Publications

An adaptive localisation algorithm of mobile node in wireless sensor network

Location information is critical to monitoring activities in wireless sensor networks. This paper proposed an adaptive localisation algorithm of mobile node in wireless sensor network for solving this problem. The structure decomposition, electronic control and kinematics model of the proposed mobile node have been investigated, respectively. Improvements have been demonstrated through eliminates the positioning error caused by situations such as node self–energy, data packet loss, low measured value and singular values. A testbed has finally been created for validating the adaptive localisation capability of mobile nodes in wireless sensor network. Experimental results show that the proposed adaptive localisation algorithm can be applied in real use, and precision and stability are upper, and promote the speed and practicability of mobile node in wireless sensor networks using in undesirable environments.

Dynamic Characteristics Analysis of the Six-Axis Force/Torque Sensor

In this study, dynamic characteristics of a robot six-axis wrist force/torque (F/T) sensor with crossbeam elastomer are analyzed by two methods of model identification, a method for simultaneous identification of order and parameters of the model (SIM) and a method based on the differential evolution (DE) algorithm. Firstly, by establishing the simplified mechanical model and finite element (FE) model, respectively, natural frequency of the six-axis wrist F/T sensor is calculated. Secondly, dynamic calibration experiment is conducted. Lastly, two dynamic models of the sensor are identified by SIM and DE methods and the dynamic characteristics of the sensor, such as natural frequency and working band, are further analyzed. Comparing experimental values with the theoretical values, the results show that this sensor has a wide dynamic range with the first natural frequency at more than 1600 Hz, working bands (±5%) are more than 400 Hz, and the step response oscillation is intense. This study can provide a reference for the application of the six-axis F/T sensor in the field of dynamic measurement.

Design and Evaluation of an Electromagnetic Bounce-type Refreshable Braille Display

To help the blind or visually impaired (BVI) read digitally conveniently and at low cost, we propose a bounce-type actuator driven by electromagnetic force, and based on this, a refreshable Braille display (RBD) which can display both Braille and tactile graphic information is manufactured. The internal components of the bounce-type actuator include an electromagnet and two permanent magnets placed in a stepped manner. By passing current in different directions to the coil, the electromagnet can bounce up and down between the two permanent magnets under the action of magnetic force, thereby achieving changes in the raised state of the Braille dot. The permanent magnets placed in staggered positions have an attractive and supportive effect on the electromagnet, so the raised Braille dot can be locked in a specific position when the electromagnet is not powered on and provide a large latching force. In this paper, the force analysis and finite element simulation of the actuator actuation condition of the Braille dot actuator are carried out, and the refresh rate is measured experimentally to be about 16 Hz. Meanwhile, the overall refresh rate of the prototype can be up to 2.7 Hz. Benefiting from the full-latching structure, the RBD proposed in this paper is characterized by a large latching force, a high refresh rate, and an easy scalability. It also has the advantages of low cost, low energy consumption, reliability, and durability, providing an easy-to-promote tool for BVI to read digital information.

Dual-hand Tracking Mirror Rehabilitation Control Algorithm Based on Behavior Prediction

Improved Admittance Control Based Berthing System for Robotic On-Orbit Refueling Mission

The growing demand for accurate and reliable on-orbit refueling missions has prompted the development of advanced solutions. In response, this paper introduces an innovative berthing system that utilizes a 6-degree-of-freedom robotic arm. The primary objective of this system is to enhance the precision and dependability of on-orbit refueling operations. To achieve improved force tracking performance, an enhanced admittance control approach is proposed, which incorporates a proportional-derivative controller. This integration enhances the traditional admittance control method and ensures precise interaction between the robotic arm and the target spacecraft during the berthing process. The effectiveness of the proposed berthing system and control algorithm is validated through extensive experimentation. The results demonstrate significant improvements in the system's fast response capability and reduction in force overshoot. Notably, when employing the designed berthing system and the improved admittance control algorithm, the maximum contact force remains below 20N, and the maximum contact torque is limited to 0.8Nm. These outcomes underscore the system's ability to achieve safe and reliable berthing operations in on-orbit refueling missions.

Motion Simulation and Human–Computer Interaction System for Lunar Exploration

When planning lunar rover missions, it is important to develop intuition and driving skills for unfamiliar environments before incurring the costs of reaching the moon. Simulators make it possible to operate in environments that have the physical characteristics of target locations without the expense of extensive physical tests. This paper proposes a motion simulation and human–computer interaction system based on a parallel mechanism to realize high-fidelity manned lunar rover simulations. The system consists of an interactive operating platform and a lunar surface simulation environment based on Unity3D. To make the 6-DOF platform simulate the posture changes of the rover, we improved the motion simulation algorithm. We designed a posture adjustment system and built virtual sensors to help astronauts perceive the lunar environment. Finally, this paper discusses the method for the realization of the multi-channel human–computer interaction system; astronauts can interactively control the rover through five channels. Experiments show that this system can realize high-fidelity rover simulation and improve the efficiency of human-computer interaction.

Design and analysis of fiber coupling system for laser diode stacks

The fiber coupling system for semiconductor laser diode stacks was simulated by Zemax. Fiber coupling system based on twenty-eight mini-bars in two stack arrays as laser sources is advantageous to reduce costs and improve coupling efficiency. Output beam could be focused into the fiber of 600 μm core diameter with 0.22 numerical aperture by collimating, combining and focusing. The output power of more than 1500 W and the coupling efficiency of more than 93 % is realizable. Importantly, the factors of alignment errors of fiber and optical elements which impact on coupling efficiency are analysed.

EOG Artifact Correction from EEG Recording Using Stationary Subspace Analysis and Empirical Mode Decomposition

Ocular contamination of EEG data is an important and very common problem in the diagnosis of neurobiological events. An effective approach is proposed in this paper to remove ocular artifacts from the raw EEG recording. First, it conducts the blind source separation on the raw EEG recording by the stationary subspace analysis, which can concentrate artifacts in fewer components than the representative blind source separation methods. Next, to recover the neural information that has leaked into the artifactual components, the adaptive signal decomposition technique EMD is applied to denoise the components. Finally, the artifact-only components are projected back to be subtracted from EEG signals to get the clean EEG data. The experimental results on both the artificially contaminated EEG data and publicly available real EEG data have demonstrated the effectiveness of the proposed method, in particular for the cases where limited number of electrodes are used for the recording, as well as when the artifact contaminated signal is highly non-stationary and the underlying sources cannot be assumed to be independent or uncorrelated.

A Novel Tensorial Scheme for EEG-Based Person Identification

Biometrics have attracted growing research interests as the information security and safety gain increasing attention to date. As a kind of important biomedical signal, Electroen-cephalogram (EEG) contains valuable information about identity, emotionality, personality, etc. Thus, automatically distinguishing the identities based on EEG is beneficial to the development of biometrics, forensics and informatics. Although deep learning has absorbed much research attention for the issue of EEG-based person identification, the performance enhancement of this methodology seems to have hit a bottleneck recently. Hence, by rethinking the problems haunting this issue, we plan to reinvigorate the conventional method pipeline, and put forward a novel and effective tensorial scheme away from the deep learning mainstream. Specifically, the proposed tensorial scheme extracts the effective tensorial representation from multi-channel EEG at first; then, the scheme performs the designed tensorial learning to improve the discriminability of the feature space; finally, the scheme carries out the devised tensorial measurement in the learned metric space for classification. Experimental results have demonstrated the superiority of proposed scheme over the related advanced approaches by means of the challenging benchmark databases DEAP, SEED and DREAMER.

Multi-perspective analysis on data augmentation in knowledge distillation

Robot-Assisted Eye-Hand Coordination Training System by Estimating Motion Direction Using Smooth-Pursuit Eye Movements

Robot-assisted eye-hand coordination rehabilitation training system is extremely urgent to study since recent evidence suggests that eye-hand coordination can be brutally disturbed by stroke with critical consequences on motor behavior. In this paper, we develop a robot-assisted eye-hand coordination training system by estimating motion direction using smooth-pursuit eye movements. Firstly, we design a Pong Game, which requires users to extrapolate the direction of a linearly moving ball and to predict whether this ball would be hit. Secondly, the motion direction of the ball is estimated via smooth-pursuit eye movements, allowing the robot quickly establish an assistive force field to hit the ball. Thirdly, adding haptic feedback technology into this training system to make users more immersive. Finally, we conduct a feasibility study with eight healthy subjects to verify the effectiveness of the proposed system. The experimental results show that the mean success rate for hitting the pong ball of the experiment group (assistance turn-on) is 28.33% higher than that of the control group (assistance turn-off), and the mean interception time of the experiment group is 0.35s shorter than that of the control group. Therefore, the developed system may be promising for transferring to the robot-assisted eye-hand coordination rehabilitation training for post-stroke patients.

Efficient Spatiotemporal-Structural Masking for Dynamic Human Activity Recognition with Optimized Computation

Robotic neurorehabilitation system design for stroke patients

In this article, a neurorehabilitation system combining robot-aided rehabilitation with motor imagery–based brain–computer interface is presented. Feature extraction and classification algorithm for the motor imagery electroencephalography is implemented under our brain–computer interface research platform. The main hardware platform for functional recovery therapy is the Barrett Whole-Arm Manipulator. The mental imagination of upper limb movements is translated to trigger the Barrett Whole-Arm Manipulator Arm to stretch the affected upper limb to move along the predefined trajectory. A fuzzy proportional–derivative position controller is proposed to control the Whole-Arm Manipulator Arm to perform passive rehabilitation training effectively. A preliminary experiment aimed at testing the proposed system and gaining insight into the potential of motor imagery electroencephalography-triggered robotic therapy is reported.

A fully actuated aerial manipulator system for industrial contact inspection applications

Purpose This paper aims to present a fully actuated aerial manipulator (AM) with a robust motion/force hybrid controller for conducting contact-typed inspection tasks in industrial plants. Design/methodology/approach An AM is designed based on a hexarotor with tilted rotors and a rigidly attached end effector. By tilting the rotors, the position and attitude of the AM can be controlled independently, and the AM can actively exert forces on industrial facilities through the rigidly attached end effector. A motion/force hybrid controller is proposed to perform contact-typed inspection tasks. The contact-typed inspection task is divided into the approach phase and the contact phase. In the approach phase, the AM automatically approaches the contact surface. In the contact phase, a motion/force hybrid controller is used for contact-typed inspection. Finally, a disturbance observer (DOB) is used to estimate external disturbances and used as feedforward compensation. Findings The proposed AM can slowly approach the contact surface without significant impact in the contact phase. It can realize constant force control in the direction normal to the contact surface in the contact phase, whereas the motion of the remaining directions can be controlled by the operator. The use of the DOB ensures the robustness of the AM in the presence of external wind disturbances. Originality/value A fully actuated AM system with a robust motion/force hybrid controller is proposed. The effectiveness of the proposed AM system for conducting contact-typed industrial inspection tasks is validated by practical experiments.

Simulating a Powered Model Wheel-Tractor on Soft Ground

ABSTRACT THE Highway-Vehicle-Object Simulation Model S(HVOSM) and the associated computer programs prowere modified to simulate the general dynamics of a mantractor on soft ground by incorporating some soil proparameters. The simulated results were verified for passtractor overturns using a powered model tractor. The passresults showed that the modified HVOSM allowed close proprediction of vehicle dynamics.

Development of a Virtual Reality-Based Teleoperated Welding Robot System for Enhanced Safety and Efficiency

A New Design of Texture Haptic Display System

In this paper, it is proposed that a new design of texture haptic display system consisting of a rotating cylinder that evokes a virtual touch sensation of texture surfaces contacted to the user's finger. Small holes, which simulate different surface texture with different rotating speed, are drilled on the cylinder made of aluminum alloy. The user places his or her finger on a small window and moves back and forth while feeling slip. By applying various rotating speed, various friction distributions can be generated on the skin, which are transferred to the fingertip as to generate surface roughness sensation in the subject's nerve system. Through doing some experiments, every user's feeling is got together under different circumstances, and then the principle of the device and some simple experimental results are reported.

Multi-Mode Haptic Display of Image Based on Force and Vibration Tactile Feedback Integration

In order to enhance the sense of reality haptic display based on image, it is widely expected to express various characteristics of the objects in the image using different kinds of haptic feedback. To this end, a multi-mode haptic display method of image was proposed in this paper, including the multi-feature extraction of image and the image expression with various types of haptic rendering. First, the device structure integrating force and vibrotactile feedbacks was designed for multi-mode haptic display. Meanwhile, the three-dimensional geometric shape, detail texture and outline of the object in the image were extracted by various image processing algorithms. Then, a rendering method for the object in the image was proposed based on the psychophysical experiments on the piezoelectric ceramic actuator. The 3D geometric shape, detail texture and outline of the object were rendered by force and vibration tactile feedbacks, respectively. Finally, these three features of the image were haptic expressed simultaneously by the integrated device. Haptic perception experiment results show that the multi-mode haptic display method can effectively improve the authenticity of haptic perception.