JPS60147654A - Attitude sensor - Google Patents

Abstract

PURPOSE:To measure an angular velocity and an angular acceleration by setting a pair of valve constituting bodies in symmetrical positions of a fluid flow passage in a ring-shaped vessel where a liquid is sealed and detecting change in the ring-shaped vessel, which is caused in accordance with flow of the liquid, as the variance of the electrostatic capacity. CONSTITUTION:Single-hinged plane valves 4 forming valve constituting bodies 3 are supported by springs 6 and 5 and are provided in the liquid flow passage in a ring-shaped vessel 2, where the liquid is sealed, in this state, and masses provided in free ends of plane valves 4 consist of insulated conductive materials. These masses are allowed to face electrodes 8 and 8 provided on the inner face of the outside wall of the ring-shaped vessel 2. Valve constituting bodies 3 are displaced by the liquid pressure which is generated by flow of the liquid due to angular speed and angular acceleration components of space motion of the system of the ring-shaped vessel and the liquid, and this displacement is measured as variance of the electrostatic capacity according to change of areas where plane valves 4 and electrodes 8 and 8 face each other.

Description

[Detailed Description of the Invention] The present invention has a low payload capacity, such as a robot arm, etc.
The present invention relates to a small-sized attitude sensor suitable for mounting on a movable work device that turns violently.

In particular, the present invention relates to a posture sensor for detecting a tilt angle, angular velocity, and angular acceleration of a subject.

Mobile machines often require some kind of attitude recognition device, and rate gyros are used in airplanes and ships, and gas rate gyros are used in recent automobiles to automatically detect orientation. Posture detectors are also effective for work robots, mobile work robots, bipedal walking robots, etc. For work robots, there is a method of placing a visual device in a system separate from the movable arm and capturing the arm posture as an image. The camera as a device has considerable weight, so
It is difficult to easily and accurately recognize the posture of the arm by directly attaching it to the tip of the arm or each joint of the arm. Furthermore, a mobile work robot can be equipped with a visual device and, if necessary, a gyro. However, most of the information from the visual device is used for recognizing the moving environment and selecting the workpiece, which is inconvenient for controlling the hand. Also, the gyro is too heavy to wear on the working arm.

On the other hand, since bipedal walking robots are unstable systems, posture control is essential, but at present, only tilt sensors are used based on the swing of the pendulum from the vertical axis, and velocity and angular velocity are not detected. However, as control technology advances in the future, it is thought that there will be a need to detect angular velocity and angular acceleration using small and lightweight sensors.

In view of the current situation, the present invention aims to provide an attitude sensor that is sufficiently smaller and lighter than gyros, visual cameras, etc., and that can be miniaturized to the point of being microscopic in principle. Focusing on the fact that the liquid flow rate inside the container depends on the angular velocity applied from the outside, the annular container-liquid system enables the detection of angle, angular velocity, and angular acceleration.

That is, in the attitude sensor of the present invention, a liquid is sealed in an annular container, a pair of valve structures having a mass and a spring component are installed at symmetrical positions in a liquid flow path in the container, and these valve structures and the container, a pair of electrodes are installed opposite each other to detect changes in the facing area or distance as a change in capacitance due to displacement of the valve structure caused by the flow of liquid in the container. This is a characteristic feature.

Hereinafter, before describing embodiments of the present invention, it will first be explained that the liquid flow rate within the annular container depends on the angular velocity applied from the outside.

Figure 1(a) shows the robot coordinate system, and Figure 1(b) shows the robot coordinate system.
This figure shows the coordinate system of an annular container-liquid system attitude sensor 1 attached to the tip of the robot's arm.

Now, the stationary coordinates 0-XYZ (
Ko) system, the arm r of the robot is set at an angle φ0. θ8
．． Rotated by ψ8, local coordinates 0' at the tip position 0'
It is assumed that the sensor system 0'-ζr ζφ ζ2 (Kζ) system shown in FIG. 1(b) is attached to the -ξr ξθ ξ medium (Ka) system. Also, the liquid in the annular container of sensor 1 is rb
The transformation matrices from the Ko system to the self system and from the ice system to the ζ system are respectively denoted as A and B. In this case, since the sensor system is fixed at the 0' position, φ
b, θb, and ψb are constant, and ωb=0.

For simplicity, it is assumed that liquid flow occurs only in the φb force direction, and υb=(0, v., 0)1. Furthermore, in the flow in this case, the pressure gradient in the φb force direction and the velocity gradient are zero.

When expressed as Ωb = Ω8 + ωb, Ω, = Bωa, the equation of motion of the liquid written in the Kc system is %Formula, where ν is the kinematic viscosity coefficient, S (r, z, t) is the external force, and this The external force S (r, z, t) is expressed as S (r, z, t) = a, + (M, X R, +
11bx rb) + 2 (Ω, xva + Ωb x υb) + (Ωa x (ΩaxRa) + Ωb x (Ωbxrb)) skewer (3).

FIG. 2(a) shows the model used in the calculation. As shown in the figure, the origin 0' of the Kζ system is K. The container is rotated around the Z-axis at an angular velocity ω2 shown in Fig. 2(b), with the origin O of the system aligned.
When rotating at It can be seen that it is proportional to the given angular velocity ω2.

FIG. 3 shows that the average flow velocity of the liquid in the annular container 0° in response to the step-like angular velocity input in FIG. 2(b) has a characteristic that depends on the kinematic viscosity coefficient ν.
When V is small, the flow velocity V can follow the angular velocity; for example, when v=0.001 (corresponding to mercury), it is found that the accuracy is 95%.

Next, angular momentum will be considered using a posture sensor model as shown in FIGS. 4(a) and 4(b). Figure 4(a)
is the radius of the center line of the flow channel cross section, and the radius of the flow channel cross section is b.
Fig. 2(b) shows a state in which the sensor 1 is arranged so as to coincide with the origin 0' of the sensor 1; One end of the planar valve 4 is shown attached by a hinge 5 on which a spring element k was previously installed.

In this way, when the valve structure 3 is arranged in the annular container 2 so as to obstruct the liquid flow by 11 degrees, and when the inspection surface surrounded by the dotted line is S and its volume is V, the angular momentum is The equation is given by. Here, ρ is the density of the liquid, rb is the position of the liquid, e is the stress acting along the inspection surface, F is the force pushing the liquid at the center of the valve, and S is the external force given by equation (3). In the above equation (5), when the first term on the right side is estimated as the laminar flow pipe friction of a smooth circular pipe, the following approximate equation is derived for the simple example shown in FIG. 2(a).

Lips+ccj++kcφ=-ω2** (6) However, Co=8 ν/b2. ko= )C/ρvb2.

Equation (8) is the vibration equation for the angle φ, and the second left side
Depending on how the constants of the third term and the third term are given, detection areas for angle, angular velocity, and angular acceleration exist. Examining it very simply, in the limit where ko → small, the formula (8) % formula % (7) is obtained, and the liquid displacement φ directly measures the angular velocity, and exponentially settles into an equilibrium state over time. . Also, when k0→large, Cc↓+kcφ key ω2 fist・(8), and the angular displacement φ directly measures the angular acceleration.

Next, an embodiment of the posture sensor of the present invention that detects the posture according to the above-mentioned method will be described.

The attitude sensor according to the present invention is shown in FIGS. 4(a) and (b) above.
As is clear from the model shown in 1, when an appropriate liquid such as water, insulating oil, mercury, etc. is sealed in a smoothly closed annular container 2, and the annular container-liquid system moves in space, the Fluid pressure fluctuations accompanying liquid flow caused by angular velocity or angular acceleration components in motion are measured as displacement of the valve structure 3. The valve structure 3 is constituted by a planar valve or a flexible thin film having a mass and a spring component, and is arranged so as to substantially obstruct the flow of liquid in the flow path within the annular container 2.

5(a) to (C) show an embodiment of the attitude sensor of the present invention, in which a surface of one side hinge constituting the valve structure 3 is placed in a liquid flow path in an annular container 2 filled with liquid. Spring 8. The mass 7 provided at the free end of the planar valve 4 is made of an insulated conductive material to function as an electrode, and this is provided on the inner surface of the outer wall of the annular container 2. By arranging the electrodes 8, 8 to face each other, when the opposing area of both electrodes changes due to displacement of the valve structure body 3, this can be detected as a change in capacitance. The electrode 8.8 on the inner surface of the outer wall of the annular container 2 is formed into a semi-cylindrical shape (or semi-circular shape) centered on the hinge axis 9 of the planar valve 4, and the mass 7 of the valve structure 3 is It has a plate shape curved to match the curvature of the outer wall, and the electrodes 8, 8 are formed in a pair of oppositely directed wedge shapes.In addition, if the liquid sealed in the annular container is not dielectric, , each electrode must be insulated.

The valve structure 3 in such a posture sensor is displaced by the liquid positive caused by the flow of the internal liquid caused by the angular velocity or angular acceleration component in the spatial motion of the annular container-liquid system, and therefore, the valve structure 3 is displaced by the liquid force generated by the flow of the internal liquid caused by the angular velocity or angular acceleration component in the spatial motion of the annular container-liquid system. By measuring the capacitance change according to the change in the facing area of the electrodes provided on the inner wall of the container, it is possible to detect the posture based on angular velocity or angular acceleration, etc. In particular, the wedge-shaped electrode 8.8 and the mass 7 provided on the planar valve 4 that also serves as an electrode.As the valve structure 3 tilts, the area facing the electrode increases on one side and decreases on the other, so that the capacitance of both of them changes. By taking out the angular velocity or angular acceleration, the magnitude and direction of the angular velocity or angular acceleration can be measured.

Moreover, when the mass of the valve structure 3 increases as described above,
Inertia can no longer be ignored, and the sensor responds not only to rotational motion but also to translational motion. The valve structure 3 and the pair of electrodes incorporated in pairs in symmetrical positions in the annular container 10 in FIGS. 4(a) and 5(a) are intended to compensate for this. That is, in those attitude sensors, since the same valve structures 3 are provided at symmetrical positions in the flow path of the annular container, the influence of the translational movement is eliminated from the difference in the tilting of both valve structures, and the rotational movement is calculated. The angular velocity and angular acceleration can be measured. Furthermore, it is not known where and how the above-mentioned attitude sensor should be attached to the robot, etc., and therefore initial deflection due to gravity occurs in the spring, but in this regard - two pairs of electrodes should be provided in the same way as above. Compensation can be made by

In the embodiment shown in FIGS. 6(a) and 6(b), a pair of arc-shaped inner peripheral walls 12.1 are arranged opposite to an outer peripheral wall 11 of the container which is shaped like a disc.
2 to form an annular container with an annular flow path 13 between them, and masses 1B and lft are attached to both ends of a planar valve 15 formed by a rigid plate,
The center position of the planar valve 15 is rotatably supported at the center of the container by a pivot 17, and a spring 18 is interposed between both sides of the planar valve 15 and the inner peripheral wall 12.12 of the container, This forms a pair of valve structures 14 that are assembled in pairs at symmetrical positions in the liquid flow path within the annular container.

Therefore, the mass 16.18 of the above planar valve 15 of several orders of magnitude is:
They are formed of an insulated conductive material to function as electrodes, and are opposed to a wedge-shaped electrode 19 provided on the inner surface of the outer peripheral wall 11 of the annular container. The pair of wedge-shaped electrodes 19.1 are arranged at symmetrical positions in the annular container.
9, when the planar valve 15 rotates in either direction around the pivot 17, the area facing the electrode provided on the planar valve 15 increases at one electrode 18, and the area facing the electrode 13 at the other electrode 13 increases.
It is wedge-shaped in the opposite direction so that it decreases at .

With this configuration, when the facing area of both electrodes changes due to displacement of the valve structure 14, the magnitude and direction of the displacement, that is, the angular velocity or angular acceleration, can be detected as a change in capacitance. Furthermore, when the force associated with the liquid flow does not act on the valve structure 14, the reaction force of the spring 18 causes the valve structure 14 to return to its initial position.

FIGS. 7(a) and 7(b) show different configuration examples of the valve structure disposed within the annular container, in which the liquid flow path 2 of the annular container 2 is
A pair of diaphragms 22 arranged to block 0,
22 are integrally connected by insulators 23, 24 and movable electrodes 25, 25 to form the valve structure 21. This valve structure 21 comprises an insulator 23.2'4 and an electrode 25.2'4.
25 has mass, and diaphragms 22, 22 also have a function as a spring. With such a configuration, the fluid on the outside of both diaphragms 22, 22 and the fluid between the two diaphragms can be made into different fluids suitable for their respective functions. For example, the fluid on the outside may be a fluid with a low viscosity. Water or mercury can be used, and air, rare gas, insulating oil, or other dielectric material can be filled between the two diaphragms.

The movable electrode 25.25 attached between the pair of diaphragms 22.22 via an insulator is wedge-shaped and faces in opposite directions, and this movable electrode 25 is shown in FIG. 7(b). It is constructed by stacking several electrode plates 25a at intervals so that they can be connected to each other, while the annular container 2
A fixed electrode 26 is provided between the electrode plates 25a of the movable electrode with several electrode plates 28a protruding parallel to the electrode plates 25a, and each electrode is covered with an insulating □ film to make them non-contact, thereby preventing the fluctuation of the diaphragm. is configured so that it can be detected as a change in capacitance between the electrodes 25 and 26.

The embodiment shown in FIG. 8 is similar to the embodiment shown in FIG.
Two diaphragms 32, 32 are provided in the liquid flow path 30 in the annular container 2, and the diaphragms 32, 32 are directly connected via an insulating rod 33, and the annular container 2 is located in the center between the diaphragms 32, 32. and the above insulating rod 3
A fixed electrode 34 having a hole 35 into which No. 3 is loosely fitted is attached. Further, movable electrodes 36.3 are provided on the insulating rod 33 at positions parallel to the fixed electrode 34 and equidistant from both sides thereof.
8 is installed.

Therefore, when the gap between the electrodes on both sides of the fixed electrode 34 changes due to the displacement of the diaphragms 32, 32, this can be detected as a change in capacitance. Incidentally, damping, dielectric constant, etc. can be improved by sealing insulating oil or the like between the diaphragms 32, 32.

The liquid flow path in the annular container in the above-mentioned attitude sensor does not need to have a uniform flow path cross-sectional area, and as shown in FIG. 4
2, and the flow part 43 between the pair of ampullae parts 42 and 42.
．． 43 can be formed, for example, by a capillary tube with a cross-sectional area of the order of 1000 in the ampullae, thereby making it possible to significantly reduce the size of the entire sensor.

Furthermore, the above-described valve structure 41 and the electrodes attached thereto are arranged not only at a pair of symmetrical positions within the annular container 40 but also at two symmetrical positions within the annular container 40, as illustrated in FIG. 1θ. It is also possible to set

In addition, in order to detect the three-dimensional posture, as shown in FIG. Each annular container 51, 52, 53 may be provided with a pair of valve structures and an electrode for detecting the displacement thereof.

As is clear from the detailed description above, according to the first invention, it is possible to obtain a simple and compact posture sensor suitable for being attached to a robot arm or the like.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are explanatory diagrams of a robot coordinate system and a sensor coordinate system for explaining the basic principle of the present invention,
Figures 2 (a) and (b) are the configuration diagram of the sensor model used in the calculations and the waveform diagram of the step-like angular velocity input, and Figure 3 shows the calculation results for the average flow velocity of the liquid in response to the step-like angular velocity input. 4(a) and 4(b) are configuration diagrams and partially enlarged configuration diagrams of a posture sensor model for calculation, and FIGS. 5(a) to (c) are part of an embodiment of the present invention. Broken front view, main part side sectional view, developed view of the inner surface of the outer wall, Figure 6 (
a) (b) is a sectional view and a developed view of the inner surface of the outer peripheral wall of another embodiment of the present invention, FIGS. 7(a), (b) and 8 are sectional views showing different configuration examples of the valve structure, 9 and 10 are plan views of still another embodiment of the present invention, and FIG. 11 is a perspective view thereof. Designated Agent: Agency of Industrial Science and Technology, Director, Product Science Research Institute, Tsutomu Tsukasa Figure 35-2 1θ (・) Figure 7 <b> Figure 8

Claims (1)

[Claims] 1. A liquid is sealed in an annular container, a pair of valve structures having a mass and a spring component are installed at symmetrical positions in the liquid flow path in the container, and between these valve structures and the container,
A position characterized by having a pair of electrodes arranged opposite each other to detect changes in the facing area or facing distance as a change in capacitance due to displacement of the valve structure caused by the flow of liquid in the container. sensor.