When developing microscale robotic systems it is desired that they are capable of performing microscale tasks such as small scale manipulation and transport. In this paper, we demonstrate the transport of microscale objects using single or multiple microrobots in low Reynolds number fluidic environment. The microrobot is composed of a ‘U’ shaped SU-8 body, coated on one side with nickel. Once the nickel coating is magnetized, the motion of the microrobots can be driven by external magnetic fields. To invoke different responses from two microrobots under a global magnetic field, two batches of microrobots were fabricated with different thicknesses of nickel coating as a way to promote heterogeneity within the microrobot population. The heterogeneity in magnetic content induces different spatial and temporal responses under the same control input, resulting in differences in movement speed. The nickel coated microstructure is manually controlled through a user interface developed using C++. This paper presents a control strategy to navigate the microrobots by controlling the direction and strength of ex-ternally applied magnetic field, as well as orientation of the microrobots based on their polarity. In addition, multiple micro-robots are used to perform transport tasks.

Amphibious robots are attracting more and more attentions from researchers worldwide for their broad applications in resource exploration, disaster rescue, and reconnaissance. Amphibious robot with transformable flipper-leg composite propul-sion mechanisms can adapt various terrestrial and water environments. In this paper, we explored the locomotion performance of a amphibious robot with flexible flipper legs on various terrains and underwater through dynamical simulation. The influence of the stiffness of the flipper legs on the locomotion performance in various environments was investigated comprehensively. The results indicate that the locomotion with flexible flipper legs is very stable, and the stiffness of the flipper legs has a great impact on the locomotion performance. The verification experiments demonstrate the accuracy of the simulation results. The study facilitates the design of the amphibious robot and indicates that the passively transformable flipper-leg mechanisms also enable amphibious robot to conquer various complex terrestrial environments.

Robotics is one area of research in which bio-inspiration is an effective way to design a system by investigating the working principles of nature. Recently, tails have received interest in robotics to increase stability and maneuverability. In this study, we investigated the effectiveness of a static tail for bio-inspired water-running locomotion. The tail was added to increase the stability in the rolling and yawing directions based on the hydrodynamic force from interaction between the tail and the water. The drag coefficient in the interaction is not easy to calculate analytically, so experimental studies were done for various static tail shapes. Five different shapes and compliances in two directions were considered for experimental design candidates. The result was applied to design a stable amphibious robot that can run on ground and water surfaces.

Nature has been a source of inspiration for developing advanced autonomous aerial and underwater vehicles. The bodies with flapping appendages produce Center of Mass (COM) oscillations as the flapping fins generate forces oscillatory in nature. The vehicles with larger COM oscillations pose the problems of control and maneuverability and this paper discusses the effect of flexibility and other operating parameters such as heaving, pitching amplitudes and operating frequency on COM oscillations. A detailed theoretical investigation has been carried out to predict the optimal operating parameters along with the fin stiffness to reduce the COM oscillations for a given Self-Propelled Speed (SPS). Experiments have been performed to validate the theoretical results. It has been observed that the flexible fins operating at larger frequencies produce lower COM oscillations compared to stiffer fins operating at lower frequencies for a given mean thrust/SPS, and that the trailing edge amplitude along with the deformation pattern play a role in the generation of COM oscillations.

Bionic jumping robot can cross the obstacles by jumping, and it has a good application prospect in the unstructured complex environment. The less Degree of Freedom (DOF) jumping leg, which has the characteristics of simple control and high rigidity, and is very important in research. Based on the experimental observation of leg physiological structure and take-off process of locust, two 1 DOF jumping leg models, which includes four-bar jumping leg model and slider-crank jumping leg model, are established, and multi objective optimization is conducted to deduce the motion law of two 1 DOF jumping leg models and jumping leg of locust is closer. Then the jumping performance evaluation indices are proposed, which include the mechanical property, body attitude, jumping distance and environmental effect. According to these evaluation indices, the jumping performances of the two jumping leg models are analyzed and compared, and the simulation is conducted for further explanations. The analysis results show that the four-bar jumping leg has smaller structural size and its motion law is closer to the hindleg of locust. The slider-crank jumping leg has better mechanical property, stronger energy storage capacity and the rough ground has less effect on it. This study offers a quantitative analysis and comparison for different jumping leg models of bionic locust jumping robot. Furthermore, a theoretical basis for future research and engineering application is established.

This work concerns biped adaptive walking control on irregular terrains with online trajectory generation. A new trajectory generation method is proposed based on two neural networks. One oscillatory network is designed to generate foot trajectory, and another set of neural oscillators can generate the trajectory of Center of Mass (CoM) online. Using a motion engine, the char-acteristics of the workspace are mapped to the joint space. The entraining property of the neural oscillators is exploited for adaptive walking in the absence of a priori knowledge of walking conditions. Sensory feedback is applied to modify the generated trajectories online to improve the walking quality. Furthermore, a staged evolutionary algorithm is developed to tune system parameters to improve walking performance. The developed control strategy is tested using a humanoid robot on irregular terrains. The experiments verify the success of the presented strategy. The biped robot can walk on irregular terrains with varying slopes, unknown bumps and stairs through autonomous adjustment of its walking patterns.

The principle of passive dynamic walking has drawn lots of attentions in the field of robotics for it provides a possibility to realize natural walking. However, stabilizing the quadrupedal passive walking remains challenging. In this paper, a novel control method is proposed to stabilize the quadrupedal quasi-passive walking. Inspired by biological concepts, this method treats the foreleg pair and hindleg pair as two bipedal walkers, and a virtual model controller is designed to maintain the quasi-passive walking of each bipedal walker independently. This control method was then verified by a planar quadrupedal model with compliant legs, which successfully achieved stable periodical walking gaits. It was found that although being controlled independently, the movement of fore and hind leg pairs still formed a time-invariant phase shift, showing remarkable resemblance to that of a walking horse. We further analyzed the influences of varying factors on the gait characteristics and stability. These analyses show the control method is robust since it can stabilize the gaits within a wide range of leg compliance parameters and resist considerably large disturbances. In addition, the optimal ranges of the leg compliance parameters for the largest stability margin were also found in this study.

An Adaptive Fuzzy Sliding Mode Controller with Nonlinear Observer (AFSMCO) for the redundant robotic manipulator is proposed in this paper. This approach could achieve a precise trajectory tracking for a robot manipulator in the presence of uncertainties and disturbances. Primarily, a suitable observer using the recursive algorithm is presented for an accurate estimation of external disturbances caused by the varying external force. Secondly, the adaptive fuzzy logic is designed to approximate the parameters of the sliding mode controller (AFSMC) to avoid chattering in real time. Moreover, it is shown using the Lyapunov theory that the tracking error asymptotically converges to zero. Finally, the effectiveness of the proposed control approach and theoretical discussion are demonstrated by simulation results on a 7-link robot and tested on a 7-DOF manipulator platform.

For the design and development of advanced prosthetic limbs, many attempts have been made to restore the function of mechanoreceptors using artificial tactile sensors. Mechanoreceptors in human skin, which make dexterous manipulation possible, respond to the mechanical stimuli in the form of spike trains. In this paper, a bio-inspired approach to replicate the Fast Adapting type I (FA-I) mechanoreceptor is developed, where piezoelectric materials, such as polyvinylidene difluoride (PVDF) films, are used to generate continuous analog electrical signals; then the analog signals are successfully converted into spike trains using the spiking neuron model. By comparing with spike trains measured from the glabrous skin of macaque monkeys, it was found that this approach can mimic FA-I afferent spiking activities in terms of both the average inter-spike interval and the first spike latency. Spike features of the FA-I mechanoreceptors, such as the variability, frequency dependent responses, and population activity, were also explored, which may play a vital role in the understanding of the functionality of FA-I mechanoreceptors and the development of advanced prosthetic limbs.

Surface modification with superhydrophobicity is a popular and challenging research field on metals. In this work, a simple method was used to fabricate a bionic superhydrophobic zinc coating with crater-like structures on pipeline steel surface. This method involved electrodeposition of zinc coating and chemical reaction in perfluorooctanoic acid ethanol solution. The per-fluorooctanoic acid with low surface free energy was not only used for chemical etching but also used for fluorinated modification. The contact angle of water on such superhydrophobic zinc coating was up to 154.21?, and the sliding angle was less than 5? due to the micro crater-like structures and the low surface free energy. Moreover, the prepared superhydrophobic zinc coating demonstrated excellent self-cleaning property and great stability at room temperature, and the contact angle of water on this coating remained stable after storage in air for more than 80 days. This superhydrophobic zinc coating will open much wider applications of electrodeposition metal coating, including self-cleaning property, and can be easily extended to other metals.

Oxidized Bacterial Cellulose (OBC)-hydroxyapatite (HAp)-gelatin (Gel) nanocomposites were prepared by a biomimetic process. HAp nanocrystals were precipitated in a mixed solution of Na2HPO4 (pH 9.2) and Gel solution at 37 ?C, and OBC was used to generate a three-dimensional (3D) network stent. The tensile strength of OBC-HAp-G was higher than 0.3 MPa, and the complete degradation time was approximately 90 d in Simulated Body Fluid (SBF). Fourier transform infrared spectroscopy demonstrated that a coordinate bond had formed possibly between HAp and the cellulose hydroxyl. X-ray diffraction showed that both the oxidation of bacterial cellulose and an increase in Gel content induced the formation of tiny HAp crystallites during composite fabrication. Specific surface area and porosity measurements indicated that a low Gel concentration contributed to retention of porous structure. The Ca and P contents on the surface of materials increased initially and then decreased with an increase in Gel content, as measured by energy dispersive spectroscopy. From the thermogravimetric data, the increase in decomposition temperature suggested the formation of chemical bonds among OBC, HAp, and Gel. The above results suggest that the OBC-HAp-G0.3 composite is a potential bone scaffold material.

The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Microscopy (ESEM) and Transmission Electron Microscopy (TEM) were used to observe the scale structure. The scale has a discrete osseous layer which is composed of boat-like unit (due to the shape). The osseous layer is embedded into fibrillary layer, and the largest thickness ratio of osseous layer to fibrillary layer is about 7, much higher than those of other reported fish scales. Nanoindentation test was used to investigate mechanical property of the scale. Elastic modulus (Er) and hardness (H) of Dabryanus scale are much lower than those of other reported fish scales. Scale models were proposed and the principles of materials mechanics were used to analyze the mechanical properties of the Dabryanus scale. The boat-like unit in osseous layer makes the scale flexible while keeping a high thickness ratio of osseous layer to fibrillary layer, which increases the flexibility and protection capacity of the scale This study may provide new strategy for the design of flexible armor or flexible devices.

Acanthocnemus nigricans is an inconspicuous pyrophilous beetle that approaches forest fires. The beetle is equipped with a pair of unique infrared (IR) receptors on its prothorax that allows it to detect hot surfaces in flight. The IR receptor consists of a little disc bearing about 90 tiny sensilla on its anterior half. The disc sensilla are unique in insects and their functions are largely unknown. Using a 3D reconstruction of the head and thorax we performed case studies to reveal different position-dependent expositions of the IR receptors to incoming radiation. Results show that the spatiotemporal pattern in which different sectors of the disc are exposed provides the beetle with unambiguous information about its current direction to an IR source. As a striking structural element, the disc sensilla contain an electron-dense rod connecting an outer peg to the inner sensory cell. Finite element simulations suggest that the rod serves as a heat conductor directing heat to the thermosensitive cell inside the disc. Thus the disc sensilla can be interpreted as discrete temperature reading points. The resulting pattern of stimulated/deactivated sensilla, therefore, could provide the flying beetle with spatiotemporal information about its current position relative to an IR source. Possible biomimetic perspectives of the findings are discussed.

Based on anti-wear theory of soil animals, the samples of impregnated diamond bit with bionic self-regenerated non-smooth surface were designed and fabricated. Such a bionic surface was characterized by concave-shape units of different scales that continuously maintained their shape and function during the whole working process. Abrasion tests were carried out to investigate the performance of samples. Results showed that the bionic samples exhibit excellent wear resistance and drilling performance under the action of bionic self-regenerated units, especially those with units of 2 mm – 3 mm diameter. The particle-trapping mechanism coming from the self-regenerated concaves and the lubricating mechanism coming from the continuously self-supplying of solid lubricant are important reasons for reducing or even avoiding the severe abrasions. The improved drilling performance of bionic samples derives from, on the one hand, the back edge of bionic unit that contributes to exposing new diamond and supplying additional shear stresses to increase the cutting ability, on the other hand, the enhanced load per unit area due to the decreased contact area at the frictional interface. The relationship between the wear behavior and the scale of bionic unit was revealed. The unit of smaller scale on the bionic samples can enhance the shear stress level. Further reducing the scale to a contain extent will diminish the wear resistance of sample. While increasing the scale can lead to the poor lubricating effect.

Travelers’ route choice behavior, a dynamical learning process based on their own experience, traffic information, and influence of others, is a type of cooperation optimization and a constant day-to-day evolutionary process. Travelers adjust their route choices to choose the best route, minimizing travel time and distance, or maximizing expressway use. Because route choice behavior is based on human beings, the most intelligent animals in the world, this swarm behavior is expected to incorporate more intelligence. Unlike existing research in route choice behavior, the influence of other travelers is considered for updating route choices on account of the reality, which makes the route choice behavior from individual to swarm. A new swarm intelligence algorithm inspired by travelers’ route choice behavior for solving mathematical optimization problems is introduced in this paper. A comparison of the results of experiments with those of the classical global Particle Swarm Optimization (PSO) algorithm demonstrates the efficacy of the Route Choice Behavior Algorithm (RCBA). The novel algorithm provides a new approach to solving complex problems and new avenues for the study of route choice behavior.

Using a network of mobile sensors to track and map a dynamic spatio-temporal process in the environment is one of the current challenges in multi-agent systems. In this work, a distributed probabilistic multi-agent algorithm inspired by the bacterium foraging behavior is presented. The novelty of the algorithm lies in being capable of tracking and mapping a spatio-temporal quantity without the need of machine learning, estimation algorithms or future planning. This is unlike most current techniques that rely heavily on machine learning to estimate the distribution as well as the profile of spatio-temporal quantities. The experimental studies carried out in this work show that the algorithm works well by following the concentration gradient of a dynamic plume created under diffusive conditions. Furthermore, the algorithm is inherently capable of finding the source of a diffusive spatio-temporal quantity as well as performing environmental exploration. It is computationally tractable for simple agents, shown to adapt to its environment and can deal successfully with noise in sensor readings as well as in robot dynamics.