Frameless compact inertial navigation equipment as well as attitude detection system and method based on frameless compact inertial navigation equipment

Abstract

The invention relates to frameless compact inertial navigation equipment and an attitude detection system and method based on the frameless compact inertial navigation equipment. The equipment comprises a base, a spherical rotor shell, three groups of motor stators, a motor control module and an inertial component IMU (Inertial Measurement Unit), the inertial component IMU is mounted in the spherical rotor shell; the spherical rotor shell is a spherical ultrasonic motor rotor and is arranged above the base, three groups of ultrasonic motor stators are uniformly distributed on the periphery of the spherical rotor shell in the circumferential direction, and the three groups of ultrasonic motor stators are mounted on the inner sides of the upper ends of respective motor shell frames and are in contact with the surface of the spherical ultrasonic motor rotor shell through spherical surfaces; the lower ends of the three motor shell frames are fixedly connected with the upper end of the base; the three groups of ultrasonic motor stators are matched with the spherical ultrasonic motor rotor shell to form a spherical ultrasonic motor; the motor control module is fixedly installed at the upper end of the base and used for controlling movement of the spherical ultrasonic motor. The detection system is composed of a group of annular transmitting bands and three groups of annular receiving bands. The invention has the advantages of compact structure, small volume, light weight and high reliability.

Description

Technical Field

[0001] This invention belongs to the field of attitude detection of inertial navigation device inertial unit (IMU), and specifically relates to a frameless compact inertial navigation device and an attitude detection system and method based on the device. Background Technology

[0002] Inertial navigation systems have generally gone through three stages: platform-type inertial navigation, strapdown inertial navigation, and rotating inertial navigation (hybrid inertial navigation). Compared to platform-type and strapdown inertial navigation, rotating inertial navigation utilizes rotation modulation to effectively suppress the position error accumulated over time caused by the drift of the gyroscope's residual constant. Under the condition of using the same horizontal gyroscope, the system accuracy far exceeds that of platform-type and strapdown inertial navigation. Taking a traditional three-axis rotating system as an example, the outer ring frame is used to isolate the carrier's azimuth motion, while the inner ring frame and platform are used to isolate the carrier's horizontal motion. The inertial measurement unit (IMU) is mounted on the platform, the platform is mounted on the inner ring frame, and the inner ring frame is mounted on the outer ring frame. Platform position sensors, inner frame position sensors, and outer frame position sensors are used to measure the real-time angular position of the frames. Position sensors are mainly divided into two types: rotary transformers and circular grating rotation mechanism angle sensors, which can achieve angular measurement accuracies of 10 arcseconds and 2 arcseconds, respectively.

[0003] Existing frame-type inertial navigation systems suffer from large overall size and weight, making them less suitable for use in compact spaces. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a frameless compact inertial navigation device and an attitude detection system and method based on the device.

[0005] One of the above-mentioned objectives of the present invention is achieved by the following technical solution: A frameless compact inertial navigation device includes a base, a spherical rotor housing, three sets of motor stators, a motor control module, and an inertial measurement unit (IMU). The IMU is installed inside the spherical rotor housing. The spherical rotor housing is a spherical ultrasonic motor rotor, which is positioned above the base. Three sets of ultrasonic motor stators are evenly distributed around the periphery of the spherical rotor housing along the circumferential direction. The three sets of ultrasonic motor stators are installed on the inner upper end of their respective motor housings and contact the surface of the spherical ultrasonic motor rotor housing through their spherical surfaces. The lower ends of the three motor housings are fixedly connected to the upper end of the base. The three sets of ultrasonic motor stators and the spherical ultrasonic motor rotor housing cooperate to form a spherical ultrasonic motor. The motor control module is fixedly installed on the upper end of the base and is used to control the movement of the spherical ultrasonic motor.

[0006] Furthermore, the spherical rotor housing is composed of a spherical rotor housing body, an upper spherical cup portion connected to the upper end of the spherical rotor housing body via a flange, and a lower spherical cup portion connected to the lower end of the spherical rotor housing body; the upper spherical cup portion, the lower spherical cup portion, and the spherical rotor housing body are integrally spherical structures; ball bearings are evenly distributed and embedded on the upper and lower spherical cups, with the ball bearings protruding from the outer surface of the corresponding spherical cups, respectively forming an upper dense ball spherical cup and a lower dense ball spherical cup.

[0007] The second objective of this invention is achieved through the following technical solution: An attitude detection system based on the aforementioned frameless compact inertial navigation device includes a set of annular transmitting belts and three sets of annular receiving belts. The set of annular transmitting belts is embedded in the equator of a spherical rotor housing, and consists of a ring of laser transmitter probes. The equator coincides with the reference XOY plane. In the outer space of the spherical rotor housing, annular receiving belts are arranged along the reference XOY plane, along the XOZ plane, and along the YOZ plane, respectively. The three sets of annular receiving belts are arranged orthogonally in pairs, and each set of annular receiving belts is densely covered with laser receiver probes. Each set of laser receiver probes corresponds one-to-one with the laser transmitter probes on the annular transmitting belts. When the spherical rotor housing rotates, two receiver probes on each set of annular receiving belts respond to the laser signal, and the position information of six points on the surface of the inertial navigation system spherical rotor is obtained on the three sets of annular receiving belts.

[0008] Furthermore, the distance between the annular receiving belt along the reference XOY plane and the surface of the rotor sphere outer shell is approximately 15 mm.

[0009] The third objective of this invention is achieved through the following technical solution. An attitude parsing method based on the above attitude detection system includes the following steps: From the six points obtained by the three sets of ring receiving bands of the attitude detection system, select the coordinates of three points, and let the XOY plane point be (x... z1 ,y z1 ,0), XOZ plane points are (x y1 ,0,z y1 The YOZ plane point is (0, y x1 ,z x1 ), resulting in two three-dimensional space vectors A 1 and A 2 :

[0010] The three-dimensional space vector can be obtained from the above formula. A1 andA2 Normal vector of the plane formed A N :

[0011] From the normal vector A N The angle between the rotor's rotation axis projected onto the XOY plane in a clockwise direction and the positive half-axis of the X-axis is θ. Z The angle between the projection onto the XOZ plane and the positive Z-axis is θ. Y The angle between the projection onto the YOZ plane and the positive Y-axis is θ. X :

[0012] Suppose the sphere rotates from time t1 to time t2. Decompose its rotational motion into rotation about the Z-axis by α, rotation about the Y-axis by β, and rotation about the X-axis by γ. Then:

[0013] From the above parameters, we know the angular velocity vector of the rotor sphere in its own coordinate system at time t2. ω N expression:

[0014] Angular velocity vector in this coordinate system ω N The expression for converting to a local horizontal coordinate system unit vector:

[0015] The actual rotation axis direction and corresponding rotation angular velocity of the universal rotating spherical rotor in actual operation are obtained, and the angular velocity components of each coordinate axis direction in the local horizontal coordinate system are obtained to complete the IMU closed-loop rotation control.

[0016] The advantages and positive effects of this invention are as follows: 1. This invention adopts a spherical ultrasonic motor with three stators and one spherical rotor. Traveling waves are formed on the stators, driving the spherical ultrasonic motor rotor to move. This realizes the composite motion of the inner and outer frames of the existing inertial navigation system, and realizes the frameless design of the inertial navigation system. It has the advantages of compact structure, small size, light weight and high reliability.

[0017] 2. The posture detection system of this invention uses a laser sensor. Compared with commonly used non-contact measurement methods for spherical motors, such as photoelectric encoder rings, machine vision, optical mouse sensors, Hall sensors, color sensors, piezoelectric sensors, etc., it has the advantages of low cost and highly controllable detection accuracy, and can achieve accurate acquisition of posture data. Attached Figure Description

[0018] Figure 1 This is an overall structural diagram of the frameless compact inertial navigation device of the present invention; Figure 2 This is a schematic diagram of the arrangement of the grayscale sensor for inertial navigation attitude detection according to the present invention. Detailed Implementation

[0019] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] A frameless, compact inertial navigation device, please see [link / reference]. Figure 1 The system mainly includes a base 4, a spherical rotor housing 1, three sets of motor stators 2, a motor control module 3, and an inertial measurement unit (IMU) 6. The IMU is installed inside the spherical rotor housing. The spherical rotor housing is a spherical ultrasonic motor rotor, positioned above the base. Three sets of ultrasonic motor stators are evenly distributed circumferentially around the periphery of the spherical rotor housing. Each set of stators is mounted on the inner upper side of its respective motor housing frame and contacts the surface of the spherical ultrasonic motor rotor housing via a spherical surface. The lower ends of the three motor housing frames are fixedly connected to the upper end of the base. The three sets of ultrasonic motor stators and the spherical ultrasonic motor rotor housing together constitute a spherical ultrasonic motor.

[0021] This invention is an improved design based on an existing toroidal ultrasonic motor. The core driving element of the ultrasonic motor is a piezoelectric ceramic transducer. In a traditional toroidal traveling-wave ultrasonic motor, the piezoelectric transducer on the stator is divided into two phases, A and B, with each phase further divided into several equal-length, opposite-polarity partitions. An alternating electric field is applied to the electrodes of any partition, generating a standing wave in that partition. By changing the frequency, amplitude, and phase of the driving voltage signals applied to phases A and B, the frequency, amplitude, and phase of the standing waves on the ceramic plates of phases A and B can be altered. When the phase difference between the driving voltage signals of phases A and B is 90 degrees and the driving voltage amplitudes are equal, the mechanical wave synthesized by the standing waves generated by phases A and B is the traveling wave with the largest amplitude and longest wavelength. The synthesized traveling wave generates a relative positive pressure with the vertical vibration of the rotor or slider, and the traveling wave is transmitted in the horizontal direction relative to the rotor or slider, generating a frictional force in the opposite direction. Under the action of friction, the rotor disk or slider undergoes a macroscopic motion opposite to the direction of the transmitted synthesized traveling wave.

[0022] Compared to existing ring-shaped ultrasonic motors, the spherical ultrasonic motor of this invention breaks through the one-stator-one-rotor principle by using three stators to one rotor, and the rotor adopts a spherical shape. Similarly, traveling waves are formed on the stators to drive the rotor of the spherical ultrasonic motor, realizing the composite motion of the existing inner and outer frames.

[0023] The motor control module is fixedly installed on the upper end of the base and is used to control the movement of the spherical ultrasonic motor.

[0024] The spherical rotor housing consists of a main body, an upper ball-shaped cup connected to the upper end of the main body via a flange, and a lower ball-shaped cup connected to the lower end of the main body. The upper and lower ball-shaped cups and the main body form an integral spherical structure. Ball bearings are evenly distributed and embedded in the upper and lower ball-shaped cups, protruding from the outer surface of their respective cups, forming the upper dense ball-shaped cup 7 and the lower dense ball-shaped cup 5, respectively. The installation method of the ball bearings on the cups can refer to the ball bearing installation method on the base of the universal caster wheel used in existing mobile home appliances. By using the upper and lower dense ball-shaped cups, and through the rolling engagement of the ball bearings with the corresponding upper and lower support structures (not shown in the attached drawings), the spherical ultrasonic motor rotor can be constrained in a fixed spatial position, achieving close contact with the three sets of ultrasonic motor stators. Furthermore, it allows for smooth rotation of the spherical ultrasonic motor rotor without obstructing its movement.

[0025] In this embodiment of the invention, the radius R of the spherical ultrasonic motor rotor is designed. rotor The radius R of the arc surface where the three sets of ultrasonic motor stators contact the surface of the spherical ultrasonic motor rotor is 200mm. stator The diameter is 52.5 mm. The angle α between the line connecting the center of the arc surface of the three sets of ultrasonic motor stators to the center of the spherical ultrasonic motor rotor and the horizontal plane intercepted by the equator of the spherical rotor shell is 15°.

[0026] Traditional frame structures mostly employ inductive synchros or absolute grating encoders to measure angular position information in real time and feed it back to the system for calculation. However, the problem situation addressed by this invention, due to the multi-degree-of-freedom rotation of the inertial navigation system's spherical rotor, makes this type of attitude measurement method unsuitable. Common measurement methods for this spherical rotor mechanism include photoelectric encoder rings, machine vision, optical mouse sensors, Hall effect sensors, color sensors, and piezoelectric sensors. Considering the structural characteristics of the spherical rotor and rotating components in this patent, this invention proposes an attitude detection system and attitude analysis method based on a laser sensor.

[0027] The attitude detection system includes a set of annular transmitting strips 8 and three sets of annular receiving strips. Figure 2 This diagram illustrates the arrangement of grayscale sensors for attitude detection on the spherical rotor of the inertial navigation system. A ring of laser emitter probes, represented by small red cylinders, is arranged along the equator of the spherical rotor shell (coinciding with the reference XOY plane). Each emitter probe has a diameter of dsensor, forming a ring-shaped emission band. The ring-shaped emission band is embedded in a groove set along the equator of the spherical rotor shell.

[0028] A ring-shaped receiving band 9 is arranged around the equator of the spherical rotor (coinciding with the reference XOY plane). The distance between this ring-shaped receiving band and the surface of the rotor's spherical outer shell is approximately 15 mm. Laser receiver probes are densely arranged on the ring-shaped receiving band (the receivers are specially designed to only receive vertically incident laser signals). The receivers on the ring-shaped receiving band are represented by small green cylinders, and their number is equal to that of the transmitter, ensuring that each receiver can receive the signal from the transmitter when the plane of the transmitter probe coincides with the XOY plane.

[0029] Similarly, a set of annular receiving strips is arranged along the XOZ and YOZ planes respectively. In the attached diagram, these two sets of annular receiving strips are labeled 10 and 11, respectively. The three sets of annular receiving strips are orthogonal to each other, and the points on the surface of the spherical rotor corresponding to the laser receiver probes when they respond have unique coordinates in the local horizontal coordinate system. Regardless of how the spherical rotor shell rotates, two receiver probes on each set of annular receiving strips respond to the laser signal, and the position information of six points on the surface of the inertial navigation system's spherical rotor is obtained from the three sets of annular receiving strips.

[0030] The attitude parsing method based on the above attitude detection system includes the following steps: Take the coordinates of three points from the above six points, and let the point on the XOY plane be (x z1 ,y z1 ,0), XOZ plane points are (x y1 ,0,z y1 The YOZ plane point is (0, y x1 ,z x1 ), resulting in two three-dimensional space vectors A 1 and A 2 :

[0031] The three-dimensional space vector can be obtained from the above formula. A1 and A2 Normal vector of the plane formed A N :

[0032] From the normal vector A N The angle between the rotor's rotation axis projected onto the XOY plane in a clockwise direction and the positive half-axis of the X-axis is θ. Z The angle between the projection onto the XOZ plane and the positive Z-axis is θ. Y The angle between the projection onto the YOZ plane and the positive Y-axis is θ. X :

[0033] Let the axis of rotation of the sphere be (the axis of rotation is along the normal vector). A N The direction) rotates from time t1 to time t2 (the change time is Δt), and its rotational motion is decomposed into a rotation about the Z-axis α (from θ). Z1 Transform into θ Z2 Rotate β about the Y-axis (from θ) Y1 Transform into θ Y2 ), rotate γ about the X-axis (from θ) X1 Transform into θ X2 ):

[0034] From the above parameters, we know the angular velocity vector of the rotor sphere in its own coordinate system at time t2. ω N expression:

[0035] Angular velocity vector in this coordinate system ω N The expression for converting to a local horizontal coordinate system unit vector:

[0036] This allows us to obtain the actual rotation axis direction and corresponding rotation angular velocity of the omnidirectional spherical rotor in actual operation, and to derive its angular velocity components in each coordinate axis direction under the local horizontal coordinate system, thereby completing the IMU closed-loop rotation control.

[0037] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A frameless, compact inertial navigation device, characterized in that: The device includes a base, a spherical rotor housing, three sets of motor stators, a motor control module, and an inertial measurement unit (IMU). The IMU is installed inside the spherical rotor housing. The spherical rotor housing is a spherical ultrasonic motor rotor, positioned above the base. Three sets of ultrasonic motor stators are evenly distributed circumferentially around the periphery of the spherical rotor housing. The three sets of ultrasonic motor stators are mounted on the inner upper part of their respective motor housings and contact the surface of the spherical ultrasonic motor rotor housing through their spherical surfaces. The lower ends of the three motor housings are fixedly connected to the upper end of the base. The three sets of ultrasonic motor stators and the spherical ultrasonic motor rotor housing together constitute a spherical ultrasonic motor. The motor control module is fixedly installed on the upper end of the base and is used to control the movement of the spherical ultrasonic motor.

2. The frameless compact inertial navigation device according to claim 1, characterized in that: The spherical rotor housing consists of a main body, an upper spherical cup connected to the upper end of the main body via a flange, and a lower spherical cup connected to the lower end of the main body. The upper spherical cup, the lower spherical cup, and the main body form an integral spherical structure. Balls are evenly distributed and embedded in the upper and lower spherical cups, with the balls protruding from the outer surface of the corresponding spherical cups, forming an upper dense ball spherical cup and a lower dense ball spherical cup, respectively.

3. An attitude detection system based on the frameless compact inertial navigation device according to claim 1 or 2, characterized in that: It includes one set of annular emitting belts and three sets of annular receiving belts. One set of annular emitting belts is embedded on the equator of the spherical rotor shell. Each set of annular emitting belts consists of a ring of laser emitter probes. The equator coincides with the reference XOY plane. In the outer space of the spherical rotor shell, annular receiving belts are arranged along the reference XOY plane, along the XOZ plane, and along the YOZ plane, respectively. The three sets of annular receiving belts are arranged orthogonally in pairs. Each set of annular receiving belts is densely covered with laser receiver probes. The laser receiver probes on each set of annular receiving belts correspond one-to-one with the laser emitter probes on the annular emitting belts. When the spherical rotor housing rotates, two receiver probes on each set of annular receiving belts respond to the laser signal, and the position information of six points on the surface of the inertial navigation system spherical rotor is obtained on the three sets of annular receiving belts.

4. The attitude detection system according to claim 3, characterized in that: The distance between the annular receiving belt along the reference XOY plane and the surface of the rotor sphere housing is approximately 15 mm.

5. An attitude analysis method based on the attitude detection system of claim 3 or 4, characterized in that: The process includes the following: From the six points obtained by the three sets of ring receiving bands of the attitude detection system, select the coordinates of three points, and let the XOY plane point be (x... z1 ,y z1 ,0), XOZ plane points are (x y1 ,0,z y1 The YOZ plane point is (0, y x1 ,z x1 ), resulting in two three-dimensional space vectors A 1 and A 2 : The three-dimensional space vector can be obtained from the above formula. A1 and A2 Normal vector of the plane formed A N : From the normal vector A N The angle between the rotor's rotation axis projected onto the XOY plane in a clockwise direction and the positive half-axis of the X-axis is θ. Z The angle between the projection onto the XOZ plane and the positive Z-axis is θ. Y The angle between the projection onto the YOZ plane and the positive Y-axis is θ. X : Suppose the sphere rotates from time t1 to time t2. Decompose its rotational motion into rotation about the Z-axis by α, rotation about the Y-axis by β, and rotation about the X-axis by γ. Then: From the above parameters, we know the angular velocity vector of the rotor sphere in its own coordinate system at time t2. ω N expression: Angular velocity vector in this coordinate system ω N The expression for converting to a local horizontal coordinate system unit vector: The actual rotation axis direction and corresponding rotation angular velocity of the omnidirectional spherical rotor in actual operation are obtained, and the angular velocity components of each coordinate axis direction in the local horizontal coordinate system are obtained to complete the IMU closed-loop rotation control.

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