CN109341719B - A Trimming Method of Inertial Navigation System with Rotating Mechanism Based on Measuring and Compensating Static Unbalanced Moment - Google Patents

Abstract

The invention discloses an inertial navigation system trimming method with a rotating mechanism based on measuring and compensating static unbalanced moment. The steps are as follows: three high-precision pressure sensors are installed and fixed on a trimming tool according to the positional relationship of the three vertices of an equilateral triangle , After completing the electrical connection of the sensors, fix the inertial navigation system on the three sensors, lock the motor rotation axis of the inertial navigation system at 0° and 180° respectively, record the sensor output, list the torque balance formula and make a difference, Calculate the static unbalance moment. According to the actual situation of the system, select a weight block suitable for the position and weight to balance and repeat the above steps to check the effect. When the trim effect reaches the standard, the trim work is completed. The method can effectively compensate the static unbalanced moment of the inertial navigation system with a rotating mechanism around a rotating shaft of a motor, and complete the inertial navigation system trim work with low cost and high efficiency, which is of great significance.

Description

A Trimming Method for Inertial Navigation System with Rotating Mechanism Based on Measuring and Compensating Static Unbalanced Moment

technical field

The invention relates to an inertial navigation system trimming method with a rotating mechanism in the field of inertial technology, which is suitable for an inertial navigation system with a rotating mechanism, in particular to an inertial navigation system trimming with a rotating mechanism based on measuring and compensating static unbalanced moment method.

Background technique

Rotation modulation technology is an effective method to suppress the influence of device constant drift on navigation accuracy. Taking the continuous-rotation rotary modulation inertial navigation system as an example, it can modulate the projection of the constant drift of the two gyroscopes perpendicular to the rotation axis under the carrier system into a sine and cosine variation with a mean value of zero, thereby greatly reducing the amount of navigation. The divergence of errors improves the navigation accuracy. The rotation modulation technology is widely used in the new generation inertial navigation system, mainly including the rotation modulation inertial navigation system and the hybrid inertial navigation system, which are collectively referred to as the inertial navigation system with a rotating mechanism in the present invention.

Since the component distribution of the inertial navigation system needs to be reasonably arranged according to the actual situation, the center of mass after assembly cannot be guaranteed to remain on the rotating shaft of the motor, which brings about the static unbalanced moment of the inertial navigation system relative to the rotating shaft of the motor. The generation of static unbalanced torque will aggravate the loss of the motor, affect the frame stability of the inertial navigation system, and in severe cases, affect the control and navigation accuracy of the inertial navigation system. It is a harmful torque and needs to be eliminated. The hazard of static unbalanced moment is particularly prominent in the case of instantaneous large overload of the inertial navigation system. For example, the overload acceleration of an inertial navigation system airborne test reaches 10 times the gravitational acceleration within a certain period of time. The definition of torque is M=F·l =m·a·l, it can be seen that the static unbalance moment of 100g·cm will expand by 10 times under non-overload conditions. Once the static unbalanced torque exceeds the maximum control torque of the motor, the motor is likely to fly directly, resulting in the failure of the inertial navigation system, which is a very dangerous situation and must be avoided. The methods of inertial navigation to eliminate the static unbalanced moment are collectively called trimming, and the moment balance method belongs to one of them.

In the inertial navigation system with a rotating mechanism discussed in the present invention, two coordinate systems need to be used, and their definitions are given below:

IMU coordinate system (s): OX _s Y _s Z _s : Orthogonal system, the origin O is the center of the inertial navigation system, and the X _s OY _s plane is formed by the origin O and the X and Y summation sensitive axes pointing together, OX _s Pointing along the X-accumulator sensitive axis, OY _s is along the direction perpendicular to OX _s and at an acute angle with the Y-accumulator sensitive axis, OZ _s , OX _s and OY _s together form a right-hand rectangular coordinate system.

原点O为惯导系统中心所在点，当各框光栅转角均为0°时，

沿内框旋转轴方向，IMU坐标系OX_s在与

铅锤的平面上的投影指向为

与

共同组成右手直角坐标系。Inner frame coordinate system (r ₁ )

The origin O is the center of the inertial navigation system. When the angle of each frame grating is 0°,

Along the rotation axis of the inner frame, the IMU coordinate system OX _s is in the

The projection on the plane of the plumb bob is

and

Together they form a right-handed rectangular coordinate system.

The trim method in the specific implementation method of the present invention is mainly aimed at the inner frame coordinate system, but the method of the present invention is also applicable to the trim problem of other motor shaft coordinate systems of the inertial navigation system with a rotating mechanism.

SUMMARY OF THE INVENTION

建立力矩分析图，利用固定在等边三角形三顶点处的三个高精度压力传感器，完成配平工作。The technical problem to be solved by the present invention is: to propose a method for balancing an inertial navigation system with a rotating mechanism based on measuring and compensating the static unbalanced torque, which can effectively compensate the static unbalanced torque of a certain motor rotating shaft of the inertial navigation system with a rotating mechanism, Trim the motor shaft coordinate system. According to the established inner frame coordinate system, the normal plane along the motor rotation axis

A moment analysis diagram is established, and three high-precision pressure sensors fixed at the three vertices of the equilateral triangle are used to complete the trimming work.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for balancing an inertial navigation system with a rotating mechanism based on measuring and compensating static unbalanced moment, and the steps are as follows:

Step (1), complete the assembly of three high-precision pressure sensors on the trim tooling, and fix the inertial navigation system with the rotating mechanism on the pressure sensor;

Step (2), control the motor rotation mechanism of the inertial navigation system to lock the sensor output at 0° and 180°;

Step (3), establish a moment balance formula equation system to do differential calculation of static unbalanced moment;

Step (4), according to the calculation result, balance the weight and experiment again to check the balance effect.

Further, as described in step (1), three high-precision pressure sensors are assembled on the trim tool, and the inertial navigation system with a rotating mechanism is fixed on the pressure sensor. In the moment analysis diagram of Figure 1, the three vertices a, b, and c of an equilateral triangle are projected on the trim tool and marked, and three high-precision pressure sensors are installed at the marked position of the trim tool and fixed.

After completing the electrical connection of the sensors, fix the three-axis inertial navigation system with a rotating mechanism on the pressure sensor, adjust the position of the system so that the readings of the three pressure sensors are similar, and ensure that the X and Y axes of the system are basically aligned with the preset directions, and the system The Z-axis basically refers to the sky, fixing the external equipment and power lines of the system.

Further, in step (2), the motor rotation mechanism of the control inertial navigation system is locked at the zero position and the 180° recording sensor output. The specific steps are, the system is powered on, and the inner, middle and outer frame motors are controlled to rotate to the zero position of the grating. and lock it, record the sensor output, then control the target frame motor to rotate until the grating reading is 180° and lock it, and record the sensor output again.

Further, in step (3), set up torque balance formula equations to do differential calculation of static unbalanced torque, and the specific steps are, using torque analysis diagram as shown in accompanying drawing 1, taking coordinate origin o as a fulcrum, establishing the motor rotation axis The torque balance formula for the rotation angle of 0° and 180°:

Among them, m _ai , m _bi , m _ci , i=1,2 are the average output of three high-precision pressure sensors, i=1, the rotation angle of the motor rotation axis is 0°, and i=2 the rotation angle of the motor rotation axis is 180° , min _inn is the rotor mass, o is the coordinate origin, a, b, c are the force positions of the three high-precision pressure sensors, o _inn is the rotor mass point, and o _out is the mass center of other parts after removing the rotor. It should be noted that the establishment of the moment balance formula is based on the premise that the total mass remains unchanged, and it needs to be verified before calculation.

Differentiate (4) and (5) to get the following formula:

获得中心点o′。等式右边计算结果的一半即为内框坐标系的静不平衡力矩。Among them, since the actual rotation axis of the system cannot completely coincide with the preset during the tooling process, the real rotation axis is projected on the

Obtain the center point o'. The half of the calculation result on the right side of the equation is the static unbalance moment of the inner frame coordinate system.

Further, according to the calculation result in step (4), the weight is counterweighted and the experiment is performed again to check the effect of trimming. The specific steps are, according to the calculation result of the static unbalanced moment in step (3), select to install a counterweight of a certain quality in a suitable counterweight position. weight, and again according to steps (1), (2), (3) to calculate the static unbalanced moment of the motor shaft of the inner frame, and check the trim effect of the inner frame coordinate system. The specific flowchart is shown in Figure 2.

The advantages of the present invention compared with the prior art are:

(1), the present invention performs measurement and trimming under static conditions, avoids the influence of dynamic errors such as the friction torque of the rotating shaft, and ensures trimming accuracy;

(2), the experimental equipment of the present invention is simple, and the cost is lower;

(3), the trim compensation calculation amount of the present invention is small, and the trim efficiency is greatly improved;

(4) The invention has a wide range of application, is suitable for various inertial navigation systems with rotating mechanisms, has good ductility, and can be applied to various shafting trim problems with rotating mechanisms after modifying the experimental scheme.

Description of drawings

Figure 1 is an analysis diagram of the normal plane torque of the motor rotation axis.

Figure 2 is an overall flow chart.

Figure 3 is a schematic diagram of a three-axis hybrid inertial navigation system, wherein 1 is a rotating structure, 2 is an electrical device, 3 is a three-axis gyroscope and a three-axis accelerometer, and 4 is a complete machine casing.

FIG. 4 is a schematic diagram of the rotation mechanism of the three-axis hybrid inertial navigation system, wherein 5 is an outer frame, 6 is a middle frame, and 7 is an inner frame.

Detailed ways

The method of the present invention will be described in detail below with reference to specific embodiments.

The present invention proposes a method for balancing an inertial navigation system with a rotating mechanism based on measuring and compensating static unbalanced torque. The inertial navigation system in this embodiment is a three-axis hybrid inertial navigation system. The schematic diagram of the whole system is shown in the figure. 3, including a three-axis gyro, a three-axis accelerometer 3, a rotating mechanism 1, an electrical device 2 and a complete machine casing 4.

The schematic diagram of its rotating mechanism is shown in Figure 4. The rotating mechanism is divided into an inner frame 7, a middle frame 6 and an outer frame 5. The three frames have different degrees of freedom, so that the entire system can rotate around three axes. Outside the three-axis frame, the system is equipped with a complete machine casing, as shown in Figure 3. In the process of fixing the inertial navigation system, the system assembly is mainly realized by adjusting the position of the casing.

The trim work in this embodiment is mainly aimed at the inner frame motor shaft system, that is, the r ₁ coordinate system. The specific experimental steps are:

(1) The trim device is assembled and the inertial navigation system is fixed.

The torque analysis diagram as shown in Figure 1 is established in the normal plane of the motor rotation axis of the inner frame. Point o is the origin of the coordinates, and the three vertices a, b, and c of an equilateral triangle are projected on the trimming tool plane and marked, and the three high-precision The pressure sensor is installed in the corresponding position and fixed.

Three pressure sensors are used to build a three-point support platform. The centers a, b, and c of the three force-bearing surfaces form an equilateral triangle with a side length of 8 cm. Point o is the center of the equilateral triangle, and the three force-bearing points are basically the same height. After completing the electrical connection of the sensors, place the system on the pressure sensor, adjust the position of the system so that the readings of the three pressure sensors are similar, and ensure that the X and Y axes of the system are basically aligned with the preset directions, and the Z axis of the system basically points to the sky. At the same time, it is necessary to fix the external power lines and signal lines of the system.

(2), system control and data acquisition.

When the system is powered on, the outer frame motor is controlled to rotate to the zero position of the grating and locked, and the inner frame motor is rotated to the grating 0° and locked, and the respective readings of the three sensors at this time are recorded as m _a1 , m _b1 , m _c1 . Control the outer grating unchanged, turn the inner frame motor to the grating reading of 180° and lock it, record the respective readings of the three sensors at this time, which are respectively recorded as m _a2 , m _b2 , m _c2 , and the measurement results are shown in the following table.

Table 1 Measurement results of three pressure sensors

(3) Calculate the static unbalanced moment.

Before the calculation, check whether the total mass recorded twice is equal, that is, check whether the formula (7) holds, and then calculate the static unbalance moment M ₀ =127.4453 g·cm according to the formula (6).

m _a1 +m _b1 +m _c1 =m _a2 +m _b2 +m _c2 (7)

(4), use the counterweight to balance and check the effect of the balance.

According to the previous description of the system, it can be found that there are many irregular gaps in the inertial navigation system, and not every position can be selected as a key point. In order not to affect the radius of gyration and to ensure that the counterweight can be installed at the selected position, a counterweight with a fixed mass of 20g at a distance of about 6cm from the center of rotation is finally selected for counterweight, and steps (1), (2), (3), the measurement results are shown in the following table, and the static unbalanced moment M′ ₀ =4.4001 g·cm is obtained after the counterweight compensation is calculated.

Table 2. Measurement results of three pressure sensors after counterweight

The experimental results show that the effect of the trimming method is remarkable. If the trimming is required to achieve higher precision, the above steps can be repeated until the trimming accuracy reaches the standard.

The parts of the present invention that are not disclosed in detail belong to the well-known technology in the art.

Although the illustrative specific embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, As long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the inventive concept are included in the protection list.

Claims (1)

1. A method for balancing an inertial navigation system with a rotating mechanism based on measuring and compensating static unbalanced moments, the system at least comprising a lockable rotating mechanism, and the balancing device at least comprises a balancing tool, a pressure sensor and a counterweight, It is characterized in that, comprises the following steps: Step (1), complete the assembly of the pressure sensor on the trim tool, and fix the system on the pressure sensor; The assembling method in the step (1) specifically includes: installing and fixing the pressure sensor according to the positional relationship of the three vertices of an equilateral triangle, and after completing the electrical connection of the sensor, installing and fixing the system on the pressure sensor above; Step (2), locking the rotating mechanism of the system at 0° and 180°, and recording the sensor output; Step (3), list the moment balance formula, and calculate the static unbalanced moment by difference; the specific formula is as follows:

Among them, m _ai , m _bi , m _ci , i=1,2 are the average output of three high-precision pressure sensors, i=1, the rotation angle of the motor rotation axis is 0°, and i=2 the rotation angle of the motor rotation axis is 180° , min _inn is the rotor mass, o is the coordinate origin, a, b, c are the force positions of the three high-precision pressure sensors, o _inn is the rotor mass point, o _out is the mass center of other parts after removing the rotor, (1) and (2) ) to get:

Among them, since the actual rotation axis of the system cannot completely coincide with the preset during the tooling process, the real rotation axis is projected on the

Obtain the center point o′, and the half of the calculation result on the right side of the equation is the static unbalanced moment of the inner frame coordinate system; Step (4), select a suitable position in the system, select a suitable weight block for trimming, and check the trimming effect.

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