A temperature field control method suitable for an inertial measurement system

Abstract

The application discloses a temperature field control method suitable for an inertial measurement system, adopts a multi-stage partition temperature field control strategy, and divides the system into two-stage temperature fields between an inner dome and an outer dome and a table body from outside to inside for partition temperature control; first-stage temperature field control is performed, a fuzzy control method is used to calculate corresponding heating piece heating duty cycles and fan rotating speed control instructions, and influence caused by external environment temperature fluctuation is effectively inhibited; second-stage temperature field control is performed, an extended observer is used to estimate disturbances of each temperature control point, and compensation is made to heating resistance heating duty cycle control instructions calculated based on a PID control method, and influence caused by complex coupling heat sources in the system is effectively inhibited; compared with other temperature field control methods of the inertial measurement system, the application realizes real-time control of the temperature field of the system, reduces measurement errors of inertial instruments caused by temperature field fluctuation, and further improves the measurement precision and long-term stability of the inertial measurement system, and has important significance for improving long-term navigation precision.

Description

TECHNICAL FIELD

[0001] The application relates to a temperature field control method suitable for an inertial measurement system, in particular to a temperature field control method suitable for a platform-type inertial measurement system, and belongs to the technical field of inertial measurement systems. BACKGROUND

[0002] The inertial measurement system has the advantages of higher navigation precision and smaller data calculation amount, and is widely applied to long-time high-precision inertial navigation fields such as marine resource exploration and aerospace. However, the working precision of the inertial instruments (gyroscopes and accelerometers) contained in the inertial measurement system is temperature-sensitive, and the navigation precision of the inertial measurement system is easily affected by temperature. The change of the internal temperature of the system will cause the working temperature of the gyroscopes and the accelerometers to fluctuate, thus generating measurement errors and affecting the precision of the inertial measurement system. Therefore, the temperature field control of the high-precision inertial measurement system is the premise and guarantee for realizing the high-precision inertial platform.

[0003] During the working period of the inertial measurement system, the temperature field in the system is affected by multiple factors. Firstly, the power consumption of the inertial instruments, torque motors, angle sensors and related circuit modules in the system changes with the working state; meanwhile, the geometric relationship between the frames changes with the movement of the carrier, which will cause the change of the heat transfer coefficient of the system to the outside; in addition, the external environmental temperature of the inertial measurement system is also changing. The coupling of multiple heat sources and the change of the external environmental temperature make the internal temperature field of the inertial measurement system complex and changeable, and have a great influence on the working temperature of the inertial instruments.

[0004] At present, most platform-type inertial measurement systems adopt individual temperature control of each inertial measurement instrument to ensure the measurement precision of the inertial instruments. However, the unclear coupling relationship of multiple heat sources in the inertial measurement system and the obvious influence of the fluctuation of the external environmental temperature make the temperature control precision of the instruments unsatisfactory, and the fluctuation of the working temperature of the instruments is still large, which still has a great influence on the measurement results of the inertial instruments. Therefore, reducing the temperature fluctuation in the platform-type inertial measurement system, realizing high-precision control of the temperature field in the system, and ensuring the stable working temperature of each inertial instrument, fundamentally guarantee the measurement precision of the inertial instruments, which has become a problem to be solved in engineering.

[0005] In order to meet the requirement of high-precision temperature field control of the high-precision inertial measurement system, a temperature field control method suitable for the inertial measurement system needs to be designed to actively control the temperature field in the system in multiple stages, effectively reduce the temperature gradient in the system, and make the internal temperature field of the system stable and uniform. The influence of the coupling of the complex internal heat sources and the change of the external environmental temperature is inhibited, and the temperature field fluctuation in the system is avoided to cause the decrease of the measurement precision of the inertial instruments, so as to effectively improve the precision of the platform-type inertial measurement system and the adaptability in complex environments. SUMMARY

[0006] The technical solution of the present application is to overcome the shortcomings of the prior art and provide a temperature field control method suitable for an inertial measurement system, which avoids the influence of complex internal heat source coupling and external environment temperature changes on the internal temperature field of the inertial measurement system, and realizes internal temperature field control of the inertial measurement system.

[0007] The technical solution of the present application is: in a first aspect, an inertial measurement system is provided, comprising: an inertial measurement system tool, an outer spherical cover, a convection fan, an inner spherical cover, a table body support indexing mechanism, a table body, an inertial instrument assembly, a heating sheet, a heating resistor, a temperature sensor, and an external control unit, wherein:

[0008] The inner spherical cover is located inside the outer spherical cover, and the table body is located inside the inner spherical cover; the outer spherical cover, the inner spherical cover, and the table body are all spherical and share a common center;

[0009] One end of the table body support indexing mechanism passes through the outer spherical cover and the inner spherical cover in sequence and is fixed to the table body, and the other end is connected to the inertial measurement system tool;

[0010] The inertial instrument assembly is placed inside the table body; the heating resistor is attached to the inertial instrument assembly for controlling the temperature of the inertial instrument assembly to a stable state;

[0011] The inner spherical cover is provided with air holes for gas circulation; two convection fans are symmetrically installed above the left and right of the inner spherical cover, respectively, for driving the air inside the inner spherical cover to flow upward into the interlayer of the outer spherical cover and the inner spherical cover;

[0012] A plurality of heating sheets are distributed around the air holes below the inner spherical cover, and heat the gas flowing into the inner spherical cover from the interlayer;

[0013] A plurality of temperature sensors are distributed around the two convection fans and the plurality of heating sheets for monitoring real-time temperature;

[0014] The external control unit receives the temperature measured by the temperature sensor in real time, performs temperature field regulation and control calculation, and sends control instructions to the heating sheet and the convection fan, respectively, to regulate the heating duty cycle of the heating sheet and the fan speed.

[0015] Preferably, the area around the two convection fans is defined as the air outlet area, i.e., the area where air flows out of the inner spherical cover; and the area around the plurality of heating sheets is defined as the air inlet area, i.e., the area where air flows into the inner spherical cover;

[0016] Based on the requirement of multi-level partition temperature field control, the inertial measurement system is divided into: a first-level temperature field and a second-level temperature field; wherein:

[0017] The first-stage temperature field is the temperature field of the interlayer between the outer spherical cover and the inner spherical cover, and is divided into an air outlet area and an air inlet area, and the temperature is controlled by a convection fan and heating fins.

[0018] The second-stage temperature field is the temperature field inside the platform body, and the temperature is controlled by heating resistors.

[0019] Preferably, the air inside the system flows upwards from the platform body, out of the inner spherical cover, into the interlayer of the double-layer spherical cover, downwards in the interlayer, into the inner spherical cover from the bottom, and finally to the platform body, and the air inside the inertial measurement system as a whole flows in the shape of a magnetic field.

[0020] The heat flow emitted by the platform body is sent into the interlayer of the double-layer spherical cover by the convection fan, and then conducted to the external environment of the inertial measurement system by the outer spherical cover through the flow of the air inside the inertial measurement system.

[0021] In the second aspect, a temperature field control method suitable for an inertial measurement system is provided, comprising:

[0022] S1, measuring the temperature field state inside the inertial measurement system in real time by a temperature sensor arranged;

[0023] S2, obtaining the heating duty cycle control instruction H of the heating fins in the air outlet area of the first-stage temperature field of the inertial measurement system, the heating duty cycle control instruction H of the heating fins in the air inlet area, and the fan speed control instruction F by a fuzzy control method based on the state of the first-stage temperature field of the inertial measurement system; 出 进

[0024] S3, estimating the disturbance z of each temperature control point of the second-stage temperature field by an extended observer based on the state of the second-stage temperature field of the inertial measurement system; the temperature control point is the position of the temperature sensor; 2j

[0025] S4, calculating the heating duty cycle control instruction u of each heating resistor of the second-stage temperature field based on the state of the second-stage temperature field and the estimated disturbance of each temperature control point; 2j

[0026] S5, adjusting the heating duty cycle of the heating fins and the heating resistors and the fan speed according to the control instructions of each stage of the temperature field;

[0027] S6, returning to step S1 to repeatedly iterate to realize the temperature field control of the inertial measurement system.

[0028] Preferably, the heating duty cycle H of the heating fins in the air outlet area and the heating duty cycle H of the heating fins in the air inlet area of the first-stage temperature field are calculated by a fuzzy control method in S2. 出 进 ​​​​​The method for controlling the fan rotating speed F is:

[0029] calculating the outlet temperature error e 出 (t i ) of the first-stage temperature field outlet area; 出 (t i );

[0030] calculating the inlet temperature error e 进 (t i ) of the first-stage temperature field inlet area;

[0031] according to the values of the outlet temperature error e 出 (t i ), the inlet temperature error e 进 (t i ) and the outlet temperature error change rate Δe 出 (t i ), each parameter is divided into fuzzy intervals respectively;

[0032] a fuzzy control rule table is made according to the fuzzy intervals;

[0033] by locating the fuzzy intervals of the outlet temperature error e 出 (t i ) and the outlet temperature error change rate Δe 出 (t i ) of the outlet area, the heating duty cycle H 出 and the fan rotating speed F under the current state are obtained by looking up the table;

[0034] the fuzzy interval of the inlet temperature error e 进 (t i ) of the inlet area is located, and the heating duty cycle H 进 of the inlet area is obtained by looking up the table.

[0035] Preferably, the outlet temperature error e 出 (t i ), the inlet temperature error e 进 (t i ) and the outlet temperature error change rate Δe 出 (t i ) are respectively:

[0036] e 出 (t i ) = T m出 -T d出 ;

[0037]

[0038] e进 (t i ) = T m进 -T d进 ;

[0039] wherein T d出 is the set reference temperature of the outlet region, T m出 is the average of the measured temperatures of the points in the outlet region, T d进 is the set reference temperature of the inlet region, T m进 is the average of the measured temperatures of the points in the inlet region, and Δt is the sampling period.

[0040] Preferably, the fuzzy control rule table includes an outlet region fuzzy control rule table and an inlet region fuzzy control rule table, wherein:

[0041] In formulating the outlet region fuzzy control rule table, the outlet temperature error e 出 (t i ) and the outlet temperature error rate Δe 出 (t i ) are considered simultaneously: when Δe 出 (t i ) is constant and e 出 (t i ) changes from negative to positive, both the heating sheet duty cycle and the fan speed gradually decrease; when e 出 (t i ) is constant and Δe 出 (t i ) changes from negative to positive, the heating sheet duty cycle remains constant while the fan speed gradually increases depending on the situation; for the heating sheet duty cycle and the fan speed of each fuzzy interval in the outlet region, the corresponding heating sheet heating duty cycle control command H 出 and the fan speed control command F are formulated;

[0042] In formulating the inlet region fuzzy control rule table, the inlet region temperature error e 进 (t i ) is considered: when e 进 (t i ) changes from negative to positive, the heating sheet heating duty cycle H 进 in the inlet region gradually decreases; for the heating sheet duty cycle in each fuzzy interval in the inlet region, the corresponding heating sheet heating duty cycle control command H 进 is formulated.

[0043] Preferably, in adjusting the fan speed, in order to ensure uniform temperature inside the system and minimize the influence of heat convection, the fan must remain working, at least maintaining the minimum speed F min .

[0044] The second-stage temperature field disturbance z is estimated by an extended observer 2j , specifically:

[0045] The temperature error of each temperature measurement point of the second-stage temperature control is calculated as e 2j (t i ) = T m2j - T d2j

[0046] The total disturbance of the uncertainty and the cross-coupling disturbance of the heat source acting on the system is estimated, and the linear extended observer equation is:

[0047]

[0048] wherein j = 1,...,n is the number of the multi-channel temperature sensor, T d2j and T m2j are the set reference temperature and the measured temperature of each point of the table body, respectively; z 1j is the temperature of the temperature sensor estimated by the observer, z 2j is the total disturbance of the temperature sensor estimated by the observer, u 2j is the input of the heating duty cycle of the heating resistor corresponding to the j number, and β1 and β2 are the observer gains.

[0049] The control instruction u 2j of the heating duty cycle of each heating resistor of the second-stage temperature field is preferably:

[0050]

[0051] wherein k pj , k ij , and k dj are the PID controller parameters.

[0052] Compared with the prior art, the present application has the following advantages:

[0053] (1) The existing inertial measurement system temperature field control method is sensitive to the external environment temperature fluctuation, and the internal temperature field of the system is seriously affected by the change of the external environment temperature. The method of the present application adopts a multi-stage partition temperature field control strategy and a fuzzy control method with good robustness, can quickly warm up, and step by step adjusts the heating duty cycle of the heating sheet and the fan speed level, avoids the impact on the power system and the electromagnetic interference on the surrounding devices, layer by layer weakens the influence of the external environment temperature fluctuation on the internal temperature field of the system, and can well inhibit the influence of the external environment temperature fluctuation.

[0054] ​(2) The existing inertial measurement system temperature field control method considers less or too complex the influence of complex coupling of internal heat sources on the temperature field, and is difficult to apply in engineering. The method of the application regards the coupling of internal heat sources and unknown interference as the total disturbance of the system, observes and compensates through an easily implemented linear extended observer, realizes multi-input-multi-output decoupling of the inertial measurement system temperature, and improves the anti-interference ability.

[0055] (3) The existing inertial measurement system temperature field control method is sensitive to acceleration, and the internal temperature field of the system is seriously affected by acceleration. The method of the application guarantees constant air temperature of air convection and into the inner sphere cover through the first stage temperature field control, establishes a stable temperature field around the table body, and greatly weakens the influence of acceleration.

[0056] (4) Compared with the existing inertial measurement system temperature field control method, the method of the application can be expanded to three levels, four levels, etc. according to the specific differences of the structure of the inertial measurement system, and can also expand the number of partition control and the number of temperature control channels, and can be popularized to the inertial measurement device also with a multi-layer cover structure and a high overload application scene, and has good economy and universality. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 a flow chart of a temperature field control method suitable for an inertial measurement system of the application;

[0058] Figure 2 a cross-sectional schematic diagram of an inertial measurement system provided by an embodiment of the application;

[0059] Figure 3 a multi-stage partition temperature field control schematic diagram of an inertial measurement system provided by an embodiment of the application;

[0060] Figure 4 a temperature field control result diagram of an inertial measurement system provided by an embodiment of the application.

[0061] IDENTIFICATION OF DRAWINGS

[0062] 1-inertial measurement system tooling, 2-outer sphere cover, 3-convection fan, 4-inner sphere cover, 5-table body support indexing mechanism, 6-table body, 7-inertial instrument assembly, 8-heating sheet, 9-first stage temperature field, 901-inner sphere cover air outlet area, 902-inner sphere cover air inlet area, 10-second stage temperature field. DETAILED DESCRIPTION

[0063] The technical solution of the present application is: a temperature field control method suitable for an inertial measurement system, the inertial measurement system comprising: an inertial measurement system tool 1, an outer spherical cover 2, a convection fan 3, an inner spherical cover 4, a table body support indexing mechanism 5, a table body 6, an inertial instrument assembly 7, heating fins 8, a heating resistor, a temperature sensor, and an external control unit, wherein:

[0064] The inner spherical cover 4 is located inside the outer spherical cover 2, and the table body 6 is located inside the inner spherical cover 4; the outer spherical cover 2, the inner spherical cover 4, and the table body 6 are all spherical bodies and share a common center;

[0065] One end of the table body support indexing mechanism 5 passes through the outer spherical cover 2 and the inner spherical cover 4 in sequence and is fixed to the table body 6, and the other end is connected to the inertial measurement system tool 1;

[0066] The inertial instrument assembly 7 is placed inside the table body 6; the heating resistor is attached to the inertial instrument assembly 7 and is used to control the temperature of the inertial instrument assembly 7 to be in a stable state;

[0067] The inner spherical cover 4 is provided with air permeable holes for gas flow; two convection fans 3 are symmetrically installed above the left and right of the inner spherical cover 4, respectively, for driving the air inside the inner spherical cover 4 to flow upward into the interlayer of the outer spherical cover 2 and the inner spherical cover 4;

[0068] A plurality of heating fins 8 are arranged around the air permeable holes below the inner spherical cover 4, for heating the gas flowing into the inner spherical cover 4 from the interlayer;

[0069] A plurality of temperature sensors are distributed around the two convection fans 3 and the plurality of heating fins 8, respectively, for monitoring the real-time temperature;

[0070] The external control unit receives the temperature measured by the temperature sensor in real time, performs temperature field regulation and control calculation, and sends control instructions to the heating fins and the convection fans, respectively, to regulate the heating duty cycle of the heating fins and the fan speed.

[0071] The area around the two convection fans 3 is defined as an air outlet area 901, i.e., the area where the air flows out of the inner spherical cover 4; the area around the plurality of heating fins 8 is defined as an air inlet area 902, i.e., the area where the air flows into the inner spherical cover 4;

[0072] Based on the requirement of multi-level partition temperature field control, the inertial measurement system is divided into a first-level temperature field 9 and a second-level temperature field 10; wherein:

[0073] The first-level temperature field 9 is the temperature field of the interlayer between the outer spherical cover 2 and the inner spherical cover 4, which is divided into two areas, the air outlet area 901 and the air inlet area 902, for temperature control by the convection fan 3 and the heating fin 8;

[0074] The second temperature field 10 is the temperature field inside the platform 6, which is controlled by the heating resistance.

[0075] The air inside the system flows upwards from the platform 6, out of the inner sphere 4, into the interlayer of the double-layer sphere, flows downwards in the interlayer, flows into the inner sphere 4 from the bottom, and finally flows to the platform 6. Overall, the air inside the inertial measurement system flows in the shape of a magnetic field.

[0076] Through the flow of air inside the inertial measurement system, the heat flow emitted by the platform 6 is sent into the interlayer of the double-layer sphere by the convection fan 3, and then conducted to the external environment of the inertial measurement system by the outer sphere 2.

[0077] The temperature field control method includes the following steps:

[0078] (1) arranging multiple temperature sensors, heating fins / heating resistors, and fans in the inertial measurement system;

[0079] (2) dividing the internal temperature field of the inertial measurement system into a first temperature field and a second temperature field from outside to inside;

[0080] (3) measuring the internal temperature field state of the inertial measurement system in real time through the arranged temperature sensors;

[0081] (4) based on the first temperature field state of the inertial measurement system, calculating the control instructions F of the heating duty cycle H 出 of the heating fins in the air inlet area, the heating duty cycle H 进 of the heating fins in the air inlet area, and the fan speed through the fuzzy control method of the first temperature field control;

[0082] (5) based on the second temperature field state of the inertial measurement system, estimating the disturbance z 2j of each temperature control point of the second temperature field control through the extended observer; the temperature control point is the position of the temperature sensor.

[0083] (6) based on the second temperature field state and the estimated disturbance of each temperature control point, calculating the control instructions u 2j of the heating duty cycle of each heating resistor of the second temperature field;

[0084] (7) adjusting the heating duty cycle of the heating fins / heating resistors and the fan speed according to the control instructions of each temperature field.

[0085] (8) continuously repeating (3) to (7) to realize the temperature field control of the inertial measurement system.

[0086] The temperature sensors of step (1) are distributed in the inertial instrument, the surface of the platform, and the internal space of the inertial measurement system, which can fully measure the internal temperature field state of the inertial measurement system.

[0087] The fan in step (1) forces the internal air to flow, ensuring that the internal temperature of the inertial measurement system is uniform, and that the air inside the system flows in a magnetic field shape with the platform as the center.

[0088] The heating element in step (1) is located in the air outlet area and the air inlet area, and the heating resistor is located next to each inertial instrument.

[0089] The first-level temperature field and the second-level temperature field divided in step (2) correspond to the temperature field between the inner and outer spherical covers of the inertial measurement system and the temperature field of the platform, respectively.

[0090] The implementation method of step (4) is as follows:

[0091] The first-level temperature field is divided into air outlet and air inlet areas, that is, the areas where air flows out of the inner spherical cover and the areas where air flows into the inner spherical cover, and then controlled in zones.

[0092] The temperature error in the first-stage temperature control outlet area is calculated as e. 出 (t i ) = T m出 -T d出 ;

[0093] Calculate the temperature change rate of the first-stage temperature control outlet area.

[0094] The temperature error in the first-stage temperature control inlet area is calculated as e. 进 (t i ) = T m进 -T d进 ;

[0095] Based on the air outlet temperature error e 出 (t i Temperature error in the air inlet area e 进 (t i ) and the rate of change of error in the air outlet area Δe 出 (t i The value of ) is used to divide each parameter into fuzzy intervals, which can be divided into five fuzzy intervals: NB, NM, Z, PM, and PB.

[0096] Based on the fuzzy control rule table, inference is performed to calculate the servo control command H for the first-level temperature field control of the heating element's duty cycle and the fan speed. 出 H 进 、F.

[0097] Among them, T d出 and T m出 T represents the average of the set reference temperature for the air outlet area and the measured temperature at various points in the air outlet area, respectively. d进 and Tm进 respectively, Δt is the sampling period.

[0098] The step (5) is implemented as follows:

[0099] The temperature error of each temperature measuring point of the second stage temperature control is calculated as e 2j i ) = T m2j - T d2j

[0100] The total disturbance of the uncertainty and the cross-coupling disturbance of the heat source acting on the system is estimated, and the linear extended state observer (LESO) equation is:

[0101]

[0102] wherein j = 1,...,n is the number of the multi-channel temperature sensor, T d2j and T m2j are the set reference temperature and the measured temperature of each point of the table body respectively. z 1j is the temperature of the temperature sensor estimated by the observer, z 2j is the total disturbance of the temperature sensor estimated by the observer, u 2j is the input of the heating duty cycle of the heating resistor corresponding to the number j, and β1, β2 are the observer gains.

[0103] The step (6) is implemented as follows:

[0104] The servo control command u 2j of the heating duty cycle of each heating resistor of the second stage temperature field is calculated.

[0105]

[0106] wherein k pj , k ij , k dj are the PID controller parameters.

[0107] The step (8) is implemented as follows:

[0108] The steps (3)-(7) are repeated to continuously adjust the heating duty cycle of each heating sheet / heating resistor and the fan speed in the inertial measurement system, so as to realize the temperature field control of the inertial measurement system.

[0109] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples.

[0110] Example:

[0111] ​like Figure 1 As shown, this embodiment is implemented within an inertial measurement system prototype, providing a temperature field control method suitable for inertial measurement systems. The method includes the following steps:

[0112] (1) Arrange multiple temperature sensors, heating elements / heating resistors and fans in the inertial measurement system;

[0113] (2) Divide the internal temperature field of the inertial measurement system from the outside to the inside into a first-level temperature field 9 and a second-level temperature field 10;

[0114] (3) The internal temperature field state of the inertial measurement system is measured in real time by deploying temperature sensors;

[0115] (4) Based on the state of the first-level temperature field 9 of the inertial measurement system, the heating duty cycle H of the heating element 7 is calculated using the fuzzy control method controlled by the first-level temperature field. 出 H 进 The control command F for fan speed 3;

[0116] (5) Based on the second-level temperature field 10 state of the inertial measurement system, the disturbance z of each temperature control point is controlled by estimating the second-level temperature field through an extended observer. 2j .

[0117] (6) Based on the state of the second-stage temperature field 10 and the estimated disturbances at each temperature control point, calculate the control command u for the heating duty cycle of the heating resistor in the second-stage temperature field. 2j ;

[0118] (7) Adjust the heating duty cycle of the heating element 7 / heating resistor and the fan speed 3 according to the control instructions of each temperature field.

[0119] (8) Repeat (3) to (7) continuously to achieve temperature field control of the inertial measurement system.

[0120] The prototype structure of the inertial measurement system in the above embodiments is as follows: Figure 2 The system comprises an inertial measurement system fixture 1, an outer spherical cover 2, a convection fan 3, an inner spherical cover 4, a platform support and rotation mechanism 5, a platform 6, inertial instrument components 7, heating elements 8, and heating resistors distributed within the platform body. The inertial measurement system employs a multi-level zoned temperature field control system consisting of a first-level temperature field 9 and a second-level temperature field 10. The first-level temperature field 9 controls the temperature of the double-layered spherical cover, dividing the system into two areas: an air outlet area 901 and an air inlet area 902, representing the areas where air flows out of and into the inner spherical cover 4. The second-level temperature field 10 controls the temperature of the platform 6.

[0121] The airflow inside the inertial measurement system in the above embodiments is as follows: Figure 3As shown, the inertial measurement system uses convection fans 3 to force internal airflow, minimizing the impact of acceleration-sensitive natural convection on the temperature field. The symmetrically arranged convection fans 3 on the inner spherical housing cause the air inside the system to flow upwards from the platform 6, leaving the inner spherical housing 4, flowing into the interlayer between the two spherical housings, then downwards into the inner spherical housing 4, and finally flowing towards the platform 6. Overall, the airflow inside the inertial measurement system exhibits a magnetic field-like flow pattern.

[0122] In this embodiment, the heat flow emitted by the platform (6) is sent into the interlayer of the double-layer spherical cover through the convection fan 3 by the air flow inside the inertial measurement system, and then conducted to the external environment of the inertial measurement system by the outer spherical cover 2.

[0123] The temperature sensors arranged in step (1) are distributed in the inertial instrument 7, the platform surface 6 and the internal space of the inertial measurement system, which can fully measure the internal temperature field state of the inertial measurement system; the heating plates 8 are symmetrically distributed on the outside of the inner spherical cover 4, and the heating resistors are distributed around each inertial instrument in the platform 6.

[0124] The implementation method of step (4) is as follows:

[0125] The temperature error of the first-stage temperature control outlet area 901 is calculated to be e. 出 (t i ) = T m出 -T d出 ;

[0126] Calculate the temperature error change rate of the first-stage temperature control outlet area 901.

[0127] The temperature error of the first-stage temperature control air inlet area 902 is calculated to be e. 进 (t i ) = T m进 -T d进 ;

[0128] Based on the air outlet temperature error e 出 (t i Temperature error in the air inlet area e 进 (t i ) and the rate of change of error in the air outlet area Δe 出 (t i The value of ) is divided into five fuzzy intervals: NB, NM, Z, PM, and PB. One method for dividing the intervals is shown in Table 1 below.

[0129] Table 1. Schematic diagram of fuzzy interval division

[0130] NB e 出 (t i )<-3.0℃]]> Δe 出 (t i )<-0.05℃]]> e 进 (t i )<-3.0℃]]> NM -3.0°C < e 出 (t i -0.1°C / -3.0°C < e 进 (t i -0.1°C Z -0.1 °C < e 出 (t i )<0.1 °C -0.05°C < Δe 出 (t i )<0.05°C -0.1 °C < e 进 (t i )<0.1 °C PM 0.1 °C < e 出 (t i )<3 °C / 0.1 °C < e 进 (t i )<3 °C PB 3.0°C < e 出 (t i )]]> 0.05°C < Δe 出 (t i )]]> 3.0°C < e 进 (t i )]]>

[0131] According to the inference of the outlet region fuzzy control rule table, the servo control command H of the first-stage outlet region heating fin heating duty ratio and the fan rotating speed is calculated 出 The specific adjustment mode is shown in Table 2.

[0132] Table 2 Outlet region fuzzy control rule table

[0133]

[0134] According to the inference of the inlet region fuzzy control rule table, the servo control command H of the first-stage inlet region heating fin heating duty ratio is calculated 进 The specific adjustment mode is shown in Table 3.

[0135] Table 3 Inlet region fuzzy control rule table

[0136] e 进 (t i )]]> Control instructions NB H 进max ]]> NM H 进+ ]]> Z H 进keep ]]> PM H 进- <!-- 8 -->]]> PB H 进- ]]>

[0137] Wherein, T d出 and T m出 are the average values of the set outlet region reference temperature and the measured temperature of each point in the outlet region, T d进 and T m进 are the average values of the set inlet region reference temperature and the measured temperature of each point in the inlet region, and Δt is the sampling period.

[0138] H represents the adjustment of the heating fin duty ratio, and the duty ratio is between 0-100%. H 出max represents that the outlet region heating fin duty ratio is 100%, H 出+ represents that the outlet region heating fin duty ratio is 1% higher than the present, H 出- represents that the outlet region heating fin duty ratio is 1% lower than the present, H 出keep represents that the outlet region heating fin duty ratio remains the present value. H 进max represents that the inlet region heating fin duty ratio is 100%, H 进+ represents that the inlet region heating fin duty ratio is 1% higher than the present, H 进- represents that the inlet region heating fin duty ratio is 1% lower than the present, H 进keep represents that the inlet region heating fin duty ratio remains the present value.

[0139] F represents the adjustment of the fan rotating speed, and the convection fan rotating speed is divided into 0 to 10 levels. In order to ensure the uniformity of the internal temperature of the system and minimize the influence of heat convection, the fan must be kept working and at least maintain the minimum rotating speed F min When the system is working, the fan rotating speed cannot be lower than F min . F max represents that the fan rotating speed is the highest 10 levels, F +F - F F

[0140] The step (5) is implemented as follows:

[0141] The temperature error of each temperature measuring point of the second stage temperature control 10 is calculated as e 2j i ) = T m2j - T d2j ;

[0142] The total disturbance of the uncertainty and the cross-coupling disturbance of the heat source acting on the system is estimated, and the linear extended state observer (LESO) equation is as follows:

[0143]

[0144] wherein j = 1,...,6 is the number of the multi-channel temperature sensor, corresponding to three gyroscopes and three accelerometers respectively, T d2j and T m2j are the set reference temperature and the measured temperature of each point of the table body respectively. z 1j is the temperature of the temperature sensor estimated by the observer, z 2j is the total disturbance of the temperature sensor estimated by the observer, u 2j is the input of the heating duty cycle of the heating resistor corresponding to the number j, and β1, β2 are the observer gains.

[0145] The step (6) is implemented as follows:

[0146] The servo control command u 2j of the heating duty cycle of each heating resistor of the second stage temperature field is calculated.

[0147]

[0148] wherein k pj , k ij , and k dj are the PID controller parameters.

[0149] The step (8) is implemented as follows:

[0150] The steps (3)-(7) are repeated to continuously adjust the heating duty cycle of each heating sheet / heating resistor inside the inertial measurement system and the fan speed, so as to realize the temperature field control of the inertial measurement system.

[0151] The measurement results of each temperature measuring point inside the inertial measurement system of the embodiment are as follows: Figure 4As shown, it is illustrated that the method can effectively control the temperature field inside the inertial measurement system, the temperature of each temperature measuring point inside the system is stable, the influence caused by the fluctuation of external environment temperature can be effectively inhibited, and the influence of the complex coupling heat source inside can be reduced.

[0152] The technical effects of the embodiments of the present application are as follows: (1) the first level temperature field control 9 of the inertial measurement system ensures the heat dissipation of the heat generating element and the stability of the air temperature flowing to the table body, and establishes a stable temperature field around the table body 6. (2) the second level temperature field control 10 of the inertial measurement system establishes multiple temperature control points on the table body 6, and simultaneously observes and compensates the influence of disturbance through the extended observer, so that the temperature field of the table body is uniform and stable. (3) the inertial measurement system adopts a multi-level and regional temperature field control strategy, combines the fuzzy control and the extended observer to improve the robustness of the system, effectively reduces the influence of the complex coupling of the internal heat source and the fluctuation of the environment temperature on the temperature field inside the system, and improves the temperature adaptability of the inertial measurement system.

[0153] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art.

Claims

1. An inertial measurement system, characterized by The inertial measurement system tool (1), the outer spherical cover (2), the convection fan (3), the inner spherical cover (4), the table body support indexing mechanism (5), the table body (6), the inertial instrument assembly (7), the heating sheet (8), the heating resistance, the temperature sensor and the external control unit are included, wherein: The inner spherical cover (4) is located inside the outer spherical cover (2), and the table body (6) is located inside the inner spherical cover (4); the outer spherical cover (2), the inner spherical cover (4) and the table body (6) are all spherical and share the same center; One end of the table body support indexing mechanism (5) is fixed on the table body (6) through the outer spherical cover (2) and the inner spherical cover (4) in sequence, and the other end is connected with the inertial measurement system tool (1); The inertial instrument assembly (7) is placed inside the table body (6); the heating resistance is attached to the inertial instrument assembly (7) for controlling the temperature of the inertial instrument assembly (7) to be stable; The inner spherical cover (4) is provided with air permeable holes for gas circulation; two convection fans (3) are symmetrically installed above the left and right of the inner spherical cover (4) respectively for driving the air inside the inner spherical cover (4) to flow upwards into the interlayer of the outer spherical cover (2) and the inner spherical cover (4); A plurality of heating sheets (8) are arranged around the air permeable holes below the inner spherical cover (4) for heating the gas flowing into the inner spherical cover (4) from the interlayer; A plurality of temperature sensors are distributed around the two convection fans (3) and the plurality of heating sheets (8) respectively for monitoring the real-time temperature; The external control unit receives the temperature measured by the temperature sensors in real time, performs temperature field regulation and control calculation, and sends control instructions to the heating sheets and the convection fans respectively to regulate the heating duty ratio of the heating sheets and the rotating speed of the fans.

2. The inertial measurement system according to claim 1, wherein: The area around the two convection fans (3) is defined as an air outlet area (901), i.e. the area where the air flows out of the inner spherical cover (4); and the area around the plurality of heating sheets (8) is defined as an air inlet area (902), i.e. the area where the air flows into the inner spherical cover (4); Based on the requirement of multi-level partition temperature field control, the inertial measurement system is divided into a first-level temperature field (9) and a second-level temperature field (10); wherein: The first-level temperature field (9) is the temperature field of the interlayer between the outer spherical cover (2) and the inner spherical cover (4), which is divided into the air outlet area (901) and the air inlet area (902) and is controlled by the convection fans (3) and the heating sheets (8); The second-level temperature field (10) is the temperature field inside the table body (6) and is controlled by the heating resistance.

3. The inertial measurement system according to claim 1, wherein: The air inside the system flows upwards from the center of the table body (6), flows out of the inner spherical cover (4), flows into the interlayer of the double-layer spherical cover, flows downwards in the interlayer, flows into the inner spherical cover (4) from the bottom and finally flows towards the table body (6); overall, the air inside the inertial measurement system flows like a magnetic field. ​ The heat flow emitted by the platform (6) is sent into the interlayer of the double-layer spherical cover through the flow of the internal air of the inertial measurement system by the convection fan (3), and then is conducted to the external environment of the inertial measurement system by the outer spherical cover (2).

4. A temperature field control method for an inertial measurement system, characterized by The method comprises the steps that: S1, measuring the temperature field state inside the inertial measurement system in real time through the arranged temperature sensor; S2, based on the first-stage temperature field state of the inertial measurement system, obtaining a heating duty cycle control instruction H of the heating sheet at the air outlet region of the first-stage temperature field (9) through a fuzzy control method 出 , a heating duty cycle control instruction H of the heating sheet at the air inlet region 进 and a fan rotation speed control instruction F; S3, based on the state of the second level temperature field (10) of the inertial measurement system, estimating the disturbance z of each temperature control point of the second level temperature field by an extended observer 2j ; the temperature control point is the location of the temperature sensor; S4, based on the second level temperature field state and the estimated disturbance of each temperature control point, calculating the control instruction u of the heating duty cycle of each heating resistor of the second level temperature field 2j ; S5, adjusting the heating duty cycle of the heating sheet and the heating resistance and the fan rotating speed according to the control instructions of the temperature fields at all levels; S6, returning to step S1 and repeatedly iterating to realize the temperature field control of the inertial measurement system.

5. The temperature field control method for an inertial measurement system according to claim 4, wherein: The heating duty cycle H of the air outlet area heating sheet is calculated by a fuzzy control method in S2 出 , the heating duty cycle H of the air inlet area heating sheet 进 and the fan rotating speed control instruction F is calculated by the method calculating an outlet temperature error e of the first-stage temperature field outlet area (901) 出 (t i ) and the outlet temperature error change rate Δe 出 (t i ) calculating an inlet temperature error e for the first stage temperature field inlet region (902) 进 (t i ); According to the outlet temperature error e 出 (t i ), the inlet area temperature error e 进 (t i ), and the outlet temperature error change rate Δe 出 (t i ), the fuzzy intervals are divided for each parameter respectively; The fuzzy control rule table is formulated according to the fuzzy interval; By positioning the outlet temperature error e of the outlet area (901) 出 (t i ) and the outlet temperature error change rate Δe 出 (t i ) in the fuzzy interval, the outlet area heating sheet heating duty cycle H 出 and the fan speed F in the current state are obtained by table lookup. Positioning the temperature error e of the air inlet area (902) in the fuzzy interval where the temperature error e of the air inlet area (902) is located, and obtaining the heating duty cycle H of the air inlet area heating sheet from the table 进 (t i ) in the fuzzy interval, and obtaining the heating duty cycle H of the air inlet area heating sheet from the table 进 .

6. The temperature field control method for an inertial measurement system of claim 5, wherein: outlet temperature error e 出 (t i ), the inlet temperature error e 进 (t i ), and the outlet temperature error change rate Δe 出 (t i ) are respectively: e 出 (t i )=T m出 -T d出 ; e 进 (t i )=T m进 -T d进 ; wherein T d出 is a set reference temperature of the air outlet area, T m出 is an average of the measured temperatures of the points of the air outlet area, T d进 is a set reference temperature of the air inlet area, T m进 is an average of the measured temperatures of the points of the air inlet area, and Δt is a sampling period.

7. The temperature field control method for an inertial measurement system of claim 5, wherein: The fuzzy control rule table comprises an air outlet area fuzzy control rule table and an air inlet area fuzzy control rule table, wherein: The fuzzy control rule table of the outlet area is formulated by considering the outlet temperature error e 出 (t i ) and the outlet temperature error change rate Δe 出 (t i ) 出 (t i ) is unchanged and e 出 (t i ) changes from a negative value to a positive value, the heating sheet duty ratio and the fan rotating speed are gradually reduced; when e 出 (t i ) is unchanged and Δe 出 (t i ) changes from a negative value to a positive value, the heating sheet duty ratio is unchanged, and the fan rotating speed gradually increases according to the situation; for the heating sheet duty ratio and the fan rotating speed of each fuzzy interval of the outlet area, the corresponding heating sheet heating duty ratio control instruction H 出 and the fan rotating speed control instruction F of the inlet area are formulated. When the fuzzy control rule table of the air inlet area is formulated, the air inlet area temperature error e 进 (t i ) is considered 进 (t i ) changes from a negative value to a positive value, the heating duty cycle H 进 of the air inlet area heating sheet gradually decreases; for the heating duty cycle of the air inlet area heating sheet of each fuzzy interval, the corresponding heating duty cycle control instruction H 进 of the air inlet area heating sheet is formulated.

8. The temperature field control method for an inertial measurement system according to claim 7, wherein: To ensure uniform temperature inside the system and minimize the effect of heat convection, the fan must remain in operation, at least at a minimum speed F, when adjusting the fan speed min .

9. The temperature field control method for an inertial measurement system of claim 4, wherein: The second stage temperature field disturbance z of each temperature control point is estimated by an expansion observer 2j Specifically, The temperature error e of each temperature measuring point of the second stage temperature control is calculated 2j (t i ) = T m2j - T d2j ; The total disturbance of the uncertainty and the cross-coupling disturbance of the heat source acting on the system is estimated, and the linear extended observer equation is: where j = 1,...,n is the number of the multi-channel temperature sensor, T d2j and T m2j are the set reference temperature and the measured temperature at each point of the table body respectively; z 1j is the temperature of the temperature sensor estimated by the observer, z 2j is the total disturbance to the temperature sensor estimated by the observer, u 2j is the input of the heating resistance duty cycle corresponding to the j number, β1, β2 are the observer gains.

10. The temperature field control method for an inertial measurement system of claim 9, wherein: The control command u of the heating duty ratio of the second-stage temperature field each heating resistor 2j is: where k pj , k ij , k dj are PID controller parameters.

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