Robust Tracking Control for Self-balancing Mobile Robots Using Disturbance Observer

In this paper,a robust tracking control scheme based on nonlinear disturbance observer is developed for the self-balancing mobile robot with external unknown disturbances.A desired velocity control law is firstly designed using the Lyapunov analysis method and the arctan function.To improve the tracking control performance,a nonlinear disturbance observer is developed to estimate the unknown disturbance of the self-balancing mobile robot.Using the output of the designed disturbance observer,the robust tracking control scheme is presented employing the sliding mode method for the selfbalancing mobile robot.Numerical simulation results further demonstrate the effectiveness of the proposed robust tracking control scheme for the self-balancing mobile robot subject to external unknown disturbances.

The Development of Self-Balancing Controller for One-Wheeled Vehicles

The purpose of this study is to develop a self-balancing controller (SBC) for one-wheeled vehicles (OWVs). The composition of the OWV system includes: a DSP motion card, a wheel motor, and its driver. In addition, a tilt and a gyro, for sensing the angle and angular velocity of the body slope, are used to realize self-balancing controls. OWV, a kind of unicycle robot, can be dealt with as a mobile-inverted-pendulum system for its instability. However, for its possible applications in mobile carriers or robots, it is worth being further developed. In this study, first, the OWV system model will be derived. Next, through the simulations based on the mathematical model, the analysis of system stability and controllability can be evaluated. Last, a concise and realizable method, through system pole-placement and linear quadratic regulator (LQR), will be proposed to design the SBC. The effectiveness, reliability, and feasibility of the proposal will be con- firmed through simulation studies and experimenting on a physical OWV.

Research on Self-balancing Two Wheels Mobile Robot Control System Analysis

The paper presents the research on self-balancing two-wheels mobile robot control system analysis with experimental studies.The research problem in this work is to stabilize the mobile robot with self-control and to carry the sensitive things without failing in a long span period.The main objective of this study is to focus on the mathematical modelling of mobile robot from laboratory scale to real world applications.The numerical expression with mathematical modelling is very important to control the mobile robot system with linearization.The fundamental concepts of dynamic system stability were utilized for maintaining the stability of the constructed mobile robot system.The controller design is also important for checking the stability and the appropriate controller design is proportional,integral,and derivative-PID controller and Linear Quadratic Regulator(LQR).The steady state error could be reduced by using such kind of PID controller.The simulation of numerical expression on mathematical modeling was conducted in MATLAB environments.The confirmation results from the simulation techniques were applied to construct the hardware design of mobile robot system for practical study.The results from simulation approaches and experimental approaches are matched in various kinds of analyses.The constructed mobile robot system was designed and analyzed in the control system design laboratory of Yangon Technological University(YTU).

Motor Learning Based on the Cooperation of Cerebellum and Basal Ganglia for a Self-Balancing Two-Wheeled Robot

A novel motor learning method is present based on the cooperation of the cerebellum and basal ganglia for the behavior learning of agent. The motor learning method derives from the principle of CNS and operant learning mechanism and it depends on the interactions between the basal ganglia and cerebellum. The whole learning system is composed of evaluation mechanism, action selection mechanism, tropism mechanism. The learning signals come from not only the Inferior Olive but also the Substantia Nigra in the beginning. The speed of learning is increased as well as the failure time is reduced with the cerebellum as a supervisor. Convergence can be guaranteed in the sense of entropy. With the proposed motor learning method, a motor learning system for the self-balancing two-wheeled robot has been built using the RBF neural networks as the actor and evaluation function approximator. The simulation experiments showed that the proposed motor learning system achieved a better learning effect, so the motor learning based on the coordination of cerebellum and basal ganglia is effective.

Isolated Bipolar Modular Multilevel DC-DC Converter with Self-balancing Capability for Interconnection of MVDC and LVDC Grids

Bipolar medium-voltage DC(MVDC)and lowvoltage DC(LVDC)grids have the advantages of flexible integration of distributed renewable-energy generation and reliable power supply.In order to achieve voltage conversion,power transfer,and electrical isolation for bipolar MVDC and LVDC grids,a high-power DC-DC converter is essential.Therefore,this paper proposes an isolated bipolar modular multilevel DCDC converter(BiMMDC)with power self-balancing capability for interconnection of MVDC and LVDC grids.The proposed BiMMDC consists of two series connected MMCs in the MV stage to configure a bipolar MVDC interface,and interleaved converters combined with a dual-transformer are designed in the LV stage to configure the bipolar LVDC interface and to provide a self-balancing capability.Equivalent circuits of two series-connected MMCs and a dual-transformer with interleaved converters are derived.After that,operation principles of the proposed BiMMDC are introduced,considering balanced/unbalanced power transfer of bipolar LVDC grid and monopolar shortcircuit or open-circuit faults at MVDC grid.The control scheme is also presented for the proposed BiMMDC under different operating conditions.Finally,a Matlab simulation and controller hardware-in-the-loop(CHIL)evaluation results are provided to validate the feasibility and effectiveness of the proposed typology and its operating performance.

Control System of Two-Wheel Self-Balancing Vehicle

This study mainly concerns a motion model and the main control algorithm of two-wheel self-balancing vehicle models.Details of the critical parameters fetching and output value of two-wheel self-balancing vehicle models are introduced,including those concerning balance control,speed control and direction control.An improved cascade coupling control scheme is proposed for two-wheel vehicles,based on a proportional-integral-derivative(PID)control algorithm.Moreover,a thorough comparison between a classic control system and the improved system is provided,and all aspects thereof are analyzed.It is determined that the control performance of the two-wheel self-balancing vehicle system based on the PID control algorithm is reliable,enabling the vehicle body to maintain balance while moving smoothly along a road at a fast average speed with better practical per-formance.

Conversion factor analysis of self-balanced loading test of cast-in-situ piles based on analogue test method

Based on the characteristics of pile-soil interaction and the Mohr-Coulomb strength theory,a new method of determining the side friction at a pile-soil interaction is proposed.Combined with the actual engineering cases,the effectiveness of the analogue test method is verified by comparing it with the traditional anchor pile method and self-balanced method.Taking the self-balanced test of the bridge pile foundation in the Songhua River as an example,the conversion factor of sandy soil and weathered mudstone are confirmed by the analogue test method.The results show that the conversion factor of sandy soil and weathered mudstone in the Songhua River area should consider the geological conditions and the construction technology,etc.The standard values are relatively conservative.It is suggested that the engineering application should be properly revised.The recommended range of the conversion factor of sandy soil in this area is 0.65 to 0.85,and that of weathered mudstone is 1.0.

Self-Balanced Charge Pump with Fast Lock Circuit

A self-balanced charge pump （CP） with fast lock circuit to achieve nearly zero phase error is proposed and analyzed. The proposed CP is designed based on the SMIC 0.25μm 1P5M complementary metal oxide semiconductor （CMOS） process with a 2.5 V supply voltage, HSPICE simulation shows that even if the mismatch of phase/frequency detector （PFD） was beyond 10%, the charge pump could still keep nearly zero phase error, Incorporated fast lock circuit can shorten start-up time to below 300 ns.

An improved method of generating the self-balanced chaotic spread-spectrum code

An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization, inversion, all upside down, radix-S block upside down and shift combination, the proposed code is achieved. Theory analysis and simulation performance of the improved code are illustrated. And the results indicate that the suggested method gains a better performance than the traditional one by reasonable choices of the initial value and the S parameter in the im- proved method. Meanwhile the chaotic sequence＇ s characteristic of large addresses is inherited when the chaotic-map is used as the source. This advantage makes this improved code very suitable for the multiple access application in communication system.

EXPERIMENTAL STUDY ON TIME EFFECT OF WET DRILLING PILE

Time effect of wet drilling pile is investigated through the static load experiment on pile No. 22 of Guanhe Bridge. Post-grouting under pile tip is adopted in the project. To study the bearing performance of the pile, the self-balanced method is used and two load cells are assembled in the pile body. The experiments are carried out before and after post-grouting. The upper part of the pile is not influenced by post-grouting under the pile tip. Experimental results of the upper part of the pile show that the bearing capacity and the rigidity of wet drilling pile increase with time passing on. Analysis results show the time effect of wet drilling pile is influenced by many factors, such as alteration of stress field around pile, characteristics of soil around pile, variety of mud cake, and property of residue under pile tip.

Mobileman,Construction Agile Goods Delivery Robot

The traditional automated guided vehicle(AGV) on goods delivery faces the challenges when task space expands beyond 2 D plans. 3 D environments such as uneven terrain, ramps, and staircase are typical in construction site. Thus, the key to introducing this technology into construction industry is to improve AGV’s stability and autonomous navigation ability in more complex three-dimensional environments. In this paper, mobileman, a novel tracked autonomous guide vehicle, is introduced. Compared with other construction robots, mobileman maximizes its load capacity on the basis of assuring accessibility. Furthermore, its modular designs and self-balancing platform enable it to cope with more complex challenging scenarios, such as staircase with 35-degree sloped staircase, while another modular design featured automated loading and unloading functionality. The mobile base specifications were presented in section two, and modular designs and exploration of the navigation system on construction site were illustrated in the rest of sections.

Loading System for Full-Scale Heavy-Duty Support Node Test with Multi-Directional Loading Requirements

This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.

Measurement of intensity difference squeezing via non-degenerate four-wave mixing process in an atomic vapor

We report the measurement of the intensity difference squeezing via the non-degenerate four-wave mixing process in a rubidium atomic vapor medium. Two pairs of balanced detection systems are employed to measure the probe and the conjugate beams, respectively. It is convenient to get the quantum shot noise limit, the squeezed and the amplified noise power spectra. We also investigate the influence of the input extra quadrature amplitude noise of the probe beam. The influence of the extra noise can be minimized and the squeezing can be optimized under the proper parameter condition. We measure the -3.7-dB intensity difference squeezing when the probe beam has a 3-dB extra quadrature amplitude noise. This result is slightly smaller than -4.1 dB when the ideal coherent light （no extra noise） for the probe beam is used.

Development of a novel autonomous lower extremity exoskeleton robot for walking assistance

Today, exoskeletons are widely applied to provide walking assistance for patients with lower limb motor incapacity. Most existing exoskeletons are under-actuated, resulting in a series of problems, e.g., interference and unnatural gait during walking. In this study, we propose a novel intelligent autonomous lower extremity exoskeleton(Auto-LEE), aiming at improving the user experience of wearable walking aids and extending their application range.Unlike traditional exoskeletons, Auto-LEE has 10 degrees of freedom, and all the joints are actuated independently by direct current motors, which allows the robot to maintain balance in aiding walking without extra support.The new exoskeleton is designed and developed with a modular structure concept and multi-modal human-robot interfaces are considered in the control system. To validate the ability of self-balancing bipedal walking, three general algorithms for generating walking patterns are researched, and a preliminary experiment is implemented.

Generalized Switched-Capacitor Step-up Multilevel Inverter Employing Single DC Source

In this paper,a new generalized step-up multilevel DC-AC converter is proposed,which is suitable for applications with low-voltage input sources,such as photovoltaic power generation and electric vehicles.This inverter can achieve a high voltage gain by controlling the series-parallel conversion of the DC power supply and capacitors.Only one DC voltage source and a few power devices are employed.The maximum output voltage and the number of output levels can be further increased through the switched-capacitor unit’s extension and the submodule cascaded extension.Moreover,the capacitor voltages are self-balanced without complicated voltage control circuits.The complementary operating mechanism between each pair of switches simplifies the modulation algorithm.The inductiveload ability is fully taken into account in the proposed inverter.Additionally,a remarkable characteristic of the inverter is that the charging and discharging states among different capacitors are synchronous,which reduces the voltage ripple of the frontend capacitors.The circuit structure,the working principle,the modulation strategy,the capacitors and losses analysis are presented in detail.Afterwards,the advantages of the proposed inverter are analyzed by comparing with other recently proposed inverters.Finally,the steady-state and dynamic performance of the proposed inverter is verified and validated by simulation and experiment.

Experimental study on pile-end post-grouting piles for super large bridge pile foundations

The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper.There are totally 21 test piles.The maximum pile diameter varies from 2.5 m to 3 m,and the maximum length is 125m;the bearing capacity of the post-grouting piles is over ten thousands tons.Based on the test results,the bearing capacity,displacement,and beating characteristics before and after grouting were analyzed.The results show that the beating capacity of the piles is increased in different degrees after grouting although the technical parameters,including the patterns of grouting pipes,pressure,dosages of cement,duration of grouting lasting time,are different.However,the obtained values are very discrete.In addition,the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles.The research results have been applied in the design of bridge foundation.