打桩对码头岸坡稳定的不利影响和防治措施

高桩码头的打桩施工常常对码头岸坡的稳定性造成极大的不利影响.研究了打桩施工产生的超孔隙水压力、打桩对土体的扰动、打桩振动以及打桩速度等因素对岸坡稳定的不利影响,并总结了由打桩引起的码头岸坡滑移的防治措施.     

侧向干扰下双层门式刚架静力屈曲的计算机模拟

用ANSYS有限元软件,对柱脚固接、在不规则竖向荷载和三种侧向荷载作用下的双层门式刚架的屈曲进行了计算机模拟,得到了不同大小的侧向干扰力作用下的双层门式刚架的临界屈曲荷载,以及结构的屈曲模态。模拟结果表明:在侧向集中干扰力的作用下,双层门式刚架的临界屈曲荷载随着作用力的大小和作用点的不同发生变化;在侧向三角形荷载干扰下,双层门式刚架发生了明显的屈曲变形,结构的右侧柱子中点处发生较大的位移,并且首先发生屈曲,影响了结构的整体稳定性。模拟结果对工程应用有一定的参考价值。     

船舶运动干扰力和力矩数学模型

为了准确计算船舶运动参数,以提高航海模拟器的模拟精度,本文基于欧拉理论建立船舶运动干扰力和力矩数学模型,考虑了水流压力、水力矩、风压力、风力矩、螺旋桨推力、螺旋桨力矩等力学参数对船身运动的影响。以某试验船为实例进行计算研究。结果表明,本文建立的数学模型与相关文献计算结果较为一致,本文建立的船舶运动干扰力和力矩数学模型具有较好的准确性。     

拖曳系统运动传递计算

由母船、拖缆和拖体构成的拖曳系统,在拖航作业中,母船受风浪扰动发生升沉和纵摇运动,水面扰动沿缆传递至拖体,影响探测设备性能。文中研究的合理简化的母船波浪运动预报模型、结合已有的拖缆动力学计算模型耦合拖体空间运动模型,构造衔接条件和转换关系式,建立较为完整的水下拖曳系统运动传递模型。编制相应计算程序,计算了二段式拖曳方式对扰动的传递,归纳其扰动传递特性。表明该模型可应用于拖曳运动稳定的设计分析。     

Velocity control with disturbance observer for pedal-assisted electric bikes

This paper proposes a velocity control approach for light electric bicycles with human power assistance. A disturbance observer mechanism is used to estimate the sum of the human torque and resistance torques. The resulting vehicle velocity control provides better battery energy efficiency by knowledge of the instantaneous human torque assistance and better speed control by knowledge of the instantaneous resistive torque. The disturbance observer is tuned in terms of the DC gain of a low-passed Q-filter for both open-loop and closed-loop schemes. Assuming that the slow varying nature of the disturbance has been properly estimated and compensated, the torque control law is designed via an optimal control approach to achieve multi-objective performances regarding the external disturbance input, control signal magnitude, and velocity tracking error. The three main parameters of the electric bike, including the moment of inertia, the radius of tyre and the vehicle weight are allowed to be variational. Specifically, the deviation of the inertia moment and deviation of the tyre radius are addressed during the controller design in terms of linear matrix inequalities. On the other hand, the effect of vehicle weight deviation on the system behaviour is evaluated when the vehicle is implemented with the constructed control law. Based on the parameters and specifications of the EL-168 electric bike produced by KENTFA Advanced Technology, Taiwan, the design results are verified through time–response simulations.     

Steering disturbance rejection using a physics-based neuromusculoskeletal driver model

The aim of this work is to develop a comprehensive yet practical driver model to be used in studying driver–vehicle interactions. Drivers interact with their vehicle and the road through the steering wheel. This interaction forms a closed-loop coupled human–machine system, which influences the driver's steering feel and control performance. A hierarchical approach is proposed here to capture the complexity of the driver's neuromuscular dynamics and the central nervous system in the coordination of the driver's upper extremity activities, especially in the presence of external disturbance. The proposed motor control framework has three layers: the first (or the path planning) plans a desired vehicle trajectory and the required steering angles to perform the desired trajectory; the second (or the musculoskeletal controller) actuates the musculoskeletal arm to rotate the steering wheel accordingly; and the final layer ensures the precision control and disturbance rejection of the motor control units. The physics-based driver model presented here can also provide insights into vehicle control in relaxed and tensed driving conditions, which are simulated by adjusting the driver model parameters such as cognition delay and muscle co-contraction dynamics.     

蓝牙与802.11b 相互干扰分析

由于使用相同频段,使得蓝牙网络与IEEE802.11b无线局域网之间存在干扰,严重影响系统正常工作。本文主要对蓝牙网络与IEEE802.11b无线局域网之间存在干扰情况进行分析与综述,然后简要介绍了克服干扰实现两者共存的方法,以期为相关问题的深入研究给出背景。     

Motion Control of Underwater Vehicle Based on Least Disturbance BP Algorithm

Up to now, some technology of neural networks are developed to solve the non-linearity of researched objects and toimplement the adaptive control in many engineering fields, and some good results were achieved. Though it puts some questionsover to design application structure with neural networks, it is really unknowable about the study mechanism of those.But, theimportance of study ratio is widely realized by many scientists now, and some methods on the modification of that are provided.     

基于模糊 PID 的光电跟踪系统自适应前馈补偿控制*

为降低干扰力矩对光电跟踪系统精度的影响,提出了基于模糊 P ID的光电跟踪系统前馈补偿控制方法。首先,分析了按扰动前馈补偿的控制原理,提出了自适应前馈补偿方法;然后,对用直流力矩电机驱动的光电跟踪系统进行了建模;最后,为光电跟踪系统位置环设计了模糊PID控制器,并在此基础上设计了与之相匹配的自适应前馈补偿函数。仿真结果表明,相对于PID控制的固定前馈补偿控制器,所设计的控制器加快了反应速度,大幅提高了控制精度。