FEA-Based Fatigue Life Assessment of Cycloidal Displacement Cam and Flat-Faced Follower Mechanism

Cam-followers provide reliable and controlled motions in various mechanical systems. Due to the highly fluctuating load between the cam and follower in operation, the cam-follower may be subjected to a high risk of contact fatigue failure. This paper assesses the fatigue life of a cycloidal displacement cam and a flat-faced follower under the defined loads and constraints. Computer-aided design (CAD) model of the cam-follower is developed in CATIA software and imported to ANSYS software for finite element analysis (FEA) of fatigue life. MATLAB programming is developed for determining the appropriate spring constant and pre-load force to always keep the cam and follower in contact. The fatigue life of the cam-follower has been estimated under the specified operating conditions. The analysis method can be applied to investigate the fatigue life of cams with other profiles, including the modified trapezoidal functions, polynomial functions, etc.

基于Leader-follower与人工势场的多移动机器人编队控制

目的提出一种基于Leader-follower法和人工势场法相结合的多移动机器人编队控制方法,从而克服传统Leader-follower法中由微分方程确定的控制率无法将队形控制与避障统一的缺点.方法确定关于参数l和φ的人工势场函数,通过控制参数l和φ,使多移动机器人保持预定队形;机器人follower通过主动避障方法躲避障碍物,确定一个总的人工势场控制队形和避障.结果算法能使多移动机器人系统成功地进行编队和避障.结论通过仿真试验,机器人系统能够顺利通过狭窄通道,躲避静态障碍物和动态障碍物,并在避障后恢复队形,顺利到达目标,算法简单,从而验证了算法的有效性.

采用Leader-follower和模糊反馈机制的机器鱼队形控制

在Leader-follower框架下的多机器鱼系统队形控制中,针对Leader和Follower相对独立及落后机器鱼离队等问题,在传统的Leader-follower队形控制算法中引入模糊反馈控制器进行反馈调节,使得领航机器鱼Leader能定时检查Follower的位置,将多机器鱼系统的队形控制问题转化为具有反馈调节的Follower跟踪Leader的位置和方向的问题,以增强多机器鱼队形控制的稳定性,更好地协同作业完成任务.仿真试验验证了所提出的方法能较好地实现多机器鱼系统的队形控制.

基于Leader-Follower的多机器鱼模糊队形控制

针对多机器鱼系统队形控制中队形发生突变,机器鱼无法快速反应的问题,本文采用模糊控制的方法对机器鱼的速度和航向角度进行控制,使跟随者快速准确的到达期望位姿。同时,以3条鱼为例,对多机器鱼队形运动进行仿真验证,仿真结果表明,当领航者直行时,跟随者与领航者的运动和速度相等;当领航者改变方向和速度后,跟随者可在较短时间内通过速度和方向挡位的改变达到期望位置,并保持规定队形。该方法可以调节运动参数,保持队形稳定,实现多机器鱼按一定队形完成规定路径,其跟随效果良好。

A Novel NeuMOS Source Follower Cell with High Precision

A novel neuMOS source follower circuit is presented.The cell can complete the s ource follower function even if the input voltage is lower than the threshold of the source follower,thus high-precision operation of the circuit is achieved. The simulation and the measurement results show that its precision is higher tha n that of other neuMOS source follower circuits.

基于条件反馈机制Leader-follower多机器人队形控制

针对Leader-follower多机器人系统队形控制中,Leader和follower相对独立及落后机器人离队等问题,采用基于条件反馈机制的Leader-follower多机器人队形控制方法,建立基于条件反馈机制和Lead-follower相结合的多机器人队形控制模型。将多机器人系统的队形控制问题转化为基于条件反馈机制的follower跟踪leader的位置和方向的问题,通过实例仿真验证了方法的有效性。仿真结果表明所提出的方法是合理有效的,使多机器人系统能够有效地完成编队控制任务。

基于Leader-follower的自主车辆跟随控制器设计

为解决自主车辆的跟随控制中误差系统的稳定性问题,基于Leader-follower法设计了车辆跟随控制器。对自主车辆进行运动学建模,采用Leader-follower模型描述车辆跟随结构,用L-φ控制方法建立车辆跟随误差系统,设计跟随车辆的速度控制器,以实现跟随车辆对领航车辆的稳定跟随。通过Matlab仿真实验结果证明,该控制器使误差最终收敛到0,能达到跟随控制的目的。

基于Leader-Follower和一致性理论的多机器鱼避障控制研究

主要研究了多机器鱼队形控制的主要方法,提出了一种基于Leader-Follower框架和一致性理论的多机器鱼避障控制方法。分别分析了多机器鱼在无障碍环境和运动到障碍物区域时的队形运动。这种方法结合了Leader-Follower法和一致性理论的优点,能更好地实现多机器鱼在遇到障碍物后实现避障,从而完成整个系统的队形控制。最后仿真结果验证了该方法的可行性。

往复工作路径下Leader-follower算法的编队控制研究

多智能体编队在实际作业中,多以往复的工作路径进行,如货箱的搬运、区域的巡视监控等,如何在重复工作中确保多智能体编队的稳定性成为人们较为关注的问题。因此,利用Leader-follower控制算法理论中的l-φ法,规划follower的线速度和角速度,来保持多智能体队型的稳定性,并通过调整闭环控制系数来控制编队的收敛速度。通过MATLAB数值仿真,分别刻画了多智能体往复运动的位移时间响应图和相轨迹图等,从而验证了多智能体编队在往复工作路径任务下的稳定性。

Design of Cylindrical Cam with Oscillating Follower Based on 3D Expansion of Planar Profile Model

Cylindrical cam with oscillating follower is widely applicable and used in many mechanical devices and machines. However, a common error exists in the methods of designing planar profile for oscillating follower cylinder cam. In this study, we propose a new hypothesis to solve this design problem with the inclusion of deviation angle. On the basis of this new concept, equations for planar profile expansion and methods of calculating pressure angle are deduced by applying 3D expansion formula of the follower＇s motion orbit. When the pressure angle is less than allowable value, the minimum base radius can be determined by using MATLAB software. Accordingly, the planar profile of oscillating follower cylinder cam is generated by CAD software. This new method is practical and can be easily adopted for the design of oscillating follower cylindrical cam with desirable accuracy. We applied the method in the design of cylindrical cam for paper feeding mechanism used in high-speed printers. We calculated the planar profile and used it to direct the NC machine for the manufacture of the groove of cylindrical cam. The improved cylindrical cam met all of the requirements of speed and accuracy demanded by high-speed printers. Therefore, our new method has been validated by practical application.

A Parallel Indexing Cam Mechanism with Internal Placed Followers

A new type of parallel indexing cam mechanism is discovered.The composition of the cam profile is proposed and the formulas of the mechanism parameters are established by synthesis of its configuration and size.The equations for working pro- file and pressure angle of the cam are derived based on the inverse model and the derivative of pitch curve of cams.An example is given and demonstrates that it is available to design the new mechanism using the derived expressions.

Analysis of 3D curve expansion of conical cam with oscillating tapered roller follower

This paper focuses on the analysis of running conditions and machining processes of conical cam with oscillating follower. We point out the common errors existing in the design and machining of the widely used plane expansion method of conical cam trough-out line. We show that the motion can be divided into two parts, i.e. the oscillating motion of oscillating bar and the rotary motion of oscillating bar relative to the conical cam. By increasing the rotary motion of oscillating bar, the motion path of tapered roller on oscillating bar (i.e. contour surface of conical cam) can be expanded on the cylinder. Based on these analyses, we present a creative and effective designing and machining method for 3D curve expansion of conical cam with oscillating follower.

Wall Follower Autonomous Robot Development Applying Fuzzy Incremental Controller

This paper presents the design of an autonomous robot as a basic development of an intelligent wheeled mobile robot for air duct or corridor cleaning. The robot navigation is based on wall following algorithm. The robot is controlled using fuzzy incremental controller (FIC) and embedded in PIC18F4550 microcontroller. FIC guides the robot to move along a wall in a desired direction by maintaining a constant distance to the wall. Two ultrasonic sensors are installed in the left side of the robot to sense the wall distance. The signals from these sensors are fed to FIC that then used to determine the speed control of two DC motors. The robot movement is obtained through differentiating the speed of these two motors. The experimental results show that FIC is successfully controlling the robot to follow the wall as a guidance line and has good performance compare with PID controller.

Anti-follower jamming wide gap multi-pattern frequency hopping communication method

This paper deals with the follower jamming(FJ)resistance for the frequency hopping(FH)communication system over additive white Gaussian noise(AWGN)channel.Conventional FH systems are susceptible to be jammed by FJ,and multi-pattern frequency hopping(MPFH)has good resistance to FJ.To further improve the FJ rejection capability of MPFH,we propose a wide gap multi-pattern frequency hopping(WGMPFH)scheme.WGMPFH uses channels to represent messages,and the data channel and complementary channel are hopping on orthogonal frequency slots according to wide gap FH patterns.The transmitted signal lures FJ to aim at the data channel and the complementary channel is away from FJ by adopting wide gap frequency patterns.FJ does not affect the complementary channel but increases the signal energy in the data channel,thus the effect of FJ is reduced.Its bit error rate(BER)is derived under FJ and the effects of three FJ parameters(tracking success probability,jamming duration ratio and jamming bandwidth ratio)on the BER performance of WGMPFH are investigated versus the co nventional FH/BFSK and MPFH system.Numerical and simulation results show that when under the worst-case FJ,the proposed WGMPFH outperforms the MPFH by about 1-3 dB and outperforms the conventional FH/BFSK by more than 4 dB.The proposed WGMPFH shows superior jamming rejection performance under FJ especially in severe signal-to-jamming ratio(SJR).

Transverse Vibration and Stability Analysis of Circular Plate Subjected to Follower Force and Thermal Load

Transverse vibration and stability analysis of circular plate subjected to follower force and thermal load are analyzed.Based on the thin plate theory in involving the variable temperature,the differential equation of transverse vibration for the axisymmetric circular plate subjected to follower force and thermal load is established.Then,the differential equation of vibration and corresponding boundary conditions are discretized by the differential quadrature method.Meanwhile,the generalized eigenvalue under three different boundary conditions are calculated.In this case,the change curve of the first order dimensionless complex frequency of the circular plate subjected to the follower force in the different conditions with the variable temperature coefficient and temperature load is analyzed.The stability and corresponding critical loads of the circular plate subjected to follower force and thermal load with simply supported edge,clamped edge and free edge are discussed.The results provide theoretical basis for improving the dynamic stability of the circular plate.

Robust Leader-Follower Formation Tracking Control of Multiple Underactuated Surface Vessels

This paper is concerned with the formation control problem of multiple underactuated surface vessels moving in a leader-follower formation. The formation is achieved by the follower to track a virtual target defined relative to the leader. A robust adaptive target tracking law is proposed by using neural network and backstepping techniques. The advantage of the proposed control scheme is that the uncertain nonlinear dynamics caused by Coriolis/centripetal forces, nonlinear damping, unmodeled hydrodynamics and disturbances from the environment can be compensated by on line learning. Based on Lyapunov analysis, the proposed controller guarantees the tracking errors converge to a small neighborhood of the origin. Simulation results demonstrate the effectiveness of the control strategy.

Robust Leader-follower Formation Control of Mobile Robots Based on a Second Order Kinematics Model

在这份报纸，我们学习为活动机器人的领导人追随者形成建模并且控制的问题。首先，为领导人追随者机器人形成的一个新奇 kinematics 模型基于在机器人和追随者机器人的本地运动之间的相对运动状态被提出。用这个模型，向心的亲戚和在机器人之间的 Coriolis 加速被测量相对、本地的运动传感器直接计算，并且利用了线性化非线性的系统方程。一个形成控制器，由反馈 linearization 部分和一个滑动模式赔偿者组成，被设计包括内部动力学稳定全面系统。控制获得被解决坚韧性不平等决定并且假定满足保证形成系统的零动力学的稳定性的一个合作协议。建议控制器为追随者机器人产生命令的加速并且使形成控制系统柔韧到领导人机器人的无节制的加速的效果。而且，一个柔韧的适应控制器被开发在系统处理参量的无常。模拟和试验性的结果表明了建议控制方法的有效性。

Adaptive leader follower control for multiple quadrotors via multiple surfaces control

Based on the multiple surface and fixed undirected communication topology, the adaptive leader follower contrul for multiple quadrotors is discussed. Our approach is based on leader follower architecture. Multiple surface control （MSC） is used to design consensus controller to make multiple quadrotors construct a formation during flying with the presence of uncertainty item caused by the ground effect during landing or taking off. Simulation results are presented to validate the effectiveness of the proposed controller.

Investigating the characteristic delay time in the leader–follower behavior in children single-file movement

The single-file movement experiment offered a convenient way to investigate the one-dimensional leader–follower behavior of pedestrians. This study investigated the time delays of children pedestrians in the leader–follower behavior by introducing a time-dependent delayed speed correlation. A total of 118 German students from the fifth grade(aged11–12 years old) and the 11th grade(aged 17–18 years old) participated the single-file experiment. The characteristic delay time for each pedestrian was identified by optimising the time-dependent delayed speed correlation. The influences of the curvature of the experimental scenario, density, age, and gender on the delay time were statistically examined. The results suggested that to a large extent, the revealed characteristic delay time was a density-dependent variable, and none of the curvatures, the age and gender of the individual, and the age and gender of the leader had a significant influence on it. The findings from this study are variable resources to understand the leader–follower behavior among children pedestrians and to build related simulation models.

基于Leader-Follower策略的双联AGV协同运载控制方法

针对面向大部件协同运载的双联AGV系统,融合单台全向移动AGV的路径跟踪运动学模型与Leader-Follower策略下的队形保持方法建立了一种双联AGV的协同偏差模型。基于该模型,采用Lyapunov反演法,提出一种双联AGV协同运载的运动学控制模型。最后通过软件仿真和系统实验验证了该控制模型的运行稳定性、精确性和协调性。