JPS60153170A - Sense of contact force sensor - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of the titled device by the reduction of the number of manufacturing and assembly processes by a method wherein a plurality of pressure-sensitive cells in the column direction are prepared integrally by means of stripform single crystal Si, and this prepared strip is arranged on a substrate into this device. CONSTITUTION:A plurality of small-sized circular holes 52 and large-sized circular holes 53 are alternately bored in the vertical plane of the stripform single crystal Si 51 almost at equal intervals along the longitudinal direction, and further a diffused type strain gauge group 54 is formed around each circular hole 52 by the diffusion technique. Thereby, a plurality of pressure-sensitive cells 55 detecting the force, impressed on a pressure reception plane 51a via pressure reception plane 40 of the Si 51 with the variation in resistance value of the group 54, by decomposition into three component forces are constructed integrally. The lower end 51b of the stripform Si 51 thus constructed is fitted to each groove 31 of the lower substrate 30 and fixed vertically at a given position; thereafter, pressure reception plates 40 are fixed to the pressure reception plane 51a in the upper part of each stripform Si 51 in every pressure-sensitive module, resulting in the formation of a piece of pressure sensor.

Description

[Detailed Description of the Invention] [Technical Field to Which the Invention Pertains] The present invention is a three-component force detection sensor that detects force such as a load applied to a pressure-receiving surface by decomposing it into component forces in three directions perpendicular to the sieve. The present invention relates to a pressure sensor in which a pressure module is used as a unit, and a large number of pressure modules are arranged in an array so that a load or the like can be detected.

[Prior art and its problems] A pressure-sensitive module that can decompose forces such as the load mentioned above into a basic orthogonal coordinate system and detect them separately as components of force in three directions can detect the three components of force separately. By composing them using arithmetic expressions, it is possible to determine the magnitude and direction of the force, and furthermore, it is possible to determine the force in the direction of Renhui, so it is of course useful as a single loading meter, etc. However, in particular, pressure sensors arranged in an array have relatively new uses because they can measure the distribution of force, the center of force (center of gravity), and the resultant force.

An example of this can be seen in human body dynamics experiments such as the one shown in FIG. The figure shows the foot 2 of a person walking on the pressure sensor 1, and in the right side of the figure, the heel of the foot is on the load cell 1.
However, in the state on the left side of the figure indicated by the bag-shaped arrow, the toe is in contact with the pressure sensor l. As the walking dynamics progress, the distribution of the load applied to the pressure sensor and the three component forces Fx, Fy, and Fz of charge naturally change over time. Measuring the 1/f weight during the gait Qj dynamics using a normal weight scale does not provide very useful information, even if it is possible to measure the temporal fluctuations in the overall load. However, if it is possible to accurately measure the planar distribution of load and the transition of component forces during walking dynamics, very useful knowledge can be obtained regarding individual differences in walking dynamics and patterns of physical disorders. It is known. Furthermore, by attaching this pressure sensor l to the back of the robot's foot, it becomes possible to provide the robot with a sophisticated walking control function.

The need to detect the distribution of Isa gravity component exists widely in the industrial field, and FIG. 2 shows an example of a pressure sensor for a robot. This figure shows a state in which an object 6 is gripped by a pair of fingers 5.5 of a robot hand 4 attached to the tip of a multi-joint arm 3. If the object has sufficient hardness and strength, such as many industrial parts, there will be no problem with mating, but if the object 8 is soft or perishable, such as fruit, it may be difficult to apply strong force. Gripping is not allowed. In order to handle this type of object with a robot without damaging it, the gripping force, that is, the component force of the load applied to the fingers 5 and its distribution, must be measured with great precision, and an appropriate force that will not damage the object and cause it to fall is determined. must be grasped with.

Also, in order to know whether the grip is being performed correctly, it is useful to know the planar distribution of the load component force. For example, when gripping a relatively elongated object 6 as shown in the figure, the distribution of the load component force differs depending on the part of the object to be gripped, so if the distribution is abnormal, it is likely that the gripping is being performed inappropriately. I understand. Furthermore, when a soft object is being gripped with a relatively small gripping force, the risk of the object falling off can be predicted from the time course of the load component force.

FIG. 3 shows an outline of the configuration of such a pressure sensor. The illustrated pressure sensor l has a pressure sensitive module l on a common substrate 30.
A large number of O cells are arranged in a plane array in both the x and y directions, and receive a load having a component force of "+FY+FZ" through the pressure receiving plate 40 of each pressure sensitive module 1o, and the pressure sensitive cell 2o receives a load having a component force of "+FY+FZ". In addition to the vertical force F2 that the body receives, it also detects the lateral forces Fx and Fy.As a result, for example, as illustrated in Fig. 1, in addition to the distribution of the weight of the human body acting on the pressure sensor l, It is possible to know the magnitude and distribution of the kicking force Fx and the force FY pushing out in the lateral direction with respect to the walking direction.Each pressure-sensitive module 1o is a pressure-sensitive element as shown surrounded by a dashed line in the figure. The pressure sensitive cell 20, the common substrate 30, and the upper pressure receiving plate 4o are separated.

By the way, as shown in FIGS. 4 and 5, the conventional pressure sensitive cells 2o that have already been proposed are
Each tube was made up of 21.2 liters of separate and independent pressure-sensitive rings (ring-shaped pressure-sensitive actuators). Therefore, in order to form the pressure sensor l, it is necessary to form a plurality of parallel grooves 3 on the lower substrate 3o.
1, a step of engaging one end side of the plurality of rings 21 and erecting the plurality of rings 21 in a distributed manner in each groove;
a step of aligning the rings 21 distributed in the row direction along the column direction, and each ring 2 engaged with the groove 31;
At least a step such as a step of fixing one end of 1 to the substrate is required, which has the drawback of increasing the number of manufacturing and assembly steps.

Moreover, this type of pressure sensor is required to be as small as possible and to be highly integrated. For example, it is said that it is desirable that the size of the pressure receiving plate 40 be several mrrr angles, preferably less than lam angles. however,
It is not easy to accurately carry out each of the above-mentioned processes with these required dimensions because the ring 21 will also be extremely small, which may lead to a decrease in part retention, a decrease in reliability, and an increase in manufacturing costs. The problem was that it was difficult to completely automate manufacturing and assembly.

[Purpose of the invention]

The present invention aims to eliminate the above-mentioned drawbacks and to simplify the manufacture of pressure sensors.

[Summary of the Invention] The present invention uses rectangular single crystal silicon. By integrally fabricating a number of pressure-sensitive cells in the row direction in the The aim is to make manufacturing easier.

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

FIG. 6 shows an example of the main part configuration of the pressure sensor of the present invention. As shown in the figure, a plurality of small circular holes 52 and large circular holes 53 are alternately opened at approximately equal intervals along the longitudinal force in the vertical plane of a rectangular short crystalline silicon 51, and each small circular Diffusion-type strain gauge groups 54 are formed around the holes 52 by a known diffusion technique.'--As a result, a change in the resistance value of the strain gauge groups 54 causes pressure to be applied to the pressure-receiving surface 51a through the pressure-receiving surface 40 of the silicon 51. A plurality of pressure sensitive cells 55 are integrally configured to detect the applied force by decomposing it into three component forces.

The lower end 51 of the silicon strip 51 configured in this way
b are fitted into the grooves 31 of the lower plate 30 as shown in FIG. One pressure receiving plate 40 is attached to each pressure sensing module to form one pressure sensor. Note that the pressure receiving plate 40 is made by fixing an integral plate to the pressure receiving surfaces 51a of all the silicones 51, and then
The plate may be formed by cutting the plate into individual pressure-sensitive modules using a cutter.

In this way, since the cells 55 in the column direction are integrally and continuously constructed on the silicon 51 in each column, each cell is aligned and fixed at a predetermined position in the groove 31 of the substrate 30. This eliminates the need for the conventional manufacturing process, and requires a manufacturing process for each silicon strip 51, which greatly reduces the number of manufacturing steps and, in turn, reduces manufacturing costs. Furthermore, since the dimensions of the pressure-sensitive body to be handled increase in terms of the amount of longitudinal force required, work such as assembly and fixing into the groove of the lower board becomes easier, which in turn improves the part-holding and reliability, and allows for complete manufacturing and assembly. Easy to automate.

FIG. 7 shows a detailed arrangement example of each strain gauge in the strain gauge group 54 shown in FIG. First, when loads Fx, Fy, and F2 in three directions are independently applied to the pressure-receiving surface 51a via the pressure-receiving plate 40, the stress generated in the cell 55 is due to the fact that the silicon 51 is fixed to the substrate 30 and the pressure-receiving plate 40. It is approximately expressed by the following formula.

However, σ: circumferential stress, R: the average circle of the cell 55, that is, the radius of the material mechanical neutral axis when the cell 55 is viewed as a beam, that is, the midpoint between the outer edges of two adjacent circular holes 52 and 53. Radius connecting the center of the small circular hole 52, 2t: Width of the cell 55, that is, two adjacent circular holes 52
and the minimum width of the outer edge of 53, b = thickness of nacelle 5, that is, thickness of silicon 51, (2): second moment of area of nacelle 5 in the FW length direction.

T: Variable in the radial direction of the cell 55 based on the average 7R of the cell 55, α: An angular variable taken from the upper end of the cell 55.

In order to detect strain due to such stress, a strain gauge is attached to a position around the circular hole 52 shown in FIG. First, considering the case when load F11 is applied, FX
The measuring gauges 54xt and 54xc are located at the position r=-t of the inner diameter of the small circular hole 52, and are also provided at the position α-39,6'', so in (1), if R>t, cr =0.
．． 29 - Fx (4) t2 Hi? J, tensile strain occurs at the location of gauge 54xt, and compressive strain occurs at the location of gauge 54xc, but the load F
ct at the R measurement gauges 54zt and 54zc
= 80. ' Therefore, as can be seen from equation (1), the strain is 0 and therefore no detection signal is generated from these gauges.

Next, when the load IIXFz is applied alone, Fz
Since the measurement gauges 54zt and 54zc are located at the inner and outer periphery of α;800 (r=-t or r=t),
3) According to the formula, similarly, if R>t, then the gauge 54zt represents the tensile strain, and the gauge 54zt represents the tensile strain.
zc detects compressive strain. At this time, at the positions of the Fx detection gauges 54xt and 54xc, α=3i3.6
Since the spear of (2/π-5inα) in equation (3) becomes 0 at °, the strain is O and no detection signal is generated from these gauges.

From the above, component force F x i%1. ll constant gauge 5
4++t, 54xc and gauge for measuring component force Fz 54zt
, 542C, there is a difference of about twice the output signal from equations (4) and (5), but it can be seen that there is no mutual interference and the component forces can be completely separated and measured.

On the other hand, considering the gauge for measuring component force FW, the load F
Assuming that Y is applied in a direction toward the front of the plane of FIG. 7, the strain detection gauges 54yt and 54yc7 are provided as shown. In order 1σ of these gauges,
Similarly, in equation (2), α = 39.6° and R>t, σ = 0.18 R-FY L6) ■ The strain based on the stress is expressed as the tensile strain for gauge 54yt, and the tensile strain for gauge 54yc. It will be detected in the form of compressive strain, and the component force F2 measurement gauge 54zt.

At the position of 54zc, α = 80°, so σ = 0, and therefore no interference signal is generated, but at the position of component force FXX measurement gauge 4++t and 54xc, σ is the same as in the case of component force Fy measurement gauge. = 0.1!1 R-Fy (7) ■ A strain detection output based on the stress will be output. If the detection signal from this distribution Fx measurement gauge is output immediately, it will naturally become an erroneous signal, but as shown in Fig. 8 (A)
Since the bridge circuit shown in ~(C) is designed to cancel the erroneous signal in the normal state, erroneous detection No. 14 will not be output from the bridge circuit for measuring component force Fx.

In short, the small circular hole 52 is a ring hole that applies strain constituting the cell 55, and the large circular hole 53 is a ring hole that applies strain to each cell 55.
It acts as a boundary that separates each.

FIG. 8 shows another embodiment of the present invention, in which a plurality of small circular holes 56 are added to the outer periphery of the strain gauge group 54 in order to make the shape of the cell 55 more similar to the basic ring shape. This is what I did.

In FIG. 10, a small notch 57 is provided in place of the above-mentioned small circular hole 5B.

FIG. 11 also shows another embodiment of the present invention, but instead of the large circular hole 53 described above, a large cut groove 5B with an upper opening is provided as a boundary between each cell 55. This reduces interference between adjacent cells. In this case, it is more preferable to further modify the shape of the above-mentioned cut groove 5B so that the shape of the cell 55 approaches a ring shape while leaving each cell 55 connected to the integral number at the bottom position.

[Effects of the Invention] As explained above, according to the present invention, the pressure-sensitive cells in the same rows and rows are integrally and continuously formed with a rectangular single-crystal silicon upper plate, and the rectangular silicon is used as a base. Since the pressure sensor is formed by arranging and attaching the pressure sensor to the substrate, the number of manufacturing steps is greatly reduced, assembly etc. are facilitated, and there are advantages such as a reduction in manufacturing costs.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example in which the pressure sensor, which is the subject of the present invention, is used for four (11) changes in human walking dynamics, and Fig. 2 is an explanatory diagram showing an example in which the pressure sensor is used as a sensor for controlling a robot hand. FIG. 3 is a perspective view showing the basic structure of the pressure sensor; FIGS. 4 and 5 are perspective views showing the manufacturing process and structure of the conventional pressure sensor; FIG. 6 is the pressure sensor of the present invention. FIG. 7 is an explanatory diagram showing the arrangement of the strain gauge, FIGS. 8 (A) to (C) are circuit diagrams showing an example of the connection mode of the strain gauge, FIG. Figures 1 to 3 are front views showing other embodiments of the present invention. 30... Common substrate, 31... Groove, 40... Pressure receiving plate, 51... Rectangular single crystal silicon 51a...Pressure receiving surface, 52...Small sensor ring hole, 53...Large boundary hole, 54-...Strain gauge group, 55...Pressure sensitive cell, 56...・Small boundary hole, 57...Small boundary cut 1iV (,58...Large size boundary cut groove. Patent applicant Fuji Electric Research Institute Co., Ltd. Figure 4 1 Figure 5 54XC54Xt No. 8 (A) CB) (C) Fig. 9-755 55 4535257 Fig. 11 1 45258

Claims (1)

[Claims] A plurality of diffusion type strain gauge groups are formed in a rectangular single crystal silicon along the longitudinal force of a plane perpendicular to the pressure receiving surface of the silicon, and a circular strain gauge group is formed with respect to the strain gauge group. By making several holes or cuts in the perpendicular blood, a plurality of holes or cuts are made that detect the force applied to the 6iJ pressure-receiving surface by dividing it into 3 component forces by changing the resistance value of the strain gauge group. A pressure sensor characterized in that cells are formed in a band shape, and the rectangular single crystal silicon formed from the cells are arranged on two sides of a lower substrate with the pressure receiving surface facing upward. (Margin below)