Journal of Bionic Engineering最新文献

Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics (CFRP). Owl feathers are known for their unique compact structure; they are not only lightweight but also strong. In this study, an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches. The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other, forming an effective mechanical interlocking structure. These structures bring owl feathers excellent mechanical properties. Inspired by the natural structure of owl feathers, a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber (CF) fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers. To evaluate the effect of the fine feather structure on the mechanical properties of CFRP, a mechanical property study on CFRP with and without the fine feather imitation structure were conducted. The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly. Specifically, the tensile strength of the composites increased by 6.42% and 13.06% and the flexural strength increased by 8.02% and 16.87% in the 0° and 90° sample directions, respectively. These results provide a new design idea for the improvement of the mechanical properties of the CFRP, promoting the application of CFRP in engineering fields, such as automotive transportation, rail transit, aerospace, and construction.

Pneumatic soft robots have undergone significant advancements in recent years. However, the majority of robot motion control still relies on electronic computers to regulate the valves and air pumps. Despite the potential reduction in controller dependency by utilizing soft pneumatic oscillators, challenges such as low flow rates, complex manufacturing processes, and lack of adjustment ability persist. Inspired by the geckos’ spine, we propose a Spinal Bistable Oscillator (SBO) that operates without discrete components or electronic control hardware, achieving stable oscillatory motion under constant air pressure. This oscillator employs a soft control valve and lagging pin, which can switch the direction of airflow conduction based on the oscillation angle of the spine. Different types of actuators can be controlled using a series connection. In this study, the effective working range of the soft control valve, influence of the spring pretension force on the torque during oscillation, and effect of different throttle tube lengths on the oscillation frequency were investigated. Furthermore, a self-crawling robot was developed. Experimental results demonstrate that the robot can crawl at speeds ranging from 3.6 to 5.7 mm/s (or 3.1 to 4.9 body length/min) and overcome its own gravity (with a weight of 165 g) to climb vertically. The SBO proposed in this study exhibits characteristics of lightweight, low cost, high oscillation torque, and tunable frequency. It holds promise for application in joint control of future pneumatic soft robots.

Lizards are one of the most primitive reptiles in existence, with special limb structures that enable them to move quickly across diverse and complex terrains such as rock piles, shallow shoals, and deserts. A thorough exploration was conducted on the biomimetic mechanism and ground-touching mechanism of lizard limbs from both micro and macro perspectives. Inspired by the intricate torso and limb configurations of lizards, a novel Torso-leg-foot biomimetic robot has been conceptualized based on the design of the Big-Foot robot. This robot integrates a Torso-leg-foot system, featuring a parallel torso biomimetic structure with a 2-SPR/UPU/UPR(P) configuration. It utilizes the theory of finite screws to articulate the instantaneous movements of the parallel torso, and the inverse kinematics of this mechanism have been calculated. The reachable workspace of the 2-SPR/UPU/UPR parallel mechanism using FIS theory, which is closely related to the climbing height of the robot. A comprehensive dimension synthesis was conducted on the leg-foot system, and the adoption of the three-pair rod drive method was determined by investigating its Variable Rotating Velocity Characteristics (VRVC). Simulation tests have shown that with an integrated torso, the robot can climb vertical obstacles up to 600 mm in height. The experimental tests of climbing steps and slopes using physical prototypes have confirmed the robot’s obstacle-crossing capability. The potential applications of this Torso-leg-foot biomimetic robot is to carry heavy objects across obstacles to perform tasks such as planetary exploration and disaster relief.

The connection efficiency of composite pre-tightened multi-tooth joint is low because of uneven load distribution and single load transmission path. In this paper, based on the principle of bio-tooth (suture) structure, combining soft material with fractal, a composite pre-tightened multi-hierarchy tooth joint is proposed, and the bearing performance and failure process of the joint through experiments and finite element method under tensile load. First, the ultimate bearing capacity, load distribution ratio, and failure process of different hierarchies of teeth joints are studied through experiments. Then, the progressive damage models of different hierarchies of tooth joints are established, and experiments verify the validity of the finite element model. Finally, the effects of soft material and increasing tooth hierarchy on the failure process and bearing capacity of composite pre-tightened tooth joints are analyzed by the finite element method. The following conclusions can be drawn: (1) The embedding of soft materials changed the failure process of the joint. Increasing the tooth hierarchy can give the joint more load transfer paths, but the failure process of the joint is complicated. (2) Embedding soft materials and increasing the tooth hierarchy simultaneously can effectively improve the bearing capacity of composite pre-tightened tooth joints, which is 87.8% higher than that of traditional three-tooth joints.

Flexible piezoresistive pressure sensors have attracted much attention for applications in health monitoring and human-machine interfaces due to their simple device structures and easy-to-read signals. For practical applications, the deployment of flexible pressure sensors characterized by high sensitivity and fast response time is imperative for the rapid and accurate detection and monitoring of tiny signals. Such capabilities are essential for facilitating immediate feedback and informed decision-making across a spectrum of contexts. Drawing lessons from the hypersensitive and fast-responding pressure sensing structures in the dragonfly’s neck (for stable imaging during its highly maneuverable flight), a Biomimetic Piezoresistive Pressure Sensor (BPPS) with exquisite mechanically interlocking sensing microstructures is developed. Each interlocking perceptual structure pair consists of an ox-horn-shaped and a mushroom-shaped structural unit. Through the characteristic configuration of the perceptual structure pair, the BPPS realizes a fast gradient accumulation of the contact area, thus synergistically enhancing the sensitivity and fast response capability. Remarkably, the sensitivity of the BPPS reaches 0.35 kPa^− 1, which increased by 75% compared to the 0.2 kPa^− 1 of the pressure sensors without biomimetic structures. Moreover, the BPPS also achieves rapid response/recovery times (< 90/15 ms). Our BPPS finds utility in tasks such as identifying objects of different weights, monitoring human respiratory status, and tracking motion, demonstrating its potential in wearable healthcare devices, assistive technology, and intelligent soft robotics. Moreover, it possesses the advantages of high sensitivity and fast response time in practical applications.

This work examines the impact of incorporating the physiological conditions of human cancellous bone, by integrating similar porosity of porous Fe with the cancellous bone under dynamic immersion test. All of the porous Fe specimens with ~ 80% porosity were immersed in Simulated Body Fluid (SBF) with a flow rate of 0.3 ml/min integrated with cancellous bone for 7, 14 and 28 days. Porous Fe with the lowest surface area has the highest degradation rate despite having the lowest relative weight loss. The relationship between fluid induced shear stress and weight loss of specimens have been established.

Musculoskeletal Symptoms (MSS) often arise from prolonged maintenance of bent postures in the neck and trunk during surgical procedures. To prevent MSS, a passive exoskeleton utilizing carbon fiber beams to offer support to the neck and trunk was proposed. The application of support force is intended to reduce muscle forces and joint compression forces. A nonlinear mathematical model for the neck and trunk support beam is presented to estimate the support force. A validation test is subsequently conducted to assess the accuracy of the mathematical model. Finally, a preliminary functional evaluation test is performed to evaluate movement capabilities and support provided by the exoskeleton. The mathematical model demonstrates an accuracy for beam support force within a range of 0.8–1.2 N Root Mean Square Error (RMSE). The exoskeleton was shown to allow sufficient Range of Motion (ROM) for neck and trunk during open surgery training. While the exoskeleton showed potential in reducing musculoskeletal load and task difficulty during simulated surgery tasks, the observed reduction in perceived task difficulty was deemed non-significant. This prompts the recommendation for further optimization in personalized adjustments of beams to facilitate improvements in task difficulty and enhance comfort.

Shape Memory Polymers (SMPs) need to be given a temporary shape in advance to realize the shape memory process, but the manual shaping process is cumbersome and has low precision. Here, we propose a universal applicable method for 4D printing self-folding SMPs by pre-stretching extruded filaments during 3D printing, the temporary shape of the SMPs were designed and fixed during 3D printing. Prepared samples can automatically perform shape memory process under stimulation without manual temporary shape programming process. Furthermore, using carbon ink as a photothermal conversion agent enables the 4D printing SMPs to have thermal and light response characteristics. In addition, some bionic applications of self-folding SMPs were demonstrated, such as self-morphing grasper, DNA double helix structures, programmable sequential switching mimosa, self-folding box and human hand. The combination of SMP and 3D printing fully takes advantage of 4D printing technology, and the self-folding SMPs show great potential applications in the fields of tissue engineering scaffold, self-folding robots, self-assembly system and so on.

Walking is the basic locomotion pattern for bipedal robots. The walking pattern is widely generated using the linear inverted pendulum model. The linear inverted pendulum motion of each support period can be designed as a walk primitive to be connected to form a walking trajectory. A novel method of integrating double support phase into the walk primitive was proposed in this article. The method describes the generation of walking patterns using walk primitives with double support, specifically for lateral plane including walking in place, walking for lateral, and walking initiation, and for sagittal plane including fixed step length walking, variable step length walking, and walking initiation. Compared to walk primitives without double support phase, those with double support phase reduce the maximum speed required by the robot and eliminate the need to adjust foothold for achieving continuous speed. The performance of the proposed method is validated by simulations and experiments on Neubot, a position-controlled biped robot.