工业机器人及电动驱动系统外文翻译.doc

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Industrial Robots and Electric drive system
There are a variety of definitions of the term robot. Depending on the definition used, the number of robot installations worldwide varies widely. Numerous single-purpose machines are used in manufacturing plants that might appear to be robots. These machines are hardwired to perform a single function and cannot be reprogrammed to perform a different function. Such single-purpose machines do not fit the definition for industrial robots that is becoming widely accepted. This definition was developed by the Robot Institute of America:
A robot is a reprogrammable multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks.
Note that this definition contains the words reprogrammable and multifunctional. It is these two characteristics that separate the true industrial robot from the various single-purpose machines used in modern manufacturing firms. The term “reprogrammable” implies two things: The robot operates accommodate a variety of manufacturing tasks.
The term “multifunctional” means that the robot can, through reprogramming and the use of different end-effectors, perform a number of different manufacturing tasks. Definitions written around these two critical characteristics are becoming the accepted definitions among manufacturing professionals.
The first articulated arm came about in 1951 and was used by the U.S. Atomic Energy Commission. In 1954, the first programmable robot was designed by George Devil. It was based on two important technologies:
Numerical control (NC) technology.
Remote manipulator technology.
Numerical control technology provided a form of machine control ideally suited to robots. It allowed for the control of motion by stored programs. These programs contain data points to which the robot sequentially moves, timing signals to initiate action and to stop movement, and logic statements to allow for decision making.
Remote manipulator technology allowed a machine to be more than just another NC machine. It allowed such machines to become robots that can perform a variety of manufacturing tasks in both inaccessible and unsafe environments. By merging these two technologies, Devil developed the first industrial robot, an unsophisticated programmable materials handling machine.
The first commercially produced robot was developed in 1959. In 1962, the first industrial robot to be used on a production line was installed by General Motors Corporation. This robot was produced by Animation. A major step forward in robot control occurred in 1973 with the development of the T-3 industrial robot by Cincinnati Milacron. The T-3 robot was the first commercially produced industrial robot controlled by a minicomputer.
Numerical control and remote manipulator technology prompted the wide-scale development and use of industrial roots. But major technological developments do not take place simply because of such new capabilities. Something must provide the impetus for taking advantage of these capabilities. In the case of industrial robots, the impetus was economics.
The rapid inflation of wages experienced in the 1970s tremendously increased the personnel costs of manufacturing firms. At the same time, foreign competition became a serious problem for U.S. manufacturers. Foreign manufacturers who had undertaken automation on a wide-scale basis, such as those in Japan, began to gain an increasingly large share of the U.S. and world market for manufactured goods, particularly automobiles.
Through a variety of automation techniques, including robots, Japanese manufacturers, beginning in the 1970s, were able to produce better automobiles more cheaply than no automated U.S. manufacturers. Consequently, in order to survive, U.S. manufacturers were forced to consider any technological developments that could help improve productivity.
Though a variety of automation techniques, including robots, Japanese manufacturers, beginning in the 1970s, were able to produce better automobiles more cheaply than no automated U.S. manufacturers. Consequently, in order to survive, U.S. manufacturers were forced to consider any technological developments that could help improve productivity.
It became imperative to produce better products at lower costs in order to be competitive with foreign manufacturers. Other factors such as the need to find better ways of performing dangerous manufacturing tasks contributed to the development of industrial robots. However, the principal rationale has always been, and is still, improved productivity.
One of the principal advantages of robots is that they can be used in settings that are dangerous to humans. Welding and parting are examples of applications where robots can be used more safely than humans, Even though robots are closely associated with safety in the workplace, they can, in themselves, be dangerous.
Robots and robot cells must be carefully designed and configured so that they do not endanger human workers and other machines. Robot work envelopes should be accurately calculated and a danger zone surrounding the envelope clearly marked off. Red flooring strips and barriers can be used to keep human workers out of a robot’s work envelope.
Even with such precautions it is still a good idea to have an automatic shutdown system in situations where robots are used. Such a system should have the capacity to sense the need for an automatic shutdown of operations. Fault-tolerant computers and redundant systems can be installed to ensure proper shutdown of robotics systems to ensure a safe environment.
The robot electrically operated servo drive system sds is uses the moment of force and the strength which each kind of electric motor produces, directly or indirectly actuates the robot main body to obtain the robot each kind of movement implementing agency. The electric motor actuates which to the industry robot joint, the request has the maximum work rate quality compared to with the torque inertia compared to, rises up the dynamic torque, the is low inertia and broader also the smooth velocity modulation scope. Specially (hand fingernail) should use the volume, the quality as far as possible small electric motor like the robot terminal execution, when in particular requests the fast response, the servo motor must have a higher reliability and the stability, and has the bigger momentary overload ability. This is the servo motor in the industry robot the application precondition.
The robot actuates the electrical machinery to the joint overriding demand the gauge natrium as follows:
1) rapidity. The electric motor from obtains the command signal to complete the active status time which the instruction requests to be supposed to be short. Response command signal time shorter, the electricity servosystem sensitivity higher, the fast response performance is better, generally is explains the servo motor fast response by the servo motor mechanical and electrical time-constant size the performance.
2) the starting moment inertia is bigger than. In in the actuation load situation, requests the robot the servo motor starting moment in a big way, the rotation inertia is small.
3) the control characteristic continuity and the straight line, along with the control signal change, the electric motor rotational speed can continuously change, sometimes also needs the rotational speed and the control signal has the direct ratio or approximately has the direct ratio.
4) modulates velocity the scope to be wide. Can use to 1: 1,000 ~ 10,000 velocity modulation scopes.
5)the volume small, the quality small, the axial size is short.
6) can undergo the harsh movement condition, may carry on the extremely frequent pro and con to and adds and subtracts the fast movement, and can withstand the overload in the short time.
Industry robot direct motor drive principle like chart 1 shows. The industry robot electrically operated servosystem general structure is three closed-loops control, namely electric current link, speed ring and snap ring.
At present the overseas many electric motors produce the factory to develop the actuation product which suitably matches with the exchange servo motor, the user act according to oneself need the function stress to choose the different servo-control way differently, in the ordinary circumstances, exchanges the servo driver below, passable has carried on the artificial hypothesis to its internal function parameter to realize the function:
1) position control way;
2) speed control way;
3) torque control mode;
4) position, speed mixed mode;
5) position, torque mixed mode;
6)speed, torque mixed mode;
7) torque limitation;
8) the position deviation oversized reports to the police;
9) speed PID parameter establishment;
10) speed and acceleration forward feed parameter establishment;
11) zero floats compensates the parameter establishment;
12) adds and subtracts the fast time establishment and so on
1. direct current servo motor driver direct current servo motor driver to use the pulse-duration modulation (PWM) the servo driver, changes through the change pulse width adds in the motor armature beginnings and ends average voltage, thus changes the electric motor the rotational speed. The PWM servo driver has the velocity modulation scope width, the low-speed characteristic well, responds, the efficiency quickly high, the overload capacity is strong and so on the characteristic, often takes the direct current servo motor driver in the industry robot.
2. synchronized types exchange servo motor driver same direct current servo motor actuates the system to compare, the synchronized type exchange servo motor driver has the torque rotation inertia electronics brush and commutation spark merit and so on to be higher than, not to have, obtains the widespread application in the industry robot. The synchronized type exchange servo motor driver usually uses the electricity flow pattern pulse-duration modulation (PWM) the inversion and has the electric current link for the inner rim, the speed ring for the outer ring multi- closed-loop control system, realizes to the three-phase permanent magnetism synchronization servo motor electric current control. According to its principle of work, the actuation current waveform and the control mode difference, it may divide into two kind of servosystems:
1) rectangular wave electric current actuation permanent magnetism A.C. servomechanism.
2) sinusoidal current actuation permanent magnetism A.C. servomechanism. Uses the rectangular wave electric current actuation the permanent magnetism exchange servo motor to be called not brushes the direct current servo motor, uses he sinusoidal current actuation the permanent magnetism exchange servo motor to be called not brushes the exchange servo motor.
3. direct drives so-called direct drives (DD) the system, is the load conductive coupling which the electric motor if actuates in the same place, middle does not have any reduction gear. The same traditional electric motor servo actuates to compare, the DD actuation reduced the reduction gear, thus reduced the gap which in the system transmission process the reduction gear produces and becomes less crowded, enormously increased the robot precision, simultaneously also reduced because the reduction gear friction and the transmission torque pulsation creates the robot control precision reduces. But DD actuation because has above merit, therefore mechanical rigidity good, may the high speed high accuracy movement, also has the part few, the structure simple, is easy to service, the reliable higher characteristic, in the high accuracy, in the high speed industry robot application more and more brings to people's attention. As the DD actuation technology essential link is the DD electric motor and its the driver. Below it should have the characteristic:
1) outputs the torque in a big way: For tradition drive type in servo motor output torque 50 ~ 100 times.
2) torque pulsation small: The DD electric motor torque pulsation may suppress

为了与国外制造厂家进行竞争，必须以比较低的成本，生产出更好的产品。其他的因素，诸如寻找能够更好地完成带有危险性的制造工作的方式也促进了工业机器人的发展。但是，主要的理由一直是，而且现在仍然是提高生产率。
机器人的一个主要优点是它们可以在对于人类来说是危险的位置上工作。采用机器人进行焊接和切断工作上比由人工来完成这些工作更安全的例子。尽管机器人与工作地点的安全密切相关，它们本身也可能是危险的。
应该仔细地设计和配置机器人和机器人单元，使它们不会伤害人类和其他机器。应该精确地计算出机器人的工作范围，并且在这个范围的四周清楚地标出危险区域。可以采用在地面上画出红颜色的线和设置障碍物以阻止工人进入机器人的工作范围。
即使有了这些预防措施，在使用机器人的场地中设置一个自动停止工作的系统仍然上不失为一个好主意。机器人的这个系统应该具有能够检测出是否有需要自动停止工作的要求的能力。为了保证能有一个安全的环境，应当安装容错计算机和冗余系统来保证在适当的时候停止机器人的工作。
机器人电动伺服驱动系统是利用各种电动机产生的力矩和力，直接或间接地驱动机器人本体以获得机器人的各种运动的执行机构。
对工业机器人关节驱动的电动机，要求有最大功率质量比和扭矩惯量比、高起动转矩、低惯量和较宽广且平滑的调速范围。特别是像机器人末端执行器（手爪）应采用体积、质量尽可能小的电动机，尤其是要求快速响应时，伺服电动机必须具有较高的可靠性和稳定性，并且具有较大的短时过载能力。这是伺服电动机在工业机器人中应用的先决条件。
机器人对关节驱动电机的主要要求规纳如下：
1）快速性。电动机从获得指令信号到完成指令所要求的工作状态的时间应短。响应指令信号的时间愈短，电伺服系统的灵敏性愈高，快速响应性能愈好，一般是以伺服电动机的机电时间常数的大小来说明伺服电动机快速响应的性能。
2）起动转矩惯量比大。在驱动负载的情况下，要求机器人的伺服电动机的起动转矩大，转动惯量小。
3）控制特性的连续性和直线性，随着控制信号的变化，电动机的转速能连续变化，有时还需转速与控制信号成正比或近似成正比。
4）调速范围宽。能使用于1：1000～10000的调速范围。
5）体积小、质量小、轴向尺寸短。
6）能经受得起苛刻的运行条件，可进行十分频繁的正反向和加减速运行，并能在短时间内承受过载。
工业机器人电动伺服系统的一般结构为三个闭环控制，即电流环、速度环和位置环。
目前国外许多电动机生产厂家均开发出与交流伺服电动机相适配的驱动产品，用户根据自己所需功能侧重不同而选择不同的伺服控制方式，一般情况下，交流伺服驱动器，可通过对其内部功能参数进行人工设定而实现以下功能：
1）位置控制方式
2）速度控制方式；
3）转矩控制方式；
4）位置、速度混合方式；
5）位置、转矩混合方式；
6）速度、转矩混合方式；
7）转矩限制；
8）位置偏差过大报警；
9）速度PID参数设置；
10）速度及加速度前馈参数设置；
11）零漂补偿参数设置；
12）加减速时间设置等
1．直流伺服电动机驱动器
直流伺服电动机驱动器多采用脉宽调制（PWM）伺服驱动器，通过改变脉冲宽度来改变加在电动机电枢两端的平均电压，从而改变电动机的转速。
PWM伺服驱动器具有调速范围宽、低速特性好、响应快、效率高、过载能力强等特点，在工业机器人中常作为直流伺服电动机驱动器。
2．同步式交流伺服电动机驱动器
伺服电动机驱动系统相比，同步式交流伺服电动机驱动器具有转矩转动惯量比高、无电刷及换向火花等优点，在工业机器人中得到广泛应用。
同步式交流伺服电动机驱动器通常采用电流型脉宽调制（PWM）相逆变器和具有电流环为内环、速度环为外环的多闭环控制系统，以实现对三相永磁同步伺服电动机的电流控制。根据其工作原理、驱动电流波形和控制方式的不同，它又可分为两种伺服系统：
1）矩形波电流驱动的永磁交流伺服系统。
2）正弦波电流驱动的永磁交流伺服系统。
矩形波电流驱动的永磁交流伺服电动机称为无刷直流伺服电动机，采用正弦波电流驱动的永磁交流伺服电动机称为无刷交流伺服电动机。
3．直接驱动
驱动（DD）系统，就是电动机与其所驱动的负载直接耦合在一起，中间不存在任何减速机构。
同传统的电动机伺服驱动相比， DD驱动减少了减速机构，从而减少了系统传动过程中减速机构所产生的间隙和松动，极大地提高了机器人的精度，同时也减少了由于减速机构的摩擦及传送转矩脉动所造成的机器人控制精度降低。而DD驱动由于具有上述优点，所以机械刚性好，可以高速高精度动作，且具有部件少、结构简单、容易维修、可靠性高等特点，在高精度、高速工业机器人应用中越来越引起人们的重视。
作为DD驱动技术的关键环节是DD电动机及其驱动器。它应具有以下特性：
1）输出转矩大：为传统驱动方式中伺服电动机输出转矩的50～100倍。
2）转矩脉动小： DD电动机的转矩脉动可抑制在输出转矩的5％～10％以内。
3）效率：与采用合理阻抗匹配的电动机（传统驱动方式下）相比， DD电动机是在功率转换较差的使用条件下工作的。因此，负载越大，越倾向于选用较大的电动机。
目前，DD电动机主要分为变磁阻型和变磁阻混合型，有以下两种结构型式：
l）双定子结构变磁阻型DD电动机；
2）中央定子型结构的变磁阻混合型DD电动机。
5．特种驱动器
1）压电驱动器。众所周知，利用压电元件的电或电致伸缩现象已制造出应变式加速度传感器和超声波传感器，压电驱动器利用电场能把几微米到几百微米的位移控制在高于微米级大的力，所以压电驱动器一般用于特殊用途的微型机器人系统中。
2）超声波电动机。
3）真空电动机，用于超洁净环境下工作的真空机器人，例如用于搬运半导体硅片的超真空机器人等。