JPH067053B2 - Attitude sensor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a posture sensor used for detecting a tilt angle, a tilt azimuth angle or an angular velocity, an angular acceleration, etc. of a structure or a moving body.

Conventional technology For industrial robots, ships, civil engineering construction works, special vehicles, etc., there is a demand to always detect the omnidirectional tilt angle.In this case, if the maximum tilt angle and the azimuth angle are not detected at the same time, the detected value is automatically detected. In many cases, it cannot be used for control or other purposes.

Most of the conventional tilt angle measuring devices can display the tilt angle only in one axis direction, but there is an example described in Japanese Utility Model Publication No. 494374 as a device that can display the tilt angle in two axis directions.

In the same example, "a cross-shaped beam 1, which is fixed at both ends and intersects at right angles,
The weight arm 2 is attached to the center of 1 ', the weight 3 is attached to the tip of the weight arm 3 to form an upright or inverted pendulum, and the bending moment generated in the beam due to the inclination is detected by the strain gauge adhered to the beam and the orthogonal 2 Measuring axial tilt "
It is a thing.

Problems to be Solved by the Invention However, since both ends of the cross-shaped beams 1 and 1'are fixed, if there is a tilt, one of the cross-shaped beams 1 and 1'will always be twisted, and depending on the tilt direction, It produces a deformed twist rather than a symmetrical twist about the neutral axis.

If there is a deformed twist, there is a possibility that a resistance change will appear in the gauge, which affects the output of the bridge and thus the measurement accuracy of the tilt angle.

Therefore, when the tilt direction is the same as that of one beam, it is possible to measure the tilt angle with high accuracy, but it is difficult to measure with high accuracy in all directions.

Means and Actions for Solving Problems The present invention has been made in view of the above points, and an object of the present invention is to be able to accurately calculate the tilt angles of all directions of an object to be measured in real time and to obtain the angular velocity and the angular acceleration. The point is to provide a posture sensor that enables accurate calculations such as.

That is, the present invention, a support frame fixed to the object to be measured,
A base end member located in the center of the support frame and a base end member radially disposed on the support frame to support the base end member and fix one of the base end and the tip end and radiate the other end. A plurality of flexure plates rotatably supported about a direction, a biasing means for biasing the base end member to keep the base member always horizontal, and a strain detector attached to each of the flexure plates. An attitude sensor including an element.

When the object to be measured is tilted, a plurality of flexure plates respectively distort between a predetermined portion of the support frame that tilts integrally with the measured object and the base end member that is biased so as to always be kept horizontal by the biasing means. Occurs,
This strain can be detected by the strain sensing element.

Since one end of the strain plate is rotatably supported by either the support frame or the base member, no twist occurs,
Since it does not affect the measurement of the tilt angle, the tilt angle can be measured with high accuracy in all directions.

By analyzing the combination of strains detected by each sensing element, the tilt angle, azimuth angle, angular velocity, angular acceleration, etc. can be calculated in real time.

Embodiment An embodiment according to the present invention shown in FIGS. 1 to 5 will be described below.

FIG. 1 is a partially cutaway perspective view of the attitude sensor 1 according to the present embodiment.

Band-shaped spring plates 2 and 3 with large elastic restoring force on two strain plates
Are crossed in a cross shape, and a base plate 4 serving as a base member is fixed to the upper and lower surfaces of this crossing part, and a weight 6 is attached to the lower end of a vertical rod 5 vertically oriented downward from the center of the lower base plate 4. Is stuck.

Further, a vertical rod 7 is provided so as to project vertically upward from the center of the upper substrate 4, and a float 8 is fixed to the upper end of the vertical rod 7.

The base plate 4 need not be provided as long as the rigidity is maintained sufficiently by the overlapping of the spring plates 2 and 3, and the vertical bar may be directly fixed by using the intersecting portion as it is as the base end member.

Further, one strain plate formed in a cross shape from the beginning may be used, or four strain plates in four directions may be used.

Supporting rods 9 are provided at the tips of the spring plates 2 and 3 extending in all directions from the base plate 4 so as to project further in the centrifugal direction.

Strain gauges 10 are attached to the front and back surfaces of the spring plates 2 and 3 extending in all directions.

The spring plates 2 and 3 are located at the center of the inside of the annular support frame 20, and the tip ends of the spring plates 2 and 3 are inserted into the circular holes 21 formed at four locations on the side wall of the support frame 20 at equal intervals. The support rods 9 provided at the inner side of the support rod 9 penetrate from the inner side toward the outer side.

A stroke bearing 22 is built in each circular hole 21 to support the support rod 9 so as to be reciprocally rotatable.

The container 23 has a watertight effect by covering the above spring plates 2 and 3 and the stroke bearing 20 and the like in a watertight manner, and the inside of the container 23 is filled with silicone liquid.

Therefore, the spring plates 2 and 3 are supported by the four stroke bearings 22 of the support frame 20, and when the attitude sensor 1 is placed horizontally, the central substrate 4 is vertically gravitated by the weight 6 through the vertical rod 5. At the same time, the buoyancy is lifted vertically upward by the float 8 via the vertical rod 7, and the spring plates 2 and 3 are maintained horizontally at the height position in a flat state where no bending occurs.

Moreover, the movable part has a damper effect by the silicon liquid.

Spring plate 2 when this attitude sensor 1 is kept horizontal
The central axes of the support rods 9 of 3 are defined as x-axis and y-axis.

When the attitude sensor 1 is tilted by an angle β about the x axis (the support rod 9 of the spring plate 3 is swung about the x axis by an angle β), the state shown in FIG. 2 is obtained.

That is, although the support frame 20 is inclined, the central substrate 4 is urged by the weight 6 and the float 8 so as to be maintained horizontally.

Therefore, the substrate 4 is supported in a tilted posture in which the force balance between the biasing force of the weight 6 and the float 8 which tends to be horizontal and the restoring force due to the bending of the spring plate 3 is established (see FIG. 3).

The spring plate 2 is kept in parallel with the substrate 4 by the rotating action of the stroke bearings 22 at both ends and does not cause distortion, but the other spring plate 3 is bent at both ends thereof to be bent to cause bending distortion. .

Both ends of the spring plate 3 are displaced relative to the support frame 20 by the sliding action of the stroke bearing 22, so that no tensile force is generated in the spring plate 3 and there is no tensile strain.

Therefore, the strain gauge 10 attached to the spring plate 2 is unchanged, but the strain gauge 10 attached to the spring plate 3 detects the bending strain of the spring plate 3 and outputs a detection value according to the magnitude of the strain. .

The above is the case where the attitude sensor 1 is tilted about the x-axis, but when tilted about the y-axis, the spring plate 3 is unchanged and the spring plate 2 is bent.

Further, when the attitude sensor 1 is tilted about a horizontal axis other than the x-axis and the y-axis, bending strain occurs in both spring plates 2 and 3, and strain gauges attached to both spring plates 2 and 3 are generated.
10 detects this.

Also at this time, due to the action of the stroke bearing 22, the spring plates 2 and 3 are hardly twisted or stretched.

Each of the four strain gauges 10 attached to the spring plates 2 and 3 constitutes a bridge circuit and is capable of outputting a highly-accurate detected value with temperature compensation.

FIG. 3 shows a sectional view when the spring plate 3 is curved.

4 strain gauges attached to both sides of the spring plate 3
Bends along the spring plate 3 as shown in the figure, and the left spring plate 3
The resistance R ₃₁ of been strain gauges 10 affixed to the front and rear surfaces of the R _32, the resistance of the strain gauges 10 affixed on both surfaces of the right spring plates 3 and R _34, R _33, R ₃₁ and R
₃₂ , R _33, and R ₃₄ have different sign equal distortion, and these resistors are combined to form a bridge circuit as shown in FIG.

FIG. 4 is a block diagram of an electric system when the posture sensor 1 is used for an omnidirectional tilt angle meter. In FIG. 4, the broken line portion corresponds to the posture sensor 1, and the bridge circuit on the inner and lower sides thereof is the above-mentioned. It is formed by the strain gauge 10 attached to the spring plate 3, and the upper bridge circuit has resistances R ₂₁ of the four strain gauges 10 attached to the spring plate 2,
It is formed of R ₂₂ , R ₂₃ , and R _{24 in} a structure similar to that of the spring plate 3.

A voltage Ei is applied to the two bridge circuits by the power supply 30, and an output voltage E _α is output from the bridge circuit related to the spring plate 2 and an output voltage E _β is output from the bridge circuit related to the spring plate 3.

Both outputs of the attitude sensor 1 are amplified by amplifiers 31 and 32, respectively, and input to a calculator 33, and detected voltages E _α and E _β
Based on, the maximum tilt angle of the attitude sensor 1 and the azimuth angle forming the maximum tilt are calculated.

The calculation result is the maximum tilt angle display 34 and the azimuth angle display.
It is output to 35 and displayed.

The basis for calculating the maximum tilt angle θ and the azimuth angle ψ will be briefly described below.

First, in FIG. 3, when the central axes of the support rods 9 at both ends of the spring plate 3 form an angle β with the horizontal plane, the strain ε of the strain gauge portion of the spring plate 3 and the angle β have the following relationship. .

Here, A = Mrl, M is the weight of the weight 6, and the float 8
And r is the distance from the center of the cross of the spring plates 2 and 3 to the center of gravity of the weight 6 and the buoyancy of the float 8, and l
Is the length of the spring plates 2 and 3.

E is the longitudinal elastic modulus of the spring plates 2 and 3, and I is the moment of inertia of area.

Equation (1) uses strain gauge 10 from the end of spring plate 3
It is a relational expression when affixed to the length position of / 3.

The strain ε in equation (1) is proportional to the rate of change of resistance ΔR / R, and this ΔR / R is proportional to the output voltage E _β of the bridge circuit.

That is, ε = kE _β (k: proportional constant), and
By substituting E _β for E in the equation (1), the angle β can be calculated.

Similarly, regarding the spring plate 2, the angle α formed by the central axes of the support rods 9 at both ends with the horizontal plane is the output voltage E of the bridge circuit.
It will be calculated based on _α .

FIG. 5 shows the relationship between the maximum tilt angle θ and the azimuth angle ψ, where α and β are the angles formed by the central axes of the support rods 9 of the spring plates 2 and 3 with the horizontal plane.

The central axes of the support rods 9 at both ends of the spring plate 2 are straight lines a, and the central axes of the support rods 9 at both ends of the spring plate 3 are straight lines b.

The angles formed by the straight line a and the straight line b with the horizontal plane h are α and β.
Is.

When the plane s including the straight line a and the straight line b makes an angle with the horizontal plane h, that is, the maximum inclination angle θ, and a straight line passing through the center O and forming the maximum inclination angle θ is OM, the OM is positive to the horizontal plane h. The angle formed by the oblique line and the regular oblique line of the straight line a with respect to the horizontal plane h is the azimuth angle ψ.

That is, the azimuth angle ψ is the straight line α from the direction of the maximum inclination angle θ.
Shows an angle on the horizontal plane h.

The following relationships are established between α and β and θ and ψ.

cos θ = (1 + tan ² α + tan ² β) ^-1/2 … (2) cos ψ ＝ (1 + cot ² α × tan ² β) ^-1/2 … (3) Therefore, the maximum inclination angle θ is obtained from the angles α and β. And azimuth ψ
Can be calculated.

As described above, depending on the output voltages E _α and E _β of the bridge circuit,
The angles α and β can be calculated based on the equation (1), and the maximum tilt angle θ and the azimuth angle ψ can be obtained from the angles α and β based on the equations (2) and (3).

This calculation is performed by the calculator 33, and the result is the maximum tilt angle display 3
4, will be displayed by the azimuth indicator 35.

As described above, in the present embodiment, the maximum inclination angle θ and the azimuth angle ψ are instantly calculated and displayed based on the detected angles α and β regardless of the posture within 90 degrees. be able to.

Therefore, by mounting this instrument on various moving bodies, it can be used for various controls capable of detecting the omnidirectional tilt angle of the moving body in real time.

When the posture sensor is used for a certain automatic control, it is not always necessary to obtain α, β or θ, ψ from the detected voltages E _α , E _β , and the required control amount can be obtained directly from E _α , E _β. Of course it is good.

Since the basic structure is such that the strain gauge is attached to the cross-shaped strain plate, the amount of movement of each component is small, and the attitude sensor itself can be made compact, robust and cost-effective.

Since the ends of the strain-flexing plate are supported by stroke bearings, strain that is not intended, such as twisting and pulling on the strain-flexing plate, can be reduced regardless of the measurement direction, and the strain gauge resistance is configured in a bridge circuit. Therefore, it is possible to remove the disturbance such as temperature and accurately detect only the bending strain that should be originally measured, and the posture sensor has high accuracy.

Since the container is filled with the silicon liquid, the movable part of the sensor has a damper effect against the fluctuation, and the detected value can be stabilized early even when the sloped surface having the severe unevenness is moved.

In this embodiment, the end portions of the spring plates 2 and 3 are supported by stroke bearings so that they can slide simultaneously with the rotation so as to remove tensile strain, but they are simply supported by bearings that allow only rotation. The effect of tensile strain caused by this can be eliminated by configuring the resistance of the strain gauge 10 in a bridge circuit.

Further, even if the center of the spring plates 2 and 3 is slightly lowered by the weight 6 without using the float 8, the inclination angle can be detected.

Next, another embodiment will be described with reference to FIG.

The end portions are fixed at equal intervals on four sides of the annular support frame 40, and four spring plates 41, 42, 43, 44 extend toward the center, and the center of each spring plate is at the tip. A support rod 45 is projected toward.

A disk 46, which is a base end member, is located at the center of the support frame 40, and circular grooves are formed at four equal intervals on the outer peripheral surface thereof, and bearings 47 are built in the inside thereof. Four support rods 45 are rotatably inserted and supported.

A vertical bar 48 is vertically projected from the center of the lower surface of the disk 46, and a weight 49 is fixed to the tip thereof.

Strain gauges 50 are attached to the front and back surfaces of the spring plates 41, 42, 43 and 44, respectively, and the above members are all containers 51.
Is sealed by.

The strain gauges 50 attached to the respective spring plates 41, 42, 43, 44 constitute a bridge circuit similar to the above embodiment with four strain gauges 50 of the spring plates having symmetrical positions, and their outputs are It is amplified by an amplifier and operated by an arithmetic unit.

This embodiment is an attitude sensor having the above-mentioned configuration,
The central disk 46 is supported only by the spring force of the four spring plates, and is slightly lowered by the weight 49 even in the horizontal posture.

When the attitude sensor is tilted, the disc 46 acts by the weight 49 so as to maintain the horizontal state, thus causing the spring plate to be distorted.

The torsion strain is minimized by the action of the bearing 47, and the tensile strain is removed by the bridge circuit, so that only the originally intended bending strain is detected.

Even when the posture sensor is in the horizontal posture, the disc 46 is slightly dropped and the spring plate is bent. If such a state is set in advance as a reference, it is possible to accurately measure the inclination. The tilt angle and the like can be calculated.

Since the resistance of the strain gauge 50 is built into the bridge circuit, the effect of temperature can be ignored, and stable and highly accurate detection output can be obtained, and the configuration is extremely simple and the moving amount of each part is small, so it is small and lightweight. The cost can be reduced as well.

Further, it is also possible to fill the container 51 with a silicone liquid in the same manner as in the above embodiment so as to have a more damper effect, and at that time, the disk
A float may be provided on the upper surface of 46 to increase the vertical biasing force.

Although a strain gauge is used as the strain sensing element in the above embodiments, a flexible piezoelectric film or the like can be used.

The spring plate is not limited to the cross shape but may be a plurality of spring plates arranged radially. In that case, the strain sensing element may be appropriately attached and the tilt angle or the like can be calculated based on the detected value.

EFFECTS OF THE INVENTION According to the present invention, a strain sensing element is attached to a strain-flexing plate that is radially arranged and has one end fixed and the other end rotatably supported, and a central base end member supported by the strain-flexing plate is horizontal. It is possible to obtain a highly accurate and stable detection output in all directions with a simple configuration biased to.

Therefore, it is possible to achieve size reduction, weight reduction, and robustness as well as low cost.

The highly accurate detection output can be used to calculate the maximum tilt angle, azimuth angle, and other angular velocities and angular accelerations, and the display accuracy can be maintained high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view of a posture sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view of essential parts when the posture sensor is tilted in one direction. FIG. 3 is a diagram modeling a bent state of a spring plate, FIG. 4 is an electric system block diagram of the same embodiment, and FIG. The drawing is a partially cutaway perspective view of the attitude sensor of another embodiment. 1 ... Attitude sensor, 2, 3 ... Spring plate, 4 ... Substrate, 5 ... Vertical bar, 6 ... Weight, 7 ... Vertical bar, 8 ... Float, 9 ... Support bar, 10
… Strain gauge, 20… Support frame, 21… Circular hole, 22… Stroke bearing,
23 ... Container, 30 ... Power supply, 31, 32 ... Amplifier, 33 ... Computing unit, 34 ... Maximum tilt angle display, 35 ... Azimuth angle display 40 ... Support frame, 41, 42, 43, 44 ... Spring plate, 45 ... support rod,
46 ... Disc, 47 ... Bearing, 48 ... Vertical bar, 49 ... Weight, 50
… Strain gauge, 51… Container.

Claims (1)

[Claims] 1. A support frame body fixed to an object to be measured, a base end member located at the center of the support frame body, and a base end member radially arranged from the base end member to the support frame body. A plurality of strain-flexing plates that support one end of the base member and one end of the base member is fixed, and the other end is rotatably supported about the radial direction. An attitude sensor, comprising: a biasing means; and a strain sensing element attached to each of the plurality of flexure plates.