Robot

Abstract

To provide a robot capable of reducing fluid resistance.SOLUTION: A robot 10 includes a mechanical arm 23 for outputting power for underwater action, a first thruster 25a and a second thruster 25b, and a surface unit S with dimples 41 formed thereon. The surface unit S has a configuration formed such that the prescribed speed of a relative water flow underwater corresponds to a Reynolds number indicating a supercritical region regarding variation in resistance coefficient (for example, fluid resistance coefficient Cd). The surface unit S is provided on respective surfaces of a first skeleton F1, respective control units 29a and 29b, a cover member 30, and the mechanical arm 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a robot. [Background technology]

[0002] Conventionally, small or medium-sized underwater robots are known that are expected to move at low speeds underwater, operate in stagnant or slow-flowing water, and prioritize portability and operability. For such small or medium-sized underwater robots, improvements such as increased thruster output and reduced fluid resistance are desired so that they can operate in high-speed water currents. Conventionally, for example, a structure has been known in which, by providing a plurality of protrusions and depressions on the surface of an object, laminar flow is maintained even when the flow velocity of the fluid (surface flow) contacting the surface of the object increases, thereby reducing flow resistance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-7846 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, when increasing the output of the propulsion units, problems arise in that it becomes necessary to add more propulsion units and increase the power supply, etc. Furthermore, when downsizing or changing the shape of the vehicle to reduce fluid resistance, for example, problems arise when effective improvements become difficult due to restrictions on the size of the mounted components and the structure or function of exposed parts such as the arms. Furthermore, for example, when maintaining laminar surface flow as in the above-mentioned conventional structure, boundary layer separation is likely to occur, and the increased pressure drag makes it difficult to operate under high-speed water currents.

[0005] An object of the present invention is to provide a robot that can reduce fluid resistance. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the above object, the present invention employs the following aspects. (1): A robot according to one aspect of the present invention (e.g., robot 10 in the embodiment) includes a power unit (e.g., power unit 23b, first thruster 25a, and second thruster 25b in the embodiment) that outputs power for underwater operation, and a surface portion (e.g., surface portion S in the embodiment) on which dimples (e.g., dimple 41 in the embodiment) are formed.

[0007] (2): In the robot described in (1) above, the shape of the surface portion may be formed so that a predetermined speed of the relative water flow in the water corresponds to a Reynolds number that indicates a supercritical region regarding the change in the drag coefficient (e.g., the fluid resistance coefficient Cd in the embodiment).

[0008] (3): The robot described in (1) above may have a main body portion (e.g., the first skeleton F1, each control unit 29a, 29b, and cover member 30 in the embodiment) and an exposed portion exposed from the main body portion (e.g., the mechanical arm 23 in the embodiment), and the surface portion may have the surface of each of the main body portion and the exposed portion.

[0009] (4) In the robot described in (3) above, the exposed portion may be a mechanical arm (for example, the mechanical arm 23 in the embodiment).

[0010] (5): In the robot described in (2) above, the shape of the surface portion on the downstream side of the relative water flow may be formed so that the relatively smaller predetermined velocity corresponds to the Reynolds number indicating the supercritical region compared to the shape on the upstream side.

[0011] (6): In the robot described in (2) above, at least one of the size (e.g., diameter h in the embodiment) of the peripheral portion (e.g., peripheral portion 41a in the embodiment) forming the dimple and the depth (e.g., depth k in the embodiment) of the surface (e.g., surface 41A in the embodiment) forming the dimple is set according to the magnitude of the predetermined speed, and at least one of the size of the peripheral portion tends to increase and the depth tends to decrease as the predetermined speed corresponding to the Reynolds number indicating the supercritical region increases.

[0012] (7): The robot described in any one of (1) to (5) above may have a buoyancy section (e.g., second section 13 in the embodiment) that generates buoyancy, and the surface section may have the surface of the buoyancy section. [Effects of the Invention]

[0013] According to the above (1), the provision of a surface portion with dimples makes it easier to generate a turbulent boundary layer, and by shifting the separation point during laminar separation, it is possible to suppress an increase in pressure drag and facilitate operation under conditions of high relative water flow speeds. Conditions that cause high relative water flow speeds include, for example, water flows caused by ocean currents and tidal currents in a stationary state, as well as high-speed relative water flows caused by movements such as movement and turning due to the power of a power unit or the operation of a specific part. For example, it is possible to accurately and appropriately maintain a stationary state or move or turn under high-speed water flow, and to accurately and appropriately operate a movable member such as a mechanical arm.

[0014] In the case of (2) above, by making the predetermined speed of the water flow relative to the robot correspond to the Reynolds number indicating the supercritical region, the drag coefficient can be significantly reduced compared to, for example, when the predetermined speed corresponds to the critical region.

[0015] In the case of (3) above, by forming dimples on the surfaces of the main body and exposed portion where the relative water flow speed is likely to increase, an increase in pressure drag can be effectively suppressed.

[0016] In the case of (4) above, in addition to the fact that the mechanical arm is easily exposed toward the outside of the robot, which tends to increase the relative water flow speed, the increase in pressure drag can be effectively suppressed by forming dimples on the surface of the mechanical arm, which is difficult to reduce by changing the shape due to shape constraints.

[0017] In the case of (5) above, the speed of the water flow relative to the robot is more likely to decrease downstream of the relative water flow than upstream, so by setting the shape of the surface portion so that a smaller predetermined speed corresponds to the Reynolds number that indicates the supercritical region, the increase in pressure drag can be effectively suppressed.

[0018] In the case of (6) above, by setting at least one of the size of the peripheral portion of the dimple shape and the depth of the concave surface according to a predetermined speed of the water flow expected relative to the robot, the increase in pressure drag can be easily suppressed.

[0019] In the case of (7) above, since fluid resistance tends to increase in the buoyancy section, which is preferably enlarged for ease of control of the center of buoyancy and center of gravity, forming dimples on the surface of the buoyancy section can effectively suppress the increase in pressure drag. Also, forming dimples on the surface of the buoyancy section can improve the ease of control of the center of buoyancy and center of gravity while suppressing the increase in fluid resistance that accompanies an increase in the size of the buoyancy section. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing a configuration of a robot according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a cover member that forms a surface portion of the robot according to the embodiment of the present invention. [Figure 3]FIG. 3 is a cross-sectional view showing dimples on the surface of the robot according to the embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing an example of the correspondence relationship between the fluid resistance coefficient and the Reynolds number on the surface of a cylindrical portion of the robot according to the embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing an example of the correspondence between the shape of dimples on the surface of the robot, the fluid resistance coefficient, and the Reynolds number according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a robot according to an embodiment of the present invention will be described with reference to the accompanying drawings. The robot 10 of the embodiment is, for example, an unmanned mobile object on water or underwater, such as an unmanned undersea vehicle (UUV) or an unmanned surface vehicle (USV). For example, an unmanned underwater vehicle, such as a UUV, includes a remotely operated ROV (remotely operated vehicle) and an autonomous underwater vehicle (AUV). For example, a remotely operated ROV includes a so-called underwater drone.

[0022] FIG. 1 is a perspective view showing the configuration of a robot 10 according to an embodiment. In the following description, the X-axis, Y-axis, and Z-axis directions, which are orthogonal to one another in three-dimensional space, are parallel to each other. For example, as shown in Fig. 1, the X-axis direction is parallel to the front-to-rear direction of the robot 10, the Y-axis direction is parallel to the left-to-right direction of the robot 10, and the Z-axis direction is parallel to the up-to-down direction of the robot 10. For example, the positive direction of the X-axis is the forward direction of the robot 10, the positive direction of the Y-axis is the leftward direction of the robot 10, and the positive direction of the Z-axis is the upward direction of the robot 10.

[0023] As shown in FIG. 1, the robot 10 comprises a lower first section 11 and an upper second section 13 that are connected to each other. The first section 11 includes, for example, a plurality of connecting members 21a and frame members 21b that form a first skeleton F1. The outer shape of each of the plurality of connecting members 21a is, for example, a columnar shape extending in the vertical direction. The plurality of connecting members 21a are fixed to, for example, corners of the frame member 21b, and are connected to the second section 13 described below. The outer shape of the frame member 21b is, for example, a rectangular ladder shape. The frame member 21b supports, for example, various devices mounted on the first section 11.

[0024] The first section 11 includes, for example, two mechanical arms 23, four first thrusters 25a and two second thrusters 25b, a camera system 27a and a sensor 27b, one front control unit 29a and two rear control units 29b.

[0025] The base ends of the two mechanical arms 23 are fixed to the left and right corners of the front of the frame member 21b. Each mechanical arm 23 is, for example, a manipulator and includes a hinge (joint) driven by an actuator and multiple beams (links) connected by the hinges (joints). Each mechanical arm 23 includes, for example, an end effector (hand) 23a provided at the tip end thereof for performing various tasks such as grasping and moving an object. Each mechanical arm 23 includes, at the base end thereof, a power unit 23b that outputs power for operation. For example, when stopped, each mechanical arm 23 is disposed inside the left and right ends of the frame member 21b, and when operating, the tip end thereof protrudes outward (forward, etc.) from the robot 10.

[0026] The four first thrusters 25a are arranged, for example, two on each side at the front and rear of the frame member 21b, side by side. The two second thrusters 25b are arranged, for example, side by side on the left and right in the center of the frame member 21b in the front-rear direction. Each of the first thrusters 25a is a so-called azimuth thruster. Each of the first thrusters 25a includes, for example, a support that rotates around a first rotation axis along the vertical direction, and a propeller that is supported by the support and rotates around a second rotation axis that is perpendicular to the first rotation axis. Each of the first thrusters 25a generates, for example, a thrust in a direction perpendicular to the vertical direction. Each second thruster 25b includes, for example, a propeller that rotates around a rotation axis that is inclined at an acute angle with respect to the vertical direction. Each second thruster 25b generates, for example, thrust in directions that include at least the vertical direction.

[0027] The camera system 27a is disposed, for example, at the center in the left-right direction at the front of the frame member 21b. The camera system 27a includes, for example, a camera that captures images of the outside in front of the robot 10, and a plurality of lights that illuminate the outside in front of the robot 10. Sensor 27b is disposed, for example, below camera system 27a in the front of frame member 21b. Sensor 27b is, for example, a Doppler Velocity Log (DVL) that detects relative velocity based on emitting sound waves and detecting reflected and scattered waves.

[0028] One front control unit 29a is disposed, for example, at a position in front of the frame member 21b and behind the camera system 27a. The two rear control units 29b are arranged, for example, side by side on the left and right at the rear of the frame member 21b. Each of the control units 29a, 29b includes, for example, a box-shaped housing that seals the interior, a power supply and an electronic control unit disposed inside the housing, etc. Each of the control units 29a, 29b controls, for example, the operation of each of the mechanical arms 23, each of the thrusters 25a, 25b, the camera system 27a, the sensor 27b, and a drive unit of the second portion 13 described below.

[0029] The second section 13 includes a cover member 30, a second skeleton, a buoyant member, and a drive unit that are covered by the cover member 30. The second section 13 generates buoyancy by the buoyant member that is disposed inside the cover member 30. The cover member 30 has an outer shape, for example, a rectangular box shape, and has a surface formed with a plurality of through holes that allow the inside and outside to communicate with each other. The cover member 30 is fixed to the second skeleton. The second framework is fixed to, for example, the multiple connecting members 21a of the first framework F1, and supports the cover member 30 and the drive unit. The buoyant member is moved by a drive unit inside the cover member 30 to change at least one of the center of buoyancy and the center of gravity of the entire robot 10. The buoyant member is moved to maintain or change the posture of the robot 10, for example, when the robot 10 moves or when each mechanical arm 23 is operated. The drive unit includes, for example, a power source and a transmission mechanism that transmits the power output from the power source to the buoyant member.

[0030] The robot 10 has a surface portion S on which dimples 41 of a predetermined shape are formed, for example, by covering the surface of a predetermined portion with a dimple cover member 40. The predetermined portion is at least a portion that comes into contact with a fluid such as water underwater, such as the main body portion of the robot 10 and an exposed portion exposed from the main body portion. The main body portion of the robot 10 is, for example, each of the first portion 11 and the second portion 13, which are fixed or stationary and have a relatively large surface area that comes into contact with a fluid such as water. The main body portion of the robot 10 is, for example, the first skeleton F1, the control units 29a and 29b, and the cover member 30. The exposed portions of the robot 10 are, for example, each of the first portion 11 and the second portion 13, which are exposed to the outside when the first portion 11 and the second portion 13 are in a moving state, and have a relatively large surface area that comes into contact with a fluid such as water. The exposed portions of the robot 10 are, for example, each of the mechanical arms 23.

[0031] Fig. 2 is a perspective view of a dimple cover member 40 that forms the surface portion S of the robot 10 of the embodiment. Fig. 3 is a cross-sectional view showing a dimple 41 on the surface portion S of the robot 10 of the embodiment. As shown in Fig. 2, the outer shape of the dimple cover member 40 is, for example, cylindrical. The dimple cover member 40 has, for example, a surface 40A on which a plurality of dimples 41 are dispersed. The outer shape of the periphery 41a forming each dimple 41 is, for example, circular. As shown in Fig. 3, each dimple 41 is formed by a concave surface 41A that curves, for example, into a concave spherical shape from the circular periphery 41a in the thickness direction.

[0032] The shape of surface 40A on which multiple dimples 41 are formed is a shape formed, for example, so that a predetermined speed of the relative water flow in water corresponds to the Reynolds number Re, which indicates a supercritical region for the change in the drag coefficient. The relative water flow includes, for example, water flow caused by ocean currents and tidal currents relative to robot 10 in a stationary state, and relative water flow caused at appropriate parts by movement such as the movement and turning of robot 10 or the operation of each mechanical arm 23. FIG. 4 is a diagram showing an example of the correspondence relationship between the fluid resistance coefficient Cd and the Reynolds number Re on the surface S of the cylindrical portion of the robot 10 according to the embodiment. As shown in Figure 4, the critical Reynolds number Rec indicates the boundary between a critical region where the fluid resistance coefficient Cd, which tends to decrease as the water flow speed increases (i.e., the Reynolds number Re increases), becomes almost constant, and a supercritical region where the value drops sharply from the value in the critical region.

[0033] FIG. 5 is a diagram showing an example of the correspondence relationship between the shape of the dimples 41 on the surface S of the robot 10 according to the embodiment, and the fluid resistance coefficient Cd and the Reynolds number Re. In the example shown in Figures 3 and 5, the shape of the dimple 41 is described by, for example, the ratio U (= k / h) of the depth k of the concave spherical surface 41A to the diameter h of the circular peripheral portion 41a. As shown in Figure 5, the Reynolds number Re, which indicates the supercritical region, varies depending on the shape of the dimple 41. For example, as the ratio U (= k / h) of the depth k to the diameter h decreases, the Reynolds number Re, which indicates the supercritical region, tends to increase. For example, the first predetermined value U1 is smaller than the second predetermined value U2, which is smaller than the third predetermined value U3, which is smaller than the fourth predetermined value U4. For example, if the diameter h of dimple 41 is constant, the Reynolds number Re, which indicates the supercritical region, tends to increase as the depth k of dimple 41 decreases. As a result, the shape of dimple 41 is set so that the predetermined speed of the water flow assumed relative to robot 10 corresponds to the Reynolds number Re, which indicates the supercritical region, thereby effectively reducing the fluid resistance coefficient Cd.

[0034] For example, if the predetermined speed of the water flow expected relative to the robot 10 corresponds to the first Reynolds number Re1 shown in Figure 5, the shape of the dimple 41 is set so that the ratio U (= k / h) of the depth k to the diameter h is a first predetermined value U1. For example, if the predetermined speed of the water flow expected relative to the robot 10 corresponds to the second Reynolds number Re2 shown in Figure 5, the shape of the dimple 41 is set so that the ratio U (= k / h) of the depth k to the diameter h is a second predetermined value U2.

[0035] In addition, the correspondence between the predetermined speed of the water flow assumed relative to the robot 10 and the optimal shape of the dimples 41 on the surface portion S may be obtained, for example, by appropriate tests that reproduce the actual fluid flow field.

[0036] As described above, the robot 10 of the embodiment includes the surface portion S on which the dimples 41 are formed. This facilitates the generation of a turbulent boundary layer, suppresses the occurrence of boundary layer separation, and thereby suppresses an increase in pressure drag, facilitating operation under conditions of high relative water flow speeds. Conditions that result in high relative water flow speeds include, for example, water flow caused by ocean currents and tidal currents in a stationary state, as well as high-speed relative water flow caused by movements such as movement and rotation caused by the thrusters 25 a, 25 b and the power unit 23 b, or the operation of the mechanical arms 23. For example, the robot 10 can accurately and appropriately maintain a stationary state or move or rotate under high-speed water flow, and can accurately and appropriately operate movable members such as mechanical arms.

[0037] By making the predetermined speed of the water flow assumed relative to the robot 10 correspond to the Reynolds number Re, which indicates the supercritical region, the drag coefficient (e.g., the fluid resistance coefficient Cd) can be significantly reduced compared to, for example, when the predetermined speed corresponds to the critical region. By forming dimples 41 on the surfaces of areas where the relative water flow speed is likely to increase, such as the main body parts such as the first skeleton F1, each control unit 29a, 29b and cover member 30, and exposed parts such as each mechanical arm 23, the increase in pressure drag can be effectively suppressed.

[0038] In addition to the fact that the mechanical arm 23 is easily exposed outward from the robot 10, which makes it easy for the relative water flow speed to increase, the formation of dimples 41 on the surface of the mechanical arm 23, which is difficult to reduce pressure drag by changing its shape due to shape constraints, makes it possible to effectively suppress the increase in pressure drag. Since fluid resistance is likely to increase in the second region 13, where an increase in size is preferable for ease of control of the center of buoyancy and center of gravity, the formation of dimples 41 on the surface of the second region 13 can effectively suppress an increase in pressure drag. Furthermore, the formation of dimples 41 on the surface of the second region 13 can improve the ease of control of the center of buoyancy and center of gravity while suppressing an increase in fluid resistance that accompanies an increase in the size of the second region 13.

[0039] (Variation) Modifications of the embodiment will be described below. Note that the same parts as those in the above-described embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified. In the above-described embodiment, the outer shape of the dimple cover member 40 is cylindrical, but this is not limiting. For example, the outer shape of the dimple cover member 40 may be other shapes, such as a sheet shape that covers the surface of a predetermined portion of the robot 10. In the above-described embodiment, the outer shape of the peripheral edge 41a forming the dimple 41 is circular, but this is not limiting. For example, the outer shape of the peripheral edge 41a may be other shapes such as oval, rectangular, or polygonal. In the above-described embodiment, the outer shape of concave surface 41A forming dimple 41 is a curved surface such as a spherical surface, but this is not limited thereto. For example, the outer shape of concave surface 41A may be a curved surface such as a concave polyhedral surface.

[0040] In the above-described embodiment, the depth k of the concave spherical surface 41A that describes the shape of the dimple 41 and the diameter h of the circular peripheral portion 41a are changed in accordance with the Reynolds number that indicates the supercritical region, but this is not limited to this, and the diameter h may also be changed. In the above-described embodiment, the shape of the dimple 41 may be described by, for example, the size of the peripheral edge 41a of various shapes forming the dimple 41 and the depth of the surface 41A of various concave shapes forming the dimple 41. For example, at least one of the size of the peripheral edge 41a and the depth of the surface 41A may be set according to the magnitude of a predetermined velocity corresponding to the Reynolds number Re indicating a supercritical region (i.e., the predetermined velocity of the water flow assumed relative to the robot 10). For example, at least one of the size of the peripheral edge 41a may increase and the depth of the surface 41A may decrease as the predetermined velocity corresponding to the Reynolds number Re indicating a supercritical region (i.e., the predetermined velocity of the water flow assumed relative to the robot 10) increases. This makes it possible to easily suppress an increase in pressure drag.

[0041] In the above-described embodiment, the surface portion S has a shape formed by dispersing a plurality of dimples 41, but this is not limited thereto. The shape of the surface portion S may be any shape that at least suppresses an increase in pressure drag or fluid resistance. For example, in the case of the cylindrical dimple cover member 40 shown in FIG. 2, at least one annular groove shape formed along the circumferential direction may be formed as a dimple.

[0042] In the above-described embodiment, the shape of the surface portion S is a shape in which a plurality of dimples 41 of the same shape are formed on the surface, but this is not limited to this. For example, dimples 41 of different shapes may be formed on the downstream side and the upstream side of the relative water flow. For example, the shape of the surface portion S on the downstream side of the relative water flow may be formed so as to correspond to a Reynolds number Re that indicates a supercritical region at a relatively smaller predetermined speed (i.e., a predetermined speed of the water flow assumed relative to the robot 10) compared to the shape on the upstream side. In this case, since the speed of the water flow relative to the robot 10 is more likely to decrease downstream of the relative water flow than upstream, the increase in pressure drag can be effectively suppressed by setting the shape of the surface portion S so that a smaller predetermined speed corresponds to the Reynolds number Re, which indicates the supercritical region.

[0043] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0044] 10...robot, 11...first part, 13...second part (buoyancy part), 23...mechanical arm (exposed part), 23a...end effector (hand), 23b...power unit, 25a...first thruster (power unit), 25b...second thruster (power unit), 27a...camera system, 27b...sensor, 29a...front control unit (main body part), 29b...rear control unit (main body part), 30...cover member (main body part), 40...dimple cover member, 40A...surface, 41a...periphery, 41A...surface, F1...first skeleton (main body part), S...surface part.

Claims

1. a power unit that outputs power for underwater operation; A surface portion on which dimples are formed Equipped with robot.

2. The shape of the surface portion is This shape is formed so that a given relative water flow velocity in the water corresponds to a Reynolds number that indicates the supercritical region for the change in the drag coefficient. The robot of claim 1 .

3. a main body portion and an exposed portion exposed from the main body portion; The surface portion is a surface of each of the main body portion and the exposed portion; The robot of claim 1 .

4. The exposed portion is a mechanical arm. The robot according to claim 3.

5. The shape of the surface portion on the downstream side of the relative water flow is formed so that the predetermined velocity is relatively smaller than the shape on the upstream side, and corresponds to a Reynolds number that indicates the supercritical region. The robot according to claim 2.

6. At least one of the size of the peripheral portion forming the dimple and the depth of the surface forming the dimple is set in accordance with the magnitude of the predetermined speed, As the predetermined velocity corresponding to the Reynolds number indicating the supercritical region increases, at least one of the size of the peripheral portion increases and the depth decreases. The robot according to claim 2.

7. A buoyancy unit that generates buoyancy is provided, The surface portion is The surface of the buoyancy portion The robot according to any one of claims 1 to 5.

Images