Optimisation-based Verification Process of Obstacle Avoidance Systems for Unicycle-like Mobile Robots

This paper presents an optimisatiombased verification process for obstacle avoidance systems of a unicycle-like mobile robot. It is a novel approach for the collision avoidance verification process. Local and global optimisation based verification processes are developed to find the worst-case parameters and the worst-case distance between the robot and an obstacle. The kinematic and dynamic model of the unicycle-like mobile robot is first introduced with force and torque as the inputs. The design of the control system is split into two parts. One is velocity and rotation using the robot dynamics, and the other is the incremental motion planning for robot kinematics. The artificial potential field method is chosen as a path planning and obstacle avoidance candidate technique for verification study as it is simple and widely used. Different optimisation algorithms are applied and compared for the purpose of verification. It is shown that even for a simple case study where only mass and inertia variations are considered, a local optimization based verification method may fail to identify the worst case. Two global optimisation methods have been investigated： genetic algorithms （GAs） and GLOBAL algorithms. Both of these methods successfully find the worst case. The verification process confirms that the obstacle avoidance algorithm functions correctly in the presence of all the possible parameter variations.

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.

Balancing control of unicycle robot by using sliding control

This paper discusses about balancing control of unicycle robot.Unicycle robot consists of pitch which acts like inverted pendulum and roll which acts like reaction wheel pendulum.The robot which does not have actuator located in yaw axis is made to derive the simple dynamics.Lagrange equation is applied to deriving dynamic equations.Obtained dynamic equations are used to design the sliding mode control.State variables of the designed control are pitch angle and roll angle.Sliding mode control has chattering problem,which is eliminated by using the sigmoid function as switching function.Finally the control performance and eliminated chattering problem is verified by simulation.

Robotic Unicycle Intelligent Robust Control Pt I: Soft Computational Intelligence Toolkit

The concept of an intelligent control system for a complex nonlinear biomechanical system of an extension cableless robotic unicycle discussed.A thermodynamic approach to study optimal control processes in complex nonlinear dynamic systems applied.The results of stochastic simulation of a fuzzy intelligent control system for various types of external/internal excitations for a dynamic,globally unstable control object-extension cableless robotic unicycle based on Soft Computing(Computational Intelligence Toolkit-SCOptKBTM)technology presented.A new approach to design an intelligent control system based on the principle of the minimum entropy production(minimum of useful resource losses)determination in the movement of the control object and the control system is developed.This determination as a fitness function in the genetic algorithm is used to achieve robust control of a robotic unicycle.An algorithm for entropy production computing and representation of their relationship with the Lyapunov function(a measure of stochastic robust stability)described.

图变换及其在图的最小特征值的应用

假设G是一个简单连通图,其顶点集V(G)={v_(1),v_(2),⋯,vn}.图G的邻接矩阵表示为A(G)=(a_(ij))n×n,其中如果两个顶点vi和vj在图G中相邻,则a_(ij)=1;否则a_(ij)=0.由于A(G)是一个实对称矩阵,所以其特征值可以排列为λ_(1)(G)≥λ_(2)(G)≥⋯≥λn(G),A(G)的特征值也是图G的特征值。文章首先给出图的三个图变换,然后应用其确定存在两个有n≥12个顶点的连通图,其最小特征值可以达到所有单圈图的补图中最小,这修改了文献[9]中的主要结果。

固定围长与最大度的单圈图的Wiener指数

Wiener指数是一种基于距离的图不变量,被定义为图中所有顶点对的距离总和。利用Wiener指数的定义,给出图变换后Wiener指数值之差的计算公式,得到围长与最大度均为3的单圈图的Wiener指数极小图的一些结构性质。

单圈图的邻点全和可区别全染色

用结构分析法完整刻画单圈图U的邻点全和可区别全染色,并得到当U■C_(n)且n■0(mod 3)时,ftndiΣ(U)=Δ(U)+2;其他情况下,ftndiΣ(U)=Δ(U)+1.表明邻点全和可区别全染色猜想在任意单圈图上都成立.

圈长为偶的单圈图(加权)Mostar指标的下界

通过图变换,给出当单圈图的圈长为偶数时其Mostar指标和加权Mostar指标的下界,并刻画达到下界的极值图.

给定悬挂点数的树和单圈图的顶点度函数研究

设G是n阶简单图,G的悬挂点数记作p(G),顶点度函数指数H_(f)(G)定义为H_(f)(G)=∑_(v∈V(G))f(d(v)).考虑在给定悬挂点数为k的n阶树和单圈图中,在f(x)是严格凸函数的情况下,顶点度函数H_(f)(G)的最大值问题.在f(x)是严格凹函数的情况下,同样的结果也适用于顶点度函数H_(f)(G)的最小值问题.通过对这些情况的分析,得出了顶点度函数H_(f)(G)在给定条件下的最值性质.这些结果对理解图论中的悬挂点和顶点度函数的性质具有重要意义.

单圈图的Steiner k-general Wiener指数

对于连通图G,当3≤k≤n-2时,图G的Steiner k-general Wiener指数定义为SW_(k)^(m)(G)=∑S■V(G)|S|=kd^(m)(S),(m≥1),其中d(S)表示点集S的Steiner距离,即图G中包含点集S的最小连通子树的边数.给出了单圈图的SW_(k)^(m)(G)下界,并得到对应的极图.

LARGEST EIGENVALUE OF A UNICYCLIC MIXED GRAPH

The graphs which maximize and minimize respectively the largest eigenvalue over all unicyclic mixed graphs U on n vertices are determined. The unicyclic mixed graphs U with the largest eigenvalue λ 1(U)=n or λ 1(U)∈(n,n+1] are characterized.

On the ordering of the Kirchhoff indices of the complements of trees and unicyclic graphs

The Kirchhoff index Kf(G) of a graph G is defined to be the sum of the resistance distances between all pairs of vertices of G. In this paper, we develop a novel method for ordering the Kirchhoff indices of the complements of trees and unicyclic graphs. With this method, we determine the first five maximum values of Kf■ and the first four maximum values of Kf(ū),where ■ and ū are the complements of a tree T and unicyclic graph U, respectively.

Unicyclic graphs with extremal Lanzhou index

Very recently D.Vukicevic et al.[8]introduced a new topological index for a molecular graph G named Lanzhou index as∑_(u∈V(G))d_(u)d^(2)_(u),where d_(u)and d_(u)denote the degree of vertex u in G and in its complement respectively.Lanzhou index Lz(G)can be expressed as(n-1)M_(1)(G)-F(G),where M_(1)(G)and F(G)denote the first Zagreb index and the forgotten index of G respectively,and n is the number of vertices in G.It turns out that Lanzhou index outperforms M_(1)(G)and F(G)in predicting the logarithm of the octanol-water partition coefficient for octane and nonane isomers.It was shown that stars and balanced double stars are the minimal and maximal trees for Lanzhou index respectively.In this paper,we determine the unicyclic graphs and the unicyclic chemical graphs with the minimum and maximum Lanzhou indices separately.

A Note on the Nullity of Unicyclic Graphs

The nullity of a graph is the multiplicity of the eigenvalue zero in its spectrum. In this paper we show the expression of the nullity and nullity set of unicyclic graphs with n vertices and girth r, and characterize the unicyclic graphs with extremal nullity.

Ordering of Unicyclic Graphs with Perfect Matchings by Minimal Matching Energies

In 2012, Gutman and Wagner proposed the concept of the matching energy of a graph and pointed out that its chemical applications can go back to the 1970s. The matching energy of a graph is defined as the sum of the absolute values of the zeros of its matching polynomial. Let u and v be the non-isolated vertices of the graphs G and H with the same order, respectively. Let wi?be a non-isolated vertex of graph Gi?where i=1, 2, …, k. We use Gu(k)?(respectively, Hv(k)) to denote the graph which is the coalescence of G (respectively, H) and G1, G2,…, Gk?by identifying the vertices u (respectively, v) and w1, w2,…, wk. In this paper, we first present a new technique of directly comparing the matching energies of Gu(k)?and Hv(k), which can tackle some quasi-order incomparable problems. As the applications of the technique, then we can determine the unicyclic graphs with perfect matchings of order 2n with the first to the ninth smallest matching energies for all n≥211.

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.

一类单圈图的最小Randic能量

考虑在圈C_(g)上的某一顶点连接一个星图S_(t)所组成的单圈图C_(g)∪S_(t)的Randic能量的极值问题,利用Randic能量的定义和性质,并结合图变换,在该类单圈图中找到取得最小Randic能量的图.