CN105259370A - Angular acceleration measuring device based on MEMS linear accelerometer - Google Patents

Abstract

The invention provides an angular acceleration measuring device based on an MEMS linear accelerometer. The angular acceleration measuring device comprises two MEMS linear acceleration chips and a sensor disc. The center of circle of the sensor disc is fixedly connected with a rotation shaft. The MEMS linear acceleration chips are respectively installed on the edge and the center of circle of the sensor disc. The linear acceleration sensing directions of the MEMS linear acceleration chips are mutually parallel and perpendicular to the radius direction of the sensor disc. When the sensor disc rotates along with the rotation disc, by subtracting the linear acceleration signals output by the MEMS linear acceleration chips, the circumferential rotation linear acceleration of the sensor disc can be obtained, and by dividing the circumferential rotation linear acceleration by the radius of the sensor disc, the final rotation angular acceleration can be obtained. According to the invention, an angular acceleration sensor is allowed to be simple in structure and highly reliable; and while the angular acceleration sensor has quite high precision, cost of the angular acceleration sensor is greatly reduced.

Description

A kind of angular acceleration measurement mechanism based on MEMS linear accelerometer

Technical field

The present invention relates to a kind of angular acceleration measurement mechanism, particularly a kind of based on MESM linear accelerometer, the device of indirect inspection angular acceleration.

Background technology

In inertial sensor, the purposes of angular acceleration transducer is very extensive, and such as automobile balance drives detection, missile inertial navigation system, hard drive eliminates shake, digital camera eliminates shake etc.The measuring method of angular acceleration can be divided into: directly measurement formula and indirect inspection formula.Direct measurement formula refers to that the sensor by responsive angular acceleration directly obtains the information of angular acceleration.Indirect inspection formula refers to and gathers other signal relevant to angular acceleration, and then by calculating angular acceleration information.

Direct measurement formula angular acceleration transducer mainly comprises: pressure resistance type angular acceleration transducer, piezoelectric type angular acceleration transducer, Pendular ring type angular acceleration transducer etc.These traditional direct-type angular acceleration transducers have formed product and have been used widely, but their price is all very expensive, mostly in tens thousand of units left and right.Therefore, in the application of some low costs, people are more prone to use indirect type angular acceleration transducer.

The measuring method of indirect type angular acceleration transducer is simply listed below.First, be application photoelectric encoder measured angular acceleration, namely by photoelectric encoder measured angular position information, and then obtain angular acceleration by differential calculation, but differential calculation can introduce larger time delay and error, affects the precision of angular acceleration.Secondly, Chinese invention patent CN201410259116 provides a kind of axle sleeve type permanent magnetism rotating angular acceleration sensor, this method uses brshless DC motor as tech-generator, export the voltage signal be directly proportional to angular velocity, and then filtering, obtain angular acceleration signal after differential, but this method cost is higher, and still need angular velocity signal for the differential of time.

MEMS technology refers to MEMS (micro electro mechanical system) (MEMS, Micro-Electro-MechanicalSystem), also being called microelectromechanical systems, is a kind of electromechanical devices grown up on microelectric technique (semiconductor fabrication) basis.It has the advantage that volume is little, lightweight, reliability is high, MEMS technology is applied to the developing direction that angular accelerometer is angular accelerometer, such as Chinese invention patent CN200610011906 provides a kind of pendulous silicon MEMS angular acceleration transducer, but this method only obtains simulating, verifying, not with applying in practice.

Research both at home and abroad for MEMS angular accelerometer is also so not extensive, does not also have more ripe MEMS angular accelerometer chip.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides a kind of angular acceleration measurement mechanism based on MEMS linear accelerometer, application two panels price only has the MEMS linear accelerometer chip of dozens of yuan, by calculating, the linear acceleration directly measured is converted into angular acceleration, indirectly obtain the size of Angular Acceleration, angular acceleration transducer structure can be made simple, and reliability is high, and while having higher precision, greatly reduce angular acceleration transducer cost.

The technical solution adopted for the present invention to solve the technical problems is: comprise two pieces of MEMS linear acceleration chips and sensor disk.

The center of circle and the rotating shaft of described sensor disk are connected; On the edge that two pieces of MEMS linear acceleration chips are arranged on sensor disk respectively and the center of circle, the linear acceleration induction direction of two pieces of MEMS linear acceleration chips is parallel to each other, and vertical with the radial direction of sensor disk; When sensor disk rotates along with rotating shaft, the linear acceleration signals that two pieces of MEMS linear acceleration chips export is done difference, just obtains the circumference rotational line acceleration of sensor disk, then divided by the radius of sensor disk, just obtain final rotating angular acceleration.

The present invention also comprises signal conditioning circuit and V/I change-over circuit, signal conditioning circuit and V/I change-over circuit are all arranged on sensor disk, the output voltage signal of two pieces of MEMS linear acceleration chips accesses respective signal conditioning circuit respectively, carry out filtering to output voltage signal and output voltage amplitude adjusted to the acceptable scope of V/I change-over circuit, the output voltage signal after conditioning is converted into current signal through V/I change-over circuit and exports.

Described sensor disk installs PCB, and described MEMS linear acceleration chip, signal conditioning circuit and V/I change-over circuit are all integrated in PCB.

The invention has the beneficial effects as follows:

1) adopt MEMS linear accelerometer chip as main sensors, greatly reduce angular acceleration transducer cost, and sensor and signal conditioning circuit can be integrated on one piece of circuit board, thus reduced volume, improve the reliability of system.

2) method of take measurement of an angle position signalling and then differential is different from general indirect inspection, the direct slotted line acceleration signal of the present invention, being converted into angular acceleration signal by calculating, not to the differential of angle or angular velocity in calculating, thus avoiding time delay and error that differential calculation causes.

3) use the mode of two panels MEMS linear acceleration chip, can directly eliminate the impact of acceleration of gravity for angular acceleration from the angle of hardware, make the calculating of angular acceleration very easy.

4) PCB on sensor disk can realize accurate location easily, and therefore MEMS linear accelerometer chip can be arranged on the ad-hoc location of sensor disk accurately, makes the manufacture and installation of whole angular acceleration transducer simple and convenient.

5) apply V/I change-over circuit, the output signal of angular acceleration transducer is converted to electric current and transmits, effectively can improve the interference free performance of sensor.

Accompanying drawing explanation

Fig. 1 is angular acceleration transducer schematic diagram;

Fig. 2 is angular acceleration transducer structural drawing;

Fig. 3 is angular acceleration measuring system one-piece construction figure;

In figure, 1-MEMS linear accelerometer one, 2-MEMS linear accelerometer two, 3-sensor disk, 4-modulate circuit, 5-V/I change-over circuit, 6-modulate circuit, 7-V/I change-over circuit, 8-external signal Acquire and process circuit, 9-slip ring, 10-sensor support frame, 11-base, 12-motor.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further described, the present invention includes but be not limited only to following embodiment.

System of the present invention comprises two pieces of MEMS linear acceleration chip Acce1 and Acce2, signal conditioning circuit, V/I change-over circuit, sensor disk.

2 MEMS linear acceleration chips, signal conditioning circuit and V/I change-over circuits are all integrated in the PCB of sensor disk, and sensor disk is connected with rotating shaft, on the circumference that Acce1 and Acce2 is arranged on disk respectively and the center of circle.The output voltage signal of Acce1 and Acce2 accesses respective signal conditioning circuit respectively, carries out filtering and output voltage amplitude is adjusted to the acceptable scope of V/I change-over circuit to signal.Voltage signal input V/I change-over circuit after conditioning is converted into current signal and exports.The principle of MEMS linear acceleration chip detection acceleration is that inside has a mass be connected with MEMS chip wall by inductor, and therefore MEMS linear acceleration chip can detect the acceleration that the outer acting force acted on chip produces and the weight component acted on mass.Sensor disk can the arbitrarily angled placement in ground relatively, as long as the linear acceleration induction direction of two panels chip is parallel to each other, and vertical with the radial direction of sensor disk.When sensor disk rotates along with rotating shaft, the linear acceleration that Acce1 senses comprises the rotational line acceleration of circumference and periodically variable weight component, and the linear acceleration that Acce2 senses only comprises periodically variable weight component.The weight component that Acce1 and Acce2 senses is equal, the output line acceleration signal of Acce1 and Acce2 is done difference and just can offset weight component impact, obtain the circumference rotational line acceleration of sensor disk, again divided by the radius of disk, just can obtain final rotating angular acceleration, the numbers translate realizing being sensed by MEMS linear accelerometer is the numerical value of angular acceleration.

Principle of the present invention as shown in Figure 1, comprises MEMS linear accelerometer one, MEMS linear accelerometer two, sensor disk 3.Sensor disk 3 is connected with rotating shaft coaxle, MEMS linear accelerometer one and MEMS linear accelerometer two be arranged on respectively sensor disk 3 circumferentially with on the center of circle.Due to the characteristic of MEMS linear accelerometer self, MEMS linear accelerometer one and MEMS linear accelerometer two can only X-direction acceleration in Sensitive Graphs, this X-axis is determined based on MEMS linear accelerometer chip local Coordinate System, therefore X-axis can change direction along with the rotation of disk, and vertical with the line of MEMS linear accelerometer two with MEMS linear accelerometer one all the time.

When sensor disk 3 together rotates along with rotating shaft, the linear acceleration in the X-direction that MEMS linear accelerometer one is responsive is a ₁, it comprises the rotational line acceleration a of circumferentially MEMS linear accelerometer one center position _ωwith acceleration of gravity component gcos θ in the X-axis direction, and angle θ rotates along with sensor disk 3 and changes.Linear acceleration in the X-direction that MEMS linear accelerometer two is responsive is a ₂, because it is positioned at the circle centre position of sensor disk 3, therefore it only comprises acceleration of gravity component gcos θ in the X-axis direction.Can obtain thus:

$\left\{\begin{array}{c}{a}_1=a_{\mathrm{\ω}}+g\·cos\mathrm{\θ}\\ a_2=g\·cos\mathrm{\θ}\end{array}\right.---\left(1\right)$

Due to a ₁and a ₂in the gravitational acceleration component that comprises completely equal, therefore by a ₁and a ₂do difference, just can obtain the rotational line acceleration a of MEMS linear accelerometer one central spot _ω, then by rotational line acceleration a _ωput the radius R in the center of circle divided by chip center, just can obtain rotating angular acceleration α.That is:

$\mathrm{\α}=\frac{a_{\mathrm{\ω}}}{R}=\frac{a_1-a_2}{R}---\left(2\right)$

Embodiments of the invention as shown in Figure 2, comprise MEMS linear accelerometer one, MEMS linear accelerometer two, sensor disk 3, modulate circuit 4, V/I change-over circuit 5, modulate circuit 6, V/I change-over circuit 7.They are all integrated in the PCB of sensor disk 3, thus the volume of angular acceleration transducer is little, reliability is high.MEMS linear accelerometer one senses the linear acceleration a at circumference place ₁voltage signal, is converted into current signal I through signal conditioning circuit 4 and V/I change-over circuit 5 ₁export, in like manner, MEMS linear accelerometer two senses circle centre position linear acceleration a ₂voltage signal, is converted into current signal I through signal conditioning circuit 6 and V/I change-over circuit 7 ₂export.On the circumference that MEMS linear accelerometer one and MEMS linear accelerometer two can be positioned at sensor disk 3 by PCB accurately and the center of circle, make the installation of angular acceleration transducer simple and convenient.And apply V/I change-over circuit, use current delivery linear acceleration signals effectively can improve the interference free performance of sensor.

Angular acceleration measuring system one-piece construction as shown in Figure 3, comprises external signal Acquire and process circuit 8, slip ring 9, sensor disk 3, sensor support frame 10, base 11, motor 12.Wherein, motor 12, slip ring 9, sensor disk 3 coaxially connects, and installs on the pedestal 11, and sensor disk 3 is fixed by sensor support frame 10, reduces the shake of sensor disk 3 when motor rotates.The current signal I that sensor disk 3 exports ₁and I ₂, be connected with external signal Acquire and process circuit 8 by slip ring 9, external signal Acquire and process circuit 8 is by current signal I ₁and I ₂be converted into voltage signal, be input in innernal CPU through conditioning and adc circuit, obtain linear acceleration a ₁and a ₂, then the value of angular acceleration is calculated according to formula (2).

Claims (3)

1. based on an angular acceleration measurement mechanism for MEMS linear accelerometer, comprise two pieces of MEMS linear acceleration chips and sensor disk, it is characterized in that: the center of circle and the rotating shaft of described sensor disk are connected; On the edge that two pieces of MEMS linear acceleration chips are arranged on sensor disk respectively and the center of circle, the linear acceleration induction direction of two pieces of MEMS linear acceleration chips is parallel to each other, and vertical with the radial direction of sensor disk; When sensor disk rotates along with rotating shaft, the linear acceleration signals that two pieces of MEMS linear acceleration chips export is done difference, just obtains the circumference rotational line acceleration of sensor disk, then divided by the radius of sensor disk, just obtain final rotating angular acceleration.

2. the angular acceleration measurement mechanism based on MEMS linear accelerometer according to claim 1, it is characterized in that: also comprise signal conditioning circuit and V/I change-over circuit, signal conditioning circuit and V/I change-over circuit are all arranged on sensor disk, the output voltage signal of two pieces of MEMS linear acceleration chips accesses respective signal conditioning circuit respectively, carry out filtering to output voltage signal and output voltage amplitude adjusted to the acceptable scope of V/I change-over circuit, the output voltage signal after conditioning is converted into current signal through V/I change-over circuit and exports.

3. the angular acceleration measurement mechanism based on MEMS linear accelerometer according to claim 1, it is characterized in that: described sensor disk installs PCB, described MEMS linear acceleration chip, signal conditioning circuit and V/I change-over circuit are all integrated in PCB.