Passive adaptive mechanism for small celestial body surface terrain

Abstract

This invention discloses a passive adaptive mechanism for the surface topography of small celestial bodies, comprising a clamping device, a fixed platform, a moving platform, and three identical motion chains located between the moving and fixed platforms. Each motion chain is circumferentially 120° apart. The clamping device is also 120° apart and mounted on the base plate of the moving platform to clamp and fix the attachment mechanism. When the attachment mechanism contacts a complex terrain and the attachment fitting spherical surface is not fully aligned, the position and attitude of the attachment mechanism shift during the attachment process. At this time, the robotic arm remains fixed, and the end effector attitude and position of the robotic arm are corrected through a parallel passive adaptive mechanism. This invention is a completely passive mechanism, requiring no control system or measurement system. The equipment structure is relatively simple, highly reliable, and easy to maintain.

Description

Technical Field

[0001] This invention belongs to the field of aerospace engineering technology, specifically to a passive adaptive mechanism for the surface terrain of small celestial bodies. Background Technology

[0002] With the rapid development of aerospace technology and space science, human interest in outer space exploration has been continuously increasing, and the scope has become increasingly broad. Today, the exploration targets of various countries are no longer limited to large celestial bodies such as the Moon and Mars; asteroids, comets, meteors, and other small celestial bodies have also become a focus of deep space exploration for major spacefaring nations. Research shows that small celestial bodies retain important information about the origin, formation, and evolution of the early solar system, serving as "living fossils" for studying the origin of the solar system and possessing significant scientific value. Small celestial bodies may contain abundant rare minerals and metals, resources that could provide enormous economic value for human development. Furthermore, near-Earth asteroids also pose a certain risk of impacting Earth; conducting close-range and close-range probes can help develop asteroid defense technologies. Therefore, small celestial body exploration is of paramount importance.

[0003] The Tianwen-2 probe's target is asteroid 2016HO3. It will conduct a flyby exploration of the near-Earth asteroid 2016HO3 and return samples, a process that will take up to 10 years. Given the surface characteristics of 2016HO3—its surface compressive strength is lower than that of ordinary chondrites—commonly used destructive fixing methods such as harpoons and twist drills are unsuitable. Therefore, a biomimetic claw-like anchoring device has been designed as an attachment and detection mechanism, allowing for stable anchoring and flexible release.

[0004] When the attachment mechanism is not centered on the spherical surface fitted to the attachment area, as the claws of the attachment mechanism grip, while the robotic arm remains stationary, the torque generated by the attachment mechanism will be transmitted along the robotic arm to the detector, causing the detector to twist and resulting in data transmission errors.

[0005] To address this technical problem, this invention designs a parallel mechanism to improve the attachment mechanism and enable passive adaptive function for small celestial bodies with uncertain star surfaces and complex, unstructured terrain. Summary of the Invention

[0006] This invention relates to a passive adaptive mechanism for the surface topography of small celestial bodies, with the aim of improving the passive adaptive capability of end effectors for small celestial body exploration in complex terrain. Specifically, this invention does not specify detailed requirements for the attachment mechanism, sliding damper, rotational damper, and the mechanical interface between the robotic arm and the fixed platform.

[0007] This invention is implemented as follows:

[0008] A passive adaptive mechanism for the surface topography of a small celestial body is disclosed. The mechanism, from top to bottom, comprises: a fixed platform, a moving platform, and a clamping device. A motion chain is provided between the fixed platform and the moving platform. The motion chain includes a rotary damper, a ball joint connector, a ball head, a sliding damper, and a ball joint support. One end of the rotary damper is connected to a slot on the fixed platform, and the other end is connected to the ball joint connector. One end of the ball joint connector is connected to the rotary damper via a screw and nut, and the other end has a threaded blind hole. The ball head is connected to the threaded blind hole of the ball joint connector, and the thread lead of the thread connected to the threaded blind hole of the ball joint connector is equal to the spherical diameter of the ball head. The thread profile, pitch, and helix angle of the ball joint connector and the ball head are the same. The ball joint connector and the ball head are connected by an internally designed thread, requiring the internal and external threads to mesh. The sliding damper has ball joints at both ends. One end of the ball joint support has a threaded blind hole, and the other end is connected to the moving platform via a screw and nut.

[0009] The passive adaptive mechanism for the surface topography of small celestial bodies in this invention comprises a clamping device, a fixed platform, a moving platform, and three identical motion chains located between the moving platform and the fixed platform. Each motion chain is installed between the moving platform and the fixed platform at 120° intervals around its circumference. The clamping device is also installed at 120° intervals around the base plate of the moving platform to clamp and fix the attachment mechanism.

[0010] When the attachment mechanism comes into contact with a complex terrain and the attachment fitting sphere is not in sync, the position and attitude of the attachment mechanism itself will shift during the attachment process. At this time, the robotic arm remains fixed, and the end attitude and position of the robotic arm are corrected by a parallel passive adaptive mechanism.

[0011] During the correction process, the motion resistance provided by the rotational damper and the sliding damper of the motion chain weakens the offset torque generated by the correction, thereby achieving a compliant adhesion effect.

[0012] Furthermore, the fixed platform and the mobile platform are circular plate-shaped structures, and the motion chain is set to three, which are installed between the two platforms by screws and nuts;

[0013] The fixed platform and the mobile platform are initially positioned vertically parallel with their centers coinciding. The three motion chains have identical structures and are distributed in a 120° circle between the mobile platform and the fixed platform. The clamping devices are distributed at a 120° angle to each other and offset from the motion chains at the bottom of the mobile platform.

[0014] Furthermore, the clamping device includes a flexible pad, a movable support, a lead screw, a fixed support, and a connecting plate. The lead screw is a trapezoidal lead screw, with a hexagonal handwheel at one end and the other end bonded to the flexible pad. The fixed support is connected to the moving platform via the connecting plate. In use, the hexagonal handwheel at the end of the lead screw is manually rotated sequentially until the flexible pad contacts the attachment mechanism. Then, two sets of clamping devices are simultaneously fixed, and the third set of lead screws is rotated to clamp the device.

[0015] Furthermore, the clamping device is installed at a circumference of 120° at the bottom of the moving platform, and the moving platform and the clamping device are fixed by screws and nuts.

[0016] Furthermore, the fixed platform is designed with three sets of slots and U-shaped grooves at 120° circumference to connect the motion chain; the U-shaped groove is designed on the outer side of the circumference, and the slots are designed inside the U-shaped groove; the center of the mobile platform is a mechanical interface for connecting with the robotic arm.

[0017] Furthermore, the ball joint support is also provided with threaded blind holes, and the two ends of the sliding damper are ball joints, which are respectively connected to the ball head and the ball joint support.

[0018] Furthermore, the parallel passive adaptive mechanism is installed between the robotic arm and the attachment mechanism; when the attachment mechanism is not centered on the fitted sphere, the parallel passive adaptive mechanism passively completes the pose shift of the mobile platform relative to the fixed platform through the pose shift of the attachment mechanism during the active attachment process.

[0019] This invention is a completely passive mechanism, requiring no control or measurement systems or other supporting devices. The equipment has a relatively simple structure, high reliability, and is easy to maintain. Its beneficial technical effects are reflected in the following aspects:

[0020] Traditional adaptive mechanisms are mostly omnidirectional, which have limited adaptability to terrain. Traditional mechanisms are mainly designed for attitude deflection adaptation and lack adaptability to positional offset, while this invention improves the adaptability to positional offset.

[0021] This invention is a completely passive parallel mechanism. Compared with the traditional active adaptive parallel mechanism, it eliminates the need for the control and measurement systems of the parallel mechanism, making the whole structure more streamlined and reliable.

[0022] This invention adds a rotating joint, i.e., a rotational damper, to the traditional 3-SPS configuration, also known as a 3-RSPS mechanism. This improvement allows the mechanism to occupy less space while expanding the workspace and significantly enhancing its adaptability to terrain. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0024] Figure 2 This is a structural diagram of a fixed platform.

[0025] Figure 3 This is a schematic diagram of the ball joint connector.

[0026] Figure 4 This is a schematic diagram of the components of a kinematic branch.

[0027] Figure 5 This is a schematic diagram of the clamping device.

[0028] Figure 6 This is a schematic diagram of the installation of the present invention.

[0029] Figure 7 A schematic diagram of fitting a non-centered sphere to the attachment region.

[0030] Wherein: 1-fixed platform, 2-motion chain, 3-moving platform, 4-clamping device, 5-rotation damper, 6-spherical hinge connector, 7-ball head, 8-sliding damper, 9-spherical hinge support, 10-flexible pad, 11-movable support, 12-lead screw, 13-fixed support, 14-connecting piece, 15-mechanical arm (partial), 16-attachment mechanism, 17-attachment fitting spherical surface. Implementation

[0031] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following examples provide a more detailed description of the invention. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0032] See Figure 1 The passive adaptive mechanism for the surface topography of small celestial bodies includes a fixed platform 1, moving chains 2, a moving platform 3, and a clamping device 4. Both the fixed platform 1 and the moving platform 3 are circular platforms, initially positioned vertically parallel with their centers coinciding. The three moving chains 2 have identical structures and are distributed in a 120° circle between the moving platform 3 and the fixed platform 1. The clamping device 4 is distributed at a 120° angle to the moving chains 2, offset from them, at the bottom of the moving platform.

[0033] See Figure 2 The fixed platform 1 is designed with three sets of slots and U-shaped grooves at 120° circumference to connect the motion support chain 2. The U-shaped groove is designed on the outer side of the circumference, and the slots are designed inside the U-shaped groove.

[0034] See Figure 3 One end of the ball joint connector 6 is a through hole, which is connected to the rotary damper 5 by a screw and nut. The other end has a threaded blind hole, which is directly connected to the ball head 7 by a thread.

[0035] See Figure 4One motion chain consists of a rotary damper 5, a ball joint connector 6, a ball head 7, a sliding damper 8, and a ball joint support 9. The sliding damper 8 is designed with ball joints at both ends. One end of the ball joint support 9 is designed with a threaded blind hole, and the other end is connected to the moving platform 4 by screws and nuts.

[0036] See Figure 5 The clamping device 4 includes a flexible pad 10, a movable support 11, a lead screw 12, a fixed support 13, and a connecting piece 14. The lead screw 12 is a trapezoidal lead screw, with a hexagonal handwheel at one end and the other end bonded to the flexible pad 10. The fixed support 13 is connected to the movable platform 4 via the connecting piece 14.

[0037] See Figure 6 and Figure 7 When the attachment mechanism 16 comes into contact with a complex terrain and the attachment fitting sphere 17 is not in place, the position and attitude of the attachment mechanism 16 itself will shift during the attachment process. At this time, the robotic arm 15 remains fixed, and the end attitude and position of the robotic arm 15 are corrected through the parallel passive adaptive mechanism.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A passive adaptive mechanism for the topography of a small celestial body's star surface, characterized in that, The mechanism is a completely passive mechanism, comprising: a fixed platform (1), a moving platform (3), and a clamping device (4); a kinematic link (2) is provided between the fixed platform (1) and the moving platform (3); The motion chain (2) includes a rotary damper (5), a ball joint connector (6), a ball head (7), a sliding damper (8), and a ball joint support (9); one end of the rotary damper (5) is connected to the slot of the fixed platform, and the other end is connected to the ball joint connector (6); one end of the ball joint connector (6) is connected to the rotary damper (5), and the other end is designed with a threaded blind hole; the ball head (7) is connected to the threaded blind hole of the ball joint connector (6), and the thread lead connected to the threaded blind hole of the ball joint connector (6) is equal to the spherical diameter of the ball head (7); the thread profile, pitch, and helix angle of the ball joint connector (6) and the ball head (7) are the same; the two ends of the sliding damper (8) are respectively connected to the ball head (7) and the ball joint support (9); the motion chain (2) is installed on the moving platform at 120° intervals around the circumference. Between the fixed platforms, the clamping devices (4) are also installed at 120° to each other on the base plate of the mobile platform to clamp the fixed attachment mechanism (16). When the attachment mechanism (16) contacts a complex terrain and the attachment fitting spherical surface (17) is not centered, the position and posture of the attachment mechanism (16) will shift during the attachment process. At this time, the robotic arm (15) remains fixed and the end posture and position of the robotic arm (15) are corrected through the parallel passive adaptive mechanism. During the correction process, the motion resistance provided by the rotation damper (5) of the motion chain and the sliding damper (8) weakens the offset torque generated by the correction, thereby playing a role in compliant attachment. The clamping device (4) includes a flexible pad (10), a movable support (11), a lead screw (12), a fixed support (13), and a connecting piece (14) in sequence. The lead screw (12) of the clamping device (4) is a trapezoidal lead screw with a hexagonal handwheel at one end and a flexible pad (10) bonded to the other end. The fixed support (13) is connected to the moving platform (3) through the connecting piece (14). The clamping device (4) is installed at the bottom of the moving platform (3) in a circumference of 120°. The moving platform (3) and the clamping device (4) are fixed by screws and nuts. The fixed platform (1) and the moving platform (3) are circular plate-shaped structures. The motion chain (2) is set to three, and the motion chain (2) is installed between the two platforms by screws and nuts. The fixed platform (1) and the mobile platform (3) are initially parallel vertically and their centers coincide. The three motion chains (2) have the same structure and are distributed in a 120° circle between the mobile platform (3) and the fixed platform (1). The clamping device (4) is distributed at a 120° angle to the motion chains (2) at the bottom of the mobile platform (3). The fixed platform (1) is designed with three sets of slots and U-shaped grooves at 120° circumference to connect the motion chain (2); the U-shaped groove is designed on the outside of the circumference, and the slots are designed inside the U-shaped groove; the center of the fixed platform (1) is a mechanical interface for connecting with the robotic arm (15); The ball joint support (9) is also provided with a threaded blind hole. The two ends of the sliding damper (8) are ball joints, and the two ends of the ball joints are connected to the ball head (7) and the ball joint support (9) respectively.

2. The passive adaptive mechanism for the surface topography of a small celestial body according to claim 1, characterized in that, The parallel passive adaptive mechanism is installed between the robotic arm (15) and the attachment mechanism (16). When the attachment mechanism grips the fitted sphere (17) but is not centered, the parallel passive adaptive mechanism passively completes the positional shift of the moving platform (3) relative to the fixed platform (1) through the positional shift of the active gripping process of the attachment mechanism (16).

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