Adaptive tracking control of two-wheeled welding mobile robot with smooth curved welding path

This paper proposes an adaptive controller for partially known system and applies to a two-wheeled Welding Mobile Robot (WMR) to track a reference welding path at a constant velocity of the welding point. To design the tracking controller, the errors from WMR to steel wall is defined, and the controller is designed to drive the errors to zero as fast as desired. Additionally, a scheme of error measurement is implemented on the WMR to meet the need of the controller. In this paper, the system moments of inertia are considered to be partially unknown parameters which are estimated using update laws in adaptive control scheme. The simulations and experiments on a welding mobile robot show the effectiveness of the proposed controller.     

Sliding mode control of two-wheeled welding mobile robot for tracking smooth curved welding path

In this paper, a nonlinear controller based on sliding mode control is applied to a two-wheeled Welding Mobile Robot (WMR) to track a smooth curved welding path at a constant velocity of the welding point. The mobile robot is considered in terms of dynamics model in Cartesian coordinates under the presence of external disturbance, and its parameters are exactly known. It is assumed that the disturbance satisfies the matching condition with a known boundary. To obtain the controller, the tracking errors are defined, and the two sliding surfaces are chosen to guarantee that the errors converge to zero asymptotically. Two cases are to be considered : fixed torch and controllable torch. In addition, a simple way of measuring the errors is introduced using two potentiometers. The simulation and experiment on a two-wheeled welding mobile robot are provided to show the effectiveness of the proposed controller.     

Development of a new 5 dof mobile robot arm and its motion control system

In this paper, a new revolute mobile robot arm with five degree of freedom (d.o.f) was developed for autonomous moving robots. As a control system for the robot arm, a distributed control system composed of the main controller and five motor controllers for arm joints was developed. The main controller and the motor controllers were developed using the ARM microprocessor and the TMS320c2407 microprocessor, respectively. A new trajectory tracking algorithm for the motor controllers was devised employing pre-generated off-line trajectory data. Also, a 3-D simulator based on the OpenGL software to simulate the motion of the robot arm was developed. To validate the performance of the robot system, experiments to track a specified trajectory were performed.     

基于LM629的移动机器人控制系统的研究

利用PIC16F877单片机和运动芯片LM629建立移动机器人底层控制系统。控制系统的硬件结构主要包括感知模块、监控模块、运动模块、功率模块和无线通讯模块。运动模块由LM629运动芯片和少量的外围电路构成,简化了整个控制系统的硬件电路结构。实验表明,由PIC16F877和LM629建立的底层控制系统,具有控制精度高、起停速度快、同步性好等特点。     

基于Trio的车身焊接定位机器人控制系统研究

研发了在汽车白车身底板焊接过程中起快速准确定位作用的三轴定位机器人控制系统.基于IPC+Trio运动控制器,提出了开放式定位机器人控制系统总体方案,并进行了详细的控制系统的软硬件设计,开发了在Visual Studio.NET 2008软件环境中的控制系统上位机管理软件和在Trio Motion Perfect2软件环境下的底层控制程序.实践结果表明,该控制系统能够满足白车身底板焊接的定位控制要求,且运行稳定可靠.     

Trajectory planning and tracking control of a ground mobile robot:A reconstruction approach towards space vehicle

With the development of the similarity calculation method, the orbital motion of space vehicle can be translated into a sequence of waypoints that reflect position and velocity on the ground. In this paper, a motion control system is proposed to make the mobile robot pass through the desired waypoints for reconstructing the orbital motion. First, the parameterized trajectory optimization method is applied to generate a curvature-continuous trajectory from the waypoints, the position and velocity demands are presented as the equality constraints. Virtual positions are introduced to reduce the oscillation, and the total execution time of the whole trajectory is selected as the optimization parameter to reduce the computational burden. Then, an equivalence transformation is provided to translate the error system into an affine form, which is beneficial for the feedback controller design. Based on this, a nonlinear trajectory tracking controller is proposed, which includes a feedforward controller and an error feedback controller, and its exponential stability is proved using Persistency of Excitation Lemma. In addition, a shunting neural dynamics model is employed to avoid sharp velocity jumps. Finally, the performed experiments verify the effectiveness of the proposed method.     

The end point control for a MMAM controlled flexible manipulator

For a high bandwidth, accurate end of arm motion control with good disturbance rejection, the Momentum Management Approach to Motion control (MMAM) is proposed. The MMAM is a kind of position control technique that uses inertial forces, applied at or near the end of arm to achieve high bandwidth and accuracy in movement and in the face of force disturbances. To prove the concept of MMAM, the end point control of a flexible manipulator is considered. For this purpose, a flexible beam is mounted on the x-y table, and the MMAM actuator is attached on the top of the flexible beam. A mathematical model is developed for the flexible beam being controlled by the MMAM actuator and slide base DC motor. A system identification method is applied to estimate some system parameters in the model which can not be determined because of the complexity of the mechanism. In order to optimize the result of the position (/velocity) estimation of a beam end point of which movement is monitored by an accelerometer and machine vision, a Kalman filter technique is applied. For the end point control of the flexible beam, the optimal linear output feedback control is applied.     

Robust adaptive tracking control for nonholonomic mobile manipulator with uncertainties

In this paper, mobile manipulator is divided into two subsystems, that is, nonholonomic mobile platform subsystem and holonomic manipulator subsystem. First, the kinematic controller of the mobile platform is derived to obtain a desired velocity. Second, regarding the coupling between the two subsystems as disturbances, Lyapunov functions of the two subsystems are designed respectively. Third, a robust adaptive tracking controller is proposed to deal with the unknown upper bounds of parameter uncertainties and disturbances. According to the Lyapunov stability theory, the derived robust adaptive controller guarantees global stability of the closed-loop system, and the tracking errors and adaptive coefficient errors are all bounded. Finally, simulation results show that the proposed robust adaptive tracking controller for nonholonomic mobile manipulator is effective and has good tracking capacity.     

Adaptive model reference control based on Takagi-Sugeno fuzzy models with applications to flexible joint manipulators

The control scheme using fuzzy modeling and Parallel Distributed Compensation (PDC) concept is proposed to provide asymptotic tracking of a reference signal for the flexible joint manipulators with uncertain parameters. From Lyapunov stability analysis and simulation results, the developed control law and adaptive law guarantee the boundedness of all signals in the closed-loop multi-input/multi-output system. In addition, the plant state tracks the state of the reference model asymptotically with time for any bounded reference input signal.     

A robust control with a neural network structure for uncertain robot manipulator

A robust position control with the bound function of neural network structure is proposed for uncertain robot manipulators. The uncertain factors come from imperfect knowledge of system parameters, payload change, friction, external disturbance, and etc. Therefore, uncertainties are often nonlinear and time-varying. The neural network structure presents the bound function and does not need the concave property of the bound function. The robust approach is to solve this problem as uncertainties are included in a model and the controller can achieve the desired properties in spite of the imperfect modeling. Simulation is performed to validate this law for four-axis SCARA type robot manipulator.     

Robust nonlinear control of a 6 DOF parallel manipulator : Task space approach

This paper presents a robust nonlinear controller for a 6 degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker. With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.     

气动机械手控制回路设计

介绍一种全气动控制机械手的控制回路,克服了信号-动作(X-D)状态图法、卡诺图图解法等较繁琐的缺点.     

无线遥控机械手的参数化控制系统

为了使机电一体化的设备在更多的企业中得以推广使用，进而推动高新技术向生产力的转化，有必要研制时机械手及其它自动化机械的参数化控制系统。这里介绍了具有参数化即时控制、延时控制和互锁功能的无线遥控系统的组成及其对机械手控制的实际应用。     

Vibrational control of underactuated mechanical systems control design through averaging analysis

An open loop vibrational control for an underactuated mechanical system with amplitude and frequency modulation is investigated. Since there is no direct external input to an unactuated joint, the dynamic coupling between the actuated and unactuated joint is utilized for controlling the unactuated joint. Feedback linearization has been performed to fully incorporate the known nonlinearities of the underactuated system considered. The actuated joints are firstly positioned to their desired locations, and then periodic oscillatory inputs are applied to the actuated joints to move the remaining unactuated joints to their target positions. The amplitudes and frequencies of the vibrations introduced are determined through averaging analysis. A systematic way of obtaining an averaged system for the underactuated system via a coordinate transformation is developed. A manipulator in the zero gravity space can be vibrationally controlled in the event of actuator failure. A control design example of the 2R planar manipulator with a free joint with no brake is provided.     

Sliding mode control with fuzzy adaptive perturbation compensator for 6-DOF parallel manipulator

This paper proposes a sliding mode controller with fuzzy adaptive perturbation compensator (FAPC) to get a good control performance and reduce the chatter. The proposed algorithm can reduce the chattering because the proposed fuzzy adaptive perturbation compensator compensates the perturbation terms. The compensator computes the control input for compensating unmodeled dynamic terms and disturbance by using the observer-based fuzzy adaptive network (FAN). The weighting parameters of the compensator are updated by on-line adaptive scheme in order to minimize the estimation error and the estimation velocity error of each actuator. Therefore, the combination of sliding mode control and fuzzy adaptive network gives the robust and intelligent routine to get a good control performance. To evaluate the control performance of the proposed approach, tracking control is experimentally carried out for the hydraulic motion platform which consists of a 6-DOF parallel manipulator.     

Reference trajectory analysis and trajectory control by bank angle for re-entry vehicle

The re-entry problem consists of guidance design and trajectory control. This paper summarizes the detailed relationships between the velocity, drag acceleration and altitude in determining reference trajectories. The computational issues are also addressed, and the performance of the proposed simple nonlinear control of a bank angle for the longitudinal/lateral trajectory is demonstrated. In particular, the fixed bank angle methods that can reduce the drag acceleration errors at low-speeds are proposed. The importance of bank reversals with respect to the azimuth errors is also elucidated.     

抓取箱形物品的机械手的优化设计

应用复合型优化设计方法,对抓取箱形物体机械手的平行四边形连杆机构进行了优化设计。优化设计的结论应用于机械手的总体设计。     

超超临界锅炉受热面管系连接件自动化焊接系统设计

超超临界锅炉是今后火电机组的发展方向,在超超临界锅炉受热面管系中,由于受到结构布置等原因大量使用活动连接件,目前全部采用焊条电弧焊(SMAW)技术,产品制造精度不高,产品质量不稳定,生产效率低下。针对活动连接件的焊接技术要求以及分布规律、件形状、尺寸一致的特点,设计了龙门式气体保护焊接机器人机械结构,使用OTC的DP400全数字IGBT逆变控制直流脉冲自动焊接电源,构建了基于触摸屏的自动焊PLC控制系统。该系统能实现多组合的焊接参数设定,优化焊接工艺参数匹配。     

基于虚拟仪器的双轴柔性辊弯成型机控制系统设计

在介绍变截面辊弯成型原理的基础上,描述了双轴变截面辊弯成型机结构,阐述了基于虚拟仪器思想的成型机控制系统构成,给出了实现变截面成型的软件设计思想,最后通过成型实验分析了成型轨迹控制精度.     

Combination of robot control and assembly planning for a precision manipulator

This paper researches how to realize the automatic assembly operation on a two-finger precision manipulator. A multi-layer assembly support system is proposed. At the task-planning layer, based on the computer-aided design (CAD) model, the assembly sequence is first generated, and the information necessary for skill decomposition is also derived. Then, the assembly sequence is decomposed into robot skills at the skill-decomposition layer. These generated skills are managed and executed at the robot control layer. Experimental results show the feasibility and efficiency of the proposed system.