Trajectory planning for biped robot walking on uneven terrain - Taking stepping as an example

According to the features of movements of humanoid robot, a control system for humanoid robot walking on uneven terrain is present. Constraints of stepping over stairs are analyzed and the trajectories of feet are calculated by intelligent computing methods. To overcome the shortcomings resulted from directly controlling the robot by neural network （NN） and fuzzy logic controller （FLC）, a revised particle swarm optimization （PSO） algorithm is proposed to train the weights of NN and rules of FLC. Simulations and experiments on different control methods are achieved for a detailed comparison. The results show that using the proposed methods can obtain better control effect.

SHUYU Robot:An Automatic Rapid Temperature Screening System

The health of people around the world and the global economy are under substantial threat from the outbreak of pandemics[1].Controlling pandemics is extremely challenging,with preventing the spread of pathogens the most important and critical step.Of all preventative actions,body temperature screening is undoubtedly highly necessary and effective[2].

Esophageal surgery in minimally invasive era

The widespread popularity of new surgical technologies such as laparoscopy, thoracoscopy and robotics has led many surgeons to treat esophageal diseases with these methods. The expected benefits of minimally invasivesurgery(MIS) mainly include reductions of postoperative complications, length of hospital stay, and pain and better cosmetic results. All of these benefits could potentially be of great interest when dealing with the esophagus due to the potentially severe complications that can occur after conventional surgery. Moreover, robotic platforms are expected to reduce many of the difficulties encountered during advanced laparoscopic and thoracoscopic procedures such as anastomotic reconstructions, accurate lymphadenectomies, and vascular sutures. Almost all esophageal diseases are approachable in a minimally invasive way, including diverticula, gastro-esophageal reflux disease, achalasia, perforations and cancer. Nevertheless, while the limits of MIS for benign esophageal diseases are mainly technical issues and costs, oncologic outcomes remain the cornerstone of any procedure to cure malignancies, for which the long-term results are critical. Furthermore, many of the minimally invasive esophageal operations should be compared to pharmacologic interventions and advanced pure endoscopic procedures; such a comparison requires a difficult literature analysis and leads to some confounding results of clinical trials. This review aims to examine the evidence for the use of MIS in both malignancies and more common benign disease of the esophagus, with a particular emphasis on future developments and ongoing areas of research.

Review:Recent advances in nonlinear control technologies for shape memory alloy actuators

This paper reviews recent developments in nonlinear control technologies for shape memory alloy (SMA) actuators in robotics and their related applications. SMA possesses large hysteresis, low bandwidth, slow response, and non-linear behavior, which make them difficult to control. The fast response of the SMA actuator mostly depends upon, (1) type of controller, (2) rate of addition and removal of heat, and (3) shape or form of the actuator. Though linear controllers are more desirable than nonlinear ones, the review of literature shows that the results obtained using nonlinear controllers were far better than the former one. Therefore, more emphasis is made on the nonlinear control technologies taking into account the intelligent controllers. Various forms of SMA actuator along with different heating and cooling methods are presented in this review, followed by the nonlinear control methods and the control problems encountered by the researchers.

An Improved Differential Evolution Trained Neural Network Scheme for Nonlinear System Identification

This paper presents an improved nonlinear system identification scheme using di？erential evolution （DE）, neural network （NN） and Levenberg Marquardt algorithm （LM）. With a view to achieve better convergence of NN weights optimization during the training, the DE and LM are used in a combined framework to train the NN. We present the convergence analysis of the DE and demonstrate the efficacy of the proposed improved system identification algorithm by exploiting the combined DE and LM training of the NN and suitably implementing it together with other system identification methods, namely NN and DE＋NN on a number of examples including a practical case study. The identification results obtained through a series of simulation studies of these methods on different nonlinear systems demonstrate that the proposed DE and LM trained NN approach to nonlinear system identification can yield better identification results in terms of time of convergence and less identification error.

Design Procedure and Simulation of a Novel Multi-Modal Tactile Display Device for Biomedical Applications

Tactile display is recently attracting much attention in the field of human computer interaction. There is a strong need for such a device especially for application in which the touch feeling is lost, such as surgeons willing to feel the tissue hardness during laparoscopic surgeries. In this paper, a novel multi-modal tactile display device which can display both surface shape and stiffness of an object is introduced. The conceptual design is built upon using two springs, made of Shape Memory Alloys-SMA, to control both shape and stiffness. The design parameters of this device are selected based on the spatial resolution of human finger and the stiffness range of the soft tissue. The display device is simulated using Finite Element Method, FEM, to study the effect of design parameters on the resulting stiffness. The results showed that the device can display stiffness of an object independent of its shape display. Simulation results confirmed that the stiffness display is stable when applying force by the finger during indentation for feeling stiffness, since the total stiffness error does not exceed 1.2%.

Wideband Cognitive Radio Networks Based Compressed Spectrum Sensing: A Survey

Spectrum sensing is a core function at cognitive radio systems to have spectrum awareness. This could be achieved by collecting samples from the frequency band under observation to make a conclusion whether the band is occupied, or it is a spectrum hole. The task of sensing is becoming more challenging especially at wideband spectrum scenario. The difficulty is due to conventional sampling rate theory which makes it infeasible to sample such very wide range of frequencies and the technical requirements are very costly. Recently, compressive sensing introduced itself as a pioneer solution that relaxed the wideband sampling rate requirements. It showed the ability to sample a signal below the Nyquist sampling rate and reconstructed it using very few measurements. In this paper, we discuss the approaches used for solving compressed spectrum sensing problem for wideband cognitive radio networks and how the problem is formulated and rendered to improve the detection performance.

Design Methodology of a Micro-Scale 2-DOF Energy Harvesting Device for Low Frequency and Wide Bandwidth

A detailed design methodology of a micro-scale 2-DOF energy harvesting device that can harvest human motion energy of low frequency and wide bandwidth is developed. Based on the concept of the 2-DOF vibration absorber, device parameters are selected to harvest energy at low frequency of 1-10 Hz and wide bandwidth with ±20% of the mean frequency, which matches the human motion. The device dimensions are limited to 40 × 30 × 10 mm3 to fit with the human wrist size. Then, a finite element model is developed to investigate the system performance with the selected parameters. When subjected to harmonic excitation of 1 g, the proposed 2-DOF device is able to provide a power of at least 10 μW in between the two close resonant peaks of 4 Hz and 6 Hz, which is the target frequency range. The device shows very high power per square frequency compared with the reported harvesters.

Nanodiamond for Structural Biomimetic Scaffolds

Bio-mechanically active scaffolds for tissue engineering combining hydrophilic polymeric matrix and nano-diamond fillers properties are presented and discussed in this paper. The resulting scaffolding materials revealed re-markable mechanical and biological properties to be exploited in advanced biomedical applications. The novel hybrid material is based on 2 and 5 vol-ume % of detonation nano-diamond particles in a hydrophilic poly-(hydroxyl- ethyl-methacrylate) matrix. According to its mechanical and biological properties, the nanocomposite shows a hybrid nature. The base analytical procedures for the preparation of the hybrid nanocomposites and some preliminary mechanical characteristics are presented. The proposed hybrid system has been considered for potential biomimetic, osteoconductive and osteoinductive scaffolds application in bio-mechanically active bone scaffolds for osteoblast, and stem cell differentiation and growth. These more rigid hybrid nano-composites are predicted to possess improved mechanical strength overcoming the mechanical weaknesses of traditional hydrogels clinically utilized for bone regeneration.

Simulation of Graphene Piezoresistivity Based on Density Functional Calculations

The piezoresistive effect in graphene ribbon has been simulated based on the first-principles electronic-state calculation for the development of novel piezoresistive materials with special performances such as high flexibility and low fabrication cost. We modified theoretical approach for piezoresistivity simulation from our original method for semiconductor systems to improved procedure applicable to conductor systems. The variations of carrier conductivity due to strain along with the graphene ribbon models (armchair model and zigzag model) have been calculated using band carrier densities and their corresponding effective masses derived from the one-dimensional electronic band diagram. We found that the armchair-type graphene nano-ribbon models have low conductivity with heavy effective mass. This is a totally different conductivity from two-dimensional graphene sheet. The variation of band energy diagrams of the zigzag-type graphene nano-ribbon models due to strain is much more sensitive than that of the armchair models. As a result, the longitudinal and transverse gauge factors are high in our calculation, and in particular, the zigzag-type graphene ribbon has an enormous potential material with high piezoresistivity. So, it will be one of the most important candidates that can be used as a high-performance piezoresistive material for fabricating a new high sensitive strain gauge sensor.

A novel weld-pool-length monitoring method based on pixel analysis in plasma arc additive manufacturing

The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive manufacturing.To obtain a high deposition accuracy,it is essential to maintain a stable weld pool size.In this study,a novel passive visual method is proposed to measure the weld pool length.Using the proposed method,the image quality was improved by designing a special visual system that employed an endoscope and a camera.It also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry changes.This algorithm can also be applied to materials with different solidification characteristics.Calibration was performed to measure the real weld pool length in world coordinates,and outlier rejection was performed to increase the accuracy of the algorithm.Additionally,tests were carried out on the intersection component,and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.

An energy efficiency evaluation method for parallel robots based on the kinetic energy change rate

Benefit from the high payload-to-weight ratio, parallel robots are expected to have a high potential for energy savings. However,it is a challenging issue to evaluate the energy efficiency of parallel robots with a quantitative method. Quantitative energy efficiency evaluation methods include energy efficiency evaluation models and indices which mathematically describe the relationship between energy consumers in models and design variables of robots, such as geometry, mass and inertia parameters.Considering the structural features of parallel robots, the chains and the end effectors are identified as two separated energy consumers. Besides, the chains in parallel robots are identified as a transmission system which transfers energy from drives to the end effectors. On this basis, an energy efficiency evaluation model considering the change rate of kinetic energy stored in chains is built. The kinetic energy change rate of chains is influenced by design variables of robots as well as motion of the end effector.In order to give a quantitative description of energy efficiency performance of parallel robots, indices considering arbitrary velocity vector of the end effector are proposed. The evaluation method is suitable for all kinds of parallel robots with various motion conditions. Furthermore, the method can be used to optimize machining parameters and guide the design of energyefficient machines.

Trajectory planning and base attitude restoration of dual-arm free-floating space robot by enhanced bidirectional approach

When free-floating space robots perform space tasks,the satellite base attitude is disturbed by the dynamic coupling.The disturbance of the base orientation may affect the communication between the space robot and the control center on earth.In this paper,the enhanced bidirectional approach is proposed to plan the manipulator trajectory and eliminate the final base attitude variation.A novel acceleration level state equation for the nonholonomic problem is proposed,and a new intermediate variable-based Lyapunov function is derived and solved for smooth joint trajectory and restorable base trajectories.In the method,the state equation is first proposed for dual-arm robots with and without end constraints,and the system stability is analyzed to obtain the system input.The input modification further increases the system stability and simplifies the calculation complexity.Simulations are carried out in the end,and the proposed method is validated in minimizing final base attitude change and trajectory smoothness.Moreover,the minute internal force during the coordinated operation and the considerable computing efficiency increases the feasibility of the method during space tasks.

Adaptive inter-intradomain alignment network with class-aware sampling strategy for rolling bearing fault diagnosis

Existing unsupervised domain adaptation approaches primarily focus on reducing the data distribution gap between the source and target domains,often neglecting the influence of class information,leading to inaccurate alignment outcomes.Guided by this observation,this paper proposes an adaptive inter-intra-domain discrepancy method to quantify the intra-class and inter-class discrepancies between the source and target domains.Furthermore,an adaptive factor is introduced to dynamically assess their relative importance.Building upon the proposed adaptive inter-intradomain discrepancy approach,we develop an inter-intradomain alignment network with a class-aware sampling strategy(IDAN-CSS)to distill the feature representations.The classaware sampling strategy,integrated within IDAN-CSS,facilitates more efficient training.Through multiple transfer diagnosis cases,we comprehensively demonstrate the feasibility and effectiveness of the proposed IDAN-CSS model.

Design and Stability of Operating Mechanism for a Spacecraft Hatch

This article introduces the working principles of a spacecraft hatch including its operating process and moving trajectory. On this basis, an operating mechanism is designed to execute automatic open and close action of the hatch and measure the operating torques. Analysis on the mechanism＇s configuration and topological structure of each phase of movement proves that it is a typical variable freedom mechanism. The mechanism manipulates the hatch in accordance with the moving trajectory requirements through configuration transformation. Kinematic analysis and simulation of some typical configurations show that the velocity differences among mechanism components themselves and the components and their abutting components could exert influences on its working stability during configuration transformation. To solve the problem, stability conditions of configuration transformation are proposed. Appropriate control models are established for the output velocity curves of the driving servo motor and solved based on the stability conditions and rules of movement. Results from another simulation demonstrate that the proposed control models ensure smooth configuration transform and stable operation.

Adaptive Tracking Control of an Autonomous Underwater Vehicle

This paper presents the trajectory tracking control of an autonomous underwater vehicle(AUV). To cope with parametric uncertainties owing to the hydrodynamic effect, an adaptive control law is developed for the AUV to track the desired trajectory. This desired state-dependent regressor matrix-based controller provides consistent results under hydrodynamic parametric uncertainties.Stability of the developed controller is verified using the Lyapunov s direct method. Numerical simulations are carried out to study the efficacy of the proposed adaptive controller.

Finite-time coordinated path-following control of leader-following multi-agent systems

This paper presents applications of the continuous feedback method to achieve path-following and a formation moving along the desired orbits within a finite time.It is assumed that the topology for the virtual leader and followers is directed.An additional condition of the so-called barrier function is designed to make all agents move within a limited area.A novel continuous finite-time path-following control law is first designed based on the barrier function and backstepping.Then a novel continuous finite-time formation algorithm is designed by regarding the path-following errors as disturbances.The settling-time properties of the resulting system are studied in detail and simulations are presented to validate the proposed strategies.

Generation of three-dimensional versatile vortex linear light bullets(Invited Paper)

We generate and measure the versatile vortex linear light bullet, which combines a high-order Bessel beam and an Airy pulse. This three-dimensional optical wave packet propagates without distortion in any medium, while carrying an orbital angular momentum. Its non-varying feature in linear propagation is verified by a three- dimensional measurement. Such a novel versatile linear light bullet can be useful in various applications such as micromachining.

Bioactive injectable composites based on insulin-functionalized silica particles reinforced polymeric hydrogels for potential applications in bone tissue engineering

Novel bioactive injectable composites based on biopolymeric hydrogels reinforced with insulin-functionalized silica particles were synthesized.The insulin(INS)was immobilized on the surface of amine-modifed silica particles employing covalent attachment by EDC/NHS chemistry and via electrostatic interaction.The resulting formulations were examined for the morphology(SEM),chemical composition(FTIR,XPS)as well as protein content.To facilitate the injectability and support the bone regeneration,developed particles were dispersed in biopolymeric sol composed of collagen,chitosan and lysinemodifed hyaluronic acid and crosslinked with genipin.By means of rheological study,the sol-gel in situ transition of obtained systems was verifed.It was found in vitro study that MG-63 cells cultured on the developed composites exhibit signifcantly higher alkaline phosphatase(ALP)activity,compared to the pristine hydrogel.Furthermore,the biomineralization ability in the simulated body fluid(SBF)model was also demonstrated.Our fndings suggest that proposed herein novel hydrogel-based composites might be the promising formulation for regeneration of bone defects,especially as a less-cost effective support/alternative for BMP-2 systems.

网络能扭转当前趋势吗?

前言针对投资放缓的背景,Andy Pre公司注意到机器人领域的创新发展,以及现场总线所扮演的角色。英国制造业几乎停止了对机器人的投资。上季度销售给英国制造商的机器人比前一个季度几乎削减了一半,从199台降至110台。这与销售正旺的大陆市场形成鲜明的对照。Warwick大学的英国自动化和机器人协会(他们统计了这方面的数据)认为,这是几方面的因素所造成的。首先,英国制造业采用比其大陆竞争对手更短期的投资观念。部分原因是要满足股东的要求。例如,德国工业界就有许多大型的私营企业。