JPH02297067A - Angular velocity sensor for detecting attitude of vehicle - Google Patents

Abstract

PURPOSE:To detect only the angular velocity without causing a malfunction by placing this sensor so that a bimorph structure of a detecting element becomes vertical to the road surface on which a vehicle runs. CONSTITUTION:A first and a second angular velocity sensors 11, 12 are placed in a vehicle so that a bimorph structure of detecting elements 11a, 11b, 12a and 12b becomes vertical to an X - Y plane being the running direction surface of a vehicle. These first and second angular velocity sensors 11, 12 can detect an angular velocity in the roll direction and in the pitch direction. In this state, for instance, when a translational motion of a Z axis is applied to the elements 11a, 11b, displacement shown by a broken line is generated, but to the element 11a, 11b, the displacement is applied in the direction in which a reverse piezoelectric phenomenon is not generated, therefore, no charge is generated on the surface of the elements 11a, 11b. In such a way, by placing the sensor 11 in the vehicle, a malfunction can be reduced against vibration generated in the Z axis direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an angular velocity sensor for detecting vehicle attitude that detects the angular velocity generated in a vehicle.

BACKGROUND OF THE INVENTION In recent years, advances in semiconductors have led to the development of LSIs and microcomputers with complex arithmetic processing functions, and these have been used to realize control devices with detailed control functions. The reliability of these control devices has also improved, and technology has been realized that guarantees normal operation even in extremely harsh environments such as those installed in vehicles. Against this background, it is being utilized particularly for vehicle control that requires fine-grained control. Particularly recently, there has been active development of attitude control devices aimed at improving ride comfort and handling of vehicles. Conventionally, this type of device operates an actuator based on information from sensors installed in the vehicle to ensure ride comfort and maneuverability in response to vehicle disturbances that occur while the vehicle is being operated. . As a sensor for detecting these vehicle disturbances, there is an angular velocity sensor that detects angular velocity. This angular velocity sensor will be explained based on FIGS. 3 to 5.

The angular velocity sensor has a structure as shown in Fig. 3, and consists of a driving element mainly consisting of four piezoelectric bimorphs, and a first monitoring element.
and a second sensing element, and includes a driving element 101 and a first sensing element.
A connecting plate 107 connects a first vibration unit 109 in which a detection element 103 is orthogonally joined at a joint 105, and a second vibration unit 110 in which a monitor element 102 and a second detection element 104 are orthogonally joined at a joint 106. , and this connecting plate 107 is supported at one point by a support rod 108 to form a tuning fork structure.

When a sinusoidal voltage signal is applied to the drive element 101, the first vibration unit 109 starts vibrating due to the inverse piezoelectric effect, and the second vibration unit 110 also starts vibrating due to the tuning fork vibration.

Therefore, the charge generated on the surface of the monitor element 102 due to the piezoelectric effect is proportional to the sinusoidal voltage signal applied to the drive element 101. The charge generated in the monitor element 102 is detected, and the drive element 1 is arranged so that the charge has a constant amplitude.
By controlling the sinusoidal voltage signal applied to 01, stable tuning fork vibration can be obtained.

The mechanism by which this sensor generates an output proportional to the angular velocity will be explained using FIG. 4 and FIG.

FIG. 4 shows the angular velocity sensor shown in FIG. 3 viewed from above. When rotation at an angular velocity ω is applied to the sensing element 103, which is vibrating at a speed υ, the r Coriolis force is applied to the sensing element 103.
occurs. This "Coriolis force" is perpendicular to the speed υ and has a magnitude of 2mυω.

Since the sensing element 103 is vibrating like a tuning fork, if the sensing element 103 is vibrating at a speed υ at a certain point, the sensing element 104 is vibrating at a speed -〇, which is the "Coriolis force".
is −2mυω. Therefore, the sensing elements 103 and 104 are deformed toward each other in the direction of the "Coriolis force" as shown in FIG. 5, and charges are generated on the surfaces of the elements due to the piezoelectric effect. Here, υ is the motion caused by tuning fork vibration, and the tuning fork vibration is v=a-sin ωOt a: amplitude of tuning fork vibration ω
0: If it is the period of tuning fork vibration, the "Coriolis force" is Fc = a "ω' s jn ct) Ot, which is proportional to the angular velocity ω and the tuning fork amplitude a, and the detection element 103,
This becomes a force that deforms 104 in the plane direction. Therefore, the surface charge Q of the sensing elements 103 and 104 is Qoca11ω@Sin ωat, and if the tuning fork amplitude a is controlled to be constant, Q oc a 11 S i n ωo t, and the surface charge generated on the sensing elements 103 and 104. The quantity Q is obtained as an output proportional to the angular velocity ω, and this signal is called ωot
If synchronous detection is performed with , a DC signal proportional to the angular velocity ω can be obtained.

The angular velocity sensor described above can be used as a sensor for detecting the attitude of a vehicle, and is used in a system that drives an actuator that controls the attitude of the vehicle based on information from the sensor to improve ride comfort and steering performance.

Problems to be Solved by the Invention However, malfunction of sensors becomes an important problem for the reliability of the system in severe imaging conditions during operation such as in a vehicle. In particular, when capturing images in the height direction of a vehicle, the angular velocity sensor is arranged so that the detection axis is parallel to the road surface on which the vehicle is running, the tuning fork structure explained in Figures 3 to 5 is used. The imaging type angular velocity sensor also has a problem in that the sensor malfunctions due to translational motion other than angular velocity displacement. The mechanism of malfunction in this translational movement will be explained with reference to FIG. Considering that an angular velocity sensor having a detection axis on the Y-axis undergoes a translational movement in the Z-axis direction in the figure, the detection elements 103 and 104 of the angular velocity sensor
Since the bimorph structure is perpendicular to the Z axis, a displacement as shown by the broken line in the figure occurs. In the conventional example, when the sensing elements 103 and 104 are displaced, the sensing elements 103
．． An electric charge will be generated on the surface of 104. In order to cancel this behavior, the A side of the first sensing element 103 and the B side of the second sensing element 104 are connected as shown in FIG. 7, which is a view seen from the direction of the arrow in FIG. Similarly, the 8 surfaces of the first sensing element 103 and the A side of the second sensing element 104 are connected to have the same potential, which is used as the sensor output of the angular velocity sensor. The charges detected by the second detection elements 103 and 104 are canceled out. However, there are subtle differences between the first and second sensing elements 103 and 104, such as differences in size and orthogonality of the vibration units 109 and 110, which completely cancels malfunctions caused by translational motion. I couldn't do anything.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a tuning fork structure vibrating angular velocity sensor having an angular velocity detection axis parallel to the road surface on which the vehicle travels, and the bimorph structure of the sensing element is adapted to the vehicle. An angular velocity sensor is placed on the vehicle so that it is perpendicular to the road surface on which the vehicle is traveling, so that the attitude of the vehicle can be detected.

If the above-described configuration is adopted, the bimorph structure of the sensing element is perpendicular to the road surface on which the vehicle travels, so the angular velocity sensor is not affected by the translational motion of the vehicle's vibration in the vehicle height direction. It is possible to detect the attitude of the vehicle by detecting the position of the vehicle.

Embodiment Hereinafter, an embodiment of a vehicle attitude detection angular velocity sensor according to the present invention will be described based on the drawings.

Figure 1 shows two vehicle attitude detection angular velocity sensors 11 and 12.
This is an embodiment in which a first angular velocity sensor 11 has a detection axis on the X-axis, which is the traveling direction of the vehicle, and detects roll angular velocity, and a detection axis is on the Y-axis, which is the width direction of the vehicle. Two second angular velocity sensors 12 that detect pitch angular velocity are arranged in the vehicle. The first and second angular velocity sensors 11 and 12 include detection elements 11a and llb.

The bimorph structures 12a and 12b are arranged on the vehicle so as to be perpendicular to the X-Y plane, which is the plane in the running direction of the vehicle. The first and second angular velocity sensors can detect angular velocity in the roll direction and pitch direction, which is important displacement information for controlling the attitude of the vehicle.

FIG. 2 is an enlarged view of the first angular velocity sensor 11 shown in FIG. 1, and the translational movement along the Z axis in the figure, which is the largest vibration generated during vehicle operation, is detected by the sensing element 11a.

11b, the displacement shown by the broken line in the figure occurs, but since the displacement is applied to the sensing elements 11a and Ilb in a direction in which no inverse piezoelectric phenomenon occurs, no charge is generated on the surfaces of the sensing elements 11a and Ilb. . In this way, the angular velocity sensor 11
By disposing the sensor in a vehicle, it is possible to provide a sensor that is less likely to malfunction due to vibrations generated in the vehicle height direction (Z-axis direction).

As described in detail, the present invention provides an angular velocity sensor mounted on a vehicle such that the angular velocity detection axis is parallel to the road surface on which the vehicle travels, and the bimorph structure of the sensing element is perpendicular to the road surface on which the vehicle travels. This arrangement eliminates malfunctions due to vibrations in the height direction of the vehicle, making it possible to provide a highly reliable vehicle attitude detection angular velocity sensor.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the vehicle attitude detection angular velocity sensor according to the present invention, showing how it is mounted on a vehicle, FIG. 2 is an explanatory diagram of the operation of the first angular velocity sensor in FIG. 1, and FIG. 3 1 is a perspective view of a tuning fork structure vibration type angular velocity sensor, FIGS. 4 and 5 are operation explanatory diagrams, and FIGS. 6 and 7 are operation explanatory diagrams showing an arrangement example of a conventional angular velocity sensor. 11...First angular velocity sensor, 12...
・Second angular velocity sensor, 11a, 1 lb, 12a, 1
2b...detection element, 101...drive element, 102...monitor element, 103...
...First sensing element, 104... Second sensing element, 105, 106... Joint part, 107...
...Connecting plate, 109...First vibration unit, 110...Second vibration unit. Name of agent: Patent attorney Shigetaka Awano et al.

Claims (1)

[Claims] A first vibration unit in which a driving piezoelectric bimorph element and a first sensing bimorph element are orthogonally connected to each other, and a monitoring piezoelectric bimorph element and a second sensing bimorph element are orthogonally connected to each other. the driving piezoelectric bimorph element and the monitoring piezoelectric bimorph element are connected to each other at their free ends such that the first and second vibration units are parallel to each other along the detection axis; The angular velocity sensor has a tuning fork structure connected by a plate, the angular velocity detection axis is parallel to the road surface on which the vehicle is running, and the bimorph structure of the first and second detection bimorph elements is parallel to the road surface on which the vehicle is running. An angular velocity sensor for detecting vehicle attitude, wherein the angular velocity sensor is arranged vertically on the vehicle.