无人机滑降着陆控制系统设计

针对滑跑型无人机回收阶段对下滑角跟踪以及触地时姿态角的高要求,设计了一种无人机滑降着陆控制方式。首先,给出了滑降控制系统结构图,在此基础上分别进行了滑降横侧向控制器和滑降纵向控制器的设计,具体进行了直线航迹和圆航迹的控制方法以及下滑段的高度控制量算法的分析。然后,进行了滑降着陆控制模式设计,将滑降过程分解为降高、平飞、下滑以及拉平四个阶段分别进行设计,并在拉平阶段给出了俯偏航距仰角控制量与离地高度的关键技术公式。仿真结果表明,该无人机滑降着陆控制系统平飞段偏航距小于5m,接地时偏航距约为0m;平飞段高度跟踪误差为0m,下滑段高度跟踪误差2m;落地姿态角为0.4度。具有高度控制误差小、偏航距离短、落地姿态角安全性高的优点,能满足滑跑无人机对滑降阶段的控制要求。     

VSS motion control for a laser-cutting machine

An advanced position-tracking control algorithm has been developed and applied to a CNC motion controller in a laser-cutting machine. The drive trains of the laser-cutting machine are composed of belt-drives. The elastic servomechanism can be described by a two-mass system interconnected by a spring. Owing to the presence of elasticity, friction and disturbances, the closed-loop performance using a conventional control approach is limited. Therefore, the motion control algorithm is derived using the variable system structure control theory. It is shown that the proposed control effectively suppresses the mechanical vibrations and ensures compensation of the system uncertainties. Thus, accurate position tracking is guaranteed.     

Computer control system for a metal cutting machine

This paper reviews the work carried out by the Industrial Research Laboratory in cooperation with the Machine Tool Laboratory at the University of Florida to design and build a Supervision System for Machining Centers. The objective of the Supervision System is to perform three main functions: Chatter Detection and Control, Cutter Breakage Detection, and Adaptive Feed Control [1], [2]. Our contribution to this project consists of providing low-level intelligence to the machine tool controller and high-level user-friendly operator interface (monitoring screen), so that the machine tool, as a unit will be more robust and efficient, thus more economical to operate. A simple PC based embedded control system for chatter and tool breakage detection as well as a user-friendly operator interface unit will be discussed.     

Sliding mode control for Markovian jumping systems with actuator nonlinearities

This article considers the design of sliding mode control for stochastic Markovian jumping systems with actuator nonlinearities. In the design of integral sliding surfaces, a set of specified matrices are employed such that the connections among sliding surfaces corresponding to each mode are established. And then, a sliding mode controller depending on the transition rates is synthesised such that the reachability of the specified sliding surface can be ensured. Moreover, sufficient conditions for the stability of the sliding motions are derived. It is shown that the effect of Markovian switching can be coped with by the present sliding mode control method. Finally, the simulation results illustrating the proposed method are provided.     

Reachability Analysis of Landing Sites for Forced Landing of a UAS

This paper details a method to ascertain the reachability of known emergency landing sites for any fixed wing aircraft in a forced landing situation. With a knowledge of the aircraft’s state and parameters, as well as a known wind profile, the area of maximum glide range can be calculated using aircraft equations of motion for gliding flight. A landing descent circuit technique used by human pilots carrying out forced landings called high key low key is employed to account for the extra glide distance required for an approach and landing. By combining maximum glide range analysis with the descent circuit, all the reachable landing sites can be determined. X-Plane flight simulator is used to demonstrate and validate the techniques presented.     

Implementing machine-directional basis weight control for a pilot paper machine

The model of a paper machine is very complex and difficult to describe completely by a mathematical model. There are a lot of parameters in both the wet and dry end of the machine and there is a very large time delay in the system which effects the quality of the paper being produced. Although the PID controller is widely used for these types of applications, it is often not tuned very well. In this work, a newly developed algorithm (Munro, The systematic design of PID controllers, IEE Colloquium in Robust Control: Theory, Software and Applications, Austin Court, Birmingham, 1999) is used for tuning the PID controller. Along with this controller, a Smith-predictive controller is applied to the plant and the transient and steady-state behaviours of these controllers are compared. Hardware and software implementations of the closed-loop control are also presented in the paper.     

The OR dataflow architecture for a machine embedded control system

This paper presents a new architecture for embedded systems and describes an appropriate method for programming a control system. A grinding machine control system was built and an experimental verification of the theoretical approach was performed. The efficiency of this novel system was compared with the conventional control systems by grinding a workpiece up to the stringent quality requirements. The superior performance of the OR dataflow control system lead to the encouraging conclusions presented in this paper.     

A novel adaptive control system for a custom-built tension-torsion machine

Mathematical theories of elasticity–plasticity have received considerable development in recent years. However, the quantity of accurate experimental work, carried out to examine the validity of these theories appears to be limited. As the theories have increased in sophistication, the accuracy to which the experiments must be performed has also increased. In this paper the development and application of a novel adaptive control system for performing combined tension and torsion experiments on solid and tubular specimens is described. National Instruments LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is used to control the axial and torsional loads on the specimen through data acquisition boards. LabVIEW software in conjunction with data acquisition board, servo-controllers and servomotors form the adaptive control system for the custom-built tension-torsion machine. Accurate control of the axial and torsional loads in the specimen is achieved with the application of the adaptive control system and a sample of the test results are presented in this paper.     

Modeling and intellligent chatter control strategies for a lathe machine

In the active chatter control of machine tools, the most effective way to suppress the chatter is to place the actuator as close as possible to the tool tip. However, in practice, it is almost impossible to put the actuator at the same location of the tool tip. Also, in many machines the cutting tools are usually long and may be flexible. Both of these problems pose serious problems in machine chatter control. In order to control the chatter effectively and efficiently, a systematic methodology is proposed in this paper to deal with the modeling and control system design aspects of this challenging problem. Because of the flexibility effect in the tool shaft, conventional active control approaches may not perform in an efficient and effective manner. Here, two advanced control algorithms (LMS adaptive filter and fuzzy CMAC neural network) are proposed to counteract this problem. Experimental results on a lathe machine are also included. Approximately 20 dB reduction in chatter has been achieved.     

足式机器人SLIP模型向上跳跃台阶的运动控制

由于存在地势起伏,台阶对足式机器人运动稳定性会带来较大挑战.弹簧负载倒立摆模型(SLIP)作为研究足式机器人的优良模板,能否完成向上跳跃台阶的动作与其腿部摆角,起跳位置和跳跃高度都有密切的关系.由于调整模型腿部摆角规律容易引发运动失效,故本文在算法中引入虚拟弹簧腿,根据虚拟弹簧腿的运行规律确定合理起跳位置,根据起跳位置来控制系统跳跃高度进而完成跳跃台阶的动作.最后利用仿真软件进行多组仿真,结果表明本文算法对起跳区间划分合理,对起跳高度控制精准,能够实现SLIP模型跳跃台阶前后的稳定运动.     

Optimal governor control of a synchronous machine

This paper considers a fairly accurate synchronous machine model useful for digital computation of transient and dynamic behavior of power systems. A linear optimal governor controller is designed to stabilize a controllable power system. The controller requires neither a state estimator nor an observer for its implementation.     

Microcomputer control of a precision grinding machine

Production-orientated cylindrical grinding machines have presented problems to the designer which have made conventional numerical control techniques unsuited to a full-function machine. The use of microprocessor control overcomes this limitation. This article shows the particular problems involved in controlling such a machine, and gives some guidelines for interfacing to the real world in a production machine. The simplification of the hardware interface using suitable software structures is shown to be practical.     

离散随机Markov跳跃系统有限时间有界控制

研究一类带乘性噪声的离散时间随机Markov跳跃系统的有限时间控制问题.首先,定义系统的有限时间稳定和有限时间有界,通过逐次迭代和条件期望给出系统有限时间稳定的充分必要条件;其次,针对含干扰的系统,利用Lyapunov方法和线性矩阵不等式技术得到系统有限时间有界的充分条件并设计状态反馈镇定控制器;然后,进一步考虑转移概率信息不完全下的有限时间有界问题;最后,通过数值例子验证了所提出方法的有效性.     

Microcomputer control for an industrial sewing machine

The application of the microcomputer to various industrial machinery or equipment is expanding. The sewing industry is no exception to this trend, positively employing microcomputers for more advanced automation, labour saving and further industrialization. To satisfy recent needs, a sewing machine motor equipped with eddy current variable-speed clutch, LIMI-STOP Z, was developed. The LIMI-STOP Z features, besides a friction-free low inertial clutch used instead of the conventional friction type clutch, the use of a 4-bit microcomputer in the control system. This paper describes the principle, composition and functions of the LIMI-STOP Z.     

Modeling and control for a Gough‐Stewart platform CNC machine

In this paper, a complete dynamic model on task space for a 6 degrees of freedom (DOF) Gough‐Stewart platform‐type computer numerical control (CNC) machine is derived. The rotation terms of the legs are included for those inertia effects cannot be negligible in the machine tool applications. The formulation derived by means of the Euler‐Lagrange method is convenient for designing the adaptive control law. Also, the average‐type force model for end milling process is derived and included in the dynamic model and control. A composite adaptive control scheme is developed by use of filtering dynamics technique. An appropriate estimator gain is designed in the parameter adaptation law that is useful for estimating the selected important cutting parameters. Experimental results verify the proposed adaptive control scheme can achieve good tracking performance. © 2004 Wiley Periodicals, Inc.     

Inverse kinematics and inverse dynamics for control of a biped walking machine

Analytical techniques are presented for the motion planning and control of a 12 degree-of-freedom biped walking machine. From the Newton-Euler equations, joint torques are obtained in terms of joint trajectories, and the inverse dynamics are developed for both the single-support and double-support cases. Physical admissibility of the biped trajectory is characterized in terms of the equivalent force-moment and zero-moment point. This methodology has been used to obtain reference inputs and implement the feedforward control of walking robots. A simulation example illustrates the application of the techniques to plan the forward-walking trajectory of the biped robot. The implementation of a prototype mechanism and controller is also described.     

Adaptive control of basis weight and moisture content for a paperboard machine

The development and industrial application of a MIMO adaptive control strategy for a paperboard machine are investigated. The control strategy incorporates a conventional regulatory control technique, multivariable k-incremental predictor and self-tuning control algorithm. The pulp consistency and flow rate, and the steam pressure are simultaneously manipulated to control the reel basis weight and moisture content. The control system demonstrates a satisfactory performance. The variations in reel basis weight and moisture content are greatly reduced.     

A CMAC neural-network-based algorithm for the kinematic control of a walking machine

In this paper a hierarchical, neural network control architecture of a walking machine is proposed. The neural network is based on the theory of the Cerebellum Model Articulation Controller (CMAC) which is a neuromuscular control system. Some preliminary studies of kinematic control and gait synthesis are presented to demonstrate the effectiveness of the CMAC neural network. After having been trained to learn the multivariable, nonlinear relationships of the leg kinematics and gaits, CMAC is utilized to perform feedforward kinematic control of a quadruped in straight-line walking and step climbing. Simulation examples are provided and discussed. This algorithm can be extended to control other highly nonlinear processes which are hierarchical in nature and cannot be modeled by mathematical equations.