The Effect of a Viscous Coupling Used as a Front-Wheel Drive Limited-Slip Differential on Vehicle Traction and Handling
1 ABCTRACT
The viscous coupling is known mainly as a driveline component in four wheel drive vehicles. Developments in recent years, however, point toward the probability that this device will become a major player in mainstream front-wheel drive application. Production application in European and Japanese front-wheel drive cars have demonstrated that viscous couplings provide substantial improvements not only in traction on slippery surfaces but also in handing and stability even under normal driving conditions.
This paper presents a serious of proving ground tests which investigate the effects of a viscous coupling in a front-wheel drive vehicle on traction and handing. Testing demonstrates substantial traction improvements while only slightly influencing steering torque. Factors affecting this steering torque in front-wheel drive vehicles during straight line driving are described. Key vehicle design parameters are identified which greatly influence the compatibility of limited-slip differentials in front-wheel drive vehicles.
Cornering tests show the influence of the viscous coupling on the self steering behavior of a front-wheel drive vehicle. Further testing demonstrates that a vehicle with a viscous limited-slip differential exhibits an improved stability under acceleration and throttle-off maneuvers during cornering.
2 THE VISCOUS COUPLING
The viscous coupling is a well known component in drivetrains. In this paper only a short summary of its basic function and principle shall be given.
The viscous coupling operates according to the principle of fluid friction, and is thus dependent on speed difference. As shown in Figure 1 the viscous coupling has slip controlling properties in contrast to torque sensing systems.
This means that the drive torque which is transmitted to the front wheels is automatically controlled in the sense of an optimized torque distribution.
In a front-wheel drive vehicle the viscous coupling can be installed inside the differential or externally on an intermediate shaft. The external solution is shown in Figure 2.
This layout has some significant advantages over the internal solution. First,
there is usually enough space available in the area of the intermediate shaft to provide the required viscous characteristic. This is in contrast to the limited space left in today’s front-axle differentials. Further, only minimal modification to the differential carrier and transmission case is required. In-house production of differentials is thus only slightly affected. Introduction as an option can be made easily especially when the shaft and the viscous unit is supplied as a complete unit. Finally, the intermediate shaft makes it possible to provide for sideshafts of equal length with transversely installed engines which is important to reduce torque steer (shown later in section 4).
This special design also gives a good possibility for significant weight and cost reductions of the viscous unit. GKN Viscodrive is developing a low weight and cost viscous coupling. By using only two standardized outer diameters, standardized plates, plastic hubs and extruded material for the housing which can easily be cut to different lengths, it is possible to utilize a wide range of viscous characteristics. An example of this development is shown in Figure 3.
3 TRACTION EFFECTS
As a torque balancing device, an open differential provides equal tractive effort to both driving wheels. It allows each wheel to rotate at different speeds during cornering without torsional wind-up. These characteristics, however, can be disadvantageous when adhesion variations between the left and right sides of the road surface (split-μ) limits the torque transmitted for both wheels to that which can be supported by the low-μwheel.
With a viscous limited-slip differential, it is possible to utilize the higher adhesion potential of the wheel on the high-μsurface. This is schematically shown in Figure 4.
When for example, the maximum transmittable torque for one wheel is exceeded on a split-μsurface or during cornering with high lateral acceleration, a speed difference between the two driving wheels occurs. The resulting self-locking torque in the viscous coupling resists any further increase in speed difference and transmits the appropriate torque to the wheel with the better traction potential.
It can be seen in Figure 4 that the difference in the tractive forces results in a yawing moment which tries to turn the vehicle in to the low-μside, To keep the vehicle in a straight line the driver has to compensate this with opposite steering input. Though the fluid-friction principle of the viscous coupling and the resulting soft
transition from open to locking action, this is easily possible, The appropriate results obtained from vehicle tests are shown in Figure 5.
Reported are the average steering-wheel torque Ts and the average corrective opposite steering input required to maintain a straight course during acceleration on a split-μtrack with an open and a viscous differential. The differences between the values with the open differential and those with the viscous coupling are relatively large in comparison to each other. However, they are small in absolute terms. Subjectively, the steering influence is nearly unnoticeable. The torque steer is also influenced by several kinematic parameters which will be explained in the next section of this paper.
4 FACTORS AFFECTING STEERING TORQUE
As shown in Figure 6 the tractive forces lead to an increase in the toe-in response per wheel. For differing tractive forces, Which appear when accelerating on split-μwith limited-slip differentials, the toe-in response changes per wheel are also different.
Unfortunately, this effect leads to an undesirable turn-in response to the low-μside, i.e. the same yaw direction as caused by the difference in the tractive forces.
Reduced toe-in elasticity is thus an essential requirement for the successful front-axle application of a viscous limited-slip differential as well as any other type of limited-slip differential.
Generally the following equations apply to the driving forces on a wheel
μV T F F =
With =T F Tractive Force
=V F Vertical Wheel Load
=μUtilized Adhesion Coefficient
These driving forces result in steering torque at each wheel via the wheel disturbance level arm “e ” and a steering torque difference between the wheels given by the equation:
△e T =()lo H hi H F F e ---??δcos
Where △=e T Steering Torque Difference
e=Wheel Disturbance Level Arm
=δKing Pin Angle
hi=high-μside subscript
lo=low-μside subscript
In the case of front-wheel drive vehicles with open differentials, △Ts is almost unnoticeable, since the torque bias (lo H hi T F F --/) is no more than 1.35.
For applications with limited-slip differentials, however, the influence is significant. Thus the wheel disturbance lever arm e should be as small as possible. Differing wheel loads also lead to an increase in △Te so the difference should also be as small as possible.
When torque is transmitted by an articulated CV-Joint, on the drive side (subscript 1) and the driven side (subscript 2),differing secondary moments are produced that must have a reaction in a vertical plane relative to the plane of articulation. The magnitude and direction of the secondary moments (M) are calculated as follows (see Figure 8):
Drive side M1 =v v T T ββηtan /)2/tan(2-?
Driven side M2 =v v T T ββηtan /)2/tan(2+?
With T2 =dyn T r F ?
ηT =()system Jo T f int ,,2β
Where v β∧
=Vertical Articulation Angle
β∧=Resulting Articulation Angle
d y n r ∧=Dynamic Wheel Radius
ηT ∧=Average Torque Loss
The component δcos 2?M acts around the king-pin axis (see figure 7) as a steering torque per wheel and as a steering torque difference between the wheels as follows: ])tan /2/tan ()sin /2/tan [(cos 22li w hi w T T T T T ----+±=?νηννηνβββββδ where ∧
=?βT Steering Torque Difference
W ∧=Wheel side subscript
It is therefore apparent that not only differing driving torque but also differing
articulations caused by various driveshaft lengths are also a factor. Referring to the moment-polygon in Figure 7, the rotational direction of M2 or βT respectively change, depending on the position of the wheel-center to the gearbox output.
For the normal position of the halfshaft shown in Figure 7(wheel-center below the gearbox output joint) the secondary moments work in the same rotational direction as the driving forces. For a modified suspension layout (wheel-center above gearbox output joint, i.e. v βnegative) the secondary moments counteract the moments caused by the driving forces. Thus for good compatibility of the front axle with a limited-slip differential, the design requires: 1) vertical bending angles which are centered around 0=v βor negative (0 The influence of the secondary moments on the steering is not only limited to the direct reactions described above. Indirect reactions from the connection shaft between the wheel-side and the gearbox-side joint can also arise, as shown below: Figure 9: Indirect Reactions Generated by Halfshaft Articulation in the Vertical Plane For transmission of torque without loss and vd vw ββ= both of the secondary moments acting on the connection shaft compensate each other. In reality (with torque loss), however, a secondary moment difference appears: △W D DW M M M 12-= With - +=ηT T T W D 22 The secondary moment difference is: =D W M ()VW W VW W VD VD W T T D T w T T ββββηηηtan /2/tan sin /tan 22/2+-++ For reasons of simplification it apply that V VW VD βββ==and ηηηT T T W D == to give △()V V V D W T M βββηtan /1sin /12/tan ++?= △DW M requires opposing reaction forces on both joints where L M F D W D W /?=. Due to the joint disturbance lever arm f, a further steering torque also acts around the king-pin axis: L f M T D W f /cos δ???= ()lo lo D W hi hi D W f L M L M f T //cos ---??=? Where ∧=f T Steering Torque per Wheel ∧ =?f T Steering Torque Difference ∧=f Joint Disturbance Lever ∧=L Connection shaft (halfshaft) Length For small values of f, which should be ideally zero, f T ? is of minor influence. 5．EFFECT ON CORNERING Viscous couplings also provide a self-locking torque when cornering, due to speed differences between the driving wheels. During steady state cornering, as shown in figure 10, the slower inside wheel tends to be additionally driven through the viscous coupling by the outside wheel. Figure 10: Tractive forces for a front-wheel drive vehicle during steady state cornering The difference between the Tractive forces Dfr and Dfl results in a yaw moment MCOG , which has to be compensated by a higher lateral force, and hence a larger slip angle af at the front axle. Thus the influence of a viscous coupling in a front-wheel drive vehicle on self-steering tends towards an understeering characteristic. This behavior is totally consistent with the handling bias of modern vehicles which all under steer during steady state cornering maneuvers. Appropriate test results are shown in figure 11. Figure 11: comparison between vehicles fitted with an open differential and viscous coupling during steady state cornering. The asymmetric distribution of the tractive forces during cornering as shown in figure 10 improves also the straight-line running. Every deviation from the straight-line position causes the wheels to roll on slightly different radii. The difference between the driving forces and the resulting yaw moment tries to restore the vehicle to straight-line running again (see figure 10). Although these directional deviations result in only small differences in wheel travel radii, the rotational differences especially at high speeds are large enough for a viscous coupling front differential to bring improvements in straight-line running. High powered front-wheel drive vehicles fitted with open differentials often spin their inside wheels when accelerating out of tight corners in low gear. In vehicles fitted with limited-slip viscous differentials, this spinning is limited and the torque generated by the speed difference between the wheels provides additional tractive effort for the outside driving wheel. this is shown in figure 12 Figure 12: tractive forces for a front-wheel drive vehicle with viscous limited-slip differential during acceleration in a bend The acceleration capacity is thus improved, particularly when turning or accelerating out of a T-junction maneuver ( i.e. accelerating from a stopped position at a “T” intersection-right or left turn ). Figures 13 and 14 show the results of acceleration tests during steady state cornering with an open differential and with viscous limited-slip differential . Figure 13: acceleration characteristics for a front-wheel drive vehicle with an open differential on wet asphalt at a radius of 40m (fixed steering wheel angle throughout test). Figure 14: Acceleration Characteristics for a Front-Wheel Drive Vehicle with Viscous Coupling on Wet Asphalt at a Radius of 40m (Fixed steering wheel angle throughout test) The vehicle with an open differential achieves an average acceleration of 2.0 2 /s m while the m(limited by /s vehicle with the viscous coupling reaches an average of 2.3 2 engine-power). In these tests, the maximum speed difference, caused by spinning of the inside driven wheel was reduced from 240 rpm with open differential to 100 rpm with the viscous coupling. During acceleration in a bend, front-wheel drive vehicles in general tend to understeer more than when running at a steady speed. The reason for this is the reduction of the potential to transmit lateral forces at the front-tires due to weight transfer to the rear wheels and increased longitudinal forces at the driving wheels. In an open loop control-circle-test this can be seen in the drop of the yawing speed (yaw rate) after starting to accelerate (Time 0 in Figure 13 and 14). It can also be taken from Figure 13 and Figure 14 that the yaw rate of the vehicle with the open differential falls-off more rapidly than for the vehicle with the viscous coupling starting to accelerate. Approximately 2 seconds after starting to accelerate, however, the yaw rate fall-off gradient of the viscous-coupled vehicle increases more than at the vehicle with open differential. The vehicle with the limited slip front differential thus has a more stable initial reaction under accelerating during cornering than the vehicle with the open differential, reducing its understeer. This is due to the higher slip at the inside driving wheel causing an increase in driving force through the viscous coupling to the outside wheel, which is illustrated in Figure 12. the imbalance in the front wheel tractive forces results in a yaw moment M acting in direction of the turn, countering the CSD understeer. When the adhesion limits of the driving wheels are exceed, the vehicle with the viscous coupling understeers more noticeably than the vehicle with the open differential (here, 2 seconds after starting to accelerate). On very low friction surfaces, such as snow or ice, stronger understeer is to be expected when accelerating in a curve with a limited slip differential because the driving wheels-connected through the viscous coupling-can be made to spin more easily (power-under-steering). This characteristic can, however, be easily controlied by the driver or by an automatic throttle modulating traction control system. Under these conditions a much easier to control than a rear-wheel drive car. Which can exhibit power-oversteering when accelerating during cornering. All things, considered, the advantage through the stabilized acceleration behavior of a viscous coupling equipped vehicle during acceleration the small disadvantage on slippery surfaces. Throttle-off reactions during cornering, caused by releasing the accelerator suddenly, usually result in a front-wheel drive vehicle turning into the turn (throttle-off oversteering ). High-powered modeles which can reach high lateral accelerations show the heaviest reactions. This throttle-off reaction has several causes such as kinematic influence, or as the vehicle attempting to travel on a smaller cornering radius with reducing speed. The essential reason, however, is the dynamic weight transfer from the rear to the front axle, which results in reduced slip-angles on the front and increased slip-angles on the rear wheels. Because the rear wheels are not transmitting driving torque, the influence on the rear axle in this case is greater than that of the front axle. The driving forces on the front wheels before throttle-off (see Figure 10) become over running or braking forces afterwards, which is illustrated for the viscous equipped vehicle in Figure 15. Figure 15:Baraking Forces for a Front-Wheel Drive Vehicle with Viscous Limited-Slip Differential Immediately after a Throttle-off Maneuver While Cornering As the inner wheel continued to turn more slowly than the outer wheel, the viscous coupling provides the outer wheel with the larger braking force f B . The force difference between the front-wheels applied around the center of gravity of the vehicle causes a yaw moment G C M 0 that counteracts the normal turn-in reaction. When cornering behavior during a throttle-off maneuver is compared for vehicles with open differentials and viscous couplings, as shown in Figure 16 and 17, the speed difference between the two driving wheels is reduced with a viscous differential. Figure 16: Throttle-off Characteristics for a Front-Wheel Drive Vehicle with an open Differential on Wet Asphalt at a Radius of 40m (Open Loop) Figure 17:Throttle-off Characteristics for a Front-Wheel Drive Vehicle with Viscous Coupling on Wet Asphalt at a Radius of 40m (Open Loop) The yawing speed (yaw rate), and the relative yawing angle (in addition to the yaw angle which the vehicle would have maintained in case of continued steady state cornering) show a pronounced increase after throttle-off (Time=0 seconds in Figure 14 and 15) with the open differential. Both the sudden increase of the yaw rate after throttle-off and also the increase of the relative yaw angle are significantly reduced in the vehicle equipped with a viscous limited-slip differential. A normal driver os a front-wheel drive vehicle is usually only accustomed to neutral and understeering vehicle handing behavior, the driver can then be surprised by sudden and forceful oversteering reaction after an abrupt release of the throttle, for example in a bend with decreasing radius. This vehicle reaction is further worsened if the driver over-corrects for the situation. Accidents where cars leave the road to the inner side of the curve is proof of this occurrence. Hence the viscous coupling improves the throttle-off behavior while remaining controllable, predictable, and safer for an average driver. 6. EFFECT ON BRAKING The viscous coupling in a front-wheel drive vehicle without ABS (anti-lock braking system) has only a very small influence on the braking behavior on split-μ surfaces. Hence the front-wheels are connected partially via the front-wheel on the low-μ side is slightly higher than in an vehicle with an open differential. On the other side ,the brake pressure to lock the front-wheel on the high-μ side is slightly lower. These differences can be measured in an instrumented test vehicle but are hardly noticeable in a subjective assessment. The locking sequence of front and rear axle is not influenced by the viscous coupling. Most ABS offered today have individual control of each front wheel. Electronic ABS in front-wheel drive vehicles must allow for the considerable differences in effective wheel inertia between braking with the clutch engaged and disengaged. Partial coupling of the front wheels through the viscous unit does not therefore compromise the action of the ABS - a fact that has been confirmed by numerous tests and by several independent car manufacturers. The one theoretical exception to this occurs on a split-μ—surface if a yaw moment build-up delay or Yaw Moment Reduction(YMR) is included in the ABS control unit. Figure 18 shows typical brake pressure sequences, with and without YMR. figure 18: brake pressure build-up characteristics for the front brakes of a vehicle braking on split-μwith ABS. In vehicles with low yaw inertia and a short wheelbase, the yaw moment build-up can be delayed to allow an average driver enough reaction time by slowing the brake pressure build-up over the ABS for the high-μwheel. The wheel on the surface with the higher friction coefficient is therefore, particularly at the beginning of braking, under-braked and runs with less slip. The low-μwheel, in contrast, can at the same time have a very high slip, which results in a speed difference across the viscous differential. The resulting self-locking torque then appears as an extra braking force at the high-μwheel which counteracts the YMR. Although this might be considered as a negative effect and can easily be corrected when setting the YMR algorithm for a vehicle with a front viscous coupling, vehicle tests have proved that the influence is so slight that no special development of new ABS/YMR algorithms are actually needed. Some typical averaged test results are summarized in Figure 19. figure 19 : results form ABS braking tests with YMR on split-μ(V o=50 mph, 3rd Gear, closed loop ) in figure 19 on the left a comparison of the maximum speed difference which occurred in the first ABS control cycle during braking is shown. It is obvious that the viscous coupling is reducing this speed difference. As the viscous coupling counteracts the YMR, the required steering wheel angle to keep the vehicle in straight direction in the first second of braking increased from 39°to 51° (figure 19,middle). Since most vehicle and ABS manufacturers consider 90°to be the critical limit, this can be tolerated. Finally, as the self-locking torque produced by the viscous coupling causes an increase in high-μ. Wheel braking force, a slightly higher vehicle deceleration was maintained(figure 19,right). 7 SUMMARY in conclusion,it can be established that the application of a viscous coupling in a front-axle differential. It also positively influences the complete vehicle handling and stability , with only slight, but acceptable influence on torques-steer. To reduce unwanted torque-steer effects a basic set of design rules have been established: ●Toe-in response due to longitudinal load change must be as small as possible . ●Distance between king-pin axis and wheel center has to be as small as possible. ●Vertical bending angle-rang should be centered around zero(or negative). ●vertical bending angles should be the same for both sides. ●Sideshafts should be of equal length. Of minor influence on torque-steer is the joint disturbance lever arm which should be ideally zero for other reasons anyway. Braking with and without ABS is only negligibly influenced by the viscous coupling. Traction is significantly improved by the viscous limited slip differential in a front-wheel drive vehicle. The self-steering behavior of a front-wheel drive vehicle is slightly influenced by a viscous limited slip differential in the direction of understeer. The improved reactions to throttle-off and acceleration during cornering make a vehicle with viscous coupling in the front-axle considerably more stable, more predictable and therefore safer. (文档含英文原文和中文翻译) 中英文对照翻译 机械设计 摘要： 机器由机械和其他元件组成的用来转换和传输能量的装置。比如：发动机、涡轮机、车、起重机、印刷机、洗衣机和摄影机。许多机械方面设计的原则和方法也同样适用于非机械方面。术语中的“构造设计”的含义比“机 械设计”更加广泛，构造设计包括机械设计。在进行运动分析和结构设计时要把产品的维护和外形也考虑在机械设计中。在机械工程领域中，以及其它工程领域，都需要机械设备，比如：开关、凸轮、阀门、船舶以及搅拌机等。关键词：设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实用性，现有的机器需要在耐用性、效率、重量、速度，或者成本上得到改善。新的机器必需能够完全或部分代替以前人的功能，比如计算、装配、维修。 在设计的初级阶段，应该充分发挥设计人员的创意，不要受到任何约束。即使有一些不切实际的想法，也可以在设计的早期，即在绘制图纸之前被改正掉。只有这样，才不致于阻断创新的思路。通常,必须提出几套设计方案,然后进行比较。很有可能在这个计划最后指定使用某些不在计划方案内的一些想法的计划。 一般当产品的外型和组件的尺寸特点已经显现出来的时候，就可以进行全面的设计和分析。接着还要客观的分析机器性能、安全、重量、耐用性，并且成本也要考虑在内。每一个至关重要的部分要优化它的比例和尺寸，同时也要保持与其它组成部分的平衡。 选择原材料和工艺的方法。通过力学原理来分析和实现这些重要的特性，如稳定和反应的能量和摩擦力的利用，动力惯性、加速度、能量；包括材料的弹性强度、应力和刚度等物理特性，以及流体的润滑和驱动器的流体力学。设计的过程是一个反复与合作的过程，无论是正式的还是非正式的，对设计者来说每个阶段都很重要。。产品设计需要大量的研究和提升。许多的想法,必须通过努力去研究成为一种理念,然后去使用或放弃。虽然每个工 英文原文出自《Advanced Technology Libraries》2008年第5期 Robot Robot is a type of mechantronics equipment which synthesizes the last research achievement of engine and precision engine, micro-electronics and computer, automation control and drive, sensor and message dispose and artificial intelligence and so on. 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Programmable Logic Controller PLC-controlled robot control system for materials up and down movement is simple, circuit design is reasonable, with a strong anti-jamming capability, ensuring the system's reliability, reduced maintenance rate, and improve work efficiency. Robot technology related to mechanics, mechanics, electrical hydraulic technology, automatic control technology, sensor technology and computer technology and other fields of science, is a cross-disciplinary integrated technology. Current industrial approaches to robot arm control treat each joint of the robot arm as a simple joint servomechanism. The servomechanism approach models the varying dynamics of a manipulator inadequately because it neglects the motion and configuration of the whole arm mechanism. These changes in the parameters of the controlled system sometimes are significant enough to render conventional feedback control strategies ineffective. The result is reduced servo response speed and damping, limiting the precision and speed of the end-effecter and making it appropriate only for limited-precision tasks. Manipulators controlled in this manner move at slow speeds with unnecessary vibrations. Any significant performance gain in this and other areas of robot arm control require the consideration of more efficient dynamic models, sophisticated control approaches, and the use of dedicated computer architectures and parallel processing techniques. Manipulator institutional form is simple, strong professionalism, only as a loading device for a machine tools, special-purpose manipulator is attached to this machine. 密级 分类号 编号 成绩 本科生毕业设计 (论文) 外文翻译 原文标题Simple Manipulator And The Control Of It 译文标题简易机械手及控制 作者所在系别机械工程系 作者所在专业xxxxx 作者所在班级xxxxxxxx 作者姓名xxxx 作者学号xxxxxx 指导教师姓名xxxxxx 指导教师职称副教授 完成时间2012 年02 月 北华航天工业学院教务处制 译文标题简易机械手及控制 原文标题 Simple Manipulator And The Control Of It 作者机电之家译名JDZJ国籍中国 原文出处机电之家 中文译文： 简易机械手及控制 随着社会生产不断进步和人们生活节奏不断加快,人们对生产效率也不断提出新要求。由于微电子技术和计算软、硬件技术的迅猛发展和现代控制理论的不断完善,使机械手技术快速发展,其中气动机械手系统由于其介质来源简便以及不污染环境、组件价格低廉、维修方便和系统安全可靠等特点,已渗透到工业领域的各个部门,在工业发展中占有重要地位。本文讲述的气动机械手有气控机械手、XY轴丝杠组、转盘机构、旋转基座等机械部分组成。主要作用是完成机械部件的搬运工作,能放置在各种不同的生产线或物流流水线中,使零件搬运、货物运输更快捷、便利。 一.四轴联动简易机械手的结构及动作过程 机械手结构如下图1所示,有气控机械手(1)、XY轴丝杠组(2)、转盘机构(3)、旋转基座(4)等组成。 图1.机械手结构 其运动控制方式为：(1)由伺服电机驱动可旋转角度为360°的气控机械手(有光电传感器确定起始0点);(2)由步进电机驱动丝杠组件使机械手沿X、Y轴移动(有x、y轴限位开关);(3)可回旋360°的转盘机构能带动机械手及丝杠组自由旋转(其电气拖动部分由直流电动机、光电编码器、接近开关等组成);(4)旋转基座主要支撑以上3部分;(5)气控机械手的张合由气压控制(充气时机械手抓紧,放气时机械手松开)。 其工作过程为：当货物到达时,机械手系统开始动作;步进电机控制开始向下 机械手设计英文参考文 献原文翻译 Company number：【WTUT-WT88Y-W8BBGB-BWYTT-19998】 翻译人：王墨墨山东科技大学 文献题目：Automated Calibration of Robot Coordinates for Reconfigurable Assembly Systems 翻译正文如下： 针对可重构装配系统的机器人协调性的自动校准 T.艾利，Y.米达，H.菊地，M.雪松 日本东京大学，机械研究院，精密工程部 摘要 为了实现流水工作线更高的可重构性，以必要设备如机器人的快速插入插出为研究目的。当一种新的设备被装配到流水工作线时，应使其具备校准系统。该研究使用两台电荷耦合摄像机，基于直接线性变换法，致力于研究一种相对位置/相对方位的自动化校准系统。摄像机被随机放置，然后对每一个机械手执行一组动作。通过摄像机检测机械手动作，就能捕捉到两台机器人的相对位置。最佳的结果精度为均方根值毫米。 关键词： 装配，校准，机器人 1 介绍 21世纪新的制造系统需要具备新的生产能力，如可重用性，可拓展性，敏捷性以及可重构性 [1]。系统配置的低成本转变，能够使系统应对可预见的以及不可预见的市场波动。关于组装系统，许多研究者提出了分散的方法来实现可重构性[2][3]。他们中的大多数都是基于主体的系统，主体逐一协同以建立一种新的 配置。然而，协同只是目的的一部分。在现实生产系统中，例如工作空间这类物理问题应当被有效解决。 为了实现更高的可重构性，一些研究人员不顾昂贵的造价，开发出了特殊的均匀单元[4][5][6]。作者为装配单元提出了一种自律分散型机器人系统，包含多样化的传统设备[7][8]。该系统可以从一个系统添加/删除装配设备，亦或是添加/删除装配设备到另一个系统；它通过协同作用，合理地解决了工作空间的冲突问题。我们可以把该功能称为“插入与生产”。 表1：合作所需的调节和量度 在重构过程中，校准的装配机器人是非常重要的。这是因为，需要用它们来测量相关主体的特征，以便在物理主体之间建立良好的协作关系。这一调整必须要达到表1中所列到的多种标准要求。受力单元和方向的调整是不可避免的，以便使良好的协同控制得以实现。从几何标准上看，位置校准是最基本的部分。一般来说，校准被理解为“绝对”，即，关于特定的领域框架；或者“相对”，即，关于另一个机器人的基本框架。后者被称为“机器人之间的校准”。 个体机器人的校准已被广泛研究过了。例如，运动参数的识别就非常受欢迎。然而，很少有对机器人之间校准的研究。玉木等人是用一种基于标记的方法，在一个可重构的装配单元内，校准机器人桌子和移动机械手之间的相互位置/方向联系。波尼兹和夏发表了一种校准方法。该方法通过两个机械手的机械接触来实现，实验非常耗时，并要求特别小心地操作。 毕业设计（论文） 文献综述 设计（论文）题目：4自由度气动机械手设计 学院名称：机械工程学院 专业：机械设计制造及其自动化 学生姓名：卢锋学号：07403010309 指导教师：杨超珍 2010年12 月24 日 机械手的发展及应用 前言 机械工业是国民的装备部，是为国民经济提供装备和为人民生提供耐用消费品的产业。机械工业的规模和技术水平是衡量国家经济实力和科学技术水平的要标志。因此，世界各国都把发展机械工业作为发展本国经济的战略重点之一。生产水平及科学技术的不断进步与发展带动了整个机械工业的快速发展。现代工业中，生产过程的机械化，自动化已成为突出的主题。然而在机械工业中，加工、装配等生产是不连续的。单靠人力将这些不连续的生产工序接起来，不仅费时而且效率不高。同时人的劳动强度非常大，有时还会出现失误及伤害。显然，这严重影响制约了整个生产过程的效率和自动化程度。机械手的应用很好的解决了这一情况，它不存在重复的偶然失误，也能有效的避免了人身事故。 1.机械手的组成 1.1 执行机构 机械手主要由执行机构、驱动机构和控制系统三大部分组成。其组成及相互关系如下图： （1）手部 手部安装在手臂的前端。手臂的内孔装有转动轴，可把动作传给手腕，以转动、伸屈手腕，开闭手指。 机械手手部的机构系模仿人的手指，分为无关节，固定关节和自由关节三种。手指的数量又可以分为二指、三指和四指等，其中以二指用的最多。可以根据夹持对象的形状和大小配备多种形状和尺寸的夹头，以适应操作需要。 （2）手臂 手臂有无关节和有关节手臂之分本课所做的机械手的手臂采用无关节臂手臂的作用是引导手指准确的抓住工件，并运送到所需要的位置上。为了使机械手能够正确的工作，手臂的三个自由度都需要精确的定位。 总括机械手的运动离不开直线移动和转动二种，因此，它采用的执行机构主要是直线油缸、摆动油缸、电液脉冲马达、伺服油马达、直流伺服马达和步进马达等。 躯干是安装手臂、动力源和执行机构的支架。 1.2 驱动机构 驱动机构主要有四种：液压驱动、气压驱动、电气驱动和机械驱动。其中以液压气动用的最多，占90%以上，电动、机械驱动用的较少。 液压驱动主要是通过油缸、阀、油泵和油箱等实现传动。它利用油缸、马达加上齿轮、齿条实现直线运动；利用摆动油缸、马达与减速器、油缸与齿条、齿轮或链条、链轮等实现回转运动。液压驱动的优点是压力高、体积小、出力大、运动平缓，可无级变速，自锁方便，并能在中间位置停止。缺点是需要配备压力源，系统复杂成本较高。 气压驱动所采用的元件为气压缸、气压马达、气阀等。一般采用4-6 个大气压，个别的达到 8-10 个大气压。它的优点是气源方便，维护简单，成本低。缺点是出力小，体积大。由于空气的可压缩性大，很难实现中间位置的停止，只能用于点位控制，而且润滑性较差，气压系统容易生锈。 电气驱动采用的不多。现在都用三相感应电动机作为动力，用大减速比减速器来驱动执行机构；直线运动则用电动机带动丝杠螺母机构；有的采用直线电动机。通用机械手则考虑用步进电机、直流或交流的伺服电机、变速箱等。电气驱动的优点是动力源简单，维护，使用方便。驱动机构和控制系统可以采用统一形式的动力，出力比较大；缺点是控制响应速度比较慢。机械驱动只用于固定的场合。一般用凸轮连杆机构实现规定的动作。它的优点是动作确实可靠，速度高，成本低；缺点是不易调整。 1.3 控制系统 机械手控制系统的要素，包括工作顺序、到达位置、动作时间和加速度等。 控制系统可根据动作的要求，设计采用数字顺序控制。它首先要编制程序加以存储，然后再根据规定的程序，控制机械手进行工作。随着科学技术的发展，机械手也越来越多的地被应用。 外文出处：《Manufacturing Engineering and Technology—Machining》 附件1：外文原文 Manipulator Robot developed in recent decades as high-tech automated production equipment. I ndustrial robot is an important branch of industrial robots. It features can be program med to perform tasks in a variety of expectations, in both structure and performance a dvantages of their own people and machines, in particular, reflects the people's intellig ence and adaptability. The accuracy of robot operations and a variety of environments the ability to complete the work in the field of national economy and there are broad p rospects for development. With the development of industrial automation, there has be en CNC machining center, it is in reducing labor intensity, while greatly improved lab or productivity. However, the upper and lower common in CNC machining processes material, usually still use manual or traditional relay-controlled semi-automatic device . The former time-consuming and labor intensive, inefficient; the latter due to design c omplexity, require more relays, wiring complexity, vulnerability to body vibration inte rference, while the existence of poor reliability, fault more maintenance problems and other issues. Programmable Logic Controller PLC-controlled robot control system for materials up and down movement is simple, circuit design is reasonable, with a stron g anti-jamming capability, ensuring the system's reliability, reduced maintenance rate, and improve work efficiency. Robot technology related to mechanics, mechanics, elec trical hydraulic technology, automatic control technology, sensor technology and com puter technology and other fields of science, is a cross-disciplinary integrated technol ogy. First, an overview of industrial manipulator Robot is a kind of positioning control can be automated and can be re-programmed to change in multi-functional machine, which has multiple degrees of freedom can be used to carry an object in order to complete the work in different environments. Low wages in China, plastic products industry, although still a labor-intensive, mechanical hand use has become increasingly popular. Electronics and automotive industries that 译文一 机械手 机器人是典型的机电一体化装置，它综合运用了机械与精密机械、微电子与计算机、自动控制与驱动、传感器与信息处理以及人工智能等多学科的最新研究成果，随着经济的发展和各行各业对自动化程度要求的提高，机器人技术得到了迅速发展，出现了各种各样的机器人产品。现代工业机器人是人类真正的奇迹工程。一个像人那么大的机器人可以轻松地抬起超过一百磅并可以在误差 +-0.006英寸误差范围内重复的移动。更重要的是这些机器人可以每天24小时永不停止地工作。在许多应用中（特别是在自动工业中）他们是通过编程控制的，但是他们一旦编程一次，他们可以重复地做同一工作许多年。机器人产品的实用化，既解决了许多单靠人力难以解决的实际问题，又促进了工业自动化的进程。 目前，由于机器人的研制和开发涉及多方面的技术，系统结构复杂，开发和研制的成本普遍较高，在某种程度上限制了该项技术的广泛应用，因此，研制经济型、实用化、高可靠性机器人系统具有广泛的社会现实意义和经济价值。由于我国经济建设和城市化的快速发展，城市污水排放量增长很快，污水处理己经摆在了人们的议事日程上来。随着科学技术的发展和人类知识水平的提高，人们越来越认识到污水处理的重要性和迫切性，科学家和研究人员发现塑料制品在水中是用于污水处理的很有效的污泥菌群的附着体。塑料制品的大量需求，使得塑料制品生产的自动化和高效率要求成为经济发展的必然。本文结合塑料一次挤出成型机和塑料抓取机械手的研制过程中出现的问题，综述近儿年机器人技术研究和发展的状况，在充分发挥机、电、软、硬件各自特点和优势互补的基础上，对物料抓取机械手整体机械结构、传动系统、驱动装置和控制系统进行了分析和设计，提出了一套经济型设计方案。采用直角坐标和关节坐标相结合的框架式机械结构形式，这种方式能够提高系统的稳定性和操作灵活性。传动装置的作用是将驱动元件的动力传递给机器人机械手相应的执行机构，以实现各种必要的运动，传动方式上采用结构紧凑、传动比大的蜗轮蜗杆传动和将旋转运动转换为直线运动的螺旋传动。机械手驱动系统的设计往往受到作业环境条件的限制，同时也要考虑价格因素的影响以及能够达到的技术水平。由于步进电机能够直接接收数字量，响应速度快而且工作可靠并无累积误差，常用作数字控制系统驱动机构的动力元件，因此，在驱动装置中采用由步进电机构成的开环控制方式，这种方式既能满足控制精度的要求，又能达到经济性、实用化目的，在此基础上，对步进电机的功率计一算及选型问题经行了分析。在完成机械结构和驱动系统设计的基础上，对物料抓取机械手运动学和动力学进行了分析。运动学分析是路径规 机械手外文翻译 . Manipulator Along with our country the rapid development of industrial production, rapidly improve degree of automation, implementation artifacts of handling, steering, transmission or toil for welding gun, spray gun, spanner and other tools for processing, assembly operations such as automation, should cause the attention of people more and more. Manipulator is to imitate the people part of the action, according to a given program, track and demanding acquirement, handling or operation of the automatic device. Applied in the industrial production of the manipulator is referred to as "industrial manipulator". Application manipulator can improve the automation of production water in production and labor productivity; Can reduce labor fatigue strength, to ensure product quality, implement safety production; Especially in high temperature and high pressure, low temperature, low pressure, dust, explosive, toxic and radioactive gases such as harsh environment, it instead of people normal work, the more significant. Therefore, in the machining, casting, welding, heat treatment, electroplating, spray painting, assembly, and light industry, transportation industry get more and more extensive application, etc. Robot Robot is a type of mechantronics equipment which synthesizes the last research achievement of engine and precision engine, micro-electronics and computer, automation control and drive, sensor and message dispose and artificial intelligence and so on. With the development of economic and the demand for automation control, robot technology is developed quickly and all types of the robots products are come into being. The practicality use of robot products not only solves the problems which are difficult to operate for human being, but also advances the industrial automation program. At present, the research and development of robot involves several kinds of technology and the robot system configuration is so complex that the cost at large is high which to a certain extent limit the robot abroad use. To development economic practicality and high reliability robot system will be value to robot social application and economy development. With the rapid progress with the control economy and expanding of the modern cities, the let of sewage is increasing quickly: With the development of modern technology and the enhancement of consciousness about environment reserve, more and more people realized the importance and urgent of sewage disposal. Active bacteria method is an effective technique for sewage disposal，The lacunaris plastic is an effective basement for active bacteria adhesion for sewage disposal. The abundance requirement for lacunaris plastic makes it is a consequent for the plastic producing with automation and high productivity. Therefore, it is very necessary to design a manipulator that can automatically fulfill the plastic holding. With the analysis of the problems in the design of the plastic holding manipulator and synthesizing the robot research and development condition in recent years, a economic scheme is concluded on the basis of the analysis of mechanical configuration, transform system, drive device and control system and guided by the idea of the characteristic and complex of mechanical configuration, electronic, software and hardware. In this article, the mechanical configuration combines the character of direction coordinate and the arthrosis coordinate which can improve the stability and operation flexibility of the system. The main function of the transmission mechanism is to transmit power to implement department and complete the necessary movement. In this transmission structure, the screw transmission mechanism transmits the rotary motion into linear motion. Worm gear can give vary transmission 外文翻译 Introduction to Robotics Mechanics and Control 机器人学入门 力学与控制 系别：机械与汽车工程系 专业名称：机械设计制造及其自动化学生姓名：郭仕杰 学号：06101315 指导教师姓名、职称：贺秋伟副教授 完成日期2014 年2 月28日 Introduction to Robotics Mechanics and Control Abstract This book introduces the science and engineering of mechanical manipulation. This branch of the robot has been in several classical field based. The main related fields such as mechanics, control theory, computer science. In this book, Chapter 1 through 8 topics ranging from mechanical engineering and mathematics, Chapter 9 through 11 cover control theory of material, and twelfth and 13 may be classified as computer science materials. In addition, this book emphasizes the computational aspects of the problem; for example, each chapter it mainly mechanical has a brief section calculation. This book is used to teach the class notes introduction to robotics, Stanford University in the fall of 1983 to 1985. The first and second versions have been through 2002 in use from 1986 institutions. Using the third version can also benefit from the revised and improved due to feedback from many sources. Thanks to all those who modified the author's friends. This book is suitable for advanced undergraduates the first grade curriculum. If students have contributed to the dynamics and linear algebra course in advanced language program in a basic course of statics. In addition, it is helpful, but not absolutely necessary, let the students finish the course control theory. The purpose of this book is a simple introduction to the material, intuitive way. Specifically, does not need the audience mechanical engineer strict, although much of the material is from the field. At the Stanford University, many electrical engineers, computer scientists, mathematicians find this book very readable. Here we only on the important part to extract. The main content 1、B ackground The historical characteristics of industrial automation is popular during the period of rapid change. Either as a cause or an effect of automation technology, period of this change is closely linked to the world economy. Use of industrial robots, can be identified in a unique device 1960's, with the development of computer aided design (CAD) system and computer aided manufacturing (CAM) system, the latest trends, automated manufacturing process. The technology is the leading industrial automation through another transition, its scope is still unknown. In机械手机械设计中英文对照外文翻译文献
机器人外文翻译
外文翻译机械手
机械手外文翻译 修改版
机械手设计英文参考文献原文翻译
机械手文献综述
机械手臂外文文献翻译、中英文翻译、外文翻译
机械手设计外文翻译2
机械手外文翻译
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