機(jī)械手機(jī)器人外文翻譯-水下機(jī)器人的理論和設(shè)計(jì)問題【中文3150字】【PDF+中文WORD】
機(jī)械手機(jī)器人外文翻譯-水下機(jī)器人的理論和設(shè)計(jì)問題【中文3150字】【PDF+中文WORD】,中文3150字,PDF+中文WORD,機(jī)械手,機(jī)器人,外文,翻譯,水下,理論,設(shè)計(jì),問題,中文,3150,PDF,WORD
【中文3150字】
國(guó)際控制會(huì)議，儀器儀表和機(jī)電工程（CIM'07）
Johor Bahru，Johor,，Malaysia，5月28-29,2007
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水下機(jī)器人的理論和設(shè)計(jì)問題
Irfan Abd Rahman,Surina Mat Suboh, Mohd Rizal Arshad
馬來西亞理科大學(xué)
摘要
在本文中，我們將討論水下機(jī)械手設(shè)計(jì)的理論和實(shí)現(xiàn)面臨的問題。這是以前的研究人員在工作中提取的信息的方法。本文介紹了一些建模參數(shù)，這是通常包含在水下機(jī)器人的外觀設(shè)計(jì)，增加質(zhì)量，增加科里奧利力，阻力和浮力。模擬所有這些參數(shù)使用MATLAB通過修改一些運(yùn)行代碼，是由彼得·柯克通過他的機(jī)器人工具箱完成的。通過對(duì)一個(gè)土地基礎(chǔ)的設(shè)計(jì)和水下機(jī)械手的設(shè)計(jì)進(jìn)行了比較， 作為水下機(jī)械手需要執(zhí)行其工作添加參數(shù)，指出增加轉(zhuǎn)矩要求做出類似的運(yùn)動(dòng)關(guān)節(jié)鏈接。在本文中，我們使用了彪馬560配置，這作為我們的手動(dòng)工具的機(jī)器人工具箱內(nèi)部生成的。本文給出了提高和改進(jìn)的下一個(gè)方向。?
1．介紹
探索海洋已經(jīng)成為一個(gè)新興的研究領(lǐng)域，由于許多資源位于深海之下。深?？碧浇o人類帶來了不同的挑戰(zhàn)，因?yàn)槿祟惒荒軌虺惺芤恍﹪?yán)酷的條件，因此為了避免在深海中的人為因素干預(yù)，機(jī)器人的研究已進(jìn)入深海。當(dāng)前熱門的研究領(lǐng)域主要集中在AUV（自主水下載具）的開發(fā)和部署。AUV的一些應(yīng)用程序能讓水下機(jī)器人操縱自己進(jìn)入深海。這將消除人類被暴露在危險(xiǎn)環(huán)境中的水下勘探,包括檢查。水下機(jī)器人配備了照相機(jī)來執(zhí)行其檢查周圍覆蓋面積。預(yù)計(jì)水下AUV將在未來取代人類從事海洋探險(xiǎn)，并在減小危險(xiǎn)中起到至關(guān)重要的作用。
機(jī)械手的設(shè)計(jì)和應(yīng)用是深入到另一個(gè)領(lǐng)域的研究,將使機(jī)器人復(fù)制人類的手臂和手的功能。各個(gè)實(shí)用的應(yīng)用程序已被研究如擰緊裝配零件等。機(jī)械手的設(shè)計(jì)通常由它能夠執(zhí)行或“操縱”本身的度數(shù)決定,或換句話說是DOF(自由度)。自由度是指機(jī)械手擁有的基本關(guān)節(jié)的數(shù)量。機(jī)械手的自由度數(shù)字越高意味著移動(dòng)更加靈活。接頭可以分為兩種不同的類型：棱柱和回轉(zhuǎn)。柱狀關(guān)節(jié)使關(guān)節(jié)平移運(yùn)動(dòng)而轉(zhuǎn)動(dòng)關(guān)節(jié)可以使關(guān)節(jié)做旋轉(zhuǎn)運(yùn)動(dòng)。
水下機(jī)器人機(jī)械手系統(tǒng)（UVMS）在機(jī)器人研究界得到普及，因?yàn)樗峁┝怂聶C(jī)器人更大的靈活性和更廣泛的應(yīng)用。更多的應(yīng)用程序使以前需要制導(dǎo)武器的人由更靈巧的機(jī)械手取代。操縱器能夠執(zhí)行各種任務(wù)，如從海床，鉆床拿起對(duì)象，加入零件和零件的組裝都配備了水下機(jī)器人。由于這樣的事實(shí)，即它必須考慮水下存在的流體力學(xué)，更好的設(shè)計(jì)與使用現(xiàn)存的機(jī)械手是唯一可能的事。
水下機(jī)器人機(jī)械手系統(tǒng)在感興趣的研究者中構(gòu)成了不同的挑戰(zhàn)。這包括增加的質(zhì)量，浮力，阻力和摩擦。由于從流體動(dòng)力學(xué)添加效應(yīng)，這將改變機(jī)械手的動(dòng)力學(xué)。
這篇文章的目的是討論一些包括裝備水下車輛與機(jī)械手的設(shè)計(jì)問題。本文著重給出了對(duì)五個(gè)方面的設(shè)計(jì)標(biāo)準(zhǔn)：自由度、工作區(qū)范圍、末端執(zhí)行器的最大速度和可重復(fù)性、操縱器的精度。在本文中,我們進(jìn)行了模擬以顯示水下機(jī)械手和表面機(jī)械手的區(qū)別，包括水動(dòng)力效應(yīng)的機(jī)械手的動(dòng)態(tài)功能。在這個(gè)測(cè)試中我們使用6自由度的轉(zhuǎn)動(dòng)關(guān)節(jié)對(duì)配置的所有復(fù)制末端執(zhí)行器進(jìn)行定位。所有的連接參數(shù)被正確地指定，如力矩的慣性張量、重力齒輪比和摩擦。
在參數(shù)模擬時(shí)改變質(zhì)量變化的參數(shù)，也可聯(lián)系浮力變化。利用機(jī)器人工具箱函數(shù)對(duì)MATLAB的工作區(qū)所有的模擬進(jìn)行了研究。比較著重于轉(zhuǎn)矩要求，以實(shí)現(xiàn)水下和表面機(jī)械手操作之間的位置的分配。通過使用逆動(dòng)態(tài)算法牛頓歐拉法的遞歸得到的扭矩，基于關(guān)節(jié)的位置、速度和加速度計(jì)算出扭矩。通過公正的分析和模擬受到流體動(dòng)力學(xué)影響的水下機(jī)械手的運(yùn)動(dòng)結(jié)論變化的多少，從而保證在水下機(jī)械手的設(shè)計(jì)中對(duì)這一因素有足夠的考慮。通過利用電源模擬，我們能夠觀察到由于流體力學(xué)，我們的扭矩值等某些參數(shù)的變化的效果。這將確保機(jī)械手一個(gè)更好的設(shè)計(jì)。
2.?設(shè)計(jì)考慮
水下機(jī)器人機(jī)械手系統(tǒng)在感興趣的研究者中構(gòu)成了不同的挑戰(zhàn)是由于，事實(shí)上，它研究的流體力學(xué)存在于水下。在本文中注重的是對(duì)五個(gè)方面的設(shè)計(jì)：自由度、工作區(qū)范圍內(nèi)、承載能力、末端器最大速度和重復(fù)性、操縱器準(zhǔn)確性。除此之外，了解動(dòng)態(tài)運(yùn)動(dòng)的機(jī)械手的運(yùn)動(dòng)學(xué)是非常重要的。運(yùn)動(dòng)學(xué)是不考慮導(dǎo)致運(yùn)動(dòng)的力的研究。機(jī)械手的運(yùn)動(dòng)涉及幾何的研究和基于時(shí)間的運(yùn)動(dòng)屬性，特別是如何移動(dòng)各個(gè)環(huán)節(jié)，并隨著時(shí)間的推移相互對(duì)應(yīng)。在機(jī)械手的路徑規(guī)劃中，更多的是使用逆運(yùn)動(dòng)學(xué)的解決方案，使關(guān)節(jié)角度達(dá)到指定的末端執(zhí)行器的所需位置。該解決方案是關(guān)于Denavit-Hartenberg表示法確定聯(lián)合鏈接參數(shù)。機(jī)械手動(dòng)力學(xué)涉及運(yùn)動(dòng)方程，機(jī)械手動(dòng)作響應(yīng)扭矩應(yīng)用的執(zhí)行機(jī)構(gòu)或外力。N-軸運(yùn)動(dòng)的操縱器一般方程為：
如果附加質(zhì)量、浮力、液壓阻力和摩擦水下機(jī)械手的動(dòng)態(tài)參數(shù)都會(huì)增加，當(dāng)機(jī)器人在水下移動(dòng)時(shí)，額外的力和力矩系數(shù)也會(huì)添加，圍繞機(jī)器人的流體必然會(huì)促進(jìn)機(jī)器人有效質(zhì)量變化。這些系數(shù)是額外的（虛擬）的質(zhì)量，由于力系數(shù)線性和角加速度增加如轉(zhuǎn)動(dòng)慣量和交叉耦合項(xiàng)等。水下具有n關(guān)節(jié)的機(jī)械手的運(yùn)動(dòng)方程如下：
其中?q是關(guān)節(jié)角的位置，M是慣性矩陣，C為科氏力，離心力，G代表重力包括浮力的影響，F(xiàn)是摩擦條件，D是機(jī)械手相對(duì)海流和海浪的速度造成的液壓阻力，τ是向量，這實(shí)際上是應(yīng)用關(guān)節(jié)力矩控制輸入。
2.1?DOF（自由度）
操縱器可以在3-D空間中執(zhí)行的獨(dú)立的運(yùn)動(dòng)的的數(shù)目被稱為自由度的數(shù)量。機(jī)械手臂可以提供多個(gè)自由度,下面的圖1展示的是先進(jìn)的卡夫遙控機(jī)器人捕食者7。機(jī)械臂基本上有兩種類型的運(yùn)動(dòng)：平移和旋轉(zhuǎn)。即表示沿三個(gè)垂直軸直線運(yùn)動(dòng)，通過三軸指定主體的位置和角的旋轉(zhuǎn)運(yùn)動(dòng)及繞主體的旋轉(zhuǎn)方向。自由度由該機(jī)械手的任務(wù)決定。一個(gè)常見的設(shè)計(jì)策略是基于三自由度實(shí)現(xiàn)任意位置，并添加在一個(gè)3自由度球面手腕上以實(shí)現(xiàn)任意方向的運(yùn)動(dòng)。手頭的任務(wù)通常并不需要一個(gè)完整的6 - DOF，例如：任務(wù)對(duì)象表現(xiàn)出對(duì)稱時(shí)，或在沒有工作區(qū)中的障礙，或簡(jiǎn)單的任務(wù)時(shí)，涉及有限的運(yùn)動(dòng)方向。很顯然設(shè)計(jì)最低自由度的操縱實(shí)現(xiàn)任務(wù)是最佳的。這將減少成本、簡(jiǎn)化分析。大部分的商業(yè)水下機(jī)器人在水下航行器做安裝操作。其中一些只設(shè)計(jì)很少的自由度，因?yàn)檐囕v本身也有它自己的自由度。然而，JASON有一個(gè)通用的六自由度機(jī)械手。圖2顯示了JASON的機(jī)械臂。
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圖1：卡夫?遙操作機(jī)器人系統(tǒng)?“捕食者”-7
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圖2：JASON的機(jī)械臂
2.2工作范圍
一個(gè)機(jī)械手的工作空間被定義為一個(gè)操縱器的工作區(qū)中的空間體積，在該空間機(jī)械手是能夠找到它的末端。因此，在這種分析中工作區(qū)是指在周圍的水下。有時(shí)需要考慮工作區(qū)的形狀?！C(jī)械手的工作空間的特征是機(jī)械接頭限制除了配置、鏈接長(zhǎng)度和數(shù)量以外的機(jī)械手的自由度。被指定工作區(qū)存在或不存在的解決方案屬于逆運(yùn)動(dòng)學(xué)問題。通過原點(diǎn)的端部區(qū)域，可以達(dá)到至少一個(gè)方向的效應(yīng)子被稱為可達(dá)工作空間（RWS）。如果工作空間中的一個(gè)點(diǎn)只在一個(gè)方向可以達(dá)到，末端器的可操作性是非常差，只用一個(gè)固定的方向是不可能符合任何實(shí)際工作要求的。因此，它必須找到可以達(dá)到在一個(gè)以上的方向的點(diǎn)工作區(qū)。末端可以達(dá)到每點(diǎn)所有的方向的空間被稱為靈巧工作區(qū)（DWS），如果一個(gè)特定的機(jī)械手可確定構(gòu)成，沒有解決方案，這種配置被稱為“奇異”。分為奇異性的邊界和或內(nèi)部的奇點(diǎn)。對(duì)應(yīng)于這些奇異點(diǎn)代表在工作區(qū)中的奇異表面的表面補(bǔ)丁。因?yàn)槠娈惖谋砻媸且苿?dòng)操縱器的不可能的前端沿，無論選擇哪個(gè)關(guān)節(jié)率，它們是操作期間應(yīng)被避免。任何位于一個(gè)奇異表面上的點(diǎn)都將具有零可操作性。
2.3承載能力
電動(dòng)機(jī)的大小、關(guān)節(jié)和鏈接的結(jié)構(gòu)完整性決定了機(jī)器人的負(fù)載。對(duì)于相同的結(jié)構(gòu)完整水平，作為工作區(qū)的體積增大，有效載荷能力會(huì)下降。
2.4?末端執(zhí)行器的最大速度
機(jī)械手比單純自動(dòng)化或人工可以實(shí)現(xiàn)更快、更可行地完成任務(wù)。周期時(shí)間是達(dá)到一個(gè)完整的移動(dòng)花費(fèi)的時(shí)間，是一個(gè)與速度有關(guān)的函數(shù)，而且還可能與加速在加速和減速階段有關(guān)。因此，加速能力也是重要的。
2.5可重復(fù)性和準(zhǔn)確性
這是任何機(jī)器人的關(guān)鍵性能之一。構(gòu)建具有高精度和重復(fù)性的機(jī)器人是昂貴的，需要更嚴(yán)格的鏈接，更嚴(yán)格的公差，位置傳感，建模等。目標(biāo)應(yīng)該是任務(wù)所需要的最小精度和可重復(fù)性。外部傳感，特別是力感應(yīng)，在很多減少所需的水平或準(zhǔn)確性的任務(wù)中是一種有效手段。這也仍然是一個(gè)活躍的研究領(lǐng)域。
Theory and Design Issues of Underwater Manipulator Irfan Abd Rahman,Surina Mat Suboh,Mohd Rizal Arshad Univesiti Sains Malaysia ,sue_,rizaleng.usm.my Abstract In this paper we discuss the theory and implementation issue that is faced by underwater manipulators designers.It is collective information and method that was extracted from work by previous researchers.The paper presented some of the modeling parameters which is normally included in the underwater robotic designs which are add mass,added corriolis,drag force and buoyancy.Simulations of all these parameters were run using the MATLAB by modifying some of the code which was created by Peter Corke through his robotic toolbox.A comparison between land based design and underwater manipulator design were done which indicates an increase in the torque required to make similar movement in the link joints due to the added parameters as the manipulator perform its work underwater.In this paper we have used the PUMA 560 configuration which is generated inside the robotic toolbox as our manipulator tool.The paper then concludes with next direction of the project and improvement.1.Introduction Oceanic exploration has become an emerging field of research due to many human resources which is located beneath the deep sea.Deep sea exploration poses a different challenge to human being since we are not able to withstand the harsh condition that it poses.Therefore robotic research has come into place in order to prevent human intervention in the deep sea.Current field of intense research focuses on the development and deployment of AUV(Autonomous Underwater Vehicle)which is able to maneuver itself into the deep ocean.This will remove human from being exposed to the hazardous environment during underwater exploration.Some of the application of the AUV includes inspection whereby the AUV is equipped with camera to perform its duty to inspect the surrounding of the required area.Underwater AUV are expected to play a vital role in the future in replacing humans from the danger of ocean exploration.Manipulator design and application is another area of intense research which will enable robot to replicate the function of the human arms and hands.Various applications have been researched such as the use for placing and screwing assembly parts.Manipulator design are normally governs by the number of degrees that it is able to perform or manipulate itself or in other words DOF(degrees of freedom).Degree of freedom refers basically to the number of joints that the manipulator possesses.The higher the number of DOF means that the manipulator is more flexible to move around.Joints can be classified into two different types which are the prismatic and revolute.Prismatic joints are joints that are making translational motion while revolute joints are joints which are able to make rotational motion.Underwater Vehicle Manipulator System(UVMS)has gain popularity in the robotic research community as it offers underwater robots more flexibility and wider range of application.More application which previously requires the guided arms of human is being replaced by the more dexterous robotic manipulator.Underwater vehicle which are equipped with manipulator are able to perform various task such as picking up object from the ocean bed,drilling,joining parts and even part assembly.This is only possible with the use of better design existed in the manipulator.Underwater Vehicle Manipulator System poses a different challenge upon interested researcher due to the fact that it has to take the consideration of the hydrodynamics that existed underwater.This includes the added mass,buoyancy,drag and friction.This will change the dynamics of the manipulator due to the added effect from the hydrodynamics.The objective of this paper is to discuss some of the design consideration that has to be included when equipping underwater vehicle with manipulator.In this paper attention are given towards five aspects of the design criteria which are the DOF,workspace extent,end effector maximum speed and repeatability and accuracy of the manipulator.In this paper we have International Conference on Control,Instrumentation and Mechatronics Engineering(CIM07),Johor Bahru,Johor,Malaysia,May 28-29,2007725conducted simulation to show the difference between the underwater manipulator and surface manipulator by including the hydrodynamic effect in the dynamic function of the manipulator.For this test we have use 6 DOF of PUMA configuration with all revolute joints to replicate the end effector positioning.All the links parameters are properly specified such as the moment of inertia tensor,gravity the gear ratio and friction.Among parameters that were simulated are the change mass change in the link parameters and also the buoyancy change.All the simulation was conducted in the MATLAB workspace by utilizing the robotic toolbox function.The comparison focuses on the torque requirement in order to achieve the assigned position between manipulator which operates underwater and also the surface.The torque is obtained by using the inverse dynamic algorithm of recursive newton euler method,which calculates the torque based on the position,velocity and acceleration of the joints.From the analysis and simulation a fair conclusion was made indicating how much the change of the hydrodynamic will impact the movement of the underwater manipulator and thus will ensure enough consideration given towards this factor in the underwater manipulator design.By utilizing the power of simulation we are able to observe the effect on our torque value as we vary certain parameters in the hydrodynamics.This will ensure a better design of the manipulator.2.Design Consideration Underwater Vehicle Manipulator System poses a different challenge upon interested researcher due to the fact that it has to take the consideration of the hydrodynamics that existed underwater.In this paper attention are given towards five aspects of the design criteria which are degree of freedom(DOF),workspace extent,load carrying capacity,end-effector maximum speed and the repeatability and accuracy of the manipulator are needed to be considered.Besides that,it is very important to know about the kinematics and dynamic motion of manipulator.Kinematics is a study of motion without regard to the forces which cause it.The kinematics of manipulators involves the study of the geometric and time based properties of the motion,and in particular how the various links move with respect to one another and with time.Of more use in manipulator path planning is the inverse kinematic solution which gives the joint angles required to reach the specified end-effector position.The solution is regarding to the Denavit-Hartenberg notation to identifying joint-link parameters.Manipulator dynamics is concerned with the equations of motion,the way in which the manipulator moves in response to torques applied by the actuators,or external forces.The general equation of motion for an n-axis manipulator are given by =M(q,q)+C(q,q)q+F(q)+G(q)If added mass,buoyancy,hydraulic drag and friction are added on the underwater manipulator dynamics.As the robot moves underwater,additional force and moment coefficients are added to account for the effective mass of the fluid that surrounds the robot and must be accelerated with the robot.These coefficients are meant by added(virtual)mass and include added moments of inertia and cross coupling terms such as force coefficients due to linear and angular accelerations.Dynamic equation of an underwater manipulator which has n-joints is as follows:=M(q,q)+C(q,q)q+F(q)+G(q)+D(q,q)where q is the joint angular position,M is the inertia matrix,C denotes the Coriolis,centrifugal forces,G represents the gravity forces which include buoyancy effects,F is the friction terms,D is the hydraulic drag forces which caused by the relative velocity of manipulator to ocean current and waves,is the vector of applied joint torques which are actually control inputs,2.1 Dof(Degrees of Freedom)The number of independent movements that the manipulators can perform in a 3-D space is called the number of degrees of freedom.Manipulator arms can provide multiple degrees of freedom,as shown on the following figure1 of the advanced Kraft TeleRobotics Predator-7.Basically,there are two types of movement for manipulator which is translation and rotation.Translation represents linear motions along three perpendicular axes,specify the position of the body and rotation represents angular motions about the three axes,specify the orientation of the body.The determination of dof depends on the task of that manipulator.A common strategy in design is to put a 3-dof base to achieve arbitrary position,and add a 3-dof spherical wrist to achieve arbitrary orientation.Often the task at hand does not require a full 6-dof,e.g.when task objects exhibit symmetry,or when no obstacle in workspace,or simply when the task involves limited directions of movement.Obviously,it is optimum to design the manipulator with the minimum dof that will achieve the task.This reduces cost and simplifies the analysis.Most of the International Conference on Control,Instrumentation and Mechatronics Engineering(CIM07),Johor Bahru,Johor,Malaysia,May 28-29,2007726commercial underwater manipulators operate by mounting on the underwater vehicles.Some of them are just designed with a small number of dof because the vehicle itself has its own dof.However,JASON has a general purpose manipulator with six dof.Figure2 shows the manipulator arm of JASON.Figure 1:Kraft TeleRobotics Predator Figure 2 :Manipulator arm of JASON 2.2 Workspace extent The workspace of a manipulator is defined as the volume of space in which the manipulator is able to locate its end-effector.Thus,in this analysis the workspace is referring to the underwater surrounding.Sometimes the shape of the workspace needs to be considered.The manipulator workspace is characterized by the mechanical joint limits in addition to the configuration,link length and the number of degrees of freedom of the manipulator.The workspace gets specified by the existence or nonexistence of solutions to the inverse kinematics problem.The region that can be reached by the origin of the endeffector frame with at least one orientation is called the reachable workspace(RWS).If a point in workspace can be reached only in one ormanipulatability of the end-effector is very poor and it is not possible to do any practical work satisfactory with just one fixed orientation.It is,therefore,necessary to look for the points in workspace,which can be reached in more than one orientation.The space commercial underwater manipulators operate by mounting on the underwater vehicles.Some of them are just designed with a small number of dof because the vehicle itself has its own dof.However,JASON has a general purpose manipulator with six dof.shows the manipulator arm of JASON.Predator-7:Manipulator arm of JASON The workspace of a manipulator is defined as the volume of space in which the manipulator is able to effector.Thus,in this analysis the workspace is referring to the underwater surrounding.space needs to be considered.The manipulator workspace is characterized by the mechanical joint limits in addition and the number of degrees of freedom of the manipulator.The workspace nonexistence of solutions to the inverse kinematics problem.The region that can be reached by the origin of the end-effector frame with at least one orientation is called the(RWS).If a point in workspace can be reached only in one orientation,the effector is very poor and it is not possible to do any practical work satisfactory with just one fixed orientation.It is,therefore,necessary to look for the points in workspace,which n one orientation.The space where the end-effector can reach every point from all orientations is called dexterous workspaceno solution can be determined for a particular manipulator pose that configuration is said to be singular.These singularities represent the boundary and/or the internal singularities.Surface patches corresponding to these singularities represent the singular surfaces within the workspace.As it is impossible to move the tip of the manipulator along the singular surfaces,no matter which joint rates are selected,they are to be avoided during manipulation.Any point lying on a singular surface will have zero manipulability.2.3 Load carrying capacity The load required to be carried by the robot will govern the size of its motors,and theintegrity of its joints and links.For the same level of structural integrity,the payload capacity will decrease as the workspace volume increases.2.4 End effector maximum speed The faster a task can be achieved,is the robot compared to hard automation or human workers.Cycle time,the time taken to achieve a complete move,is a function endalso on the accelerations possible during the acceleration and deceleration phases.capability is also of importance.2.5 Repeatability and accuracy This is one of the critical properties of any robot.Constructing a robot with high accuracy and repeatability is expensive:stiffer links,tighter tolerance joints,position sensing,and modeling and etc.The aim should be for the minimum accuracy and repeatability required by the task.External sensing,particularly force sensing,is a means in many tasks to reduce the required level or accuracy.This has been and still is a current active research area.effector can reach every point from all dexterous workspace(DWS).If no solution can be determined for a particular manipulator pose that configuration is said to be singularities represent the boundary and/or the internal singularities.Surface patches corresponding to these singularities represent the singular surfaces within the workspace.As it is impossible to move the tip of the manipulator along the faces,no matter which joint rates are selected,they are to be avoided during manipulation.Any point lying on a singular surface will have zero The load required to be carried by the robot will ize of its motors,and the structural integrity of its joints and links.For the same level of structural integrity,the payload capacity will decrease as the workspace volume increases.2.4 End effector maximum speed The faster a task can be achieved,the more viable is the robot compared to hard automation or human workers.Cycle time,the time taken to achieve a complete move,is a function end-effector speed,but also on the accelerations possible during the ration and deceleration phases.So acceleration 2.5 Repeatability and accuracy This is one of the critical properties of any robot.Constructing a robot with high accuracy and repeatability is expensive:stiffer links,tighter tolerance joints,position sensing,and modeling and for the minimum accuracy and eatability required by the task.External sensing,particularly force sensing,is a means in many tasks to reduce the required level or accuracy.This has been and still is a current active research area.International Conference on Control,Instrumentation and Mechatronics Engineering(CIM07),Johor Bahru,Johor,Malaysia,May 28-29,20077273.Manipulator Kinematics and Dyanmics In this section we will reviewed the 2 important aspect of designing of robotic manipulator.Robotic manipulator is required to follow a trajectory to manipulate a certain object and to perform the task required in its given workspace.The first aspect is the kinematic analysis of the manipulator and the second parameter is the dynamics.3.1 Kinematic Kinematic model describes the spatial position of the joints and links and position and orientation of the end-effector 1.It is basically a way to establish a relationship between the joints variables and the link position and orientation.The forward kinematics involves the process of establishing the position and orientation of the end effector with based on the joint variables.Inverse kinematic on the other hands involves relates the joint variables when the end effector position and orientation has been ascertain.In this work we have used the Denavit-Hartenberg convention in naming the link and frame.This corresponds with the method which is also been applied to the torque computation which is been used by Peter Corke 2.Figure 3:Denavit-Hartenberg Convention 1 As we can see in this frame naming convention the frame i,for link i is located at the distal end of the link.The following are the definition for the link parameters.i)Link length,ai ii)Link twist,is the angle of between zi and zi-1 which is read from xi.iii)Link offset,di,is the distance from origin of frame i-1 to frame i.iv)Joint angle,is the angle between the xi-1 to xi from zi Another convention that is being used is the modified denavit-hartenberg convention which utilizes the framei to be the same as jointi3.The linear velocity of frame i,will be determine by the following equation?i,is the frame D,is the position matrix with respect to frame i The angular velocity of the link with respect to the base frame is described as follows?w,is the angular velocity 3.2 Dynamics Dynamic behavior of a robotic manipulator is defined as a time-varying movement of the manipulator.This time varying movement is controlled by the torque which is applied through the link joints.The internal torque generated is caused by the motion of the links itself while the external force which acts upon the links includes load and the gravitational forces.There are a number of dynamic modeling method which is applicable.The most common are the Langrange-Euler(LE)and Newton-Euler(NE).Tarn,Yang,Shoults 4,has used kanes method instead for their dynamic modeling of underwater manipulator.Kanes method is a combination of both EL and LE.In this method it actually eliminates the non-working link interaction forces.In this paper we have simulated the dynamics using the NE.The newton euler methods relys on the fundamental principle of newtons motion law and the dAlembert principle.The force that is action at the center of the mass of the link is given by?F,Force m,mass,?linear acceleration of the link The euler equation for rotational movement is defined and characterize by the following equation.The angular velocity,wi and the moment of the inertia tensor Ii relates to the total moment,Ni as follows?International Conference on Control,Instrumentation and Mechatronics Engineering(CIM07),Johor Bahru,Johor,Malaysia,May 28-29,2007728 In the recursive newton euler method,involves two part of computation.The first part is the forward iteration which involves the calculation of the velocity and acceleration starting from the base and moving towards the end-effector.The second part is the backward iteration whereby we use the velocity and acceleration that was computed initially and starting from the end-effector to calculate the force and moment and moving backwards towards the base frame.The following equation summarizes the backward iteration calculation?whereby iRi+1 is the rotational matrix of frame i+1 with respect to frame i,D is the position matrix.f and n is the force that is acting at the joints itself.is the torque which is required for the joints which depends either the joints are prismatic or revolute.4.Hydrodynamics In order to accurately model underwater manipulator,we are required to take into account additional effect that is caused by the motion of the incompressible fluids itself.These forces are a result from incompressible fluids which is determined by the Navier-Stokes equation5.In this paper we would consider 4 major hydrodynamics effect which are the added mass,added coriolis and centripetal,drag force and buoyancy.4.1 Added Mass The added mass is generated when a rigid body moves in a fluid.The fluid will also be accelerated by the movement of the body which requires an additional force.This effect is neglected in typical industrial robotic due to the low density of the air
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