机械外文翻译--液压挖掘机的半自动控制系统.doc

Hydraulic excavatorssemi-automatic controlled system AbstractA hydraulic excavators used in the semi-automatic controlled system is developed. Because of this system, even unskilled operators can easily and accurately controlled hydraulic excavators. Constructed with the hydraulic excavator controller of mathematical precision control model through simulation to develop a control algorithm, which is used in hydraulic excavators, We can estimate its efficiency. In accordance with the law, through positive feedback and feed forward control, nonlinear compensation. state feedback and gain scheduling, and other means to obtain higher accuracy and stability properties. Keywords : construction machinery; Hydraulic excavators; feed forward; State feedback; Operation 1 Introduction hydraulic excavators, known as the large articulated robot, a construction machinery. Using this machine excavation and loading operations, require drivers to have high operational skills, Even skilled driver would have considerable fatigue. The other hand, with the operators age increased, the number of skilled drivers thus will be reduced. Developed a way to let anyone will be able to easily manipulate the hydraulic excavator is very necessary. Hydraulic excavators asked for a higher operational skills, for the following reasons. 1. Hydraulic excavator operation, at least two joystick operation and must be coordinated.2. Joystick moves charged with the direction of the Jib components of the campaign in different directions. For example, the hydraulic excavator backhoe level action, we must also play three joystick (boom, the bucket handles, Bucket) to enable the bucket along the top of the horizontal movement. In this case, joystick operation shows the components of the implementation of the direction of movement, but this direction and work in different directions. If a driver to operate as long as the control rod, bar and other free arm automatic servo action, operation becomes very simple. This is the so-called semi-automatic control system. Development of a semi-automatic control system, we must address the following two technical problems. 1. Automatic control systems must use common control valve. 2. Hydraulic excavators must compensate its dynamic characteristics to improve its accuracy.2 Hydraulic excavator model To study the hydraulic excavator control algorithm, hydraulic excavators must analyze the mathematical model. The hydraulic excavator boom, the bucket handles, and the bucket is driven by fluid pressure. 2.1 Dynamic model Assumes that each of the Jib components are rigid, the Lagrange equations of motion can be in the following expression : where g is the acceleration due to gravity; i hinged angle; i is the component of torque ; li length; lgi shaft to the centers focus away from the quality ;mi components; Ii is the focus of the moment of inertia (subscript i=1-3; were expressed boom, the bucket handles, and the bucket). 2.2 Excavator model Components of each arm are driven by hydraulic cylinder, hydraulic cylinder and flow control of the slide valve. Can make the following assumptions : 1. Hydraulic valve opening and valve core proportional to the displacement. 2. System hydraulic oil leak. 3. Hydraulic oil flows through the pipeline when no hydraulic pressure loss. 4. Cylinder rod and the top of both sides are equally effective regional. On this issue, each arm components from the hydraulic cylinder pressure and flow characteristics may come to the following equation : When; Among them, Ai hydraulic cylinder is an effective cross-sectional area ;hi hydraulic cylinder is the length ;Xi sliding core is the location; Psi ;P1i of supply pressure is the maximum cylinder pressure ;P2i side of the cylinder rod edge pressure; Vi is the hydraulic cylinder and the oil pipeline is ;Bi slide valve width; is the density of oil molecules, K oil viscosity; c is the flow coefficient. 2.5 Slide valve characteristic Slide valve movement of the hydraulic excavator control characteristics have considerable influence. Thus, the assumption that Valve relative reference input following an order delay. Which is sliding core displacement reference input; Is time constant. 3 angle Angle control system is basically a servo reference input through the angle position feedback control. To obtain more accurate control, nonlinear feedback and compensation by adding location feedback. 3.1 nonlinear compensation In ordinary automatic control systems, often used as servo valve of this new type of control device. In semi-automatic control system, in order to achieve automatic control and manual coordination, the use of manually controlling the valve. This type valve, the displacement of the spool valve with the opening of the relationship is nonlinear. Therefore, the control operation, the use of such a relationship, spool displacement may be required by the valve opening to the anti-launched. Meanwhile, non-linear compensation can be. 3.2 Feedback on the first two models Discussed on the basis of If the boom angle to the dynamic characteristics of a certain standard and the location of the linear approximation of (slip displacement X-10, Cylinder pressure difference P 110, boom angle 10), the closed-loop transfer function for which, Kp location of the feedback gain coefficient; Because the system is smaller coefficient a1, the reaction is unstable. For example, large hydraulic excavator SK-16 China. X10 is 0, the coefficient is given a0=2.7 10, a1=6.0 10. a2=1.2 10. add acceleration feedback magnification factor Ka, hence the closed-loop transfer function is the addition of this factor, Coefficient on the big S, the system tends to be stable. Visibility, using acceleration feedback to improve the response characteristics obviously. However, it is very difficult to accurately measure the acceleration. To avoid this problem, use hydraulic cylinder force feedback replace acceleration feedback. Therefore, the hydraulic cylinder measured by the strength of the cylinder pressure calculation and removes some of its low frequency. This is the so-called pressure feedback.4 Semi-automatic control system Based on the simulation experiments, on the basis of semi-automatic control system has been created, Application of the type excavator SK-16 test. Field Test verifiable through its operability. This section will discuss the control system structure and function. 4.1 The structure Of control by the controller system, sensors, human-machine interface and hydraulic system. Controllers are used by the microprocessor 16, will receive automatically boom, bucket handles, and the bucket angle sensor input signal, Each joystick control of the location, the selection of control mode and calculate the actual amount of change, to the signal from the amplifier to form the output signal. Hydraulic control system of fluid pressure and the electromagnetic signal proportional valve proportional, dominated the slide-valve position control into the hydraulic cylinder hydraulic oil flow. In order to obtain high-speed, high-precision control, the controller using digital processing chip, Sensors using high-resolution magnetic encoder. In addition, in each cylinder pressure sensor installed on the pressure in order to obtain feedback signal. After the above data on the existence of memory, communication ports can be read out. 4.2 The control function control system has three control mode, can operate under the bar and choice of switching automatic switching. Their specific functions as follows. (1) Backhoe level action mode : water Switches vindicated shovel, bucket in hand with promoting stem operation, The control system automatically handles the Big Dipper and the Big Dipper handle to maintain the bottom of the horizontal movement. In such circumstances, when the fighting began stalk control rod operation, the location of its information from the ground to the bottom of the bucket stalk height. Operation of the boom pole manual operation can be suspended automatic control, because the manual operation of the priority over the control. (2) Lift bucket level model : Bucket Lift Switches level in the manual boom lifting operation, Automatic Control System bucket. Bucket perspective to maintain its lifting has just begun when the angle to prevent the raw materials from leaking bucket. (3) the manual mode of operation : When neither option backhoe level action pattern, and have no choice bucket level Lift mode, boom, the bucket handles, and the bucket is only through manual operation. System mainly uses the C programming language to accomplish these functions to create a stable module to improve system stability.5 individual components for the control test boomThe bucket handles, and the components of each bucket, to 5 gradient from the initial value began to change their point of reference value, measured response, thereby ascertain the three description of the role of the control algorithm.5.1 Nonlinear compensation Because of the role of electro-hydraulic system is insensitive, When only a simple position feedback without compensation, steady-state error still exists. Nonlinear compensation to reduce such errors can emerge. 5.2 The state feedback control For the role of the Big Dipper handle and the bucket, position feedback can only stable response However, acceleration or increase pressure feedback improves the response speed. To boom as an example, only only position feedback, the response became unstable. Acceleration or to pressure feedback, in response to the improved stability. 6 backhoe level control testingIn various locations to control and operate under the control test, in its control characteristics, Meanwhile determine the optimal control parameters. 6.1 feed forward control Is the only position feedback circumstances, increased magnification factor Kp reduce Z errors, causing instability, resulting in system delay, for example, as shown in Figure 13 of the customs and Kp is not reduced. Adopt 4.1 described in the bucket handle the Jib feedforward control can reduce the errors will not increase Kp. 6.2 Location of compensation When the backhoe up position at or backhoe moves are completed, backhoe level action tends to instability. Oscillatory instability may change its position magnification factor Kp to eliminate the discussion. their role in the show backhoe from about two meters to the level when action results. Compensation is not equipped with the devices, compared to map the relationship did not loaded, the situation of compensation is to provide a stable response. 6.3 The control layout on the role of control-operated Control interval, the study results are as follows : 1. When the interval set up the control over 100ms, unstable oscillation due to the inertia movement intensified with the position. 2. When the interval below routing control, the control can not operate for such a large increase. Therefore, in consideration of accuracy, control system selected interval control circuits.6.4 By the use of load Control system, hydraulic excavators implementation of practical mining moves to study its impact on the set. Control precision not found with no load is quite different.7 Conclusions This paper shows that state feedback and feed forward control portfolio, precision control of hydraulic excavators possible. It also proved that ordinary nonlinear compensation can control valve used in automatic control system. Thus using control technology, and allow even unskilled drivers can be easily and accurately controlled hydraulic excavators. These technologies will be applied to the control of other machines, such as crawler cranes, make general structure of the machine can be improved so that no one easy manipulation of machinery. References1 J. Chiba, T. Takeda, Automatic control in construction machines, Journal of SICE 21 8 1982 4046.2 H. Nakamura, A. Matsuzaki, Automation in construction machinery, Hitachi Review 57 3 1975 5562.3 T. Nakano et al., Development of large hydraulic excavator,. Mitsubishi Heavy Industries Technical Review 22 2 1985 4251.4 T. Morita, Y. Sakawa, Modeling and control of power shovel, Transactions of SICE 22 1 1986 6975.5 H. Araya et al., Automatic control system for hydraulic excavator, R&D Kobe Steel Engineering Reports 37 2 1987 7478.6 P.K. Vaha, M.J. Skibniewski, Dynamic model of excavator, Journal of Aerospace Engineering 6 2 1990 April.7 H. Hanafusa, Design of electro-hydraulic servo system for articulated robot, Journal of the Japan Hydraulics and Pneumatics Society 13 7 1982 18.8 H.B. Kuntze et al., On the model-based control of a hydraulic large range robot, IFAC Robot Control 1991 207212.液压挖掘机的半自动控制系统摘要开发出了一种应用于液压挖掘机的半自动控制系统。采用该系统，即使是不熟练的操作者也能容易和精确地操控液压挖掘机。构造出了具有控制器的液压挖掘机的精确数学控制模型，同时通过模拟实验研发出了其控制算法，并将其应用在液压挖掘机上，由此可以估算出它的工作效率。依照此法，可通过正反馈及前馈控制、非线性补偿、状态反馈和增益调度等各种手段获得较高的控制精度和稳定性能。关键词：施工机械；液压挖掘机；前馈；状态反馈；操作1 引言 液压挖掘机，被称为大型铰接式机器人，是一种施工机械。采用这种机器进行挖掘和装载操作，要求司机要具备高水平的操作技能，即便是熟练的司机也会产生相当大的疲劳。另一方面，随着操作者年龄增大，熟练司机的数量因而也将会减少。开发出一种让任何人都能容易操控的液压挖掘机就非常必要了。 液压挖掘机之所以要求较高的操作技能，其理由如下。1.液压挖掘机的操作，至少有两个操作手柄必须同时操作并且要协调好。2.操作手柄的动作方向与其所控的臂杆组件的运动方向不同。例如，液压挖掘机的反铲水平动作，必须同时操控三个操作手柄（动臂，斗柄，铲斗）使铲斗的顶部沿着水平面运动。在这种情况下，操作手柄的操作表明了执行元件的动作方向，但是这种方向与工作方向不同。如果司机只要操控一个操作杆，而其它自由杆臂自动的随动动作，操作就变得非常简单。这就是所谓的半自动控制系统。开发这种半自动控制系统，必须解决以下两个技术难题。1. 自动控制系统必须采用普通的控制阀。2. 液压挖掘机必须补偿其动态特性以提高其控制精度。2 液压挖掘机的模型为了研究液压挖掘机的控制算法,必须分析液压挖掘机的数学模型。液压挖掘机的动臂、斗柄、铲斗都是由液压力驱动。2.1 动态模型 假定每一臂杆组件都是刚体，由拉格朗日运动方程可得以下表达式： 其中 g是重力加速度；i铰接点角度；i是提供的扭矩；li组件的长度；lgi转轴中心到重心之距；mi组件的质量；Ii是重心处的转动惯量(下标i=1-3;依次表示动臂，斗柄，铲斗)。2.2 挖掘机模型 每一臂杆组件都是由液压缸驱动，液压缸的流量是滑阀控制的。可作如下假设： 1.液压阀的开度与阀芯的位移成比例。 2.系统无液压油泄漏。 3.液压油流经液压管道时无压力损失。4.液压缸的顶部与杆的两侧同样都是有效区域。在这个问题上，对于每一臂杆组件，从液压缸的压力流量特性可得出以下方程：当 时；其中，Ai是液压缸的有效横截面积;hi是液压缸的长度;Xi是滑芯的位置；Psi是供给压力;P1i是液压缸的顶边压力；P2i是液压缸的杆边压力；Vi是在液压缸和管道的油量；Bi是滑阀的宽度；是油的密度；K是油分子的黏度；c是流量系数。2.3滑阀的反应特性 滑阀动作对液压挖掘机的控制特性产生会很大的影响。因而，假定滑阀相对参考输入有以下的一阶延迟。其中，是滑芯位移的参考输入；是时间常数。3 角度控制系统角基本上由随动参考输入角通过位置反馈来控制。为了获得更精确的控制，非线性补偿和状态反馈均加入位置反馈中。3.1 非线性补偿在普通的自动控制系统中，常使用如伺服阀这一类新的控制装置。在半自动控制系统中，为了实现自控与手控的协调，必须使用手动的主控阀。这一类阀中，阀芯的位移与阀的开度是非线性的关系。因此，自动控制操作中，利用这种关系，阀芯位移可由所要求的阀的开度反推出来。同时，非线性是可以补偿的。3.2 状态反馈建立在第2节所讨论的模型的基础上，若动臂角度控制动态特性以一定的标准位置逼近而线性化（滑芯位移X 10，液压缸压力差P 110，动臂夹角 10），则该闭环传递函数为其中，Kp是位置反馈增益系数； 由于系统有较小的系数a1,所以反应是不稳定的。例如，大型液压挖掘机SK-16中。X10是0，给出的系数a0=2.710,a1=6.010,a2=1.210.加上加速度反馈放大系数Ka，因而闭环的传递函数就是加入这个因素,系数S就变大，系统趋于稳定。可见，利用加速度反馈来提高反应特性效果明显。但是，一般很难精确的测出加速度。为了避免这个问题，改用液压缸力反馈取代加速度反馈。于是，液压缸力由测出的缸内的压力计算而滤掉其低频部分。这就是所谓的压力反馈。 4 半自动控制系统建立在模拟实验的基础上，半自动控制系统已制造出来，应用在SK-16型挖掘机上试验。通过现场试验可验证其操作性。这一节将讨论该控制系统的结构与功能。4.1 结构控制系统由控制器、传感器、人机接口和液压系统组成。控制器是采用16位的微处理器，能接收来自动臂、斗柄、铲斗传感器的角度输入信号，控制每一操作手柄的位置，选择相应的控制模式和计算其实际改变量，将来自放大器的信号以电信号形式输出结果。液压控制系统控制产生的液压力与电磁比例阀的电信号成比例，主控阀的滑芯的位置控制流入液压缸液压油的流量。为获得高速度、高精度控制，在控制器上采用数字处理芯片，传感器上使用高分辨率的磁编码器。除此之外，在每一液压缸上安装压力传感器以便获得压力反馈信号。以上处理后的数据都存在存储器上，可以从通信端口中读出。4.2 控制功能控制系统有三种控制模式，能根据操作杆和选择开关自动切换。其具体功能如下。（1）反铲水平动作模式：用水平反铲切换开关，在手控斗柄推动操作中，系统自动的控制斗柄以及保持斗柄底部的水平运动。在这种情况下，当斗柄操作杆开始操控时，其参考位置是从地面到斗柄底部的高度。对动臂操作杆的手控操作能暂时中断自动控制，因为手控操作的优先级高于自动控制。（2）铲斗水平举升模式：用铲斗水平举升切换开关，在手控动臂举升操作中，系统自动控制铲斗。保持铲斗角度等于其刚开始举升时角度以阻止原材料从铲斗中泄漏。（3）手控操作模式：当既没有选择反铲水平动作模式，也没有选择铲斗水平举升模式时，动臂，斗柄，铲斗都只能通过手动操作。系统主要采用C语言编程来实现这些功能，以构建稳定模组提高系统的运行稳定性。5 单个组件的自动控制测试对于动臂、斗柄、铲斗每一组件，以5的梯度从最初始值开始改变其参考角度值，测量其反应，从而确定第3节所