Piezoelectric-driven amphibious extraterrestrial planet exploration robot and working method thereof

Abstract

The invention discloses a piezoelectric-driven amphibious extraterrestrial planet surveying robot and a working method thereof, the whole robot adopts a differential-driven three-wheel layout structure, and double piezoelectric driving feet arranged on the two sides of the front end drive an end paddle impeller to drive a tail end driven paddle impeller to move. The piezoelectric driving feet are fixed on the metal vehicle body through bolts, a driving controller is arranged in the metal vehicle body, buoyancy adjusting devices are arranged on two sides of the metal vehicle body, and the tail of the metal vehicle body is connected with a driven paddle wheel through a driven wheel adjusting rod. The piezoelectric driving foot part comprises a pre-tightening force bolt, a fixing flange, a piezoelectric ceramic set, a metal front end, a double-end stud, a double-bearing rotor, a rotor pre-compression spring and a locknut. According to the piezoelectric driving foot, the bending vibration mode of the cantilever beam type stator is stimulated, and the free end vibration is used for driving the double-bearing rotor to drive the driving end paddle impeller to rotate. According to the invention, the integrated design of structure and function is realized, the structure is simple, and microminiaturization is easy. The piezoelectric driving mode is adopted for underwater operation, dynamic sealing is not needed, the pressure resistance is good, and high application value and good economic benefits are achieved in the field of extraterrestrial planet exploration.

Description

Technical Field

[0001] This invention relates to the fields of piezoelectric drive and amphibious robot technology, and in particular to a piezoelectric-driven amphibious planetary exploration robot and its working method. Background Technology

[0002] In recent years, with the exploration of a series of extraterrestrial bodies such as the Moon, Mars, and Jupiter, we have gained a relatively detailed understanding of their different surface environments, making future exploration of these planets inevitable. With the launch of the US Europa Clipper probe, humanity began exploring the mysterious icy world of Europa. Planets like Europa, Ganymede, Callisto, and Enceladus have icy surfaces and potential liquid oceans. Research and development of celestial rover probes targeting such ecosystems has been underway for several years, with small mobile exploration robots gradually becoming a new direction for development due to their high cost-effectiveness and low risk. Currently, most amphibious exploration robots use electromagnetic motors combined with traditional transmission mechanisms, resulting in complex structures that are difficult to miniaturize. They also have extremely high requirements for dynamic sealing underwater, poor reliability, and cannot adapt to high water pressure environments or extreme temperature differences on extraterrestrial bodies.

[0003] A piezoelectric actuator is a type of actuator based on the inverse piezoelectric effect. It can excite high-frequency, low-amplitude vibrations of the stator through piezoelectric ceramics, thereby driving the rotor. It features simple structure and self-locking upon power failure. Furthermore, its simple structure eliminates the need to consider complex dynamic seals underwater, enabling it to adapt to various extreme temperature differences and high-pressure deep-sea environments. It is an ideal actuator for miniature planetary exploration robots.

[0004] In existing amphibious exploration robots (patent publication number: CN120056659A), four servo motors are required to connect to external connecting rods, which then connect to drive legs to achieve propulsion. This results in a complex transmission device, increasing the difficulty of structural assembly and making it difficult to achieve integrated structural functions. Furthermore, traditional electromagnetic motors cannot achieve self-locking functionality when power is off, and achieving full sealing in high water pressure environments is also quite challenging. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of planetary exploration robots mentioned in the background art in terms of adapting to marine environments and miniaturization, and to provide a piezoelectric actuator-driven amphibious planetary exploration robot and its working method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A piezoelectric-driven amphibious exoplanet exploration robot and its working method are characterized by comprising a metal vehicle body, two piezoelectric driven feet, a drive controller, a buoyancy adjustment device, a drive impeller, a driven wheel adjustment rod, a driven impeller, a driven wheel sleeve, and fixing bolts.

[0008] The metal vehicle body is a rectangular hollow structure, comprising a first top surface, a first bottom surface, and four first to fourth side surfaces connected end to end. The first top surface has a rectangular hollow structure. The first and third side surfaces are the front and rear surfaces of the vehicle body, respectively, and the second and fourth side surfaces are the left and right end surfaces of the vehicle body, respectively. A semi-cylindrical boss structure is located at the center of the first side surface, arranged outside the first front surface, with its central axis parallel to the top edge of the first front surface. A first through hole is located at the center of the cylinder along its axis, and N first threaded blind holes are evenly distributed around the through hole. The central axes of the first through hole and the first threaded blind holes are parallel. A rectangular boss structure is located at the center of the third side surface, with its top surface parallel to the top surface of the vehicle body, arranged outside the fourth end surface. A second through hole is located at the center of the rectangular boss, with its central axis parallel to the top edge of the rear surface. Two fan-shaped lug structures are located on the outer sides of the second and fourth side surfaces, flush with the top and bottom surfaces, respectively, arranged on both sides of the metal vehicle body. M evenly distributed second through holes are opened on the lugs, all of which are arranged in a straight line and parallel to the side surfaces, with their central axes arranged parallel to the vertical direction. (M is an integer greater than 2)

[0009] The piezoelectric drive foot includes a preload bolt, a fixing flange, a piezoelectric ceramic assembly, a metal front end, a double-ended stud, and a double-bearing rotor. The double-bearing rotor includes a metal rotor, two small bearings, bearing retaining rings, a preload spring, and a lock nut. The piezoelectric drive foot is fixed to the second threaded blind hole of the metal vehicle body by fixing bolts, with one piezoelectric drive foot arranged on each side.

[0010] The fixed flange is a hollow variable cross-section structure, which is composed of three parts in sequence: a first cylindrical boss, a disc structure, and a second cylindrical boss. The central axes of the three parts coincide. The inner and outer diameters of the first cylindrical boss and the second cylindrical boss are the same. Eight third through holes are evenly distributed on the outer side of the disc structure, and its central axis coincides with the central axis of the variable cross-section body. These holes are used to mate with the second threaded blind hole of the metal shell. The variable cross-section body has a second through hole along its central axis, which runs through the entire variable cross-section body.

[0011] The piezoelectric component has a near-cylindrical structure and includes 4A piezoelectric ceramic sheet groups and 4A+1 electrode sheets, where A is a natural number greater than or equal to 1.

[0012] The piezoelectric ceramic sheet is a circular double-section piezoelectric ceramic sheet with a through hole in the center, which is polarized along the thickness direction, and the two sections on both sides of the polarization boundary line have opposite polarization directions.

[0013] The electrode plate is shaped like a ring with ear pieces and has a through hole in the center. The ear pieces are used to apply electrical signals for excitation.

[0014] The 4A+1 electrode sheets and 4A piezoelectric ceramic sheets are arranged alternately to form a cylindrical structure. The polarization boundary lines of the 4c+1th piezoelectric ceramic sheet are coplanar and have the same polarization direction; the polarization boundary lines of the 4c+2th piezoelectric ceramic sheet are coplanar and have the same polarization direction; the polarization boundary lines of the 4c+3th piezoelectric ceramic sheet are coplanar and have the same polarization direction; and the polarization boundary lines of the 4c+4th piezoelectric ceramic sheet are coplanar and have the same polarization direction, where c is a natural number greater than or equal to 0 and less than A. The polarization boundary lines of the 1st and 2nd piezoelectric ceramic sheets are coplanar and have opposite polarization directions; and the polarization boundary lines of the 3rd and 4th piezoelectric ceramic sheets are coplanar and have opposite polarization directions.

[0015] The metal front end is a composite structure composed of a solid cylinder and a hollow cylinder. The end near the fixed flange is a solid cylinder structure, and the end away from the fixed flange is a hollow cylinder structure. The solid cylinder has a second threaded blind hole along the axis at the end face near the fixed flange and a first blind hole along the axis at the end face away from the fixed flange.

[0016] The preload bolt passes through the fixed flange and the piezoelectric ceramic assembly in sequence, and is connected to the second threaded blind hole of the metal front end, clamping the piezoelectric ceramic assembly between the fixed flange and the metal front end;

[0017] The dual-bearing rotor comprises a metal rotor, two small bearings, bearing retaining rings, a preload spring, and a lock nut. The metal rotor is a rotating structure composed of a frustum and a cylinder, with two identical cylindrical cavities on its front and rear end faces for embedding the small bearings via the retaining rings. The cylindrical end faces of the metal rotor have four evenly distributed fourth-thread blind holes, with their central axes coinciding with the central axes of the bearings. The dual-bearing rotor passes through a double-ended stud and connects to the metal front end, which is then pressed against the metal front end by the preload spring and lock nut.

[0018] The inner and outer rings of the drive impeller are both cylindrical surfaces. Between the inner and outer cylindrical surfaces are x blades parallel to the axis, forming a hub. The outer cylindrical surface is used for road driving, and the inner blades are used for water driving. Four evenly spaced fourth through holes are located on the central cylindrical surface of the drive impeller, with their central axes coinciding with the impeller axis. These holes are used to mate with the fourth threaded blind hole of the drive foot double-bearing rotor. (x is any integer greater than 2)

[0019] The drive controller is embedded in the metal vehicle body and includes a control module for the dual drive feet and scientific detection equipment.

[0020] The buoyancy adjustment device has a semi-cylindrical structure. The non-cylindrical part is provided with a second top surface, a second bottom surface and a fifth side surface. The top surface and the bottom surface are provided with M fifth threaded through holes near the fifth side surface for connecting with the metal vehicle body. The size and arrangement of the through holes are consistent with the second through holes. The fixing bolts pass through the second through holes on the metal vehicle body and are connected to the fifth threaded through holes of the buoyancy adjustment device.

[0021] The driven wheel adjusting rod has a flat key pin-like structure. The front and rear ends are provided with two sixth threaded through holes with parallel central axes. The front threaded hole is connected to the second through hole at the rear end of the metal vehicle body by a fixing bolt. The pitch angle of the robot can be adjusted by adjusting the angle between the driven wheel adjusting rod and the metal shell.

[0022] The driven wheel sleeve is a hollow thin-walled cylindrical structure;

[0023] The driven impeller structure has hollow cylindrical surfaces on both the inner and outer rings. Between the inner and outer cylindrical surfaces, there are x blades parallel to the axis as a hub. The outer cylindrical surface is used for road driving, and the inner blades are used for water driving. The fixing bolts pass through the driven wheel sleeve to connect the driven impeller to the driven wheel adjusting rod.

[0024] The outer cylindrical surfaces of the driving and driven impellers are used for road driving, while the inner blades are used for water driving.

[0025] The piezoelectric ceramic sheet, electrode sheet, and the surfaces in contact with seawater are all coated with an insulating coating. The internal cavity between the pre-tightening bolt of the piezoelectric drive foot and the metal front end is filled with epoxy resin. The cylindrical cavity portion of the metal front end is provided with multiple through holes penetrating the front end to ensure that there is no cavity structure in the inner and outer parts of the drive foot under high water pressure, thereby improving pressure resistance.

[0026] This invention also discloses a method for operating a piezoelectrically driven amphibious planetary exploration robot, comprising the following steps:

[0027] Regarding the driving principle of the planetary exploration robot, a first AC signal is applied to the 4c+1th and 4c+2nd piezoelectric ceramic plates of the piezoelectric components of the driving feet, and a second AC signal is applied to the 4c+3rd and 4c+4th piezoelectric ceramic plates. The first and second AC signals have a 90° or -90° time phase difference, simultaneously exciting two spatially orthogonal B-order bending vibration modes of the piezoelectric driving foot stator, one end of which is fixed and the other is free. This causes the particles on the metal front end to drive the dual-bearing rotor, which in turn rotates the driving impeller, through frictional motion. When the phase difference between the two driving foot signals is 90° or -90°, the two driving feet rotate in the same direction, enabling the planetary exploration robot to travel in a straight line; when the phase difference between the two driving foot signals is 90° and -90° respectively, the two driving feet rotate in opposite directions, enabling the planetary exploration robot to turn in place. (B is an integer greater than 0)

[0028] In terms of operating modes, the piezoelectric drive foot stator is based on a structure design with one end fixed and the other end free. This structure can excite multiple bending vibration modes with one end fixed and the other free, realizing a multi-stage variable speed operating mode. When the drive foot is driven in the low-order bending vibration mode, the operating frequency is low, and the rotor outputs low speed and high torque, which is suitable for rugged land surface environments, high water pressure environments, and extreme low temperature environments. When the drive foot is driven in the high-order bending vibration mode, the operating frequency is high, and the rotor outputs high speed and low torque, which is suitable for high-speed travel on platform land surfaces.

[0029] By changing the air filling inside the buoyancy adjustment devices on the left and right sides, the amphibious exploration robot can be controlled to rise and dive, enabling it to operate at different depths on the water surface, at the bottom, and underwater. In addition, the position of the buoyancy adjustment devices on both sides can be controlled to adjust the overall center of gravity and orientation.

[0030] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0031] 1. The piezoelectric drive foot stator structure of the present invention is a cantilever beam structure with one end fixed and the other end free. While the two stators connect to drive the two driving feet, the structure itself is fixed to the front end of the metal vehicle body, providing cantilever support. This eliminates the need for transmission mechanisms and complex components, achieving an integrated structural and functional design. Furthermore, the drive component is low in cost, small in size, simple in structure, and highly reliable.

[0032] 2. The working principle of the piezoelectric driven foot in this invention is that one end is fixed and the other end is free, with bending vibration modes coupling to drive the rotor to rotate. This structure can excite multiple bending vibration modes, realizing a multi-level speed-regulating working mode for the driven foot. In the low-order bending vibration driving mode, the stator end face amplitude is large, the vibration frequency is low, the driven foot speed is low, and the output torque is large; while in the high-order bending vibration driving mode, the stator end face amplitude is small, the vibration frequency is high, the driven foot speed is high, and the output torque is small. The robot can select different working modes according to different working conditions to achieve stable operation on flat land, steep slopes, shallow pits, or sandy environments.

[0033] 3. This invention eliminates the need for dynamic sealing of the stator-rotor contact portion of the piezoelectric drive foot. It only requires ensuring that the piezoelectric ceramic plates and electrode plates in the piezoelectric drive foot are insulated from seawater. The sealing requirements are extremely low, and it can adapt to different depth environments in potential oceans on extraterrestrial bodies. Compared to traditional motors, which suffer from increased difficulty in dynamic sealing and performance degradation in deep-sea high-pressure environments, this invention eliminates the need for dynamic sealing while exhibiting excellent pressure resistance. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0035] Figure 2 This is a schematic diagram of the exploded structure of the entire machine of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure and cross-section of the piezoelectric drive foot in this invention;

[0037] Figure 4 This is an exploded structural diagram of the piezoelectric driven foot in this invention;

[0038] Figure 5 This is a schematic diagram of the piezoelectric component in this invention;

[0039] Figure 6 This is a schematic diagram of the different bending vibration modes of a piezoelectrically driven foot under different frequency excitations;

[0040] Figure 7 This is a schematic diagram of the electrical signal excitation method of the piezoelectric component in this invention;

[0041] Figure 8 This is a schematic diagram illustrating the working principle of the piezoelectric driven foot of the present invention.

[0042] In the diagram, 1-piezoelectric drive foot, 2-drive impeller, 3-metal body, 4-drive controller and sensing equipment, 5-buoyancy adjustment device, 6-fixing bolt, 7-driven wheel adjusting rod, 8-driven impeller, 9-drive foot fixing bolt, 10-driven wheel adjusting rod fixing bolt, 11-first threaded blind hole, 12-second through hole, 13-fifth threaded through hole, 14-rotor fixing bolt, 15-second through hole, 17-sixth threaded through hole, 18-driven wheel sleeve, 19-first side, 20-third... Side view, 21-Second side view, 22-First top surface, 23-Fourth through hole, 24-Fifth side view, 25-Second bottom surface, 26-Second top surface, 27-Preload bolt, 28-Fixing flange, 29-Third through hole, 30-Second through hole, 31-Piezoelectric assembly, 32-Metal front end, 33-Double-ended stud, 34-Snap ring, 35-Small bearing, 36-Metal rotor, 37-Fourth threaded blind hole, 38-Preload spring, 39-Anti-loosening nut, 40-Dual-zone piezoelectric ceramic plate, 41-Electrode plate Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings:

[0044] This invention can be implemented in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully express the scope of the invention to those skilled in the art. In the drawings, components are enlarged for clarity.

[0045] like Figure 1 , Figure 2 As shown, this patent discloses a piezoelectric-driven amphibious exoplanet exploration robot and its working method, characterized in that it includes a metal body, two piezoelectric driven feet, a drive controller, a buoyancy adjustment device, a drive impeller, a driven wheel adjustment rod, a driven impeller, a driven wheel sleeve, and fixing bolts.

[0046] The metal vehicle body is a rectangular hollow structure, comprising a first top surface, a first bottom surface, and four first to fourth side surfaces connected end to end. The first top surface has a rectangular hollow structure. The first and third side surfaces are the front and rear surfaces of the vehicle body, respectively, and the second and fourth side surfaces are the left and right end surfaces of the vehicle body, respectively. A semi-cylindrical boss structure is located at the center of the first side surface, arranged outside the first front surface, with its central axis parallel to the top edge of the first front surface. A first through hole is located at the center of the cylinder along its axis, and N first threaded blind holes are evenly distributed around the through hole. The central axes of the first through hole and the first threaded blind holes are parallel. A rectangular boss structure is located at the center of the third side surface, with its top surface parallel to the top surface of the vehicle body, arranged outside the fourth end surface. A second through hole is located at the center of the rectangular boss, with its central axis parallel to the top edge of the rear surface. Two fan-shaped lug structures are located on the outer sides of the second and fourth side surfaces, flush with the top and bottom surfaces, respectively, arranged on both sides of the metal vehicle body. M evenly distributed second through holes are opened on the lugs, all of which are arranged in a straight line and parallel to the side surfaces, with their central axes arranged parallel to the vertical direction. (M is an integer greater than 2)

[0047] like Figure 3 , Figure 4 As shown, the piezoelectric drive foot includes a preload bolt, a fixing flange, a piezoelectric ceramic assembly, a metal front end, a double-ended stud, and a double-bearing rotor; the double-bearing rotor includes a metal rotor, two small-sized bearings, bearing retaining rings, a preload spring, and an anti-loosening nut; the piezoelectric drive foot is fixed to the second threaded blind hole of the metal car body by fixing bolts, with one piezoelectric drive foot arranged on each side.

[0048] The fixed flange is a hollow variable cross-section structure, which is composed of three parts in sequence: a first cylindrical boss, a hollow disk, and a second cylindrical boss. The central axes of the three parts coincide. The inner and outer diameters of the first cylindrical boss and the second cylinder are the same. Eight third through holes are evenly distributed on the outer side of the disk structure. The central axis of the disk coincides with the central axis of the variable cross-section body, which is used to mate with the second threaded blind hole of the metal shell. The variable cross-section body has a second through hole along the central axis, which runs through the entire variable cross-section body.

[0049] The piezoelectric component is cylindrical and contains 4A piezoelectric ceramic sheet groups and 4A+1 electrode sheets, where A is a natural number greater than or equal to 1.

[0050] The piezoelectric component described herein has a near-cylindrical structure and contains 4A piezoelectric ceramic sheet groups and 4A+1 electrode sheets, where A is a natural number greater than or equal to 1;

[0051] The piezoelectric ceramic sheet is a circular double-section piezoelectric ceramic sheet with a through hole in the center, which is polarized along the thickness direction, and the two sections on both sides of the polarization boundary line have opposite polarization directions.

[0052] The electrode plate is shaped like a ring with ear pieces and has a through hole in the center. The ear pieces are used to apply electrical signals for excitation.

[0053] The 4A+1 electrode sheets and 4A piezoelectric ceramic sheets are arranged alternately to form a cylindrical structure. The polarization boundary lines of the 4c+1th piezoelectric ceramic sheet are coplanar and have the same polarization direction; the polarization boundary lines of the 4c+2th piezoelectric ceramic sheet are coplanar and have the same polarization direction; the polarization boundary lines of the 4c+3th piezoelectric ceramic sheet are coplanar and have the same polarization direction; and the polarization boundary lines of the 4c+4th piezoelectric ceramic sheet are coplanar and have the same polarization direction, where c is a natural number greater than or equal to 0 and less than A. The polarization boundary lines of the 1st and 2nd piezoelectric ceramic sheets are coplanar and have opposite polarization directions; and the polarization boundary lines of the 3rd and 4th piezoelectric ceramic sheets are coplanar and have opposite polarization directions.

[0054] The metal front end is a composite structure composed of a solid cylinder and a hollow cylinder. When the whole machine is assembled, the end near the fixed flange is a solid cylinder structure, and the end away from the fixed flange is a hollow cylinder structure. The solid cylinder has a second threaded blind hole along the axis at the end face near the fixed flange and a first blind hole along the axis at the end face away from the fixed flange.

[0055] The preload bolt passes through the fixed flange and the piezoelectric assembly in sequence, and is connected to the second threaded blind hole of the metal front end, clamping the piezoelectric assembly between the fixed flange and the metal front end;

[0056] The dual-bearing rotor comprises a metal rotor, two small bearings, bearing retaining rings, a preload spring, and a lock nut. The metal rotor is a rotating structure composed of a frustum and a cylinder, with two identical cylindrical cavities on its front and rear end faces for embedding the small bearings via the retaining rings. The cylindrical end faces of the metal rotor have four evenly distributed fourth-thread blind holes, with their central axes coinciding with the central axes of the bearings. The dual-bearing rotor passes through a double-ended stud and connects to the metal front end, which is then pressed against the metal front end by the preload spring and lock nut.

[0057] like Figure 2 As shown, the inner and outer rings of the drive impeller are both cylindrical surfaces. Between the inner and outer cylindrical surfaces are x blades parallel to the axis, forming a hub. The outer cylindrical surface is used for road driving, and the inner blades are used for water driving. Four evenly spaced fourth through holes are opened at the center cylindrical surface of the drive impeller, with their central axes coinciding with the impeller axis. These holes are used to mate with the fourth threaded blind hole of the drive foot double-bearing rotor. (x is any integer greater than 2)

[0058] The drive controller is embedded in the metal vehicle body and includes a control module for the dual drive feet and scientific detection equipment.

[0059] The buoyancy adjustment device has a semi-cylindrical structure. The non-cylindrical part is provided with a second top surface, a second bottom surface and a fifth side surface. The top surface and the bottom surface are provided with M fifth threaded through holes near the fifth side surface for connecting with the metal vehicle body. The size and arrangement of the through holes are consistent with the second through holes. The fixing bolts pass through the second through holes on the metal vehicle body and are connected to the fifth threaded through holes of the buoyancy adjustment device.

[0060] The driven wheel adjusting rod has a flat key pin-like structure. The front and rear ends are provided with two sixth threaded through holes with parallel central axes. The front threaded hole is connected to the second through hole at the rear end of the metal vehicle body by a fixing bolt. The pitch angle of the robot can be adjusted by adjusting the angle between the driven wheel adjusting rod and the metal shell.

[0061] The driven wheel sleeve is a hollow thin-walled cylindrical structure;

[0062] The driven impeller structure has hollow cylindrical surfaces on both the inner and outer rings. Between the inner and outer cylindrical surfaces, there are x blades parallel to the axis as a hub. The outer cylindrical surface is used for road driving, and the inner blades are used for water driving. The fixing bolts pass through the driven wheel sleeve to connect the driven impeller to the driven wheel adjusting rod.

[0063] The outer cylindrical surfaces of the driving and driven impellers are used for road driving, while the inner blades are used for water driving.

[0064] The piezoelectric ceramic sheet, electrode sheet, and the surfaces in contact with seawater are all coated with an insulating coating. The internal cavity between the pre-tightening bolt of the piezoelectric drive foot and the metal front end is filled with epoxy resin. The cylindrical cavity portion of the metal front end is provided with multiple through holes penetrating the front end to ensure that there is no cavity structure in the inner and outer parts of the piezoelectric drive foot under high water pressure environment, thereby improving pressure resistance.

[0065] This invention also discloses a method for operating a piezoelectrically driven amphibious planetary exploration robot, comprising the following steps:

[0066] Regarding the driving principles of planetary exploration robots, such as Figure 7 and Figure 8As shown, a first AC signal is applied to the 4c+1th and 4c+2nd piezoelectric ceramic plates of the driving foot piezoelectric component, and a second AC signal is applied to the 4c+3rd and 4c+4th piezoelectric ceramic plates. The first and second AC signals have a time phase difference of 90° or -90°, simultaneously exciting two spatially orthogonal B-order bending vibration modes of the piezoelectric driving foot stator, one end of which is fixed and the other is free. This causes the particles on the metal front end to drive the double-bearing rotor to rotate through frictional motion. When the phase difference between the electrical signals of the two driving feet is 90° or -90°, the two driving feet rotate in the same direction, and the planetary exploration robot achieves straight-line travel; when the phase difference between the electrical signals of the two driving feet is 90° and -90° respectively, the two driving feet rotate in opposite directions, and the planetary exploration robot achieves turning in place; (B is an integer greater than 0).

[0067] In terms of operating modes, the piezoelectric drive stator is based on a structural design with one end fixed and the other free. This structure can excite multiple bending vibration modes with one end fixed and the other free, realizing multi-level variable speed operating modes, such as... Figure 7 As shown. When driven by low-order bending vibration modes, the piezoelectric driven foot operates at a lower frequency, with the rotor outputting low speed and high torque, making it suitable for rugged land surface environments, high water pressure environments, and extreme low temperature environments. When driven by high-order bending vibration modes, the piezoelectric driven foot operates at a higher frequency, with the rotor outputting high speed and low torque, making it suitable for high-speed travel on platform land surfaces.

[0068] By changing the air filling inside the buoyancy adjustment devices on the left and right sides, the amphibious exploration robot can be controlled to rise and dive, enabling it to operate at different depths on the water surface, at the bottom, and underwater. In addition, by controlling the position of the buoyancy adjustment devices on both sides, the center of gravity and orientation of the entire robot can also be adjusted.

Claims

1. A piezoelectrically driven amphibious extraterrestrial planetary exploration robot and its method of operation, characterized by, The metal vehicle body, two piezoelectric drive feet, a drive controller, a buoyancy adjusting device, a drive paddle wheel, a driven wheel adjusting rod, a driven paddle wheel, a driven wheel sleeve and a fixing bolt are provided. The metal vehicle body is a cuboid cavity structure, comprising a first top surface, a first bottom surface and four first to fourth side surfaces connected in sequence, the first top surface is provided with a rectangular hollow structure, the first and third side surfaces are respectively front and rear end surfaces of the vehicle body, and the second and fourth side surfaces are respectively left and right end surfaces of the vehicle body. A semicylindrical boss structure is arranged at the center of the first side surface, arranged outside the first front end surface, the center axis is parallel to the top edge of the first front end surface, and a first through hole is arranged in the center of the cylinder along the axis. N first threaded blind holes are uniformly distributed around the through hole, and the center axes of the first through hole and the first threaded blind hole are parallel. A cuboid boss structure is arranged at the center of the third side surface, the top surface is parallel to the top surface of the vehicle body, and the cuboid boss structure is arranged outside the fourth end surface. A second through hole is arranged in the center of the cuboid boss structure, and the center axis is parallel to the upper edge of the rear end surface. Two fan-shaped ear structures are arranged outside the second side surface and the fourth side surface, respectively flush with the top surface and the bottom surface, arranged on both sides of the metal vehicle body, and M second through holes are arranged on the ears. All the second through holes are arranged in a straight line and parallel to the side surface, and the center axis is arranged in a vertical direction. (M is an integer greater than 2) The piezoelectric drive foot comprises a pre-tightening bolt, a fixing flange, a piezoelectric ceramic group, a metal front end, a double-headed stud and a double-bearing rotor. The piezoelectric drive foot is fixed to the second threaded blind hole of the metal vehicle body by the fixing bolt, and one piezoelectric drive foot is arranged on the left and right sides. The fixing flange is a hollow variable cross-section body structure, which is composed of a first cylindrical boss, a hollow disc and a second cylindrical boss in sequence. The center axes of the three parts coincide, the inner and outer diameters of the first cylindrical boss and the second cylindrical are consistent, eight third through holes are uniformly distributed on the outer side of the disc structure, the center axis coincides with the center axis of the variable cross-section body, and is used in cooperation with the second threaded blind hole of the metal shell. The variable cross-section body is provided with a second through hole along the center axis and penetrates through the entire variable cross-section body. The piezoelectric assembly has a cylindrical structure, comprising 4A piezoelectric ceramic sheet groups and 4A+1 electrode sheets, and A is a natural number greater than or equal to 1. The piezoelectric ceramic sheet is a circular ring double-zone piezoelectric ceramic sheet with a through hole in the center, polarized in the thickness direction, and the two zones on both sides of the polarization boundary have opposite polarization directions. The electrode sheet has a circular ring structure with an ear, and the center is provided with a through hole. The ear part is used to apply an electric signal excitation. The 4A+1 electrode pieces and 4A piezoelectric ceramic pieces are arranged in a circular column structure in sequence and alternately, wherein the polarization boundary lines of the 4c+1th piezoelectric ceramic piece are coplanar and have the same polarization direction, the polarization boundary lines of the 4c+2th piezoelectric ceramic piece are coplanar and have the same polarization direction, the polarization boundary lines of the 4c+3th piezoelectric ceramic piece are coplanar and have the same polarization direction, the polarization boundary lines of the 4c+4th piezoelectric ceramic piece are coplanar and have the same polarization direction, and c is a natural number greater than or equal to 0 and less than A; the polarization boundary lines of the 1st and 2nd piezoelectric ceramic pieces are coplanar and have opposite polarization directions, and the polarization boundary lines of the 3rd and 4th piezoelectric ceramic pieces are coplanar and have opposite polarization directions; The metal front end is a composite structure composed of a solid cylinder and a hollow cylinder, and the end close to the fixed flange is a solid cylinder structure and the end away from the fixed flange is a hollow cylinder structure; the end surface of the solid cylinder close to the fixed flange is provided with a second threaded blind hole along the axis, and the end surface away from the fixed flange is provided with a first blind hole along the axis; The pre-tightening bolt passes through the fixed flange, the piezoelectric component and the second threaded blind hole of the metal front end in sequence and is connected in a threaded manner, so as to clamp the piezoelectric component between the fixed flange and the metal front end; The double-bearing rotor comprises a metal rotor, two small-size bearings, a bearing clamp spring, a pre-pressure spring and a lock nut. The metal rotor is a rotary body structure composed of a circular truncated cone and a cylinder, and two same-size cylindrical cavities are arranged on the front and rear end surfaces for embedding the small-size bearings through the clamp spring; four fourth threaded blind holes are arranged on the cylindrical end surface of the metal rotor in a uniform manner, and the central axis is coincident with the central axis of the bearing. The double-bearing rotor is connected with the metal front end through the stud bolt and is pressed on the metal front end by the pre-pressure spring and the lock nut; The inner and outer rings of the driving paddle wheel are both cylindrical surfaces, and x paddle blades parallel to the axis are arranged between the inner and outer cylindrical surfaces as the hub. The outer cylindrical surface is used for driving on the road, and the inner paddle is used for driving in water. Four fourth through holes are arranged on the central cylindrical surface of the driving end paddle wheel in a uniform manner, the central axis is coincident with the axis of the paddle wheel, and is used for cooperating with the fourth threaded blind hole of the driving foot double-bearing rotor. (x is any integer greater than 2) The driving controller is embedded in the metal vehicle body and comprises a control module for the double driving feet and a scientific exploration device; The buoyancy adjusting device is in a semi-cylindrical structure, and the non-cylindrical part is provided with a second top surface, a second bottom surface and a fifth side surface. M fifth threaded through holes for connecting with the metal vehicle body are arranged on the positions close to the fifth side surface of the top surface and the bottom surface, and the through holes have the same size and arrangement as the second through holes. The fixed bolt is connected with the fifth threaded through hole of the buoyancy adjusting device through the second through hole of the metal vehicle body. The driven wheel adjusting rod is in a flat key pin structure, two sixth threaded through holes parallel to the central axis are arranged on the front end and the rear end, and the front end threaded hole is connected with the second through hole of the rear end of the metal vehicle body through the fixed bolt. By adjusting the included angle between the driven wheel adjusting rod and the metal shell, the pitch angle of the whole robot can be adjusted. The driven wheel sleeve is a hollow thin-walled cylindrical structure. The inner and outer rings of the driven paddle wheel structure are hollow cylindrical surfaces, x paddle blades parallel to the axis are arranged between the inner and outer cylindrical surfaces as a hub, the outer cylindrical surface is used for driving the road surface, and the inner paddle is used for driving in water; the fixed bolt passes through the driven wheel sleeve to connect the driven paddle wheel and the driven wheel adjusting rod.

2. The piezoelectrically driven amphibious planetary exploration robot of claim 1, wherein, The outer cylindrical surface of the driving paddle wheel and the driven paddle wheel is used for driving the road surface, and the inner paddle is used for driving in water.

3. The piezoelectrically driven amphibious planetary exploration robot of claim 1, wherein, The surfaces of the piezoelectric ceramic sheet, the electrode sheet and the sea water contact are all provided with an insulating coating. The internal cavity between the piezoelectric driving foot pre-tightening bolt and the metal front end is filled with epoxy resin drops, a plurality of through holes penetrating the front end are arranged in the cylindrical cavity part of the metal front end, the inside and outside parts of the piezoelectric driving foot are free of cavity structure under high water pressure environment, and the pressure resistance is improved.

4. The method of operating a piezoelectrically driven amphibious planetary exploration robot according to claim 1, characterized in that The following points are included: In terms of the driving principle of the planetary exploration robot, the fourth 4c+1 and the fourth 4c+2 piezoelectric ceramic sheets of the piezoelectric component of the driving foot are applied with a first alternating current signal, and the fourth 4c+3 and the fourth 4c+4 piezoelectric ceramic sheets are applied with a second alternating current signal; the first and second alternating current signals have a 90° or -90° time phase difference, and a B-order bending vibration mode with one end fixed and one end free is excited in two spatially orthogonal directions of the piezoelectric driving foot stator, so that the mass points on the metal front end drive the double-bearing rotor to rotate by friction movement, and drive the driving paddle wheel to rotate. When the phase difference of the electric signals of the two driving feet is 90° or -90°, the two driving feet rotate in the same direction, and the planetary exploration robot realizes straight driving; when the phase difference of the electric signals of the two driving feet is 90° and -90° respectively, the two driving feet rotate in opposite directions, and the planetary exploration robot realizes turning in place; (c, B is an integer greater than 0) In terms of the working mode, the piezoelectric driving foot stator is designed based on the structure of one end fixed and one end free, which can excite multiple one-end-fixed and one-end-free bending vibration modes, and realize multi-stage variable speed working mode. When the piezoelectric driving foot is driven in the low-order bending vibration mode, the working frequency is low, the rotor outputs low speed and large torque, which is suitable for rugged land surface environment, high water pressure environment and extreme low temperature environment; when the piezoelectric driving foot is driven in the high-order bending vibration mode, the working frequency is high, the rotor outputs high speed and small torque, which is suitable for high-speed driving on platform land. In addition, while the double stator connects the double driving foot driving, the structure itself is fixed in the metal vehicle front end to play a cantilever support role, without transmission mechanism and complex components, realizing the structure function integration design. And the driving part has low cost, small size, simple structure and high reliability. By changing the air filling in the buoyancy adjusting devices on the left and right sides, the amphibious exploration robot can be controlled to float and dive, and run at different depths on the water surface, the water bottom and underwater. In addition, the positions of the two sides of the buoyancy adjusting device can also adjust the gravity center and the direction of the whole machine. In terms of sealing and pressure resistance, the piezoelectric driving foot of the present application does not need to be dynamically sealed at the contact part of the stator and rotor, only needs to ensure that the piezoelectric ceramic sheet and the electrode sheet in the piezoelectric driving foot are insulated from seawater, the sealing requirement is extremely low, and can adapt to different depth environments of potential oceans on earth and other planets. Compared with the traditional motor, the motor has good pressure resistance without dynamic sealing, and the performance of the motor is not attenuated under high water pressure in deep sea.

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