smaller than an orbit control time length threshold value, a first strategy is selected to control the satellite to execute the current orbit control task, and the first strategy comprises the step of recording the starting time length from the starting time of the current orbit control task; when the startup duration is greater than or equal to a first duration threshold value, generating a shutdown instruction to terminate the current orbit control task; under the condition that the orbit control duration is larger than or equal to the orbit control duration threshold value, a second strategy is selected to control the satellite to execute the current orbit control task, and the second strategy comprises the step of calculating the target speed increment of the satellite; and when the target speed increment is greater than or equal to a speed increment threshold value and the startup duration is greater than or equal to a second duration threshold value, generating a shutdown instruction to terminate the current orbit control task.

This invention provides a position control method and apparatus based on attitude control error feedforward compensation, relating to the field of rendezvous and docking technology. The method includes: calculating the orbital control error based on the attitude control error; determining the position error at the end of the long-range guidance segment under the influence of the orbital control error; calculating a corresponding compensation amount based on the position error at the end of the long-range guidance segment; and correcting the nominal position value based on the compensation amount, so as to use the corrected nominal position value for position control. This solution can achieve high-precision position control under large-pulse orbital control.

This invention discloses a method for analyzing the control capability of a satellite magnetic torquer, belonging to the field of satellite attitude and orbit control technology. The method first acquires the three-axis magnetic field strength data of the satellite's own system; then, it iterates through all specified torque directions. For each specified torque direction, it first calculates the average value of the maximum magnetic torque under different magnetic field strengths, and then calculates the corresponding magnetic torquer control capability; finally, based on the magnetic torquer control capability in each specified torque direction, it analyzes whether the magnetic torquer meets the control requirements. This invention can accurately obtain the control capability of the magnetic torquer, providing a decision-making basis for the selection and configuration of magnetic torquers.

The invention relates to an ultra-low orbit 100-300km single-site atmospheric wind speed modeling method based on transfer learning, and the method comprises the steps: collecting multi-source wind field data at different heights, and carrying out the preprocessing of the multi-source wind field data; performing fusion processing on the preprocessed multi-source wind field data to obtain fused wind field data; performing wavelet multi-scale decomposition on the fused wind field data to obtain multi-scale different-height feature data; inputting the multi-scale different-height feature data into a pre-constructed transfer learning framework, and extracting field-independent features and target field generalization modeling; and inputting the extracted domain irrelevant features and a target domain generalization modeling result into a pre-constructed DeepONet model, obtaining a wind speed prediction value, and obtaining a gravity wave amplitude and a tide phase parameter at the same time. The problem of height expansion is effectively solved under the small sample condition, and the method is suitable for scenes such as ultra-low orbit aircraft orbit control, space weather disturbance early warning and atmospheric density modeling.

This invention provides a ground hot-fire test method for space orbital control engines, used to assess whether the product can reliably complete on-orbit flight. The method comprises the following steps: Step 1, developing acceptance hot-fire test procedures and operating conditions; Step 2, conducting product acceptance hot-fire tests; Step 3, selecting products for random hot-fire test inspection; Step 4, developing qualification-level life assessment hot-fire test procedures and operating conditions; Step 5, conducting qualification-level life assessment hot-fire tests on randomly selected products; Step 6, evaluating whether the product passes the assessment. The method provided by this invention aims to identify orbital control engine defects in advance through hot-fire test inspections, assess the product's adaptability to flight mission profiles, and ensure the reliable on-orbit operation of long-life space orbital control engines.

The invention provides an orbit control management system for a short-wave satellite, and relates to the technical field of short-wave satellite application, and the system comprises a data collection module which is used for collecting the position data, motion state data and environment disturbance data of a moving ship, and forming a dynamic tracking input set; the trajectory prediction module is used for inputting the dynamic tracking input set into a pre-trained neural network model for processing so as to obtain a prediction result data set including the future trajectory and the position offset of the ship; the attitude pointing module is used for enabling the satellite to autonomously generate an attitude adjustment instruction according to the prediction result data set, and calculating an initial pointing expected value of a beam; and the satellite-borne execution mechanism adjusts the satellite attitude in real time according to the attitude adjustment instruction so as to obtain the initial pointing state of the wave beam and the corresponding actual pointing deviation data. Accurate beam pointing and continuous and stable energy transmission are realized, and the auxiliary power supply stability of key equipment is guaranteed.