JPH0736444B2 - Tactile sensor - Google Patents

Description

The present invention relates to a tactile sensor suitable for being mounted on a hand of a robot and detecting a force received from a grasped object.

[Prior Art] Many conventional robots, such as manipulators, sequence-type robots, and playback-type robots, work at a certain fixed place, and have a limited work range and ability. For example, a welding robot for automobiles is used in a state where it is fixed at a certain place in a production line, and a welding arm moves to weld a car body.The robot itself moves toward the car body and welds it by itself. Does not do. However, in recent years, robots having sensory functions equivalent to the five senses of humans have been developed and are being put to practical use, and it is considered that bipedal walking robots will be put to practical use in the near future.

Unlike the conventional robots, these so-called intelligent robots need to be equipped with various sensors. Typical sensors are a visual sensor and a tactile sensor, and especially the tactile sensor is indispensable for work such as grasping and grasping an object.

Performance specifications required for such a tactile sensor for an intelligent robot include the following.

High sensitivity: High sensitivity for detecting force, for example, capable of detecting a load of several grams.

High resolution: The sensor cells must be small and dense.

Wide dynamic range: Make the operating range as wide as possible.

 High reliability and durability: Withstanding harsh environments.

Linearity: Small Hysteresis: Pressure and output are proportional and there is little hysteresis.

 Response speed: The response speed of signal processing is fast.

 Flexibility: As soft as the skin of a human hand.

Slip feeling: Not only the pressure but also the slip should be detected if possible.

 Small size and low price: Thin, small size and low manufacturing cost.

Various tactile sensors satisfying some of these requirements have been proposed or put into practical use. As the tactile sensor, for example, (a) ON / O of micro switch
FF is used, (b) a pressure-sensitive rubber sheet (also referred to as a conductive rubber sheet) is used, and (c) a change in the reflection amount of light is used.

[Problems to be Solved by the Invention] However, these conventional tactile sensors have the following problems.

(A) Those that use ON / OFF of the micro switch are
Normally, when a sensor in the OFF state receives a force, it turns on, but this only detects the presence of force,
The magnitude of the force cannot be continuously detected.

(B) The one using a pressure-sensitive rubber sheet is one in which one sheet is sandwiched between electrodes and the sheet resistance is changed by the force applied to the electrodes, but linearity and hysteresis are likely to occur, There is also the problem of low heat resistance.

(C) In the case of utilizing the change in the reflection amount of light, a rubber sheet having a large number of conical projections is applied to the surface of a transparent glass plate, and a mirror or a light receiving element is arranged on the back surface of the glass plate. Light is emitted from the lateral direction of the glass plate into the glass plate, and the degree of depression of the protruding rubber of the rubber sheet, which changes according to the magnitude of the external force, is detected by a mirror or a light receiving element. However, it is difficult for a tactile sensor utilizing this reflection of light to accurately know the absolute value of an external force, and there are problems such as poor detection accuracy.

In addition to these tactile sensors, many tactile sensors have been proposed or prototyped, but none of them have sufficiently satisfied the above performance specifications. Therefore, the development of a truly practical tactile sensor is still screaming strongly.

In view of the above problems, the present invention has high practical performance,
Moreover, it is an object of the present invention to provide a tactile sensor which has a simple structure and which can be arranged thinly and densely.

[Means for Solving the Problems]

In order to achieve the above object, according to the present invention, a tactile sensor, a pressure receiving body that receives pressure, and a bottomed hole into which this pressure receiving body is fitted is formed on one surface side, and this bottomed hole forming portion is formed. A thin portion is formed, a thick portion is formed around the bottomed hole forming portion, a semiconductor strain gauge is formed in the thin portion portion on the other surface side, and the semiconductor strain gauge is formed in the thick portion portion. A switch that controls the output from the Wheatstone bridge and a solder bump are formed on the silicon cell, and the other side of this silicon cell is bonded by thermocompression bonding, and at the position corresponding to the sheet adhesive and the solder bump on the surface. It is assumed that a multilayer wiring board having the provided electrodes and having multilayer wiring, and a protective film arranged so as to cover the pressure receiving body are provided.

[Action]

As described above, the silicon sensor cell on which the semiconductor strain gauge, the switch, and the solder bump are formed, and the sheet-like adhesive and the electrode are formed, and the multilayer wiring board including the multilayer wiring board is thermocompression bonded. Therefore, a small and highly sensitive tactile sensor can be obtained.

The semiconductor strain gauge has a high detection sensitivity because it is formed in a thin portion where a large stress is generated when an external force is applied. Further, since both the switch and the solder bump are provided in the thick portion where stress is not relatively generated, the leak current of the FET is not generated, and the bonding between the bump and the electrode is ensured. .

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

 Principle of Tactile Sensor of Embodiment FIG. 1A to FIG. 1D show the principle of the embodiment of the present invention.

FIG. 1A shows the circuit configuration of a known Wheatstone bridge applied to the embodiment of the present invention. Where R ₁ , R ₂ , R ₃ , R
₄ indicates the gauge resistance on the four sides of bridge 1, respectively. V
Is a DC power supply, the negative side of which is connected to ground to apply a DC voltage to the bridge 1. The output of the bridge 1 is detected by detecting a non-parallel potential with a voltmeter E. S _X is the X-axis command, and the voltage switch S _V of the power supply V,
The one side current switch S _A2 of the bridge output is simultaneously opened or closed. S _Y is a Y-axis command, and opens or closes the other one-side current switch S _A1 of the bridge output. If these commands S _X and S _Y are conducting (ON) at the same time, an output is obtained from this bridge 1, and if at least one of the commands S _X and S _Y is non-conducting (OFF), its output is obtained. Can't get These switches S _V , S _A1 , and S _A2 are, for example, FETs.
Made of (electrolytic effect transistor). Furthermore, S _X ′
Is the X-axis command terminal, V'is the voltage terminal, G is the ground terminal, A ₁
Is a current terminal, A ₂ is a current terminal, and S _Y ′ is a Y-axis terminal, and these terminals correspond to solder bumps of a silicon cell and electrodes of a multilayer wiring board, which will be described later.

FIG. 1 (B) shows a case where strain gauges R ₂ and R ₄ are arranged at the outer peripheral position along the radial direction and strain gauges R ₁ and R ₃ are arranged at the central position on the circular diaphragm 2. Fig. 3 shows a gauge arrangement in the embodiment of the present invention. FIG. 1 (C) shows a sectional form of the tactile sensor 3 in which a semiconductor gauge resistance is formed by the gauge arrangement of FIG. 1 (B). As shown in FIG. 1 (C), when the pressure F is applied to the central position of the tactile sensor 3 as shown in FIG. 1 (C), the stress distribution on the projecting surface provided with the strain gauges R _{1 to} R ₄ is as shown in FIG. 1 (D). In addition, the distribution is such that the outer peripheral position of the diaphragm 2 receives the compressive force and the central position thereof receives the tensile force.
Thus, since the semiconductor strain gauges R ₁ and R ₃ receive the tensile stress in the central portion and the semiconductor strain gauges R ₂ and R ₄ receive the compressive force in the outer peripheral portion, the voltmeter E shown in FIG. The detection value of becomes high and high sensitivity is obtained.

Tactile Sensor Cell FIGS. 2 (A) to (D), FIG. 3 (A), (B) and FIGS. 4 (A), (B) show the manufacturing process and configuration of the tactile sensor of one embodiment of the present invention. Show. 2A to 2D show a process of manufacturing a silicon sensor cell (tactile sensor cell) of the tactile sensor 3 from a single silicon wafer by a known semiconductor processing process, and a wiring pattern of the silicon sensor cell. . FIG. 2A shows a part of the silicon wafer, that is, the material 4 of the silicon sensor cell. Then the second
As shown in FIG. 1B, a semiconductor strain gauge 5, an FET switch 6 and a bump-shaped solder bump 7 are publicly known on one surface of the material 4 of the silicon sensor cell according to a predetermined wiring pattern designed in advance. It is formed by the semiconductor processing process. Furthermore, this is reversed and the second
As shown in FIG. 3C, a cylindrical bottomed hole 8 is formed on the back surface side without the strain gauge 5 by a known etching method or the like. A cylindrical pressure receiving body, which will be described later, is fitted into the hole 8.

FIG. 2 (D) shows an example of the wiring pattern of the tactile sensor cell 9 shown in FIG. 2 (C). As shown, the semiconductor strain gauge 5 is formed in the thin portion of the material 4 of the silicon sensor cell in which the bottomed hole 8 is formed. The switch 6 and the solder bump 7 are formed in a thick portion around the thin portion. Here, A ₁ , S _Y ′, V ′, S _X ′, A ₂ and G respectively correspond to the terminals of FIG. 1 (A), and the solder bump 7 formed in the step shown in FIG. 2 (B). Is.

Further, spaces (adhesion places) 10 for placing a sheet-like adhesive described later are provided at four corners of the tactile sensor cell (silicon sensor cell) 9. The tactile sensor cell 9 and the substrate, which will be described later, are bonded to each other at these four bonding locations 10. Moreover, the adhesion place 10 is also a place where the force of the tactile sensor 3 is applied.

Multilayer Wiring Board FIGS. 3A and 3B show the structure of the multilayer wiring board 11 on which the tactile sensor cell 9 of FIG. 2 is mounted. Figure 3 (A) shows
The arrangement of the electrodes 12 and the sheet adhesive 13 on the multilayer wiring board 11 is shown by S _X ′, V ′, G, A ₁ , A ₂ , and S _Y ′. These electrodes 12
Is directly connected to the through hole of the multilayer wiring board 11 and is formed of copper or a composite plating film which is easy to solder. Then, these electrodes 12 are soldered to the solder bumps 7 shown in FIG. 2 by thermocompression bonding. On the other hand, the square sheet adhesive 13 is arranged at the four corners of the substrate 11, and since the sheet adhesive 13 supports the force received by the tactile sensor 3, it has high elasticity and is strong. There must be. Therefore, as the sheet-like adhesive 13, for example, a thermosetting adhesive which is adhered by thermocompression bonding is most suitable.

FIG. 3B shows a sectional structure of the above-mentioned multilayer wiring board 11. The substrate 11 is made of glass epoxy resin or ceramic. The first layer of the wiring board 11 is the electrode 12
The second layer is the column signal line layer 14, that is, the layer through which S _X , V, G pass, and the third layer is the row signal line layer 15, that is, S _Y , A.
_This is the layer through which ₁ and A ₂ pass. The fourth layer is the base layer 16.

Assembling of the tactile sensor alone FIGS. 4 (A) and 4 (B) bond the silicon tactile sensor cell 9 of FIG. 2 and the multilayer wiring substrate 11 of FIG. 3, and further form a pressure receiving body 17 and a protective film 18. The assembly process and completed state are shown below. That is, according to the wiring pattern of FIG. 2 (D), the upper sensor cell 9 and the lower multilayer wiring substrate 11 are aligned and overlapped as shown in FIG. 4 (A), and then heat-pressed. Connection 10 of the solder bump 7 and the electrode 12 and the sensor cell 9 with the sheet adhesive 13
Adhesion to. Finally, as shown in FIG. 4 (B), a pressure receiving body 17 formed of a high-rigidity alloy steel or the like is fitted into the bottomed hole 8 of the sensor cell 9, and a protective film 18 formed of polyimide or rubber is received. It is formed so as to cover the upper surface of the body 17, and the assembly of the tactile sensor 3 alone is completed.

Signal processing circuit By arranging a large number of single units of the tactile sensor 3 as shown in FIG. 4 (B) in a matrix or in a plane, it is possible to obtain the pressure distribution. However, there remains the problem of how to perform signal processing when detecting the pressure distribution.

FIG. 5 shows the configuration of a signal processing circuit in an embodiment of the present invention which solves this problem.

This example is an example in which nine tactile sensors alone are arranged in a matrix.

In the figure, S _{X1 to} S _X3 represent column-wise switch signals (X-axis command), and ON / OFF switching scanning is performed in the order of signals S _X1 , S _X2 , and S _X3 . Further, S _{Y1 to} S _Y3 indicate row-wise switch signals (Y-axis command), and ON / OFF switching scanning is performed in the order of signals S _Y1 , S _Y2 , and S _Y3 . In this example, the power supply V is independent of the signals S _X1 , S _X2 , S _X3 , but may be common.

As indicated by the arrow in this figure, E _Y1 is directly connected to the single-stage outputs E ₁₁ , E ₁₂ , and E ₁₃ of the first circuit, and S _{X1 to} S _X3
And S _Y1 switch scan, single output E ₁₁ , E ₁₂ , E ₁₃
Any one of the above is transmitted. Similarly, the output of the second stage E _Y2
Are directly connected to the second-stage single outputs E ₂₁ , E ₂₂ , and E ₂₃ , respectively, and any one of the single outputs E ₂₁ , E ₂₂ , and E ₂₃ can be selected by the switch scanning of S _{X1 to} S _X3 and S _Y2. To output the 3rd output E
Similarly, for _Y3 , the single outputs E ₃₁ , E ₃₂ , and E ₃₃ are sent out. Therefore, by switching between signals S _{X1 to} S _X3 and S _{Y1 to} S _Y3 , one of the tactile sensors 3 can be addressed and the output of the designated sensor 3 can be obtained.

FIG. 5 shows a case where nine tactile sensors 3 are arranged in a matrix, but the signal processing method is the same as that in FIG. 5 when ten or more tactile sensors 3 are arranged.

[Effects of the Invention] As described above, according to the present invention, as a result of adopting the above configuration, a tactile sensor that is small and thin as a whole and has excellent characteristics such as detection sensitivity, detection accuracy, and response speed is provided. There is an effect that can be obtained.

Further, according to the present invention, since it has such advantages, it becomes an extremely effective sensor when it is attached to the hand of the robot to perform an advanced work. Further, if the multilayer wiring board is made of a plastic material and made flexible, it can be attached to a curved surface, and the application is further expanded.

[Brief description of drawings]

1 (A) to 1 (D) show the principle of the embodiment of the present invention. FIG. 1 (A) is a circuit diagram, FIG. 1 (B) is a bottom view, FIG. 1 (C) is a sectional view, and FIG. D) is a characteristic diagram showing the relationship between the gauge position and stress, and FIGS. 2A to 2D show the manufacturing process and wiring pattern of the tactile sensor cell of the embodiment of the present invention.
(B) and (C) are sectional views, (D) is a bottom view, and (A) and (B) are configurations of the multilayer wiring board according to the embodiment of the present invention. FIG. 4 (A) is a plan view, FIG. 4 (B) is a sectional view, FIG. 4 (A) is a sectional view showing an assembling process of the tactile sensor of the embodiment of the present invention, and FIG. 4 (B) is a sectional view showing its completed state. FIG. 6 is a circuit diagram showing the configuration of the signal processing circuit according to the embodiment of the present invention. 1 ... Whiston Bridge, 2 ... Diaphragm, 3 ...
… Tactile sensor, 4… Silicon sensor cell material, 5…
… Strain gauge, 6… FET switch, 7… Solder bump, 8… Bottom hole, 9… Tactile sensor, 10… Adhesion location, 11… Multilayer wiring board, 12… Electrode, 13… Sheet adhesive, 14 …… Column signal line layer, 15 …… Row signal layer, 16
…… Base layer, 17 …… Pressure receiver, 18 …… Protective film.

Claims (1)

[Claims] 1. A pressure receiving body for receiving pressure, and a bottomed hole into which the pressure receiving body is fitted is formed on one surface side,
The bottomed hole forming portion forms a thin portion, the periphery of the bottomed hole forming portion forms a thick portion, a semiconductor strain gauge is formed in the thin portion on the other surface side, and the thick portion is A silicon cell in which a switch for controlling the output from the Wheatstone bridge composed of a semiconductor strain gauge and a solder bump are formed, and the other side of the silicon cell is joined by thermocompression bonding,
A multilayer wiring board having a sheet adhesive on the surface and electrodes provided at positions corresponding to the solder bumps and having multilayer wiring; and a protective film arranged so as to cover the pressure receiving body. A tactile sensor characterized by comprising: