Modular self-adaptive robot device for paper folding bionics based on SMA (Shape Memory Alloy) driving

Abstract

The invention discloses a modular self-adaptive robot device based on SMA driving paper folding bionics. The modular self-adaptive robot device is composed of peak folding rods, valley folding rods, SMA wires, a magnetic attraction connecting structure and a 3D printing bottom plate, and self-adaptive operation is achieved through driving-sensing-structure integrated cooperation. The SMA wires have driving and sensing functions, structural deformation is driven through PWM, resistance change of the structural deformation is measured in real time, and axial telescoping, radial telescoping and bending of the module can be controlled in a closed-loop mode without an external sensor. The device is combined based on the lever amplification principle, tiny deformation of the SMA wire is efficiently converted into large-stroke output of a mechanism, and the problem that the stroke of an SMA driver is limited is solved. A single module has three modes of radial expansion, linear actuation and torsion joint, and complex movement can be completed through combination. A plurality of modules are connected in series with a quick connecting piece through magnetic attraction, and the functions of bionic wriggling, rod cable climbing or multi-section operation arm can be achieved through time sequence programming. And a flexible and reconfigurable robot solution is provided for detection and rescue tasks in a complex environment.

Description

Technical Field

[0001] This invention belongs to the field of advanced robotics technology, specifically relating to a modular adaptive robot device based on SMA-driven origami bionics, which can achieve multimodal motion through module combination and is suitable for unstructured environment operation. Background Technology

[0002] In fields such as disaster relief, pipeline inspection, space exploration, and industrial inspection, the demand for robots capable of operating in confined, rugged, and unstructured environments is increasingly urgent. These environments require robots to possess high environmental adaptability, mobility, and load-bearing capacity. Traditional wheeled and tracked robots, limited by their locomotion mechanisms, suffer from severely insufficient mobility in such environments; while multi-jointed bionic robots generally face inherent challenges such as complex structures, difficult control, and low reliability.

[0003] Rigid-flexible fusion technology is seen as a powerful direction for solving the above challenges, but its development still faces two major bottlenecks. First, at the module level, how to design high-performance single-function modules that can integrate driving, sensing, and execution functions while simultaneously meeting the requirements of compact structure and high energy efficiency; second, at the system level, how to build systems capable of complex mobility functions through repeated combinations of such modules, while ensuring good scalability and robustness.

[0004] Shape memory alloy (SMA) wires possess advantages such as high power density, quiet operation, and biomimetic muscle-like linear contraction, making them ideal for space-constrained modular designs. However, their inherent low drive frequency, limited output power, and thermal control hysteresis make them unsuitable for directly driving motion mechanisms with high load requirements. In terms of functional implementation, existing research largely treats grasping, anchoring, and movement functions in isolation; for example, grippers are only used for grasping objects, and climbing mechanisms are only used for movement. This functional separation design philosophy results in complex, bulky, and limited adaptability of robot systems. Furthermore, the few modular robots that have been realized, such as chain robots and inchworm robots, mostly use traditional motor drives for their modules, leading to high structural rigidity, poor adaptability to environmental shapes, and a general lack of ability to manipulate objects during movement.

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a new modular design paradigm that integrates function, structure, and drive. The core innovation of this invention lies in designing a unified, actively adaptive module based on the SMA drive and biomimetic-origami coupling principle.

[0006] The module's key technical feature lies in its drive and transmission system. Inspired by the retractable skeletal linkage system of a carp's mouth, a unique biomimetic mechanism was designed to efficiently convert the minute contractions of SMA filaments into large-amplitude extension and contraction movements. This significantly enhances the output stroke and force of a single module, overcoming the limitation of SMA's output power. In terms of structural design and functional implementation, a Kresling origami truss is used as the drive structure. This structure can generate coupled movements of radial contraction and circumferential rotation under axial deformation. This characteristic naturally endows the module with dual capabilities: active anchoring by radially contracting to grip a rod or rope, and propulsion by axially rotating to rub against the surface. This makes a single module crucial for achieving complex movements such as climbing and crawling. Ultimately, the module is constructed as a unified whole that functions as both an independent adaptive gripper and a basic motion unit.

[0007] When multiple individual modules are connected in series to form a system, the coordinated working sequence of each module's contraction-anchoring-expansion-release can be controlled by programming. This allows the entire system to simulate the biomimetic gait of an earthworm or inchworm, enabling efficient movement on pipes, ropes, or rough surfaces. More importantly, since each module itself is a powerful gripper, the system can grasp, carry, and release objects during movement, or enhance its overall stability and load-bearing capacity by anchoring itself to environmental supports, thus achieving a fusion of movement, operation, and anchoring functions.

[0008] This invention offers significant advantages through its integrated design, incorporating biomimetic mechanisms and origami structures to efficiently compensate for the shortcomings of SMA in terms of output power and functional singularity. The modular system architecture overcomes the slow response of SMA through redundant design; that is, while one module is driving, other modules can be in a cooling-off recovery period. It simplifies the construction of complex systems to the replication and combination of single modules, ensuring the system's scalability and robustness. This provides a completely new technical path for building a new generation of highly adaptable, feature-rich, and reliable robotic systems. Summary of the Invention

[0009] The purpose of this invention is to overcome the limitations of existing technologies and propose a new modular design paradigm that integrates function, structure, and perception. The core innovation lies in designing a unified, active adaptive module based on SMA filament actuation and biomimetic-origami coupling principles. This module, through the integration of a biomimetic lever amplification mechanism, efficiently converts the minute contractions of the SMA filament into large-amplitude mechanical output, effectively solving the inherent limitations of SMA filament actuators in terms of output force and stroke, thus meeting the requirements of high-load applications. This module can function as both an independent adaptive gripper and a basic motion unit.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A modular adaptive robot device based on SMA-driven origami bionics includes a folding peak rod 1, a folding valley rod 2, SMA filaments 3, a filament holder 4, a fiberglass board 5, a cylindrical magnet 6, an upper base plate 7, a lower base plate 8, a pin 9, a screw 10, and a nut 11.

[0012] The folding rod 1 is composed of a glass fiber tube 102 and through-hole ball heads 101 glued to both ends. The through-hole ball heads 101 at both ends of the folding rod 1 are respectively installed on the ball joint mounting seats of the upper base plate 7 and the lower base plate 8, forming the peak point hinge of the Kresling origami structure, which mainly bears the axial pressure and provides rigid support for the entire structure.

[0013] The folding straw 2 is a retractable buffer structure and is the driving core for achieving biomimetic adaptive motion in this invention. The folding straw 2 consists of a left glass fiber tube 201, a through-hole ball head 202, a polyacetamide thin tube 203, a glass fiber central tube 204, a spring 205, and a right glass fiber tube 206. One end of the glass fiber tube 201 is bonded with the through-hole ball head 202 and partially inserted into the glass fiber central tube 204; a spring 205 is housed within the glass fiber central tube 204; a polyacetamide thin tube 203 is housed within the glass fiber central tube 204 and the spring 205; one end of the right glass fiber tube 206 is fitted with the through-hole ball head 202 and inserted into the glass fiber central tube 204 from the other side. The through-hole ball heads 202 at both ends of the folding straw 2 are also hinged to the ball joint mounting seats on the upper base plate 7 and the lower base plate 8, respectively, forming a Kresling origami-like valley point hinge. The design simulates the stretchable properties of the ligaments in a carp's mouth, transforming the linear contraction of the shape memory alloy wire 3 into a coupled motion of large-scale radial contraction and axial rotation of the origami structure.

[0014] The upper base plate 7 and the lower base plate 8 are 3D printed parts, and are precisely designed with ball joint mounting seats for installing the ball heads of the peak-breaking rod 1 and the valley-breaking rod 2, reserved guide holes for passing through the shape memory alloy wire 3, side connection holes for installing the glass fiber board 5, and pin holes and screw holes for series connection between modules.

[0015] The cylindrical magnet 6 is interference-fitted into the reserved hole of the lower base plate 8, and is used to generate an adsorption force with the upper base plate 7 of the adjacent module during modular assembly, so as to realize rapid pre-alignment and auxiliary connection between modules and enhance the integrity and stability of the serial mechanism.

[0016] The SMA filament 3, serving as the core driving element, passes sequentially through the glass fiber tube 204 of the folding bar 2, the pre-drilled guide hole in the lower base plate 8, and the polyimide thin tube 4, which provides insulation and wear resistance, fitted over it. Finally, both ends are fixed and tensioned to the sides of the upper base plate 7 and the lower base plate 8 by the filament holder 4. This wiring method directly and efficiently applies the driving force of the SMA filament 3 to the extension and retraction of the folding bar 2, resulting in a clear force flow path and minimal energy loss.

[0017] A modular adaptive robot device constructed from the aforementioned robot units is characterized in that at least two of the robot units are connected in series end-to-end via mechanical and electrical interfaces. Specifically, the upper base plate 7 of the lower unit is hinged to the lower base plate 8 of the upper unit via a pin 9, and simultaneously secured by screws 10 passing through their respective screw holes, thereby achieving mechanical series connection. The SMA wire 3 drive circuits of each unit are electrically connected via connectors mounted on the base plate, and are coordinated and controlled by a central controller.

[0018] By programming and controlling the energizing sequence of the SMA filaments 3 in each unit, the system can induce a biomimetic motion cycle of contraction-anchoring-expansion-release in each unit, thus achieving inchworm-like peristalsis. During climbing operations, the radial contraction function of the unit allows it to actively grip the pole or rope, providing an anchor point for crawling.

[0019] The advantages of this invention are:

[0020] 1. This invention innovatively achieves integrated fusion of drive, structure, and function, resulting in superior overall performance. Through the retractable buffer design of the folding bar 2, it deeply integrates the drive of the SMA wire 3, the coupled motion of the Kresling structure, and the biomimetic linkage mechanism of a carp's mouth. The minute contraction of the SMA wire 3 is efficiently amplified through a lever principle based on quadrilateral hinges, driving the overall structure to generate an axial extension stroke exceeding six times its initial height. The force flow path is clear, and the energy transfer efficiency is high, fundamentally solving the core problem of limited output power and stroke of the SMA actuator.

[0021] 2. Combining high load capacity and high adaptability, it breaks through the rigid-flexible performance barrier. The rigid frame formed by the folded peak rod 1 ensures overall stability and high load capacity; the buffering and adaptive deformation of the spring 205 inside the folded valley rod 2 allows the unit to gently envelop objects of different shapes. This rigid-flexible integrated architecture solves the contradiction between the weak load capacity of traditional flexible robots and the poor adaptability of rigid robots.

[0022] 3. Rich motion capabilities: A single module can achieve multiple operation modes. Driven by the SMA filament 3, a single robot unit can simultaneously generate three motion modes: axial extension, radial contraction, and circumferential rotation. The minute deformation of the folding pole 2 itself is amplified more than 24 times through the lever structure, ultimately manifesting as a huge deformation of the entire unit. This allows the unit to function as an adaptive gripper for radial contraction gripping, a rotary joint to provide torsional freedom, and a linear actuator for axial extension and push-pull movements without the need for additional actuators.

[0023] 4. The modular design offers exceptional scalability and flexible, reconfigurable system functionality. Quick and reliable connections between modules are achieved via pins 9, screws 10, and cylindrical magnets 6 on the upper base plate 7 and lower base plate 8. Multiple units can be connected in series to construct diverse robotic systems, including: a system for crawling through pipes or ropes, which uses the radial contraction function of units to provide anchor points for crawling; a system for biomimetic peristalsis on the ground, which achieves inchworm movement through multi-unit collaboration; and a multi-segment manipulator system, which achieves flexible operation by combining the rotation functions of each unit.

[0024] 5. Low energy consumption, simple control, and high system reliability and practicality. The rapid docking achieved using the cylindrical magnet 6 and the passive reset force provided by the internal spring 205 of the folding rod 2 significantly reduce the energy consumption and waiting time required for the SMA wire 3 to cool and reset. The modular design allows for a simple distributed triggering and centralized coordination strategy; complex movements can be achieved simply by sequentially triggering the energizing sequence of each unit's SMA wire 3, greatly simplifying the control algorithm.

[0025] 6. Compact structure, low cost, and easy manufacturing and promotion. The core load-bearing structure uses lightweight, high-strength standard profiles, and the structural load-bearing components are manufactured using 3D printing in a single integrated process, reducing production costs and assembly complexity, and possessing the potential for large-scale application. This invention, through its ingenious mechanical architecture, integrates the advantages of smart materials, origami art, and bionics to create a powerful and versatile robotic technology platform, providing a novel solution to the challenges of movement and operation in unstructured environments. Attached Figure Description

[0026] Figure 1 Overall structural diagram

[0027] Among them: 1. Folding peak rod; 2. Folding valley rod; 3. SMA filament; 4. Polyimide thin tube; 4. Fiber holder; 5. Fiberglass board; 6. Cylindrical magnet; 7. Upper base plate; 8. Lower base plate; 9. Pin; 10. Screw; and 11. Nut.

[0028] Figure 2 Initial structure and driving diagram

[0029] Figure 3 Rice stalk structure diagram

[0030] Among them: glass fiber capillary tube 201, through-hole ball head 202, glass fiber middle tube 204, and spring 205.

[0031] Figure 4 Broken Peak Pole Structure Diagram

[0032] Among them: through-hole ball head 101 and glass fiber tube 102.

[0033] Figure 5 Control and Sensing Principle Diagram

[0034] Figure 6 Module connection schematic diagram

[0035] Among them: 6 cylindrical magnets

[0036] Figure 7 Multi-module combined climbing principle diagram Detailed Implementation

[0037] The invention will be further described below with reference to the accompanying drawings:

[0038] like Figures 1 to 4 The diagram shows a modular adaptive robot device based on SMA-driven origami bionics. Its main structure consists of a folding peak rod 1, a folding valley rod 2, SMA filaments 3, a polyimide thin tube 4, a filament holder 4, a fiberglass board 5, a cylindrical magnet 6, an upper base plate 7, a lower base plate 8, a pin 9, a screw 10, and a nut 11.

[0039] like Figure 3 The buckle assembly 2 shown is a retractable buffer structure, consisting of a glass fiber tube 201, a through-hole ball head 202, a glass fiber tube 204, and a spring 205. One end of the glass fiber tube 201 is fixed to the through-hole ball head 202 and inserted into the glass fiber tube 204. The spring 205 is housed inside the hollow tube, providing restoring elasticity and buffering effect.

[0040] like Figure 4 The assembly of the peak-breaking rod assembly 1 is shown. The peak-breaking rod 1 consists of a glass fiber tube 102 and through-hole ball heads 101 fixed at both ends by adhesive. The through-hole ball heads 101 are made of stainless steel, and the ball head part is connected to the ball socket on the base plate to form a ball hinge connection, providing rigid support for the entire structure.

[0041] The upper base plate 7 and lower base plate 8 are formed using 3D printing technology and are equipped with ball joint mounting seats, guide holes, side connection holes, and connection interfaces. A cylindrical magnet 6 is embedded in a pre-drilled hole in the lower base plate 8. The through-hole ball heads of the three assembled peak-bending rods 1 and three valley-bending rods 2 are respectively installed into the corresponding ball joint seats on the upper base plate 7 and lower base plate 8, forming a Kresling triangular prism structure. The fiberglass board 5 is fastened to the sides of the upper and lower base plates with screws 10 and nuts 11 to enhance structural stability.

[0042] The shape memory alloy wire 3 is wrapped with a polyimide thin tube 4 as an insulating and wear-resistant layer. It passes through the guide hole of the lower base plate 8, the inside of the tube of the folding bar 2, and the guide hole of the upper base plate 7 in sequence. Its two ends are fixed and tensioned on the base plate by the wire holder 4.

[0043] The multi-module system is constructed by using the magnetic attraction of cylindrical magnets 6 to quickly pre-position individual units, which are then fastened by pins 9 and screws 10. The SMA wire 3 drive circuits of each unit are electrically interconnected through connectors to form a complete power and data transmission network.

[0044] like Figure 5 As shown, the system adopts a control strategy that alternates between pulse driving and resistance detection. The controller generates pulse signals to heat the SMA wire 3 by energizing it. During the pulse interval, the resistance value of the SMA wire 3 is measured. The control algorithm for deformation posture is based on the established resistance-strain-temperature relationship model. The driving parameters are adjusted by a control algorithm based on resistance feedback.

[0045] During system operation, the central controller precisely coordinates the energizing timing and duty cycle (PWM) of each SMA wire 3 unit, and monitors its resistance changes in real time, thereby achieving precise motion control and attitude perception. The system supports multiple operating modes: in creep mode, each unit generates propagating waveform motion through a coordinated contraction-anchoring-expansion-release cycle; in climbing mode, the units actively grip the rod or rope using the inherent radial contraction capability of the Kresling structure, achieving alternating anchoring and propulsion; in operation mode, multiple units can form a multi-segment manipulator arm, comprehensively utilizing the axial extension, radial contraction, and circumferential rotational degrees of freedom of each module to achieve flexible perception and operation of complex environments.

[0046] like Figure 6 and 7As shown, at the individual module level, precise control of its various postures relies on independent closed-loop control of the three SMA wires 3. The controller precisely adjusts the heating power and shrinkage by applying independent on / off electrical signals and adjustable duty cycles to each SMA wire 3. Simultaneously, the core technology lies in utilizing the deterministic relationship between the resistance and strain of the SMA wire 3. By sensing its resistance value in real time, the real-time deformation state of the module, such as axial displacement and bending angle, can be calculated. This constitutes a closed-loop feedback system that requires no additional posture sensors, enabling precise, sensorless control of multiple postures of a single module, such as axial extension, radial contraction, and bending in a specific direction.

[0047] At the multi-module collaborative level, the system achieves distributed control by marking the different modules connected in series. The central controller, based on the global motion strategy and combined with the attitude information sensed in real time from each module, independently issues control commands, including power-on / off timing and PWM duty cycle, to each SMA filament of each module, thereby precisely adjusting the motion phase and amplitude of each module. During inchworm crawling, different modules sequentially contract and expand to form a coordinated motion wave; when the manipulator bends, smooth trajectory tracking is achieved by coordinating the bending direction and angle of adjacent modules. This collaborative control strategy based on real-time attitude perception ensures that the multi-module system can efficiently and reliably complete complex movement and manipulation tasks.

Claims

1. A modular adaptive robot device based on SMA-driven origami bionics, characterized in that, The system includes at least one independently operating robot unit, which is mainly composed of a mechanical structure module, a drive and sensing module, and an intelligent control module. The core of the mechanical structure module is an origami structure based on the Kresling pattern. This structure is formed by multiple sets of motion branches connecting the upper base plate (8) and the lower base plate (9) in a ring array to form a stable polyhedral spatial configuration. The core component of the drive and sensing module is an SMA wire (3), which is inserted into the interior of the mechanical structure module through a specific path, serving as both a drive source and a sensor. The intelligent control module establishes an electrical connection with the SMA wire (3) and is programmed to execute a unique control strategy that alternates between pulse-driven driving and resistance measurement. It estimates the real-time motion posture of the mechanical structure module by collecting resistance signals in real time and achieves precise closed-loop motion control accordingly.

2. The modular adaptive robot device based on SMA-driven origami bionics as described in claim 1, characterized in that, Each set of motion branches in the mechanical structure module includes two folding peak rods (1) that mainly bear axial pressure and one folding valley rod (2) that mainly transmits motion and buffers. The folding peak rods (1) and the folding valley rod (2) are connected in parallel between the upper base plate (8) and the lower base plate (9). The folding valley rod (2) is a passively telescopic buffer mechanism with an internally integrated spring (205). This design enables the robot unit to generate adaptive deformation when subjected to external loads, thereby enhancing its grasping stability of objects of different shapes and its motion adaptability to complex environments.

3. The modular adaptive robot device based on SMA-driven origami bionics as described in claim 2, characterized in that, The specific structure of the grain-folding rod (2) includes a glass fiber tube (204) serving as the outer shell, a spring (205) placed inside it and providing a restoring force, and two glass fiber tubes (206) inserted into the tube from both ends. The ends of the tubes are fixed with through-hole ball heads (202). The spring (205) is in a pre-compressed state inside the tube (204), so that the grain-folding rod (2) maintains a certain initial length in its natural state and can be compressed or stretched when subjected to axial force. The robot units are connected end to end through a standardized quick-connect interface, which includes a magnetic element (7) for initial alignment, a pin (10) for positioning, and screws (11) and nuts (12) for fastening. When multiple units form a serial modular robot device, the passive telescopic structure of the grain-folding rod (2) can provide adaptive buffering in the overall movement, improving the system's motion stability and load adaptability in unstructured environments.

4. The modular adaptive robot device based on SMA-driven origami bionics as described in claim 1, characterized in that, The intelligent control module first drives each robot unit to perform various posture movements with the assistance of additional sensors, and simultaneously collects the resistance data of the SMA filaments and the corresponding unit posture data to establish an accurate mapping model from resistance to posture in an offline calibration manner. Then, in the actual operation of the system, based on the mapping model and by measuring the resistance value of the SMA filaments of each unit, the real-time posture of the structure is calculated, and the activation sequence of each unit is precisely arranged accordingly, so that the entire system exhibits at least one biomimetic gait among inchworm-like undulation, alternating anchoring crawling, or wave-like movement.

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