Jiles-Atherton-Based Hysteresis Identification of Joint Resistant Torque in Active Spacesuit Using SA-PSO Algorithm

To eliminate the influence of spacesuits’ joint resistant torque on the operation of astronauts, an active spacesuit scheme based on the joint-assisted exoskeleton technology is proposed. Firstly, we develop a prototype of the upper limb exoskeleton robot and theoretically analyse the prototype to match astronauts’ motion behavior. Then, the Jiles-Atherton model is adopted to describe the hysteretic characteristic of joint resistant torque. Considering the parameter identification effects in the Jiles-Atherton model and the local optimum problem of the basic PSO (particle swarm optimization) algorithm, a SA- (simulated annealing-) PSO algorithm is proposed to identify the Jiles-Atherton model parameters. Compared with the modified PSO algorithm, the convergence rate of the designed SA-PSO algorithm is advanced by 6.25% and 20.29%, and the fitting accuracy is improved by 14.45% and 46.5% for upper limb joint model. Simulation results show that the identified J-A model can show good agreements with the measured experimental data and well predict the unknown joint resistance torque.

A Wireless Animal Robot Stimulation System Based on Neuronal Electrical Signal Characteristics

As a stimulus signal, coded electrical signals can control the motion behavior of animals, which has been widely used in the field of animal robots. In current research, most of the stimulus signals used by researchers are traditional waveforms, such as square waves. To enrich the stimulus waveform, a wireless animal robot stimulation system based on neuronal electrical signal characteristics is presented in this paper. The stimulator uses the CC1101 wireless module to control animal behavior through brain stimulation. The LabVIEW-based graphical user interface(GUI) can manipulate brain stimulation remotely while the stimulator powered by battery. Additionally, The spikes of animals have been simulated by this system through Direct Digital Synthesizer(DDS) algorithm. The GUI enable users to customize the combination of these analog spike signals. The recombined signals are sent to the stimulator through CC1101 as stimulus signals. In vivo experiments conducted on five pigeons verified the efficacy of the stimulation mechanism. The analog spike signal with an amplitude of 3-5V successfully caused the pigeon’s turning behavior. The feasibility of the analog spike signals as stimulus signals was successfully verifified. Increased the diversity of stimulus waveforms in the field of animal robots.

Numerical Simulation on Motion Behavior of Inclusions in the Lab-Scale Electroslag Remelting Process with a Vibrating Electrode

In order to meet the requirement of high-quality ingots, the vibrating electrode technique in the electroslag remelting (ESR) process has been proposed. Non-metallic inclusions in ingots may cause serious defects and deteriorate mechanical properties of final products. Moreover, the dimension, number and distribution of non-metallic inclusions should be strictly controlled during the ESR process in order to produce high-quality ingots. A transient 2-D coupled model is established to analyze the motion behavior of inclusions in the lab-scale ESR process with a vibrating electrode, especially under the influence of the vibration frequency, current, slag layer thickness, and filling ratio, as well as type and diameter of inclusions. Simulation model of inclusions motion behavior is established based on the Euler-Lagrange approach. The continuous phase including metal and slag, is calculated based on the volume of fluid (VOF) method, and the trajectory of inclusions is tracked with the discrete phase model (DPM). The vibrating electrode is simulated by the user-defined function and dynamic mesh. The results show that when the electrode vibration frequency is 0.25 Hz or 1 Hz, the inclusions will gather on one side of the slag layer. When it increases from 0.25 Hz to 1 Hz, the removal ratio of 10 μm and 50 μm inclusions increases by 5% and 4.1%, respectively. When the current increases from 1200 A to 1800 A, the flow following property of inclusions in the slag layer becomes worse. The removal ratio of inclusions reaches the maximum value of 92% with the current of 1500 A. The thickness of slag layer mainly affects the position of inclusions entering the liquid-metal pool. As the slag layer thickens, the inclusions removal ratio increases gradually from 82.73% to 85.91%. As the filling ratio increases, the flow following property of inclusions in the slag layer is enhanced. The removal ratio of 10 μm inclusions increases from 94.82% to 97%. However, for inclusions with a diameter of 50 μm, the maximum removal ratio is 96.04% with a filling ratio of 0.46. The distribution of 50 μm inclusions is significantly different, while the distribution of 10μm inclusions is almost similar. Because of the influence of a vibrating electrode, 10 μm Al2O3 and MnO have a similar removal ratios of 81.33% and 82.81%, respectively.

Simulation of Particle Motion Behavior in Fluidized Bed Opposed Jet Mill

In order to study the influence of the internal flow field of the fluidized bed opposed jet mill on the motion behavior of particles, Computational Fluid Dynamics (CFD) and Discrete Dlement Method (DEM) are used for coupling calculations. By adjusting the nozzle spacing and inlet pressure, Numerical simulation is carried out on the process of particles collisions with each other after accelerating under the high-speed jet produced by the nozzle. The trajectory of the particles in the flow field of the collision area and the change of the collision state of the particles are analyzed. Finally, the best parameters are selected based on the total collision energy. The results show that the particles will gradually shift and spread during the acceleration process. The reduction of the nozzle spacing is beneficial to increase the probability of particle collisions. However, if the spacing is too small, the particles cannot be fully accelerated; the increase in inlet pressure will increase the kinetic energy of the particles, and number of collisions is almost unaffected. By comparing the total collision energy, the best-simulated preparation conditions are selected as 110mm and 1.1MPa.

Near-infrared manipulation of multiple neuronal populations via trichromatic upconversion

Using multi-color visible lights for independent optogenetic manipulation of multiple neuronal populations offers the ability for sophisticated brain functions and behavior dissection. To mitigate invasive fiber insertion, infrared light excitable upconversion nanoparticles (UCNPs) with deep tissue penetration have been implemented in optogenetics. However, due to the chromatic crosstalk induced by the multiple emission peaks, conventional UCNPs or their mixture cannot independently activate multiple targeted neuronal populations. Here, we report NIR multi-color optogenetics by the well-designed trichromatic UCNPs with excitation-specific luminescence. The blue, green and red color emissions can be separately tuned by switching excitation wavelength to match respective spectral profiles of optogenetic proteins ChR2, C1V1 and ChrimsonR, which enables selective activation of three distinct neuronal populations. Such stimulation with tunable intensity can not only activate distinct neuronal populations selectively, but also achieve transcranial selective modulation of the motion behavior of awake-mice, which opens up a possibility of multi-color upconversion optogenetics.

Back-off

Standstill behavior by a robot is deemed to be ineffective and inefficient to convey a robot’s intention to yield priority to another party in spatial interaction. Instead, robots could convey their intention and thus their next action via motion. We developed a back-off (BO) movement to communicate the intention of yielding priority to pedestrians at bottlenecks. To evaluate human sensory perception and subjective legibility, the BO is compared to three other motion strategies in a video study with 167 interviewees at the university and public spaces, where it excels regarding legibility. Implemented in a real encounter, objective motion behavior of 78 participants as a reaction to a stop-and-wait strategy, and two versions of BO (short and long), shows an improvement of the pedestrians’ efficiency in the second encounter with the robot’s short BO version compared to the stop strategy. Eventually, in the third encounter with all motion strategies, interaction causes only a small time consumption still required by the cognitive process of perceiving an object in the visual field. Hence, the design of kinematic parameters, BO path and time, exhibits the potential to increase the fluency of an interaction with robots at bottlenecks.