JPH0560269B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] This invention relates to an intelligent robot, a manipulator of an automatic assembly machine, a mobile robot, etc., which is attached to the sole of the foot of a mobile robot, and is used to detect touch, force, and sliding sensations in humans. The present invention relates to a pressure sensor that outputs high-level sensory information corresponding to the feedback signal to a control system, and particularly provides a pressure sensor array in which a large number of pressure-sensitive modules are arranged in an array.

[Prior art and its problems] There are force sensors as shown in FIGS. 1 and 2 that can detect applied force by decomposing it into component forces in three directions in a rectangular coordinate system. These sensors consist of an elastic support 1 such as an elastic ring body or a cross-shaped leaf spring, and a plurality of strain gauges 3 attached in each direction to the support.
These strain gauges are attached to the part corresponding to the wrist and detect the magnitude and direction of the force applied to the wrist first, and provide precise information such as the distribution of the applied force. It's not a thing.

On the other hand, pressure sensors that detect the distribution of applied force include those shown in Figures 3 and 4 A and B that use conductive rubber, and those that use a large number of thin rods as shown in Figure 5. There are some that use First, the sensor shown in Fig. 3 has a thickness of approximately 1 mm between the electrode foils 9 and 11 on the front and rear surfaces to which the lead wire 7 is connected.
The carbon fiber felt 13 is sandwiched to form a sandwich shape, and the contact area between the carbon fiber felt changes by applying force.
The fact that this causes a change in resistance value is utilized. The sensor shown in FIG. 4A uses a conductive silicone rubber cord 15 and a metal electrode 17, and also takes advantage of the fact that the contact area of the rubber cord changes due to pressurizing force, and the resistance value changes. There is. The sensor shown in FIG. 4B has silicone rubber cords 15 and metal electrodes 17 arranged in a grid pattern,
Detection is done by applying the scanning method used in ITV (industrial television) and other devices. Furthermore, the sensor shown in FIG. 5 detects the vertical movement of the tips of a large number of thin rods 19, which are vertically slidable and attached to the same surface, in response to the shape of the object to be tested. The shape of a three-dimensional part (three-dimensional part) is recognized by detecting it using a moving coil or a Hall element.

However, each of these sensors that detect force distribution detects a two-dimensional distribution of force magnitude perpendicular to the pressure-receiving surface, and does not provide information about other directions. However, the skin on the human palms and soles of the feet can precisely detect the distribution of force in non-vertical directions. Therefore, with conventional sensors, robot hands have a precise pressure sensing function as close as possible to the pressure sensing function of human palms and soles of the feet, and soft handling grips of human-level objects are difficult to achieve. It cannot be realized.

[Object of the Invention] In view of the above-mentioned problems, the present invention is capable of independently detecting not only the component force perpendicular to the pressure-receiving surface but also the two-dimensional distribution of the magnitude of the component force in two directions perpendicular to the pressure-receiving surface. The present invention aims to provide a pressure sensor array.

[Summary of the Invention] This invention converts the force applied to the pressure-receiving surface into three component forces: a component force F _z in the direction perpendicular to the pressure-receiving surface, and component forces F _x and F _y in two directions within the pressure-receiving surface. A pressure sensor array is formed by arranging pressure-sensitive modules that can be separated and detected in a high-density area array on a substrate, and detects two of the three component forces.
This allows for precise measurement of dimensional distribution.

[Embodiments of the Invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 6 shows an embodiment of the invention. Here, 2
Reference numeral 1 designates a pressure-sensitive module as a pressure-receiving fine module constituting a pressure-sensor array, which includes an upper pressure-receiving plate 23 that receives applied force, and one or more (usually two) fixed under the pressure-receiving plate. or 3
The pressure-sensitive cells 25 are made up of 1) pressure-sensitive cells 25. This pressure sensitive cell 25
In this method, a ring-shaped pressure-sensitive structure is made of, for example, single crystal silicon, and a plurality of diffusion strain gauges 27 are formed on a surface perpendicular to the pressure-receiving surface of this pressure-sensitive structure (i.e., the surface in contact with the pressure-receiving plate 23). , the three force components F _z , F _x and F _y applied to the pressure receiving surface are detected by changes in the resistance values of these strain gauges.

A plurality of the pressure sensitive modules 21 described above are arranged in a plane array (matrix shape) on a common substrate 29 at the bottom.
They are individually attached in high-density rows to form a pressure sensor array. At this time, it is more preferable to vertically fit and fix the lower end of the pressure-sensitive cell 25 into the parallel groove 31 on the substrate 29 or into the mounting hole provided for each cell, as shown in the figure. Note that a flexible and relatively thin protective film having functions such as dustproofing and waterproofing may be attached to the entire upper part of the pressure receiving plate 23, and this thin film and the pressure sensitive cell 25 may be directly fixed. Further, the substrate 29 on which the power supply line and signal line to the pressure-sensitive cell 25 are wired may be a somewhat flexible material that can be attached to a curved surface, and the entire pressure-sensor array may be placed inside an elastic material such as rubber. may be interposed.

In this way, a large number of pressure-sensitive modules 21 that independently detect the three components of the force applied to the pressure-receiving surface are arranged in a plane array to form a pressure-sensor array, so that the force applied to the pressure-receiving plate 23 can be basically detected. It is possible to decompose the force into components in three directions in a rectangular coordinate system, and detect the two-dimensional distribution of the forces in the three directions independently.

The three-component force pressure signal from the pressure-sensitive module 21 described above is sequentially scanned and amplified by the scanner amplifier integrated circuit 33 mounted on the board 29, and then sent to a microcomputer (not shown) at the subsequent stage.
It facilitates processing by the CPU (central processing unit). The output signal from the scanner amplifier integrated circuit 33 is an A/D (analog-digital) signal (not shown).
It is taken into the above-mentioned CPU via the converter, and the component force in three directions, the resultant force, the moment in three directions, etc. at each point are calculated using a basic calculation algorithm, and the calculation results are stored in a memory file (not shown).

Based on the temporal changes in the pressure distribution on the pressure receiving surface read from the memory file, slippage due to insufficient gripping force is calculated, and the holding force control calculation algorithm enables soft handling without slipping. In addition, it becomes possible to perform supervisory control and autonomous local control by a host computer at high speed, high response, and high precision using basic operation calculation algorithms such as grasping, lifting, insertion, and rotation. Furthermore, by appropriately selecting the material distribution of the pressure-receiving plate 23, it is possible to calculate the elasticity of the object, making it possible to perform soft handling that avoids deformation and damage of the object. It can also be used as auxiliary input for material determination and shape recognition. Note that it is preferable to perform scanning by the scanner amplifier 33 using vertical axis addresses and horizontal axis addresses because the number of wiring lines is reduced.

FIG. 7 shows an example of the arrangement and wiring of the strain gauge 27 of the pressure sensitive cell 25 described above. As shown in the figure, four strain gauges 27-1 to 27-4 formed near the left and right outer edges and inner edges on line A-A' parallel to the pressure-receiving surface 35 are used to apply force perpendicular to the pressure-receiving surface 35. Four strain gauges 27- are formed near the outer edges of two lines tilted at an angle α° in the left-right _direction of the line B-B' which is perpendicular to the line A-A'. 5 to 27-8, one component F _x of the force perpendicular to the pressure receiving surface 35 is detected. Furthermore, the four strain gauges 27-9 to 27-12 formed at positions on the mechanically neutral axis of the material near the center of the ring on the two lines tilted at the angle α° described above generate a force parallel to the pressure-receiving surface 35. Find other components F _y of . The above-mentioned angle α° is selected at a position that does not cause distortion when only a force perpendicular to the pressure receiving surface 8 is applied to the pressure receiving surface, and for example, in the case of a circular ring as shown in the figure, it is around 39.6°. become.

In this way, the above-mentioned strain gauges 27-1 to
27-12 is placed at a location that is highly sensitive and is theoretically unaffected by force components in other two directions. In addition, these strain gauge groups are connected to bridges, respectively, as shown in FIGS. 8A to 8C, for example, and output electric signals E _z ,
Print E _x and E _y .

Furthermore, an example of a method for manufacturing the pressure-sensitive cell 25 described above will be briefly described with reference to FIGS. 9A and 9B. First, it has a predetermined thickness (e.g. 0.6 mm),
A given conductivity type (for example, N type) and specific resistance (for example, 1
~10 Ω·cm) and a predetermined crystal orientation (for example, a formation surface in the {111} direction), a diffusion type strain arranged as shown in FIG. Gauge 27-1~2
The groups 7 to 12 and metal wiring are formed by integrated circuit manufacturing technology (planar technology) such as maskless ion beam processing and Al vapor deposition. According to this manufacturing technique, a large number of pressure sensitive cells can be fabricated on one wafer 41.

By accurately cutting out pressure-sensitive cells from a wafer 41 on which pressure-sensitive cells have been fabricated using a wire saw cut method, laser processing, or mechanical processing such as etching cut, small-sized (for example, a few mm to 1 mm diameter) with well-uniformed characteristics can be made. A planar pressure sensitive cell 25 is obtained. In this way, since the strain gauge 27 can be formed by a semiconductor process,
The pressure sensitive module 21 can be made extremely small, and the two-dimensional distribution of the magnitude of three component forces can be detected precisely. For example, in FIG. 6, two pressure sensitive cells 25 are used as one set, and one pressure sensitive module
However, it is possible to obtain a pressure sensor array in which such pressure-sensitive modules are integrated on the substrate 29 at a high density of, for example, about 25 to 100 pressure-sensitive modules per cm ² .

Therefore, by attaching this pressure-sensitive sensor array to the palm or fingers of a robot's hand, it is possible to precisely detect the two-dimensional distribution of the three components of applied pressure.
By performing calculations on the CPU using a predetermined calculation algorithm, it becomes possible to feed back high-level sensory information corresponding to the human sense of touch, force, and sliding as a feedback signal to the hand drive control system. By attaching a sensor array to the soles of the robot's feet, highly accurate walking control becomes possible.

Note that the pressure sensitive cell 25 is not necessarily limited to the configuration shown in FIGS. 6 and 7. For example, in the case of a ring-shaped pressure sensitive cell, strain gauges may be formed on the inner and outer peripheral surfaces thereof. Alternatively, a strain gauge may be formed in the vertical south plane. However, when the pressure sensitive cell 25 illustrated in this example is used, the following advantages can be obtained.

The component forces of the load applied to the pressure receiving plate 23 can be well separated and detected without mutual interference.

There is good linearity between the load applied to the pressure plate and the detected output, there is no hysteresis in measurement, and the dynamic range is large. Moreover, it can be detected as a pair of tension and compression.

Dimensions can be minimized and high-density integration can be achieved.

It can be easily created using conventional IC technology.In addition, by installing a temperature detector such as a thermistor near the pressure-sensitive module 21, and performing non-uniform gauge resistance correction and temperature compensation using the CPU of the microcomputer, it is possible to Highly accurate two-dimensional distribution measurement of three component forces becomes possible.

[Effects of the Invention] As explained above, according to the present invention, a pressure-sensitive module capable of detecting force applied to a pressure-receiving surface by decomposing it into force components in three directions orthogonal to each other in a rectangular coordinate system is installed on a substrate. Since the pressure sensor array is formed by arranging them in an array at high density, it is possible to accurately detect the two-dimensional distribution of the three components of the applied force.

[Brief explanation of the drawing]

FIGS. 1 and 2 are perspective views showing conventional force sensors, FIGS. 3, 4 A, B, and 5 are perspective views showing conventional pressure sensors, respectively.
FIG. 6 is a perspective view showing an embodiment of the present invention, FIG. 7 is an explanatory diagram showing an example of the arrangement and wiring of the strain gauges of the pressure-sensitive cell in FIG. 6, and FIGS. FIG. 9A is an explanatory diagram of a method of manufacturing the pressure sensitive cell shown in FIG. 6, and FIG. 9B is an enlarged view showing part A thereof. 1... Elastic support, 3... Strain gauge, 5
... Wrist, 7 ... Lead wire, 9 ... Front electrode foil,
11...Rear electrode foil, 13...Carbon fiber felt, 15...Silicone rubber cord, 1
7... Metal electrode, 19... Thin rod, 21... Pressure sensitive module, 23... Pressure receiving surface, 25... Pressure sensitive cell, 27, 27-1 to 27-12... Diffusion type strain gauge, 29... ... Substrate, 31 ... Parallel groove, 3
3... Scanner amplifier integrated circuit, 35... Pressure receiving surface, 41... Single crystal silicon wafer, 43... Area corresponding to pressure sensitive cell.

Claims (1)

[Claims] 1. A pressure-sensitive module that detects the force applied to the pressure-receiving surface by decomposing it into three component forces, that is, a component force in a direction perpendicular to the pressure-receiving surface and a component force in two directions within the pressure-receiving surface, is mounted on the board. A pressure sensor array comprising a plurality of pressure sensitive modules arranged in an array at high density, and a scanner amplifier for scanning and amplifying a pressure signal of three components from the pressure sensitive module on the substrate. .