Upright State Research Articles

Design of two-loop FOPID-FOPI controller for inverted cart-pendulum system

The inverted cart-pendulum system (ICPS) consists in having a pendulum mounted on a sliding cart, with the pivot point fixed. This real time experiment indeed looks like a rocket and its functionality is akin to a rocket. These are the launchers and the missile guidance and control as well as construction anti-seismic measures also. The control aim in these systems is to maintain the inverted pendulum vertically stable. The system is causal but unstable and, therefore, has no minimum phase. Therefore, the right half plane pole and zero are close to each other. Therefore, the stability of the system can be considered as problematic at some points. Unfortunately, linear time- invariant (LTI) classical controllers are incapable of offering suffient loop robustness for such systems. This paper aims to project a two-loop fractional order controller (2-LFOC) design to stabilize a higher-order nonlinear inverted cart-pendulum system (ICPS). The modeling, linearization, and control of ICPS are demonstrated in this work. The control target is adjusted so that the inverted pendulum stabilizes in its upright state when the cart reaches the required point. To fulfill the control objective, two-loop FOPID-FOPI controllers are proposed, and the Levenberg Marquardt algorithm (LMA) is utilized to tune the controllers. A novel nonlinear integral of time-associated absolute-error (ITAE) based fitness formula considering the settling time and rise time is used to fit the controller parameters for 2-LFOC. A performance comparison with the PID controller in terms of different time domain parameters such as rise_time (T R ), peak_time (T P ), settling_time (T S ), maximum overshoot (OS M ), maximum undershoot (US M ) and steady-state error (E SS ) are investigated. Stability analysis using Riemann surface observation of the system compensated with the proposed controller is presented in this work. The robust behavior of the two-loop FOPID-FOPI controller is verified by the application of disturbances in the system and the Reimann surface observation.

Array capacitive proximity sensors-based liquid level measurement under various cup postures

An array capacitive proximity sensors-based liquid level measurement under various cup postures is proposed in this study. Firstly, a total of 6 rectangular electrodes are arranged around the cup for parasitic capacitance measurement. The relationship between parasitic capacitance and liquid level is calibrated by preliminary experiments. Then, the liquid level under different parasitic capacitance can be obtained. At the same time, an IMU is fixed on the claw. By fusing the parasitic capacitance measured on multiple electrodes with the IMU data, the liquid level under different cup postures is calculated. Experiments confirm the effectiveness of the proposed method. Specifically, The measurement accuracy can be guaranteed within 91% in the upright state of the cup. An accuracy of 85% can be guaranteed when the cup inclined angle reaches 30°.

Surface profile measurement and parameter analysis of silicon wafers in the upright state.

A novel approach, to the best of our knowledge, is presented for assessing silicon wafer surface profiles using an interferometer and vertically rotatable wafer holder. This approach significantly enhances precision and reduces costs, and outperforms traditional techniques in measurement consistency and accuracy. It effectively reduces sample distortion and positional shifts owing to the removal and reinstallation of the wafers. Using this method, a global backsurface-referenced ideal range of 0.385µm, warp of 0.193µm, and other parameters were obtained, demonstrating its practicality in efficiently capturing key surface profile metrics for silicon wafers. This innovation promises substantial improvements in high-volume wafer surface profile testing, overcoming prevalent technological challenges in this industry.

Dynamics Simulation of Biped Robot with Arch Structure and Toe Joint

The arch structure of human foot absorbs impact and assists push-off movements during walking. The objective of this study is to introduce arch structures and toe joints into a biped robot, verify the effects, and devise walk control methods by dynamics simulation. We simulated the upright state and start of walking using Choreonoid. The results confirmed that the arch structure improved the impact absorption and stability in the anteroposterior direction. In addition, the arch structure could be expected to smooth the load transfer between the supporting legs during the step change.

Control and Design of Dancing Robot based on STM32

The emergence and development of robot technology not only fundamentally changed the traditional industrial production, but also had a profound impact on society. With the rapid development of social technology, the application field of robots is expanding. In this paper, the control core of the proposed dancing robot is STM32F103C8T6 single chip microcomputer, the upper arm is controlled by the steering gear, the feet are two flexible wheels, and the DC deceleration motor is used as the driving motor of the wheels, so that the wheels of the robot can realize free movement and complete the dancing action of the robot. The power needed for robot movement comes from 18650 lithium battery. In the process of robot movement, the LD3320 voice recognition module is used to control the robot's movement direction and state, the MPU6050 is used to control the robot's balance, and the JQ6500 music playback module is added to the robot to control the music playback through voice recognition. After the power of dancing robot is turned on, the dancing robot starts to adjust itself to make its posture in a balanced and upright state, and then waits for the user to issue a command. The dancing robot has simple human body function and can complete simple dance actions such as moving forward and backward, walking left and right, turning left and right, and has voice function, and can also play music. The operation password is simple in the process of application, which makes it convenient for the user to use. In addition, the dancing robot is small in size and can move freely with good practical effect, regardless of the user’s age.

Beetle-inspired oil-loaded shape memory micro-arrays with switchable adhesion to both solid and liquid

Surfaces with switchable adhesion have been vigorously investigated over the past decades by mimicking the unique adhesive mechanisms of living systems. However, designing a universal intelligent adhesive surface for both solid and liquid remains a challenge. Herein, drawing inspiration from the controllable capillary forces generated by muscle movements and oil-secretion on the foot pads of the beetle (Hemisphaerota cyanea), we report a novel oil-loaded shape memory polymer (SMP) micropillars with such smart controllability. Based on the shape memory effect (SME) of the SMP, the pillars can be reversibly switched between the tilted state and the upright state, which simultaneously changes the distribution of the trapped oil, and thus generates different capillary forces. This variation results in reversible adhesion behaviors of the surface to diverse solids including flat glass, CD disk, polytetrafluoroethylene (PTFE), rough glass, sandpaper, nylon net, and liquid droplets like acid, basic, salt-containing water droplets, and some organic liquids such as glycol, glycerol, and formamide. Given its smart adhesion, the surface was further applied in in-situ gripping/release of solid objects and directed liquid shedding. This work provides a new design strategy for smart adhesive materials, which may contribute to the development of smart grippers, microfluidics, etc.

Global asymptotic stabilization of a pendulum using a single Lyapunov proportional bang-bang control strategy

The existence of a Lyapunov function is known to ensure either local or global stability of a system’s equilibrium state. Inspired by the control-Lyapunov method, we here construct a Lyapunov candidate function by analyzing a pendulum system’s total energy and then applying appropriate control actions such that the conditions of a Lyapunov function are met. More specifically, our controller evaluates the Lyapunov function’s time derivative at each time step, and applies control torque such as to ensure that the Lyapunov function decreases for each step toward the goal upright state. Unlike the control-Lyapunov method, which aims to select control input as to minimize the Lyapunov function’s time derivative, our method provides up front the satisfactory conditions that yield a globally stable controller by using a rigorously designed proportional bang-bang control strategy. We show how to derive the controllers evaluation function, and how the controller is implemented in code. We further demonstrate the effectiveness of our method through numerical simulations. The result of our approach is a globally stable upright pendulum using a single-controller strategy.

A Novel Ratiometric Electrochemical Biosensor Using Only One Signal Tag for Highly Reliable and Ultrasensitive Detection of miRNA-21.

Herein, a novel ratiometric electrochemical biosensor with methylene blue (MB) as the only one signal tag was proposed for highly reliable and ultrasensitive detection of microRNA-21 (miRNA-21) under the assistance of an intelligent target-induced dual signal amplification (T-DSA). First, a small amount of target miRNA-21 could produce abundant mimic targets DNA S1 and Zn2+ through target-induced recycle and acid dissolution, respectively. Then, S1 triggered rolling circle amplification (RCA) to generate functional DNA nanospheres (DSP) encoded by DNAzyme and substrate sequence for loading numerous signal tag MB with a remarkable electrochemical signal (signal on), and the Zn2+ cofactor mediated the nonviolent DNAzyme-catalyzed cleavage of DSP to sharply release MB with obviously reduced electrochemical responses (signal off). Impressively, our strategy could controllably load and release the only signal tag MB through the well-designed DSP to effectively avoid the false positive responses caused by the non-ideal upright state of DNA probes connected to electrodes in traditional distance-dependent signal adjustment ratiometric strategies with two different signal tags. Meanwhile, with the aid of innovative T-DSA recycle and RCA-produced functional DSP, the detection sensitivity of this sensing platform was significantly improved. As a result, the proposed biosensor successfully realized highly reliable and ultrasensitive detection of miRNA-21 with a detection limit down to 26.7 aM, which shows exceptional promise in biological analysis and medical diagnosis.

Reclined trend of alkyl chain of sodium dodecylbenzenesulfonate molecules induced by friction

Surfactants tend to adsorb on the surface/interface mostly in a directional manner. The alkyl chain orientation and conformation order for molecular monolayers of sodium dodecylbenzenesulfonate (SDBS) at low concentrations are studied by using the sum frequency generation vibrational spectroscopy (SFG-VS). The molecular arrangement of the surfactants adsorbed at the solid/liquid interface is further investigated. It is found that the arrangement of the SDBS at the interface becomes relatively ordered with increasing bulk concentration. Meanwhile, the orientation angle reduces gradually, and the molecules tend to be upright state. In addition, the effect of friction on the conformation order and orientation angle are also analyzed. The intensity of the SDBS vibrational contraction peak becomes lower after friction, which indicates that the anion has a reorientation process at the interface. The arrangement of molecules becomes more disordered due to friction. The orientation angle increases slightly, which indicates the monolayer has an inclined trend relative to the lateral direction on the interface. A modified adsorption model considering friction effect is proposed. This work may provide a reference for the further study of adsorption mechanism and application of surfactants.

Passive indoor visible light-based fall detection using neural networks

In this paper, a passive visible light sensing (VLS) fall detection system based on luminaires is proposed that uses neural networks to learn the state (i.e., upright or prone) of a target (e.g., a person). The proposed method measures the channel impulse response (CIR) between different source-receiver pairs in a passive scenario, where the user does not hold a device or sensor. The CIR measurements are collected in a realistically modeled room and neural networks are employed to learn the relationship between the CIR measurements and the states of the target at randomly selected positions in the room. The performance evaluation of the system shows that an accuracy of more than 97% is attainable by utilizing a large number of data samples and high brightness factor of the luminaires. The robustness of the proposed method is validated by using a tilted state which is labeled with same class as the upright state, however, the tilted state is not used to train the network. One of the key applications of fall detection is in healthcare domain for patient monitoring. The correct prediction of the prone state is particularly critical in such scenarios since emergency situations may arise from a fall.

Carbon black-based NIR-responsive superhydrophobic shape memory microplate array with switchable adhesion for droplets and bubbles manipulation

Superhydrophobic stimuli-responsive shape memory polymer (SMP) surfaces with tunable wettability have been extensively explored, but in situ reversibly switching ability as well as selectively capturing and releasing different liquids or bubbles, unfortunately, is still a blockage. Here, we fabricated a kind of light-responsive superhydrophobic SMP microplate array by utilizing femtosecond laser ablation and replica-mold method to achieve in situ switchable adhesion. By combining the photothermal effect of carbon black with the shape memory effect of SMP, the reversible switching between the upright state and temporary bending state of the microplate array can be readily realized. Simultaneously, the apparent force for the microplate array can be reversibly switched between low and high adhesion. More significantly, the current surface is competent for the amphibious manipulator, that is, the microplate array is adaptive for the selective capture and release of droplets as well as underwater bubbles. The current superhydrophobic SMP microplate array will have potential applications in intelligent droplet and bubble operation.

The structure of an infectious immature flavivirus redefines viral architecture and maturation.

Flaviviruses are the cause of severe human diseases transmitted by mosquitoes and ticks. These viruses use a potent fusion machinery to enter target cells that needs to be restrained during viral assembly and egress. A molecular chaperone, premembrane (prM) maintains the virus particles in an immature, fusion-incompetent state until they exit the cell. Taking advantage of an insect virus that produces particles that are both immature and infectious, we determined the structure of the first immature flavivirus with a complete spike by cryo-electron microscopy. Unexpectedly, the prM chaperone forms a supporting pillar that maintains the immature spike in an asymmetric and upright state, primed for large rearrangements upon acidification. The collapse of the spike along a path defined by the prM chaperone is required, and its inhibition by a multivalent immunoglobulin M blocks infection. The revised architecture and collapse model are likely to be conserved across flaviviruses.

Noncontact All‐In‐Situ Reversible Reconfiguration of Femtosecond Laser‐Induced Shape Memory Magnetic Microcones for Multifunctional Liquid Droplet Manipulation and Information Encryption

AbstractShape memory polymers can change their shapes in a controlled way under external stimuli and thus promote the development of smart devices, soft robotics, and microfluidics. Here, a kind of iron particles (IPs) doped shape memory microcone is developed for noncontact all‐in‐situ reversible tuning between the tilted and upright state under near‐infrared (NIR) irradiation and magnetic field (MF) actuation. The magnetic microcones are simply fabricated by a laser‐ablated replica‐molding strategy so that their height can be precisely controlled by adjusting the laser machining parameters. In addition, it is found that the droplets can be transported unidirectionally on the tilted microcones, which is related to the variation of the adhesion force induced by the length of the triple contact line (TCL). Finally, other multifunctional applications have also been realized, such as, selective droplet release, information encryption, rewritable display, and reusable temperature switch. This work may provide a facile strategy for developing multiresponsive smart devices based on shape memory polymers.

Dressing the weightless body: Subjective verticality and the disoriented experience of dress in microgravity

Design practice has historically been constrained by the assumption that designed objects, including clothing, will be made and worn in Earth gravity. The notion that designed objects have an upright state has influenced common approaches to design, including the tendency towards depiction and presentation of designed objects in elevation view, which, for fashion, is frequently understood in terms of silhouette. However, those who have experienced weightlessness, either in space travel or on board reduced-gravity aircraft, describe a post-gravity experience that prompts them to revisit these assumptions and consider the extent to which future commercial space travel will liberate creative practitioners to operate at all angles and orientations. As we enter the commercial space age, fashion will be increasingly worn in a variety of gravitational conditions, and the dressed body will therefore be encountered at a variety of orientations, showcasing views of garments that are not often encountered on Earth, and that are therefore often overlooked by fashion designers. This article responds to descriptions of the post-gravity experience by identifying the need to consider alternative views of the clothed body, and consequently to define garments without reference to the silhouette in fashion design for the new commercial space age.

Design of Control System Based on Electromagnetic Balance Vehicle

This paper introduces the design of control system of electromagnetic balance vehicle based on kea128. From two aspects of hardware and software, the control system is designed. The hardware layer includes micro controller, vehicle model attitude measurement and road information recognition module. According to the collected information, combined with filtering algorithm and closed-loop control of upright, speed, direction, etc., through repeated practice verification, the balance car can achieve independent tracking, and can maintain upright state under different track elements, fast and stable operation.

Non-programmed gait generation of quadruped robot using pulse-type hardware neuron models

In this paper, the authors will propose the active gait generation of a quadruped robot. The theory that quadruped animals unconsciously generate gaits by some system based on neural networks in the spinal cord is widely accepted. However, how biological neurons or neural networks can generate gaits is not clear. To clarify the gait generation method, one of the solutions is using the neuron model similar to the biological neuron. We developed the quadruped robot system using self-inhibited pulse-type hardware neuron models (P-HNMs), which can output the electrical activity similar to those of biological neurons. The P-HNMs consist of the cell body model and the inhibitory synaptic model. The cell body model periodically outputs pulsed voltages; the inhibitory synaptic model inhibits the pulsed voltages. The pulse period can change by varying the synaptic weight control voltage applied to the P-HNMs. We varied the synaptic weight control voltage according to the pressure on the robot’s toes. Also, we changed the angle of the robot’s joints by a constant angle each time the P-HNMs output a pulse. As a result of the walking experiment, we confirmed that the robot generates walk gait and trot gait according to the moving speed. Also, we clarified the process by which the robot actively generates gaits from the upright state. These results show that animals may not use many biological neurons to generate gaits. Furthermore, the results suggest the possibility of realizing simple and bio-inspired robot control.

In Situ Reversible Tuning from Pinned to Roll-Down Superhydrophobic States on a Thermal-Responsive Shape Memory Polymer by a Silver Nanowire Film.

Shape memory polymer (SMP) surfaces with tunable wettability have attracted extensive attention due to their widespread applications. However, there have been rare reports on in situ tuning wettability with SMP materials. In this paper, we reported a kind of distinct superhydrophobic SMP microconed surface on the silver nanowire (AgNW) film to achieve in situ reversible transition between pinned and roll-down states. The mechanism is taking advantage of the in situ heating functionality of the silver nanowire film by voltage, which provides the transition energy for SMP to achieve the fixation and recovery of temporary shape. It is noteworthy that the reversible transition could be repeated many times (>100 cycles), and we quantitatively investigate the shape memory ability of microcones with varied height and space under different applied voltages. These results show that the tilted microcones could recover its original upright state under a small voltage (4-11 V) in a short time, and the shortest recovery time is about 0.5 min under an applied voltage of ∼10 V. Finally, we utilize SMP microcone arrays with tunable wettability to realize lossless droplet transportation, and the tilted microconed surface also achieves liquid unidirectional transport due to its anisotropic water adhesion force. The robust microconed SMP surface with reversible morphology transitions will have far-ranging applications including droplet manipulation, reprogrammable fog harvesting, and so on.

Prevalence of Abnormal Body Posture Among Chinese Children and Adolescents: A Large Population-Based Cross-Sectional Study

Abnormal body posture refers to an abnormal body state in which the body cannot maintain a stable state and the normal function of tissues and organs in an upright state...

A comparative study of weight-bearing and non-weight-bearing 3-dimensional lower extremity alignment in knee osteoarthritis

BackgroundLower extremity alignment is an important variable with respect to the development and progression of knee osteoarthritis. It is very essential for the preoperative planning of realignment surgeries such as total knee arthroplasty and high tibial osteotomy. Nevertheless, there have been no reports comparing 3D lower extremity alignment between weight-bearing upright and non-weight-bearing horizontal states in osteoarthritic knees in the same subject. Therefore, we determined whether the alignment of the lower extremity in the weight-bearing upright state differed from that in the non-weight-bearing horizontal or supine position in patients with knee osteoarthritis. MethodsAdduction–abduction, flexion–extension, and rotational angle of osteoarthritic knees were assessed in weight-bearing upright and non-weight-bearing supine positions. Knee alignment in the supine position was determined from preoperative computed tomography data. In the weight-bearing upright state, alignment was determined using a technique that utilized 2D-3D image-matching with biplanar computed radiography and 3D bone models of the complete lower extremity rebuilt using computed tomography-based information. ResultsWe assessed 81 limbs from osteoarthritic knee patients (74 women, 7 men; mean age 75.3 years, range 59–86 years). In the coronal plane, there were varus deformities in both the supine and standing positions, while there was flexion in both the supine upright state and position at the sagittal plane. In the axial plane, the rotation of the tibia to the femur was neutral in the supine position and internal in the upright state. ConclusionPatient position significantly affects lower extremity alignment in osteoarthritic knees. This study provides important data regarding the preoperative evaluation of realignment surgery in total knee arthroplasty and high tibial osteotomy. We believe that these results are an important contribution to the knowledge regarding knee osteoarthritis.

Stepping gating of ion channels on nanoelectrode via DNA hybridization for label-free DNA detection

Natural ion channels on cell membrane can gate the transport of ions and molecules by the conformational alteration of transmembrane proteins to regulate the normal physiological activities of cells. Inspired by the similarity of the conformation change under specific stimuli, here we introduce an ion channel gating model on a single nanoelectrode by anchoring DNA-gated switches on the very nanotip of gold nanoelectrode to mimic the response-to-stimulus behaviors of ion channels on bio-membranes. The surface-tethered DNA ion channels can be switched on by the Watson-Crick base pairing, which can alter the conformation of the tethered DNA from lying state to upright state. And these conformational alterations of the anchored DNA switches can effectively gate the transport of potassium ferricyanide onto the electrode interface. By continuously initiating the gates with DNA of different concentrations, we achieved the stepping gating of ion channels on a single nanoelectrode. Further, we demonstrated that the ion gating system on nanoelectrode showed excellent sensing performance. For example, the response kinetic was very fast with the signal saturation time of ~1 min, the reproducibility of the OFF/ON switch was robust enough to sustain for two cycles, and simultaneously, the specificity was high enough to distinguish complementary DNA and noncomplementary DNA. When used for label-free DNA detection, the limit of detection can be as low as 10 pM. This study provides a promising avenue to achieve label free and real-time detection of multiple biomolecules.