CN100462683C

CN100462683C - A Miniature Inertial Measurement Unit with Implicit Structure

Info

Publication number: CN100462683C
Application number: CNB2007100636356A
Authority: CN
Inventors: 房建成; 张霄; 盛蔚; 李建利; 孙宏伟; 曹娟娟
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2007-02-07
Filing date: 2007-02-07
Publication date: 2009-02-18
Anticipated expiration: 2027-02-07
Also published as: CN101038173A

Abstract

An implicit structure micro-inertial measurement unit (IMU), according to the requirements of certain verticality, flatness and smoothness, adopts a synthetic ceramic material to process a cube base. Utilizing the feature that the surface of the synthetic ceramic material with a certain smoothness can be electroplated, according to the package, circuit schematic diagram and installation requirements of the accelerometer and gyroscope, the circuit is electroplated on the surface of the base and the pad is attached. Weld the accelerometer and gyro directly on the mutually perpendicular surfaces of the base to ensure that the accelerometer and gyro in the three sensitive directions are perpendicular to each other. The corner pads are attached to the edge of the bottom surface of the cube base, so that the circuit on the bottom surface of the base can be connected with the side circuit, and can be welded to the GNC system board of the micro aircraft. The base serves as both the IMU system circuit board and the support structure for the gyroscope and accelerometer. The miniature IMU of the present invention has the characteristics of small size, light weight, high precision, low cost, etc., and can be applied to the fields of micro-miniature aircraft, miniature robots and the like.

Description

A kind of implicit type structure mini inertia measurement unit

Technical field

The present invention relates to a kind of mini inertia measurement unit (IMU), particularly a kind of based on the miniature IMU MEMS technology, that be used for micro air vehicle Navigation, Guidance and Control (GNC) system.Be applicable to the occasion that IMU volume, weight, precision and cost are had higher requirements simultaneously.

Background technology

Micro aircraft GNC system needs its critical component IMU to satisfy requirements such as volume is little, in light weight, precision is high, cost is low simultaneously.The microminiaturization of IMU becomes the key of restriction GNC system microminiaturization.

Be exercise parameter and control flights such as the position that calculates micro air vehicle, speed, attitude, micro air vehicle Navigation, Guidance and Control (GNC) system needs IMU to measure the parameters such as acceleration, angular velocity of three orthogonal directionss of micro air vehicle body axis system (X, Y, Z).For reaching the requirement of micro aircraft GNC system, IMU generally adopts mems accelerometer and MEMS gyro as its sensitive element, and all adopts wafer-level package.

Accurate installation accuracy is to guarantee the accurately prerequisite of measurement.For accurately measuring the parameter of three orthogonal directionss of micro air vehicle body axis system (X, Y, Z), generally need specific device to install and fix accelerometer and gyro, so that the accelerometer of three directions and gyro are orthogonal.The existing fixed mode has two kinds usually: a kind of is machining metal orthohormbic structure frame, and the printed circuit board (PCB) that has welded accelerometer and gyro is fixed on the structural framing according to orthogonal direction; Another kind of mode does not need structural framing, and the printed circuit board (PCB) that is welded with accelerometer and gyro is welded on the datum clamp face of GNC system by the right angle looper, makes accelerometer and gyro vertical with GNC system datum clamp face maintenance, the formation orthohormbic structure.The structural framing of preceding a kind of mode machining can reach higher precision, but installation procedure is more, and it is very big to introduce alignment error, and volume is bigger, and processing cost is very high; A kind of mode volume in back is less, and processing cost is lower, but installation accuracy is very poor, can't guarantee three verticality between the axle.In view of the foregoing, existing IMU can't take into account the demand that the micro aircraft GNC system volume is little, in light weight, precision is high, cost is low.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, propose a kind of implicit type structure mini IMU, can satisfy the requirement that micro air vehicle Navigation, Guidance and Control (GNC) system bulk is little, in light weight, precision is high, cost is low.

Technical solution of the present invention is: when mini inertia measurement unit is made of three single shaft MEMS gyros and two biaxial MEMS accelerometers, according to the requirement of certain verticality, flatness and smooth finish, adopt synthesize ceramic materials processing one square pedestal.Determine the size of pedestal according to the size of selected accelerometer of micro air vehicle IMU system and gyro.Utilization has the characteristics of the synthesize ceramic material surface electrodepositable circuit of certain smooth finish, encapsulation, circuit theory diagrams and installation requirement according to accelerometer and gyro, electroplate circuit and attach pad at base-plates surface, the gyro of three single shafts is welded on respectively on two mutually perpendicular sides of pedestal and the end face, the accelerometer of two twin shafts is welded on respectively on two other mutually perpendicular side, the base bottom surface edge adheres to the bent angle pad, pedestal is both as the IMU system circuit board, again as the supporting construction of gyro and accelerometer.

When mini inertia measurement unit is made of three single shaft MEMS gyros and three single shaft mems accelerometers,, adopt synthesize ceramic materials processing one rectangular parallelepiped pedestal according to the requirement of certain verticality, flatness and smooth finish.Determine the size of pedestal according to the size of selected accelerometer of micro air vehicle IMU system and gyro.Utilization has the characteristics of the synthesize ceramic material surface electrodepositable circuit of certain smooth finish, according to encapsulation, circuit theory diagrams and the installation requirement of accelerometer and gyro, electroplates circuit and attach pad at base-plates surface.The gyro of three single shafts is welded on respectively on two mutually perpendicular sides of pedestal and the end face, the accelerometer of three single shafts is welded on respectively on two other mutually perpendicular side and the end face, the base bottom surface edge adheres to the bent angle pad, pedestal is both as the IMU system circuit board, again as the supporting construction of gyro and accelerometer.

The principle of such scheme is: the square or the rectangular parallelepiped pedestal that use synthesize ceramic material die sinking processing required size.Grind each surface with diadust after the pedestal moulding, make its surface reach the level of electrodepositable circuit, and make its depth of parallelism, verticality satisfy the requirement of micro air vehicle IMU system.According to accelerometer, gyrostatic circuit theory diagrams and installation requirement, electroplate circuit and pad at base-plates surface.Accelerometer and gyro are welded to respectively on three orthogonal of the pedestal, make its responsive respectively acceleration and rotational angular velocity along X, Y, Z axle.The base bottom surface edge adheres to the bent angle pad, makes pedestal both can be welded on the micro aircraft GNC system plate, and the accelerometer on each face is connected with the pad of base bottom surface with the circuit that gyro is electroplated by base-plates surface.Pedestal is both as the IMU system circuit board, again as the supporting construction of gyro and accelerometer.

The present invention's advantage compared with prior art is: but but the present invention utilizes the grinding of synthesize ceramic material to reach the characteristics of higher level degree and verticality, surperficial electrodepositable circuit and welding chip, be processed into square or rectangular parallelepiped pedestal, accelerometer and gyro can be directly welded on it, constitute implicit type structure mini IMU.Because of its pedestal both as supporting construction, again as circuit board, volume is little, in light weight, advantage of high precision so implicit type structure mini IMU of the present invention has, processing cost is very low, and is convenient to very much carry out integrated with micro aircraft GNC system.

Description of drawings

Fig. 1 is that a kind of implicit type structure mini inertia measurement unit of the present invention adopts the base construction figure under two twin-axis accelerometers and three the single shaft gyro situations;

Fig. 2 adopts a kind of twin-axis accelerometer circuit theory diagrams for a kind of implicit type structure mini inertia measurement unit of the present invention;

Fig. 3 adopts a kind of single shaft gyro circuit theory diagrams for a kind of implicit type structure mini inertia measurement unit of the present invention;

Fig. 4 is that a kind of implicit type structure mini inertia measurement unit of the present invention adopts structural drawing under two twin-axis accelerometers and three the single shaft gyro situations;

Fig. 5 is a kind of implicit type structure mini inertia measurement unit base bottom surface pad connection diagram of the present invention;

Fig. 6 is a kind of implicit type structure mini inertia measurement unit of the present invention and micro aircraft GNC system plate connection diagram;

Fig. 7 is that a kind of implicit type structure mini inertia measurement unit of the present invention adopts the base construction figure under three single-axis accelerometers and three the single shaft gyro situations;

Fig. 8 is that a kind of implicit type structure mini inertia measurement unit of the present invention adopts structural drawing under three single-axis accelerometers and three the single shaft gyro situations;

Fig. 9 is the temperature required curve of a kind of implicit type structure mini inertia measurement unit chips welding of the present invention.

Embodiment

For the situation of using twin-axis accelerometer and single shaft gyro, be that example describes with ADXL320 type accelerometer (twin shaft) and ADXRS300 type gyro (single shaft).At first, determine that the square pedestal is of a size of 10mm * 10mm * 10mm according to the ADXL320 type accelerometer of micro aircraft GNC system employing and size, circuit theory diagrams and the installation requirement of ADXRS300 type gyro.Use density to be 3.6g/cm ³The aluminium nitride synthesize ceramic or the square pedestal (present embodiment adopts the aluminium nitride synthesize ceramic) of silit synthesize ceramic material die sinking processing required size, shape is (or square excises the shape behind one of them angle or two angles or three angles or four angles or five angles or six angles) as shown in Figure 1.Grind base-plates surface with diadust after the moulding of square pedestal, make its surperficial depth of parallelism be better than that 20 μ m, verticality are better than 50 μ m, surface smoothness reaches 0.4 requirement, its surface is the electrodepositable circuit.According to the circuit theory diagrams (as Fig. 2, shown in Figure 3) and the installation requirement of accelerometer, gyro, electroplate circuit and pad then at the square base-plates surface.Three gyros are welded to face C1D1D2C2, face B1C1C2B2 and face A2B2C2D2 respectively, three responsive respectively rotational angular velocities of gyro along X, Y, Z axle, and its three sensitive axes are vertical mutually; The accelerometer of two twin shafts is welded on face A1B1B2A2 (responsive to Y, Z axle acceleration) and face D1A1A2D2 (responsive to X, Z axle acceleration) respectively, and its three sensitive axes are vertical mutually, as shown in Figure 4.Square base bottom surface (face A1B1C1D1) edge adheres to the bent angle pad, as shown in Figure 5, make pedestal both can be welded on the micro aircraft GNC system plate, accelerometer on each face is connected with the pad of base bottom surface with the circuit that gyro is electroplated by base-plates surface, and mini inertia measurement unit and GNC system connection diagram are as shown in Figure 6.

For the situation of using single-axis accelerometer and single shaft gyro, be that example describes with 1221 type accelerometers (single shaft) and ADXRS300 type gyro (single shaft).At first, determine that the rectangular parallelepiped pedestal is of a size of 25mm * 10mm * 10mm according to the accelerometer of micro aircraft GNC system employing and size, circuit theory diagrams and the installation requirement of gyro.Use density to be 3.6g/cm ³The aluminium nitride synthesize ceramic or the rectangular parallelepiped pedestal (present embodiment adopts the aluminium nitride synthesize ceramic) of silit synthesize ceramic material die sinking processing required size, shape is (or rectangular parallelepiped excises the shape behind one of them angle or two angles or three angles or four angles or five angles or six angles) as shown in Figure 7.Grind base-plates surface with diadust after the moulding of rectangular parallelepiped pedestal, make its surperficial depth of parallelism be better than that 20 μ m, verticality are better than 50 μ m, surface smoothness reaches 0.4 requirement, its surface is the electrodepositable circuit.According to the circuit theory diagrams and the installation requirement of accelerometer, gyro, electroplate circuit and pad then at the rectangular parallelepiped base-plates surface.Three gyros are welded to face C1D1D2C2, face B1C1C2B2 and face A2B2C2D2 respectively, three responsive respectively rotational angular velocities of gyro along X, Y, Z axle, and its three sensitive axes are vertical mutually; The accelerometer of three single shafts is welded to face A1B1B2A2, face D1A1A2D2 and face A2B2C2D2 respectively, three responsive respectively acceleration of accelerometer along X, Y, Z axle, its three sensitive axes are vertical mutually, as shown in Figure 8.Rectangular parallelepiped base bottom surface (face A1B1C1D1) edge adheres to the bent angle pad, makes pedestal both can be welded on the micro aircraft GNC system plate, and the accelerometer on each face is connected with the pad of base bottom surface with the circuit that gyro is electroplated by base-plates surface.

The process of above-mentioned synthesize ceramic pedestal has following a few step: 1. make mould according to required form; 2. powdery synthesize ceramic material is filled to mould; 3. high-temperature firing forming process of ceramics; 4. grind base-plates surface with diadust, make its depth of parallelism be better than that 20 μ m, verticality are better than 50 μ m, surface smoothness reaches 0.4 requirement; 5. electroplating surface; 6. press the system requirements processing circuit.

When chips welding, should be noted that strict control welding temperature, need to weld according to temperature curve shown in Figure 9.Can adopt reflow machine, the chip on five faces is welded one by one.When welding chip, need cover the chip that has welded fully, to prevent to repeat to heat infringement device and pad with masking foil.

Claims

1. A kind of implicit structure miniature inertial measurement unit, is made of pedestal and three uniaxial MEMS gyroscopes and two biaxial MEMS accelerometers, is characterized in that: adopt synthetic ceramic material to process a cube pedestal, pedestal surface plating Circuits and pads, three uniaxial gyroscopes are welded on the two mutually perpendicular sides and the top surface of the base, two biaxial accelerometers are respectively welded on the other two mutually perpendicular sides, the bottom edge of the base Attached to the corner pads, the base serves as both the IMU system circuit board and the support structure for the gyroscope and accelerometer.

2. A miniature inertial measurement unit with hidden structure according to claim 1, characterized in that: the shape of the base is a cube or a cube with one corner or two corners or three corners or four corners cut off or Shapes with five or six corners.

3. A micro-inertial measurement unit with implicit structure according to claim 1, characterized in that: said synthetic ceramic material is aluminum nitride synthetic ceramic or silicon carbide synthetic ceramic.

4. A kind of implicit structure miniature inertial measurement unit according to claim 1, is characterized in that: each surface smoothness of described base is better than 0.4; The parallelism of each surface is better than 20 μm; The perpendicularity of each surface is better than at 50 μm.

5. A kind of implicit structure miniature inertial measurement unit according to claim 1, it is characterized in that: the edge of the bottom surface of the base is attached with a corner pad, and this pad not only serves as an electrical connection between the IMU and the GNC system board function, and play a role in fixing the IMU.

6. A miniature inertial measurement unit with an implicit structure, consisting of a base, three uniaxial MEMS gyroscopes and three uniaxial MEMS accelerometers, is characterized in that: a cuboid base is processed with a synthetic ceramic material, and the surface of the base is electroplated Circuits and solder pads, three uniaxial gyroscopes are respectively welded on the two mutually perpendicular sides and the top surface of the base, three uniaxial accelerometers are respectively welded on the other two mutually perpendicular sides and the top surface, the base Angle pads are attached to the edge of the bottom surface of the base, and the base serves as both the IMU system circuit board and the supporting structure for the gyroscope and accelerometer.

7. A miniature inertial measurement unit with a hidden structure according to claim 6, characterized in that: the shape of the base is a cuboid or a cuboid with one corner or two corners or three corners or four corners cut off or Shapes with five or six corners.

8 . The micro inertial measurement unit with implicit structure according to claim 6 , wherein the synthetic ceramic material is aluminum nitride synthetic ceramic or silicon carbide synthetic ceramic.

9. A kind of implicit structure miniature inertial measurement unit according to claim 6, is characterized in that: each surface smoothness of described base is better than 0.4; The parallelism of each surface is better than 20 μm; The perpendicularity of each surface is better than at 50 μm.

10. A kind of concealed structure miniature inertial measurement unit according to claim 6, it is characterized in that: the bottom surface edge of described base is attached to angle pad, and this pad not only serves as the electrical connection of IMU and GNC system board function, and play a role in fixing the IMU.