Patent Application
20190341176
The present application is based on and claims priority from JP Application Serial Number 2018-089079, filed May 7, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a pressure-sensitive device, hand, and robot.
For example, JP-A-1-150825 discloses a load sensor sandwiching a pressure-sensitive conducting rubber with a pair of electrodes and measuring a load using a change in resistance value of the pressure-sensitive conducting rubber due to the applied load.
JP-A-1-150825 is an example of the related art.
However, in the load sensor of JP-A-1-150825, a silicone rubber or the like containing conducting particles of carbon or the like dispersed therein is used as the pressure-sensitive conducting rubber. When the pressure-sensitive conducting rubber is used, in a region with a lower load, the change in resistance value of the pressure-sensitive conducting rubber becomes too large relative to the change in load, and thereby, the measurement value of the applied load varies and the load is not accurately measurable (see
A pressure-sensitive device according to an aspect of the present disclosure includes a resin mixture in which a carbon nanotube is mixed, an electrode stacked on the resin mixture, and a pressurization unit that pressurizes the resin mixture in a direction of the stacking, wherein the pressurization unit includes an adjustment mechanism of adjusting an amount of the pressurization.
As below, a pressure-sensitive device, hand, and robot according to the present disclosure will be explained in detail with reference to preferred embodiments shown in the accompanying drawings.
The pressure-sensitive device 1 shown in
Further, a stacking structure of the first electrode 14, the resin mixture 13, and the second electrode 16 is referred to as “stacking structure 10”, and the pressure-sensitive device 1 has a pressurization unit 18 that pressurizes the stacking structure 10 along an axis of the thickness thereof. Here, the thickness axis of the stacking structure 10 is, in other words, an axis crossing the axis in which the surface of the resin mixture 13 with the first electrode 14 or second electrode 16 placed thereon spreads (an axis crossing the surface). The pressurization unit 18 includes one screw 180 coupling the first board 11 and the second board 12. The screw 180 has a head portion 180 engaged with the second board 12 and a thread portion 182 screwed together with the first board 11. Accordingly, when the screw 180 is fastened (turned), a gap between the first, second boards 11, 12 becomes narrower (the distance becomes smaller), and the stacking structure 10 located between the boards may be pressurized. Further, magnitude of the pressurization may be adjusted by adjusting an amount of fastening of the screw 180. According to the configuration, the screw 180 functions as an adjustment unit (adjustment mechanism) that adjusts the pressurization on the stacking structure 10.
In the pressure-sensitive device 1 having the above described configuration, when a load along the thickness axis is applied to the pressure-sensitive device 1 that is in contact with an object, contact resistances change with changes in contact area between the first, second electrodes 14, 16 and the resin mixture 13, and a resistance value between the first electrode 14 and the second electrode 16 changes. Accordingly, the pressure-sensitive device 1 may detect the applied load based on the resistance value change between the first electrode 14 and the second electrode 16. As below, the respective parts of the pressure-sensitive device 1 will be sequentially explained.
The resin mixture 13 is formed using a material (pressure-sensitive conducting resin) containing an insulating resin 131 as a base and carbon nanotubes 132 as a conducting material. That is, the carbon nanotubes 132 are mixed in the resin 131, and the resin mixture 13 is a mixture of the resin 131 and the carbon nanotubes 132. According to the configuration, the resin mixture 13 may be easily molded in a sheet shape and reduction in thickness and weight of the pressure-sensitive device 1 may be realized. Note that the resin mixture 13 may be manufactured using e.g. injection molding or extrusion molding.
The thickness of the resin mixture 13 is not particularly limited, but e.g. preferably from 50 μm to 200 μm and more preferably from 80 μm to 120 μm. Thereby, the sufficiently thin resin mixture 13 that may sufficiently fulfill the function is obtained. Accordingly, the pressure-sensitive device 1 maybe downsized while maintaining detection characteristics of the pressure-sensitive device 1. Note that “thickness” refers to an average thickness of the resin mixture 13.
The carbon nanotube 132 is used as the conducting material, and thereby, volume resistivity of the resin mixture 13 is harder to be affected by temperature, and fluctuations of the measurement value due to temperature change may be reduced. Accordingly, for example, excessive temperature correction is not necessary, and the applied load may be accurately detected. The following explains this in detail. The graph shown in
Further, the carbon nanotube 132 is used as the conducting material, and thereby, for example, compared to a case where carbon is used as the conducting material in a related art, the resistance value of the resin mixture 13 (electrical resistance between the first, second electrodes 14, 16) maybe made sufficiently lower with a smaller content. Accordingly, mixing with the resin 131 is easier.
Note that the Young's modulus of the resin mixture 13 is not particularly limited, but e.g. preferably from 1.5 times to 2 times the Young's modulus of the resin 131. Specifically, the Young's modulus of the resin mixture 13 is preferably from 4 GPa to 6 GPa. Thereby, the resin mixture 13 is sufficiently hard and the detectable range is wider, and higher loads may be detected. Further, excessive hardening may be suppressed and degradation of the detection characteristics for lower loads maybe effectively suppressed.
A diameter of the carbon nanotube 132 is not particularly limited, but e.g. preferably from 100 nm to 200 nm and more preferably from 130 nm to 160 nm. Further, a length of the carbon nanotube 132 is not particularly limited, but e.g. preferably from 2 μm to 10 μm and more preferably from 3 μm to 8 μm. With this diameter and the length, aggregation of the carbon nanotubes maybe prevented and a stable resistance value may be obtained. Accordingly, the load applied to the pressure-sensitive device 1 may be detected with higher accuracy. Note that “diameter” refers to an average diameter of the plurality of carbon nanotubes 132 contained in the resin mixture 13, and “length” refers to an average length of the plurality of carbon nanotubes 132 contained in the resin mixture 13.
The content of the carbon nanotubes 132 in the resin mixture 13 is not particularly limited, but e.g. preferably from 2 wt % to 30 wt %, more preferably from 10 wt % to 30 wt %, and even more preferably from 20 wt % to 25 wt %. Thereby, moderate conductivity may be provided to the resin mixture 13, and reduction in mechanical strength of the resin mixture 13 due to excessive mixing of the carbon nanotube 132 may be suppressed.
The resin 131 is not particularly limited, but e.g. a deflection temperature under load thereof is preferably equal to or higher than 100° C. Note that the deflection temperature under load refers to a temperature at which magnitude of deflection becomes a constant value when a temperature of a sample is raised under a predetermined load, and the higher the temperature the higher the heat resistance. Further, the deflection temperature under load may be measured by a test method according to JIS 7191. Thereby, reduction of elasticity of the resin mixture 13 under a high-temperature environment may be suppressed, and the pressure-sensitive device 1 may exert the same detection accuracy even under the high-temperature environment as that under a normal-temperature environment or low-temperature environment.
Further, the resin 131 is not particularly limited, but, for example, the Young's modulus thereof is preferably equal to or higher than 1 GPa, more preferably equal to or higher than 1.5 GPa, and even more preferably equal to or higher than 2 GPa. Thereby, the harder resin mixture 13 is obtained and the mechanical strength of the pressure-sensitive device 1 may be improved. In addition, deformation and settling with time may be suppressed, and degradation and fluctuations of the detection characteristics with time may be suppressed.
Furthermore, the resin 131 is not particularly limited, but preferably a thermoplastic resin. Thereby, mixing of the resin 131 and the carbon nanotubes 132 is easier and dispersibility is higher, and manufacturing of the resin mixture 13 is easier. The thermoplastic resin is not particularly limited to, but includes e.g. ABS resin, PP (polypropylene), PE (polyethylene), PS (polystyrene), PMMA (polymethylmethacrylate), PET (polyethylene terephthalate), PPE (polyphenylether), PA (polyamide), PC (polycarbonate), POM (polyacetal), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), and PEEK (polyetheretherketone), and one, two, or more of the resins may be mixed for use.
Of the resins, the resin 131 preferably contains PC (polycarbonate). When the resin 131 contains PC, the resin 131 is inexpensive, easy to handle, and easily mixed with the carbon nanotubes 132. Further, the resin mixture 13 is easily formed to be harder. Accordingly, allowable load per unit area may be higher and the mechanical strength of the pressure-sensitive device 1 maybe improved, and the measurable range may be secured to be wider. In addition, deformation and settling with time of the resin mixture 13 maybe suppressed, and degradation and fluctuations of the detection characteristics with time may be suppressed. The content of PC in the resin 131 is not particularly limited, but e.g. preferably equal to or higher than 50 wt %, more preferably equal to or higher than 75 wt %, and even more preferably equal to or higher than 95 wt %. Thereby, the above described effects may be exerted more remarkably.
Further, of the resins, the resin 131 preferably contains at least one of PP (polypropylene), PET (polyethylene terephthalate), and PPS (polyphenylene sulfide). When the resin 131 contains at least one of PP, PET, and PPS, the resin 131 is inexpensive, easy to handle, and easily mixed with the carbon nanotubes 132 like PC. The contents of PP, PET, and PPS in the resin 131 are not particularly limited, but, respectively, e.g. preferably equal to or higher than 50 wt %, more preferably equal to or higher than 75 wt %, and even more preferably equal to or higher than 95 wt %. Thereby, the above described effects may be exerted more remarkably.
As shown in
Further, the first electrode 14 and the second electrode 16 are located between the first board 11 and the second board 12 and placed with the resin mixture 13 in between. Specifically, the first electrode 14 is located between the first board 11 and the resin mixture 13, and the second electrode 16 is located between the second board 12 and the resin mixture 13. The first electrode 14 is in contact with, but not joined to the lower surface of the resin mixture 13 and the second electrode 16 is is in contact with, but not joined to the upper surface of the resin mixture 13. The first, second electrodes 14, 16 are not joined to the principal surfaces of the resin mixture 13, and thereby, contact resistance between the first, second electrodes 14, 16 and the resin mixture 13 easily changes according to the load.
The constituent materials of the first electrode 14 and the second electrode 16 are not particularly limited as long as the materials have conductivity, but includes e.g. various metals such as nickel (Ni), cobalt (Co), gold (Au), platinum (Pt), silver (Ag), copper (Cu), manganese (Mn), aluminum (Al), magnesium (Mg), titanium (Ti), and tungsten (W) and alloys containing at least one of the metals, and one, two, or more of the materials may be combined (for example, as a stacking structure) for use.
Note that the placement of the first electrode 14 and the second electrode 16 is not particularly limited, but e.g. a placement in which the first electrode 14 and the second electrode 16 are insulated and disposed side by side on the upper surface side of the resin mixture 13, or a placement in which the first electrode 14 and the second electrode 16 are insulated and disposed side by side on the lower surface side.
As shown in
Similarly, the second support board 17 is located between the second board 12 and the second electrode 16. Further, the second electrode 16 is provided on a lower surface of the second support board 17, and a wire (not shown) of the second support board 17 is electrically coupled to the second electrode 16. Thereby, the second electrode 16 may be easily extracted from between the first, second boards 11, 12. Note that the second support board 17 may be omitted.
The first support board 15 and the second support board 17 are both not particularly limited, but e.g. various printed boards including flexible printed boards and rigid printed boards may be used.
As shown in
As described above, the stacking structure 10 is pressurized by the pressurization unit 18, and thereby, hysteresis maybe reduced and variations of the detection value of the applied load may be reduced compared to the case without pressurization.
The graph shown in
Note that, in the experiments shown in
The pressurization applied to the stacking structure 10 is not particularly limited, but e.g. preferably from 1 MPa to 15 MPa depending on the material of the resin mixture 13. Thereby, the above described variations of the detection value may be effectively reduced, and damage on the resin mixture due to excessive pressurization may be effectively suppressed. As below, optimum magnitude of pressurization within the above described range will be explained with respect to each material of the resin 131 of the resin mixture 13.
First, the case using PC (polycarbonate) as the resin 131 is explained. The graphs shown in
The graph shown in
Next, the case using PP (polypropylene) as the resin 131 is explained. The graphs shown in
The graph shown in
Next, the case using PET (polyethylene terephthalate) as the resin 131 is explained. The graphs shown in
The graph shown in
As above, the pressure-sensitive device 1 is explained. As described above, the pressure-sensitive device 1 has the resin mixture 13 in which the carbon nanotubes are mixed, the first, second electrodes 14, 16 as electrodes stacked on the resin mixture 13, and the pressurization unit 18 that pressurizes the resin mixture 13 in the stacking direction. Further, the pressurization unit 18 includes the adjustment mechanism for adjusting the amount of pressurization. As described above, the stacking structure 10 is pressurized by the pressurization unit 18, and thereby, hysteresis maybe reduced and variations of the detection value of the applied load may be reduced compared to the case without pressurization.
Further, as described above, the pressurization unit 18 has the first board 11, the second board 12 placed along the direction in the stacking on the first board 11, and the screw 180 as the adjustment mechanism. The distance between the first board 11 and the second board 12 changes by turning of the screw 180, and thereby, the amount of pressurization is adjusted. Thus, the resin mixture 13 may be moderately pressurized. Note that the pressurization is not particularly limited, but preferably e.g. within a range from 1 MPa to 15 MPa. Thereby, the variations of the detection value may be effectively reduced and damage on the resin mixture 13 due to excessive pressurization may be effectively suppressed.
As described above, the carbon nanotube 132 has the diameter preferably within the range from 100 nm to 200 nm, and the length preferably within the range from 2 μm to 10 μm. With this diameter and the length, the resistance value change between the first, second electrodes 14, 16 relative to the change of the load applied to the pressure-sensitive device 1 is smoother and the amount of resistance value change between the first, second electrodes 14, 16 for the load applied to the pressure-sensitive device 1 is larger. Accordingly, the load applied to the pressure-sensitive device 1 may be detected with higher accuracy.
As described above, the content rate of the carbon nanotubes 132 in the resin mixture 13 is preferably within the range from 2 wt % to 30 wt %. Thereby, moderate conductivity may be provided to the resin mixture 13 and reduction of mechanical strength and difficulty of mixing in the resin mixture 13 due to excessive mixing of the carbon nanotubes 132 may be suppressed.
As described above, the resin 131 preferably contains PC (polycarbonate). When the resin 131 contains PC, the resin 131 is inexpensive, easy to handle, and easily mixed with the carbon nanotubes 132. Further, the resin mixture 13 is easily formed to be harder. Accordingly, allowable load per unit area may be higher and the mechanical strength of the pressure-sensitive device 1 may be improved, and the measurable range may be secured to be wider. In addition, deformation and settling with time of the resin mixture 13 may be suppressed, and degradation and fluctuations of the detection characteristics with time may be suppressed.
As described above, the resin 131 preferably contains at least one of PP (polypropylene), PET (polyethylene terephthalate), and PPS (polyphenylene sulfide). When the resin 131 contains at least one of PP, PET, and PPS, the resin 131 is inexpensive, easy to handle, and easily mixed with the carbon nanotubes 132 like PC. Further, the resin mixture 13 is easily formed to be harder. Accordingly, allowable load per unit area may be higher and the mechanical strength of the pressure-sensitive device 1 may be improved, and the measurable range may be secured to be wider. In addition, deformation and settling with time of the resin mixture 13 may be suppressed, and degradation and fluctuations of the detection characteristics with time may be suppressed.
As described above, the resin mixture 13 has the sheet-like shape, and the thickness of the resin mixture 13 is preferably within the range from 50 μm to 200 μm. Thereby, the sufficiently thin resin mixture 13 that sufficiently fulfills the function may be obtained. Accordingly, the pressure-sensitive device 1 may be downsized while maintaining detection characteristics of the pressure-sensitive device 1.
As described above, the Young's modulus of the resin mixture 13 is preferably within the range from 1.5 times to 2 times the Young's modulus of the resin 131. Thereby, the resin mixture 13 is sufficiently hard and the detectable range is wider, and higher loads may be detected. Further, excessive hardening may be suppressed and degradation of the detection characteristics may be effectively suppressed.
The hand 2 shown in
The sliders 31, 32 are supported by the base 30 via slide guides SG and slidable relative to the base 30 in directions of arrows in the drawing. Further, the motor 6 is coupled to the slider 31, and the slider 31 slides by driving of the motor 6. Similarly, the motor 7 is coupled to the slider 32, and the slider 32 slides by driving of the motor 7. The motors 6, 7 are not particularly limited, but e.g. piezoelectric motors maybe used. The sliders 31, 32 are moved by the motors 6, 7, and thereby, the finger units 4, 5 may grip the object and release the gripped object.
As below, the finger units 4, 5 will be explained using the finger unit 4 as a representative example and omitting the explanation of the finger unit 5, because the finger units 4, 5 have the same configuration as each other. As shown in
The nail part 42 is fastened to the displacement portion 413 by screws and extends obliquely toward the finger unit 5 side. Further, the nail part 42 has a base portion 421 facing the base portion 411 with an air gap G in between. The pressure-sensitive device 1 is placed between the base portion 411 and the base portion 421. Note that the fastening method of the nail part 42 to the displacement portion 413 is not limited to fastening using screws.
As shown in
The pressurization unit 18 has the single screw 180, and the screw 180 is screwed into the base portion 421 of the nail part 42. The screw 180 is fastened and the second board 12 is pressed in the distal end portion of the screw 180, and thereby, the stacking structure 10 is pressurized. According to the configuration, by adjusting the amount of fastening of the screw 180, the magnitude of pressurization on the stacking structure 10 may be easily adjusted.
According to the configuration, for example, in the case where an action of pressing an object with the tip ends of the nail parts 42, 52 is performed or the like, as shown in
As described above, the hand 2 has the pressure-sensitive device 1. Accordingly, the hand 2 may enjoy the advantages of the pressure-sensitive device 1 and may exert excellent reliability.
Note that the configuration of the hand 2 is not particularly limited. For example, the hand 2 of the embodiment has the two finger units 4, 5, however, the number of finger units may be one, three, or more. Further, in the hand 2 of the embodiment, the finger units 4, 5 respectively have the pressure-sensitive devices 1, however, one of the devices maybe omitted. That is, in the case where a plurality of finger units are provided, the pressure-sensitive device 1 may be placed in at least one finger unit. Furthermore, in the hand 2 of the embodiment, the pressure-sensitive devices are placed in the finger units 4, 5, however, the pressure-sensitive device 1 may be placed in the base 30, for example.
Next, the robot according to the third embodiment of the present disclosure will be explained.
The robot 1000 shown in
The robot main body 1100 is a six-axis robot, and has abase 1110 fixed to a floor or ceiling, an arm 1120 pivotably coupled to the base 1110, an arm 1130 pivotably coupled to the arm 1120, an arm 1140 pivotably coupled to the arm 1130, an arm 1150 pivotably coupled to the arm 1140, an arm 1160 pivotably coupled to the arm 1150, an arm 1170 pivotably coupled to the arm 1160, and a control apparatus 1180 that controls driving of these arms 1120, 1130, 1140, 1150, 1160, 1170. Further, a hand coupling part is provided in the arm 1170, and the hand 2 is attached to the hand coupling part as an end effector according to work to be executed by the robot main body 1100.
As described above, the robot 1000 has the pressure-sensitive device 1. Accordingly, the robot 1000 may enjoy the advantages of the pressure-sensitive device 1 and may exert excellent reliability.
The configuration of the robot 1000 is not particularly limited. For example, the number of arms may be one to five, seven, or more. Further, the robot 1000 may be a horizontal articulated robot (scalar robot) or dual-arm robot.
As above, the pressure-sensitive device, hand, and robot according to the present disclosure are explained based on the illustrated embodiments, however, the present disclosure is not limited to those, and the configurations of the respective parts may be replaced by arbitrary configurations having the same functions. Further, another arbitrary configuration may be added to the present disclosure. Furthermore, the respective embodiments may be appropriately combined.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-089079 | May 2018 | JP | national |
