多功能封口機的設(shè)計【含CAD高清圖紙和說明書】

【溫馨提示】 dwg后綴的文件為CAD圖，可編輯，無水印，高清圖，壓縮包內(nèi)文檔可直接點開預(yù)覽，需要原稿請自助充值下載，請見壓縮包內(nèi)的文件，所見才能所得，下載可得到【資源目錄】下的所有文件哦-有疑問可咨詢QQ:1304139763 或 414951605 International Journal of Engineering and Technology Volume 2 No. 10, October, 2012An Inverse Kinematic Analysis of a Robotic SealerAkinola A. Adeniyi 1, Abubakar Mohammed 2, Aladeniyi Kehinde 31Department of Mechanical Engineering, University of Ilorin, Ilorin, Nigeria2Department of Mechanical Engineering, Federal University of Technology, Minna, Nigeria3Department of Science Laboratory Technology, Rufus Giwa Polytechnic, Owo, NigeriaABSTRACTA planar robotic sealing or brand stamping machine is presented for an automated factory line. The appropriate time to seal or to stamp an object is basically determined by a motor controller which relies critically on whether or not the object is in the best position. The extent of protraction and retraction of the piston head is largely dictated by an infrared sensor. Given the extent to protract or retract the piston head, the angular displacements of the link required are determined using the Inverse Kinematic (IK) techniques. The inertia and gravity effects of the links have been ignored to reduce the complexity of the equations and to demonstrate the technique.Keywords: Forward Kinematics, Inverse Kinematics, Robotics, Sealer1. INTRODUCTION An automated factory uses a number of mechanical links electronically controlled to achieve tasks. The benefits of factory automation are many and of strategic importance to management 1. Standard mechanical links are usually powered with electrical motors, pneumatic systems or solenoids. In a manually operated machine, the human performs visual checks and other standard checks that are to be replicated by automation. The interest of this work is centered on a hypothetical sealing machine which is used for stamping some signatures and logos as done in a branding factory line. Inverse kinematic analysis is applied to enable us determine angular displacements of the link. Kinematics involves the study of motion without consideration for the actuating forces. Inverse Kinematics (IK) is a method for determining the joint angles and desired position of the end-effectors given a desired goal to reach by the end effectors 1. A feasibility of using a PID controller was studied by Nagchaudhuri 2 for a slider crank mechanism but without an offset. Tolani et al 3 reviewed and grouped the techniques of solving inverse kinematics problems into seven. The techniques are the Newton-Raphsons method and its other variants. There are the Jacobian and the variants with pseudo-inverse (otherwise known as the Moore-Penrose inverse) for square or non-square Jacobian. Other methods are the control-theory based and the optimisation techniques. A number of authors 1, 4-7 have proposed algorithms for solving IK problems which include but not limited to Neural Network algorithm, Cyclic Coordinate Descent closure and Inexact strategy, but like every other techniques for a given problem the choice of method depends on the specifics of the problem.Buss 8 discussed the Jacobian transpose, the Moore-Penrose and the Damped Least Squares techniques. In terms of computational cost, the Jacobian transpose method is the cheap but can perform poorly based on the robot configurations. In this work the Jacobian transpose technique ill-performed but the Jacobian Inverse technique is suitable and more so it is a simple 2D planar representation of the problem with only 4 degrees of freedom.2. OPERATIONS OF THE ROBOTIC LINK Fig. 1 shows the schematic diagram of the robotic sealing system. The capping or stamping is achieved with the piston or ram head, P. C is the conveyor line. The caps or the branding heads are placed in position and sensed by an infrared sensor, S. The instruction to seal or brand is dependent on feedback from the sensor. If the item to be branded, capped or stamped is out of place at the instance when the ram head was going to touch, the sensor feedback will be to retract the head. It can also be to not go too far. There can be a range of feedback to the motor controller, M. This kind of control system is similar to what a human operator would do if it were manually operated. The use of sensors and fast responding motor controller will make this hypothetical machine a very useful tool in a factory performing this kind of mundane task. This factory sub-line is a simple slider-crank mechanism with actuator arm A. In clearer terms, the instructions would be to press the piston ram to seal if the cap and the container are in line; to reverse the piston in case of a jam; to not press the piston ram if either the container or the cap is absent; to press further if the seal length is shorter than expected as may be caused by wear and tear. This clearly shows that the piston determines the angle of the link or the direction or action of the motor. This is an inverse kinematics problem. The sensor feedback part is much of a control engineering problem, not considered in this paper.Fig. 1: The robotic sealing rig schematic3. ANALYSIS Fig. 2 is a representation of the slider-crank mechanism. There is an offset, f, of the piston axis from the motor axis, O1. O2 is the axis of the piston with moving coordinates (x,y). The motor rotates clockwise or counter clockwise about O1. If the crank makes displacement s on the piston plane, it is equivalent to a motion of ex and ey. This motion is caused by the crank making an angular motion clockwise or counter-clockwise, . The angle between the connecting rod and crank makes an angular displacement of, . This also means the angular shift of is made between the connecting rod and the piston or ram plane.Fig. 2: The offset slider crank (Cartesian coordinate world)In a computer game application for these, the angles would be explicitly required so that the links do not “physically disjoint”; for a physically connected link, the motor controller only would need the instruction to move only the crank.3.1 The World Cartesian coordinate system is adopted. Clockwise is positive and motion to right and upwards are positive. The Top Dead Centre (TDC) is attained when the crank, radius r, and the connecting rod, length l, are in line. This is attained when . fm is the maximum variable offset based on the geometry. The Bottom Dead Centre (BDC) is reached when . The TDC and BDC with the variable offset are shown in Fig. 3. Fig. 3: The Top and Bottom Dead centreThe piston has been constrained to move only in planar direction, on the vector of . In this work, the direction vector is , making the plane at 45 to the horizontal.3.2 The Forward Kinematics The displacement caused by the motor moving clockwise from the position in Fig. 2 is represented in equation (1). Where subscripts (i,f) are respectively mean initial and final values. The position at f is reached in reality smoothly for a rotating crank, but the smoothness can be reached in fine incremental steps, in the numerical approach. At the end of the stepped increments, the final displacement to the goal is seen as a function of angular parameters given as:The linear dependence of the angles, in this problem, can help to reduce the number of degrees of freedom to compute in equation (1). It can be shown that, there by making .Using trigonometry, the instantaneous initial, arbitrary, position of the piston in Fig. 2 is given by Equation (2)(3).The Jacobian matrix for is given in equation (4) and simplified to equation (5).Computing the new piston position involves solving equation (1). The new coordinate of the piston by the first term of expansion of the Taylor series can be shown to be given in equation (6). is the vector of the robot angular displacements for the related links. Mathematically, . Here, we have . Therefore the current position of the piston or the pressing head is approximately given in equation (6). It should be noted thatcan be measured from the horizontal to further reduce the equation sets, this is referred to as 0 elsewhere in this paper.3.3 Inverse Kinematics The problem is not that of solving for Xf given Xi andbut it is that of solving for given Xi, and the desired Xf. This is iteratively implemented such that the target displacement of the piston is given as .This is a vector of the piston displacement and can be represented as.Since this is a planar problem with no displacements in the other directions, it reduces to a.To smoothen the possible jerk or jumpy effect, this can be stepped using a factor ofwhich can be selected intuitively based on the ratio of r to L but and is the inverse of Jacobian matrix. The algorithm checks if the target has been reached or not. Iteration is stopped when the solution is within a pre-determined level of error or a maximum number of iterations. The choice of these limiting values should depend on the response time acceptable. This can be critical for a real time application.4. RESULT AND DISCUSSIONS Consider a current orientation of the robotic arm at any arbitrary position with the piston head at a position P. Suppose the sensor system requires the piston to move to a target new position P2. The simulation is done for several arbitrary starting positions of the crank and results are similar for reachable targets. Supposing the crank angle is at a current orientation with crank angle of -5, and there is an instruction from the sensor to retract the piston ram head by 0.1times the crank arm length. The simulation instructs the crank proceeds to counter clockwise by 15.58, this corresponds to an increase of0 to 19.26and correspondingly,reduces to 86.32. Fig. 4 shows the simulation progress of the piston head from a current position P1 to the new target P2 and the number of iterations done.Fig. 4: Crank Position and Iteration with the Jacobian Inverse MatrixThe technique used is the Jacobian inverse technique. The Jacobian transpose technique is not predictable for the same problem and in this case, the solution settles to a local minimum for only one of the angles but the convergence rate is faster, see Fig. 5.Fig. 5: Crank Positions using the Inverse and Transpose of the Jacobian MatrixIf there is a request to a physically unreachable target, such as to a more than the TDC or BDC locations, P3, the simulation runs and stops after the maximum number of iterations or if the Jacobian Matrix becomes un-invertible, Fig. 6.Fig. 6: Unreachable Target situation5. CONCLUSION This paper is focused on the application of the Inverse Kinematics technique to the analysis of a robotic link, such as obtained in a sealer of an automated factory, without consideration for the effects of inertia effects. The Jacobian inverse technique, as mentioned in literatures, is more reliable in this application. The Jacobian transpose approach is not reliable. This paper has demonstrated the application of the inverse kinematics to a simple robotic sealer; the piston is instructed to retract by 0.1 units as a test case. The new crank angle was found more accurately with the Jacobian Inverse technique better that the Jacobian Transpose technique. The problem can be extended to include the dynamics for possible selection of the optimal driving torque or electric motor selection for the driving parts.REFERENCES 1 S. Tejomurtula and S. Kak, Inverse Kinematics in robotics using neural networks, Information Sciences, vol. 116, pp. 147-164, 1999. 2 A. Nagchaudhuri, Mechantronic Redesign of Slider Crank Mechanism, in ASME International Mechnical Engineering Congress & Exposition: IMECE2002, New Orleans, Louisiana, 2002. 3 D. Tolani, A. Goswami, and N. I. Badler, Real-Time Inverse Kinematics Techniques for Anthromorphic Limbs, Graphical Models, vol. 62, pp. 353-388, 2000. 4 S. K. Saha and W. O. Schiehlen, Recursive Kinematics and Dynamics for Parallel Structured Closed-Loop multibody Systems, Mechanics of Structures and Machines, vol. 29, pp. 143-175, 2007. 5 X. Wang, A behavior-based inverse kinematics algorithm to predict arm prehension postures for computer-aided ergonomic evaluation, Journal of Biomechanics, vol. 32, pp. 453-460, 1999. 6 A. C. Nearchou, Solving the inverse kinematics problem of redundant robots operating in complex environments via a modified genetic algorithm, Mechanism and Machine Theory, vol. 33, pp. 273-292, 1998. 7 M. J. D. Powell, Some Global Convergence Properties of a variable metric Algorithm for Minimization without Exact line searches, in Symposium in Applied Mathematics of the American Mathematical Society and the Society for Industrial and Applied Mathematics, New York City, 1976. 8 S. R. Buss, Introduction to Inverse Kinematics with Jocobian Transpose, Pseudoinverse and Damped Least Square methods, University of California, San Diego2009. 2011 年第 02 期 全面了解文獻綜述與科學論文的不同才有利于我們正確 的撰寫文獻綜述與科學論文 ，更好的進行科學研究 ，這是我們 每個大學生應(yīng)該和必須了解的 ， 是我們在完成學業(yè)過程中需 要很好了解并完成的一項任務(wù) 。 有利于我們培養(yǎng)獨立獲取知 識 、 信息處理和積極創(chuàng)新的能力以及專業(yè)文獻綜述的寫作能 力 。 1相關(guān)概念的界定 1.1 文獻綜述 文獻是將知識 、信息用文字 、符號 、圖像 、音頻等記錄在一 定的物質(zhì)載體上的結(jié)合體 ，它具有存貯知識 、傳遞和交流信息 的功能 ；綜述是作者在博覽群書的基礎(chǔ)上 ，綜合地介紹和評述 某學科領(lǐng)域國內(nèi)外研究成果和發(fā)展趨勢 ， 并表明作者自己的 觀點 ，對今后的發(fā)展進行預(yù)測 ，對有關(guān)問題提出中肯意見或建 議的論文 。 由此看出 ，所謂文獻綜述是在確定了選題后 ，在對選題所 涉及的研究領(lǐng)域的文獻進行廣泛閱讀和理解的基礎(chǔ)上 ， 對該 研究領(lǐng)域的研究現(xiàn)狀 （包括主要學術(shù)觀點 、前人研究成果和研 究水平 、爭論焦點 、存在的問題及可能的原因等 ）、新水平 、新 動態(tài) 、新技術(shù)和新發(fā)現(xiàn) 、發(fā)展前景等內(nèi)容進行綜合分析 、歸納 整理和評論 ， 并提出自己的見解和研究思路而寫成的一種不 同于科學的文體 。 從上述概念中 ，我們可以看出 ，文獻綜述具有以下幾個特 點 ：（1）對所查閱資料的主要觀點進行綜合整理 、陳述 ，反映的 原始文獻有一定的時間與空間范圍 ；（2） 在分析研究成果方 面 ，這里面只是筆者對別人成果的看法 ，并沒有自己實在的研 究成果 ；（3）根據(jù)自己的理解和認識 ，對綜合整理后的文獻進 行比較專門的 、全面的 、深入的 、系統(tǒng)的論述和相應(yīng)的評價 ，而 不僅僅是相關(guān)領(lǐng)域?qū)W術(shù)研究的 “堆砌 ”。 1.2 科學論文 科學論文是指某一學術(shù)課題在實驗性 、 理論性或觀測性 上具有新的科研成果或創(chuàng)新見解和知識的科學記錄 ； 或是某 種已知原理應(yīng)用于實際中取得新的科學總結(jié) ， 用以提供學術(shù) 會議上宣讀 、交流或討論 ；或在學術(shù)刊物上發(fā)表 ；或作其他用 途的書面文件 。 科學論文有以下幾個特點 ：（1）科學性 ，即文章中的論點 客觀公允 ，論論據(jù)充分可靠 ，論證嚴謹周密 ，有較強的邏輯性 ； （2）學術(shù)性 ，即要求論文對事物的客觀現(xiàn)象和外部特征作出描 述 ，站在一定的理論高度 ，揭示事物的內(nèi)在本質(zhì)和變化規(guī)律 ； （3）創(chuàng)新性 ，即論文中所闡述科研成果 ，與以往的研究相比 ，具 有創(chuàng)新或新穎的特點 。 2.寫作目的和意義上的區(qū)別 文獻綜述和科學論文本身都有其存在的價值 ， 文獻綜述 在科技論文 、畢業(yè)論文等論文中占據(jù)重要地位 ，而對一學術(shù)課 題有一定研究后都不同程度的要寫出科學論文 ， 兩者在寫作 目的和作用上有一定的區(qū)別 。 2.1 文獻綜述的目的和意義 文獻綜述的目的在于讓作者了解當前某一領(lǐng)域中某分支 學科或重要專題的最新進展 、學術(shù)見解和建議 ，而所了解的領(lǐng) 域一般也是作者將要發(fā)展或者研究的方向 。 再者 ，文獻綜述是 要為下一步的科學論文寫作奠定一個堅實的理論基礎(chǔ)和提供 某種延伸的契機 ， 而且能表明寫作者對既有研究文獻的歸納 分析和梳理整合的綜合能力 ， 從而有助于提高對科學論文水 平的總體評價 。 對于文獻綜述的意義具體表現(xiàn)在以下三個方 面 ： 2.1.1 有利于更新專業(yè)知識 、擴大了知識面 文獻綜述能夠反映當前某一領(lǐng)域或某一專題的演變規(guī) 律 、最新進展 、學術(shù)見解和發(fā)展趨勢 ,它的主題新穎 、資料全面 、 內(nèi)容豐富 、信息濃縮 。 因此 ，不論是撰寫還是閱讀文獻綜述 ，都 可以了解有關(guān)領(lǐng)域的新動態(tài) 、新技術(shù) 、新成果 、不斷更新知識 , 提高業(yè)務(wù)水平 。 通過搜集文獻資料過程 ，可進一步熟悉科學文 獻的查找方法和資料的積累方法 ； 在查找的過程中同時也進 一步的擴大了自己的知識面 。 2.1.2 有利于選擇科研方向 綜述通過對新成果 、新方法 、新技術(shù) 、新觀點的綜合分析 和評述 , 查找文獻資料 、寫文獻綜述是科研選題及進行科研的 第一步 ，能夠幫助科技人員發(fā)現(xiàn)和選取新的科研課題 ,避免重 復 ，因此寫文獻綜述也是為今后科研活動打基礎(chǔ)的過程 。 2.1.3 有利于查閱相關(guān)資料 由于科學技術(shù)的迅速發(fā)展 , 每時每刻都有大量的文獻產(chǎn) 生 ,要全部閱讀這些文獻 ,時間和精力都是不夠的 ,通過閱讀綜 述 ,可以在較短的時間內(nèi)了解有關(guān)領(lǐng)域的發(fā)展情況 、發(fā)展趨勢 , 節(jié)省大量的時間 。 總體來說文獻綜述有利于提高獨立工作的能力和科研能 力 。 2.2 科學論文的目的和意義 科學論文是對某個科學領(lǐng)域中的學術(shù)問題進行研究后表 述科學研究成果的理論文章 ，目的在于表達觀點及研究結(jié)論 ，傳 播科研結(jié)果 。 其一般要在公開場合宣讀 、交流 、討論或在學術(shù)刊 物上發(fā)表 。 對于科學論文的意義具體表現(xiàn)在以下幾個方面 ： 2.2.1 貯存科研信息 在科學研究完成之后 ，需對其研究結(jié)果立即加以總結(jié) ，并 以論文或報告的形式闡明其發(fā)現(xiàn)及發(fā)明 。 科學論文的寫作就 是貯存這些科研信息 ，使它成為以后新的發(fā)明 、發(fā)現(xiàn)的基礎(chǔ) ， 以利于科學技術(shù)事業(yè)的延續(xù)和發(fā)展 ， 不斷的豐富人類科技寶 庫 。人類文明的延續(xù)與發(fā)展 ，正是憑借著這種連續(xù)性不斷地 積 累 、創(chuàng)造 、再積累 、再創(chuàng)造的過程中實現(xiàn)的 。 因此科學論文是貯 存科研信息的重要載體 。 2.2.2 交流實踐經(jīng)驗 ，啟迪學術(shù)思想 科學論文在大量的科研成果和實踐基礎(chǔ)上形成 ， 不同學 者的不同學術(shù)思想及實踐經(jīng)驗通過科學論文的形式進行不斷 的探索與交流 ，可以相互啟迪 ，促進科學事業(yè)的發(fā)展 。 2.2.3 培養(yǎng)科研能力 ，提高研究水平 科學論文寫作是一種創(chuàng)造性的腦力勞動 ， 它凝聚著巨大 的艱辛 。 在寫作的過程中 ，隨著思維 的深化 ，可提高科技工作 中分析問題與解決問題的能力 ，促進科研水平的提高 。 與此同 時 ， 它能培養(yǎng)作者理論聯(lián)系實際的工作作風和嚴肅認真的科 學態(tài)度 ，從而進一步鍛煉和提高作者的分析論證能力 、工程設(shè) 計能力和外語能力等 。 科 淺析文獻綜述與科學論文的區(qū)別 胡 波 楊 帆 吳金城 （南京農(nóng)業(yè)大學食品科技學院 江蘇 南京 210095） 【摘 要 】文獻綜述與科學論文是我們每個大學生所必須了解和掌握的一門課程 ，也是完成學業(yè)過程中要完成的一項任務(wù) 。而 兩者之間存在著一定的區(qū)別 ，本文在兩者的概念 、目的及其意義 、寫作方法等方面的區(qū)別進行了闡述 。 【關(guān)鍵詞 】文獻綜述 ;科學論文 ;區(qū)別 高教論述 52