Huayan Pu

Magnetic impedance biosensor: A review

Though the magnetoimpedance effect was discovered two decades ago, the biomedical applications of the magnetoimpedance sensor are still in their infancy. In this review, the authors summarized the magnetoimpedance effect in soft ferromagnetic wires, ribbons and thin films for biosensing applications. Recent progress and achievements of the magnetoimpedance-based biosensing applications including the detection of magnetic Ferrofluid, magnetic beads, magnetic nanoparticles, magnetically labeled bioanalytes and biomagnetic fields of living systems were reviewed. The modification effect of the biochemical liquids, agglomeration effect of the magnetic particles, and the effect of the stray magnetic field on magnetoimpedance were investigated in this review. Some constructive strategies were proposed for design of the high-performance magnetoimpedance biosensor, for quantitative and ultrasensitive detection of magnetically labeled biomolecules. The theoretical and experimental results suggest that the magnetoimpedance sensors are particularly suitable for highly sensitive detection of low-concentration biomolecules, and might be used for early diagnosis and screening of cancers.

Experimental study on oscillating paddling gait of an eccentric paddle mechanism

Eccentric paddle mechanism (ePaddle) is a novel locomotion mechanism designed for amphibious robot. Integrated with several paddles and a wheel, the ePaddle has versatility in locomotion gaits. In this paper, we focus on the aquatic oscillating paddling gait. The conception of the oscillating paddling gait is introduced firstly and followed by the analysis of the oscillation trajectory of the paddles. In order to verify the ability of producing effective thrust force by the oscillating paddling gait, a thrust measuring facility is built. A series of experiments have been carried out with this facility. From the results, we characterize how the amplitude and frequency of the generated net thrust force relate with the amplitude, period of the oscillation of the paddle. Finally, the influence of the number of paddles on the net thrust is analyzed.

Modeling the rotational paddling of an ePaddle-based amphibious robot

To enhance the mobility of amphibious robots for multi-terrains tasks, we have proposed an eccentric paddle locomotion mechanism (ePaddle) with several feasible terrestrial and aquatic gaits. In this paper, we present a rigid paddle model for predicting the thrust force in one of the aquatic gaits, namely the rotational paddling gait. Thrust forces calculated by this model demonstrate the idea that by relocating the paddle shaft eccentrically from its wheel center, the rotating paddles will generate vectored thrust force for swimming. The paddling motion and the validity of the rigid paddle model are verified by experiments in a water tank.

Electroencephalography(EEG)-based instinctive brain-control of a quadruped locomotion robot

Artificial intelligence and bionic control have been applied in electroencephalography (EEG)-based robot system, to execute complex brain-control task. Nevertheless, due to technical limitations of the EEG decoding, the brain-computer interface (BCI) protocol is often complex, and the mapping between the EEG signal and the practical instructions lack of logic associated, which restrict the users actual use. This paper presents a strategy that can be used to control a quadruped locomotion robot by users instinctive action, based on five kinds of movement related neurophysiological signal. In actual use, the user drives or imagines the limbs/wrists action to generate EEG signal to adjust the real movement of the robot according to his/her own motor reflex of the robot locomotion. This method is easy for real use, as the user generates the brain-control signal through the instinctive reaction. By adopting the behavioral control of learning and evolution based on the proposed strategy, complex movement task may be realized by instinctive brain-control.

Non-reciprocating legged gait for robot with epicyclic-gear-based eccentric paddle mechanism

A novel eccentric paddle mechanism based on epicyclic gear mechanism (ePaddle-EGM) has been proposed to enhance the mobility of amphibious robots for multi-terrain tasks with diverse locomotion gaits. This paper proposes a unique non-reciprocating legged walking gait for a quadruped or hexapod robot based on ePaddle-EGMs after a brief kinematic analysis of the ePaddle-EGM. During the gait, the robot can generate desired periodic motion of the legs in the swinging and supporting phases while maintaining all the actuators rotating unidirectionally. Advantages of the proposed non-reciprocating legged gaits include that influence of backlash in the epicyclic gear mechanism could be eliminated and accuracy of locomotion can be guaranteed. Experiments on a single ePaddle-EGM prototype module were conducted to validate the proposed mechanism design and the idea of deploying the non-reciprocating legged walking gait to improve locomotion accuracy and energetic efficiency of the robot. A non-reciprocating legged gait is proposed for an ePaddle-EGM-based robot.Gait sequence and planning method for this gait are discussed and verified.Locomotion accuracy is secured with the gait in the presence of gear backlash.Robot walks more efficiently in this gait than in legged crawling gait.

Experimental study on the oscillating paddling gait of an ePaddle mechanism with flexible configuration

In this paper, a novel eccentric paddle locomotion mechanism (ePaddle) has been proposed to enhance the mobility of amphibious robots for multi-terrains tasks with diverse locomotion gaits. The oscillating paddling gait of the ePaddle mechanism enables the robot to perform stationary observation or attitude maneuvering operations in shallow water. To increase the thrust generated by this gait, the ePaddle mechanism has a flexible configuration, i.e. a flexible paddle and three rigid paddles. The effects of the oscillating amplitude and period of the gait to thrust are analyzed and compared with the thrusts measured with rigid configuration. Experimental results demonstrate that the flexible configuration is able to produce much more net thrust than the rigid configuration when the ePaddle is oscillating at large amplitude. Graphical Abstract

Modeling of the oscillating-paddling gait for an ePaddle locomotion mechanism

An eccentric paddle locomotion mechanism (ePaddle) was proposed to enhance the mobility of amphibious robots for multi-terrains tasks. There are several feasible terrestrial and aquatic gaits for an ePaddle-based robot. In this paper, we present the method for modelling thrust in one of the aquatic gaits, namely the oscillating-paddling gait, for an ePaddle mechanism. The conception of the oscillating-paddling gait is introduced firstly and followed by the thrust model. In order to verify the proposed model, a thrust measuring facility is built. A series of experiments are carried out with this facility. From the results, we verify the thrust model for the oscillating-paddling gait. Furthermore, we characterize how the amplitude and direction of the generated net thrust force relate with the amplitude, period and oscillation ratio of the oscillating-paddling gait.

Design and locomotion simulation of an improved eccentric paddle mechanism for amphibious robots

Eccentric paddle mechanism (ePaddle) is a novel locomotion mechanism designed for amphibious search and rescue tasks. The ePaddle is able to enhance the mobility of amphibious robots for multi-terrains tasks. Based on the principle of ePaddle and the experiments on the prototype, an improved mechanism named ePaddle-EGM is proposed in this paper. The ePaddle-EGM is based on the epicyclic gear mechanism, and follows the concept of alternating motion pattern through actively changing the position of the paddle shaft. The key features of the improved mechanism are the motion totally achieved by revolute joints and dynamic coupling between joints. The kinematic analysis as well as the prototype design are presented in this paper. The locomotion simulations of various gaits are carried out to verify the mobility of the new design.

The Disturbing Effect of the Stray Magnetic Fields on Magnetoimpedance Sensors

The disturbing effect of the stray magnetic fields of Fe-based amorphous ribbons on the giant magnetoimpedance (GMI) sensor has been investigated systematically in this paper. Two simple methods were used for examining the disturbing effect of the stray magnetic fields of ribbons on the GMI sensor. In order to study the influence of the stray magnetic fields on the GMI effect, the square-shaped amorphous ribbons were tested in front, at the back, on the left and on the top of a meander-line GMI sensor made up of soft ferromagnetic films, respectively. Experimental results show that the presence of ribbons in front or at the back of GMI sensor shifts the GMI curve to a lower external magnetic field. On the contrary, the presence of ribbons on the left or on the top of the GMI sensor shifts the GMI curve to a higher external magnetic field, which is related to the coupling effect of the external magnetic field and the stray magnetic fields. The influence of the area and angle of ribbons on GMI was also studied in this work. The GMI sensor exhibits high linearity for detection of the stray magnetic fields, which has made it feasible to construct a sensitive magnetometer for detecting the typical stray magnetic fields of general soft ferromagnetic materials.

Improved effective design of the eccentric paddle mechanism for amphibious robots

To perform search and rescue missions in multi-terrains after natural disasters, the amphibious robot we designed is equipped with four eccentric paddle modules. The module is based on the epicyclic gear mechanism, and by changing the paddle shafts location we can achieve various gaits adapting amphibious environment. Regarding experimental results with the first generation prototype, named ePaddle-EGM, we proposed an improved one to achieve lightness, accuracy and stability. It is a scaled-down version whose transmission system has been simplified. The dustproof sealing is considered to ensure the stability and the position sensing system is optimized. The comparative analysis of ePaddle-EGM2 and ePaddle-EGM is presented in this paper and experiments of various gaits are conducted to verify the performance of the improved design.