爬壁机器人 机器人外文翻译-爬壁机器人的发展

爬壁机器人的发展

摘要——很长时间以来，人们希望能够利用爬壁机器人来营救墙壁检测和灭火，在我们的实验室里已经研制了四种非常不同的机器人，第一种机器人有一个大的吸附器其利用了与气垫船相反的原理；第二种有两足行走，并且每足上有一小吸附器；第三种通过驱动器的挤力在不规则的垂直墙壁上移动，这是一种墙体驱动机器人；第四种可在必要的时候短距离跃入空中，这里将讨论这些机器人的机构和控制系统。

1、 介绍

很长时间来，人们期望机器人能够在垂直的墙壁上移动，它可用在高楼大厦里来营救墙壁检测和灭火，在过去的二十年里，我们实验室研制了四种完全不一样的爬壁机器。第一类有大的吸附器和爬行器作为移动机构，这种被称为大吸附器机器人。最近，在日本，已发展出很多种类的这一类型机器人用于检测墙壁。这里将讨论与在吸气和风扇转动间相适用的机构和空气动力学。

第二种类型是双足行走机器人，每足上有一小吸附器而被称为双足机器人，这里也将讨论其机构和控制系统，并给出一模拟研究，由于这里模型适用于几乎所有的不规则墙面，它比第一种应用范围更广。

通常而言，行走运动不是很快，因此行走机器人爬行到墙的高处将耗费很多时间，然而，又需要这样一种机器人，它能在短时间爬到建筑物的高处，为了紧急的目的，例如携带救援工具或者给建筑里灭火。第三种机器人旨在达到这些目的，它有驱动器，这些驱动器的垂直墙面的挤力减小微弱，这样能够利用轮与墙间的摩檫力并支撑机器人自身。这是一种墙体驱动机器人。有时候意外的强风会发生在高层建筑物的墙体上，在这种情况下，用来弥补风的力量的控制系统，对于避免让机器人从墙上掉下很重要，这种情况已经在[6，7]里简单的讨论过。

通常在建筑物的低处有很多障碍，比如树，屋檐，入口等等。在这些情况下，如果机器人能够飞跃这些障碍并到达上面的墙面将很管用，另外如果机器人意外地从高处的墙面上掉

落，制作一软着陆来避免危害自身或周围环境很有必要。这些目标可通过用能使其飞的机构和控制系统来完成。由于墙壁驱动机器人有足够的挤力来支撑其自身，它可改造成一种能够飞或着陆的新的机器人。这是第四种模型，其机构和控制系统将被讨论，并提出其操纵能力的模拟研究。

2、 大吸附器机器人

2．1 大吸附器模型的机构

很久以来，人们期望研制出能够在高层建筑的垂直或悬空的墙面，或者巨轮的侧面等上面移动的移动机器人。然后，这种机器人能用来代替人搬运营救工具或做其它工作。为了实现这种机器人，需要用来支撑机器人或使其在墙上向上移动的摩擦力。磁力或真空压力可产生指向墙面的固定力，轮子或履带都可用作在平且宽的垂直墙面上的移动机构。1966年研制出了一台大吸附器机器人（如图1所示），当用机器人在墙上移动时从吸附器的外围空隙中吸取了少量的空气。利在吸附器的外围安装一刷子和（或）弹性围罩来减弱空气流和保证吸附器内部足够的负压，它能在不规则的小墙面上移动。这个模型的机构和尺寸如图2所示：离心风扇由小引擎驱动，履带由直流电动机驱动。

图1 大吸附器机器人

2．2安全条件

在墙上的固定力是负压和吸附器面积乘积；

F=PA (1)

1引擎 ○2皮带轮 ○3驱动电机 ○4刷子和围罩 ○

5直流电机 ○6履带轮 ○7风扇 ○8燃料箱 ○

图 2 大吸附器模型的结构示意图

图 3 大吸附器机器人的滑动及脱落的安全区域

下面是避免滑动和掉下的条件：

μ

(2) F/W>1

F/W>h/R

(3)

这里W是机器人的净重，μ是摩擦系数，h为墙面到重心的距离，R为吸附器中心到最低支撑点的距离。

如果机器人在条件

h/R

(4)

下设计，掉下可以避免。这些关系如图3所示，每个曲线的上半区域为安全区域。

2．3 固定力与风扇性能的匹配

由于用来支撑机器人在垂直墙壁上的固定力与风扇性能直接相关，因此，它们之间的匹配非常重要，风扇性能（粗实线）和在有效误差δe下的匹配线（点杠线）如图4所示：横坐标代表空气流质量Q，纵坐标是负压P和固定力F，并且每条曲线的参数是临界速度n,常量引擎节流的工作曲线由通过点Z,Y,X的曲线表示，在粗糙水泥墙面上得到所需最小负压测量为P=35mm水柱。

由于模型的净重W=44kgf，摩擦系数μ=1.05确定，点W，V,U是各误差δe的所需最小必须压力。例如，如果风扇在点X以大误差δe=5.3mm工作，最小压力大约为15mm水柱，来自点X与U之间的中点，因此，这种模型在更小摩擦系数的墙面上移动是危险的。

图 3 大吸附器机器人的风扇性能图

误差的突变取决于由墙面的不规则所导致对应的空气质量流和之后负压的变化。风扇的旋转速度一直变化至引擎和风扇间的达到力矩平衡。这种关系如下：

IΩ=ηmTE-TF

这里I是引擎和风扇旋转部分的惯性矩，Ω为风扇的角速度，ηm为引擎和风扇之间的机械效率，TE为驱动力矩，TF为风扇所需的

矩。如果误差从δe=5.3突变至1.8mm，风扇工作曲线通过X-Z′-Z。另一方面，如果误差增加，通过Z-Y′-X′-X。因此，间隙的突然增加过程中，负压比终点X处要大，故在变化过程中可获得足够的力。

2．4 总体安全条件

总体安全条件归纳如下：

（a）脱落是致命的，因此应避免使用公式（4）的条件。

（b）在吸附器的外部减少空气泄漏 有用的。

（c） 由于间隙的突然增加，负压变化有一定的时间滞后，因此引擎应该短时间打开以使补偿吸附器里的足够压力。

3、两足行走机器人

3、1 行走机构

图 5 双足行走机器人的结构

现在地面上行走机器人有很多种类型的行走机构，例如两足定位，四足的，六足的等等。类似的，现在爬墙机器人也有很多种机构。

垂直轨道 斜轨道

图 6 行走运动

The inverse kinematics analysis of 3-D.O.F welding robot designed for ripple

polygonal line seam of container

Yu-Qiang Zhang-Hua Mao Zhi-wei Ye Jian-xiong

（Robot&Welding Automation Key Laboratory Jiang Xi Nanchang University, Nanchang, 330029） Abstract:To resolve the welding problem existing in ripple polygonal line seam of container,we develop a 3-D.O.F welding robot. An inverse kinematics analysis of the designed welding-robot based on D-H displacement transformation matrix was put forward in this paper. In order to make the welding gun fastend on the end effector keep a certain posture, the three joints of robot should act coordinately, thus this makes an assurerance for the consistency of welding quality. This paper presents the possibility that the robot can track the trajectory under a certain unchanged welding velocity by controlling the discipline of the three joints, and it is verified by means of simulation in MATLAB.

Key words:3-D.O.F; inverse kinematics; act coordinately ; welding posture

0．

Introduction.

Figure.1 Ripple polygonal line seam of container

When welding,the welding torch makes the relative motion along the weld seam line by a certain posture .The choice of the welding posture is the key to guarantee a good welding quality,and the welding torch position posture has an important influence to forming of the weld seam.At present,in the welding process of ripple polygonal line seam of container,the welding torch cannot adjust the angle between itself and the welding speed with the profile change.As is shown in the figure.1,the shaping of weld seam at linear section is not consistent with that at hypotenuse section.To resolve the welding problem existing in ripple polygonal line seam of container,this paper make an inverse kinematics analysis of the designed 3-D.O.F welding robot through developing the kinematics equation of the robot which lets the posture of the welding torch make a suitable adjustment with the profile change ,while making sure of the welding torch movement along the curve of weld seam with an constant speed ,thus improve the shaping of the weld seam and then make sure the welding equality.

1.The principle of the mechanism movement of 3-D.O.F welding robot

To resolve the welding problem existing in ripple polygonal line seam of container at present.We developed a kind of 3-D.O.F robot.

This robot have three movement joints: about translate between right and left the welding robot main body 1; about translate up and down the cross slide 2;the terminal effector 3 which making the rotary motion.We achieve that the welding speed does not change with the change of the posture of the terminal effector through the coordinated movement of the three joints.

2.The inverse kinematics analysis of 3-D.O.F welding robot.

2.1 The simplification of kinematics models

Figure. 2 The moving diagram of 3-D.O.F welding robot .

As shown in figure.2,the welding torch(which is presented by a dark point at the end of movement joint 3) is attached at the terminal effector 3 of the welding robot.In the process of welding,the position posture of the welding torch should make a suitable adjustment with the shape change of the weld seam.The adjustment presents as the coordinated movement.

2.2 The establishment of kinematics model

In order to portray the movements of each joint ,a decca rectangular coordinate system is established for the moving mechanism of the robot ,as shown in figure.1.The initial space position relations of the coordinate systems established on each rigid body .Those coordinate systems are presented in figure.3.{0} is the base coordinate system,{1},{2},{3} are the moving coordinate sysytems established on the robot main body ,on the cross slide and the terminal effector.we will analyze the moving law of the movement joint by using the movements of {1},{2},{3}.

We could portray the coordinate value of a point of {B} in {A} by using equal time coordinate

0transformation matrix BT.Establishing three equal time coordinate transformation matrix 1T、A

1

22T、3T.

1001T0001000l0S11001001，2T001Z010000cs0L1S22，3T010010sc00

t000L2 1001Where l0,L1,L2 represent the initial distances between each coordinate system separately;S1,S2 are the displacement of {1},{2} in certain time t-t0,and S1t

t0v1t, S2v2dt, V1,V2 are the t0

speed of the zero point of {1},{2} separately ;θis the rotated angle of the third movement joint ; ccos，ssin

00By transformation equation 3T1T21T32T,we have:

cs03T00sc000l0S10L1L2S2 1Z01

Then we could establish the transformation relation between the description of one point in {0} and that in {3}:

x0cys0p03p0=3T,that is =z001110sc000l0S10L1L2S21Z01x3y3………..(a) z31

Where: (x0,y0,z0),(x3,y3,z3) are the coordinate value of point p in {0} and {3} separately.

2.3 The inverse kinematics solutions

During the process of welding ,we should make sure of the vertical angle between the welding torch and the weld seam .Its movement has two restraints: a constant speed ; a determined weld seam curve.We take a cycle of the ripple for carrying on the reverse kinematics solution ,and analyze the driving laws which the three movement joints’ coordinated actions should follow so that satisfy the two restraints .In a cycle the welding torch needs to pass through four turning points .This article take the first turning point as an example to explain the process of the reverse solution .This process is divided into three stages ,namely linear section ,circular arc change-over section and hypoteneuse section .

As the moving path of the welding torch ,in free time t ,the coordinates of the point at the end of the welding torch are (x3,y3,z3,1)=(0,r,0,1) and {x0,y0,z0,1} respect to {3} and {0} separately . By expression (a), we have

x0cys0=z0010sc000l0S10L1L2S21Z010r……………………..(b) 01

According to the weld seam in reality ,we assume the third movement joint’s angle acceleration (t). as 

2.3.1 The movement of the point in linear section

We assume the start time of the movement as t0,the coordinates of the point at time t respect to {0} are x0=l0+vwt; y0L1L2r;z0Z,

Substituting equation (b) into it , and making differentiation with respect to time on S1,S2,we have the moving law of movement joints 1 and 2:

(t)cos(t)v1vw (t)sin(t)vr2

2.3.2 The movement of the point in circular arc change-over section

Figure.4 The graphical representation of the arc transition at the turning point.

Suppose the robot move to this stage at time t1, the point’s position relative to {0} is: x0l1,y0YL1L2r,the angle speed of {3} w=0.

When the robot is moving ,by spatial geometry relations,we have :

x0l1Rsin(t),y0YR[1cos(t)]

S1l1R*sin(t),the speed law of movement joints 1 and 2 are : S2R*[1cos(t)]

(t)cos(t)v1vxR(t)sin(t) vvRy2

The speed of the end of the welding torch along the direction which is parallel to the direction of the weld seam is constant,that is the welding speed is constant.

222(t)vw,(t)vw(tt), By the spatial geometry: vxvyvw,therefore 1RR

t1tt1".

(t)cos(t)vcos(t)v1vxRwThus  vvR(t)sin(t)vsin(t)yw2

2.3.3 The movement of the point in wave hypoteneuse section

Suppose the robot moving to this stage at time t1’,the coordinates of the point respect to {0} is x0y0z01="lvv(tt)cosww102wLLrv(tt")sin2w11Z1,after the reverse solution yields

(t)cos(t)v1vwcosr . v2vwsinr(t)sin(t)

According to the same method, we could get the coordinated movements law of the three

movement joints ,and satisfy the constraint conditions in a ripple cycle .And then we could make sure of the perpendicular relation between the welding torch and the weld seam at different section.

3. The simulation of the reverse kinematic analysis of the 3-D.O.F welding robot The calculation is based on the determined moving law of the third joint and make sure that it satisfy the two constraint conditions ,and reverse deduce the moving law of the two other joints {1},{2} .

To verify the process of reverse solution ,we carry on the simulation by the matlab software .we establish some spatial geometry size : l00,L1L20.1m,the rotating radius of the rotating joint r=0.1m , the angle between the linear section and hypoteneuse section at the turning point is /4.

In a welding cycle ,the change rule of the rotating arm’s angle acceleration is shown as figure.5

Figure.5 The angle acceleration change rule of joint 3

Thus we could obtain the change rule of the third joint’s rotating angle ,as shown in figure.6