龍門式機械手結構設計
龍門式機械手結構設計,龍門,機械手,結構設計
2.3機械手手臂結構的設計
按照抓取工件的要求，車床上料機械手的手臂有三個自由度，及手臂的伸縮、左右回轉和降（或俯仰）運動。手臂的回轉和升降運動是通過立柱來實現(xiàn)的，立柱的橫向移動即為手臂的橫移。手臂的各種運動有氣缸來實現(xiàn)。
2.3.1機械手手臂設計要求
機器人手臂的作用，是在一定的載荷和一定的速度下，實現(xiàn)在機器人所要求的工作空間內的運動。在進行機器人手臂設計時，要遵循下述原則；
1.應盡可能使機器人手臂各關節(jié)軸相互平行；相互垂直的軸應盡可能相交于一點，這樣可以使機器人運動學正逆運算簡化，有利于機器人的控制。
2.機器人手臂的結構尺寸應滿足機器人工作空間的要求。工作空間的形狀和大小與機器人手臂的長度，手臂關節(jié)的轉動范圍有密切的關系。但機器人手臂末端工作空間并沒有考慮機器人手腕的空間姿態(tài)要求，如果對機器人手腕的姿態(tài)提出具體的要求，則其手臂末端可實現(xiàn)的空間要小于上述沒有考慮手腕姿態(tài)的工作空間。
3.為了提高機器人的運動速度與控制精度，應在保證機器人手臂有足夠強度和剛度的條件下，盡可能在結構上、材料上設法減輕手臂的重量。力求選用高強度的輕質材料，通常選用高強度鋁合金制造機器人手臂。目前，在國外，也在研究用碳纖維復合材料制造機器人手臂。碳纖維復合材料抗拉強度高，抗振性好，比重小（其比重相當于鋼的1/4，相當于鋁合金的2/3），但是，其價格昂貴，且在性能穩(wěn)定性及制造復雜形狀工件的工藝上尚存在問題，故還未能在生產實際中推廣應用。目前比較有效的辦法是用有限元法進行機器人手臂結構的優(yōu)化設計。在保證所需強度與剛度的情況下，減輕機器人手臂的重量。
4.機器人各關節(jié)的軸承間隙要盡可能小，以減小機械間隙所造成的運動誤差。因此，各關節(jié)都應有工作可靠、便于調整的軸承間隙調整機構。
5.機器人的手臂相對其關節(jié)回轉軸應盡可能在重量上平衡，這對減小電機負載和提高機器人手臂運動的響應速度是非常有利的。在設計機器人的手臂時，應盡可能利用在機器人上安裝的機電元器件與裝置的重量來減小機器人手臂的不平衡重量，必要時還要設計平衡機構來平衡手臂殘余的不平衡重量。
6.機器人手臂在結構上要考慮各關節(jié)的限位開關和具有一定緩沖能力的機械限位塊，以及驅動裝置，傳動機構及其它元件的安裝。
2.3.2設計具體采用方案
機械手的垂直手臂（大臂）升降和水平手臂（小臂）的伸縮運動都為直線運動。直線運動的實現(xiàn)一般是氣動傳動，液壓傳動以及電動機驅動滾珠絲杠來實現(xiàn)?？紤]到搬運工件的重量較大，考慮加工工件的質量達30KG，屬中型重量，同時考慮到機械手的動態(tài)性能及運動的穩(wěn)定性，安全性，對手臂的剛度有較高的要求。綜合考慮，兩手臂的驅動均選擇液壓驅動方式，通過液壓缸的直接驅動，液壓缸既是驅動元件，又是執(zhí)行運動件，不用再設計另外的執(zhí)行件了；而且液壓缸實現(xiàn)直線運動，控制簡單，易于實現(xiàn)計算機的控制。
因為液壓系統(tǒng)能提供很大的驅動力，因此在驅動力和結構的強度都是比較容易實現(xiàn)的，關鍵是機械手運動的穩(wěn)定性和剛度的滿足。因此手臂液壓缸的設計原則是缸的直徑取得大一點（在整體結構允許的情況下），再進行強度的較核。
同時，因為控制和具體工作的要求，機械手的手臂的結構不能太大，若僅僅通過增大液壓缸的缸徑來增大剛度，是不能滿足系統(tǒng)剛度要求的。因此，在設計時另外增設了導桿機構，小臂增設了兩個導桿，與活塞桿一起構成等邊三角形的截面形式，盡量增加其剛度；大臂增設了四個導桿，成正四邊形布置，為減小質量，各個導桿均采用空心結構。通過增設導桿，能顯著提高機械手的運動剛度和穩(wěn)定性，比較好的解決了結構、穩(wěn)定性的問題。
2.4機械手腕部的結構設計
機器人的手臂運動（包括腰座的回轉運動），給出了機器人末端執(zhí)行器在其工作空間中的運動位置，而安裝在機器人手臂末端的手腕，則給出了機器人末端執(zhí)行器在其工作空間中的運動姿態(tài)。機器人手腕是機器人操作機的最末端，它與機器人手臂配合運動，實現(xiàn)安裝在手腕上的末端執(zhí)行器的空間運動軌跡與運動姿態(tài)，完成所需要的作業(yè)動作。
2.4.1機器人手腕結構的設計要求
1.機器人手腕的自由度數(shù)，應根據(jù)作業(yè)需要來設計。機器人手腕自由度數(shù)目愈多，各關節(jié)的運動角度愈大，則機器人腕部的靈活性愈高，機器人對對作業(yè)的適應能力也愈強。但是，自由度的增加，也必然會使腕部結構更復雜，機器人的控制更困難，成本也會增加。因此，手腕的自由度數(shù)，應根據(jù)實際作業(yè)要求來確定。在滿足作業(yè)要求的前提下，應使自由度數(shù)盡可能的少。一般的機器人手腕的自由度數(shù)為2至3個，有的需要更多的自由度，而有的機器人手腕不需要自由度，僅憑受臂和腰部的運動就能實現(xiàn)作業(yè)要求的任務。因此，要具體問題具體分析，考慮機器人的多種布局，運動方案，選擇滿足要求的最簡單的方案。
2.機器人腕部安裝在機器人手臂的末端，在設計機器人手腕時，應力求減少其重量和體積，結構力求緊湊。為了減輕機器人腕部的重量，腕部機構的驅動器采用分離傳動。腕部驅動器一般安裝在手臂上，而不采用直接驅動，并選用高強度的鋁合金制造。
3.機器人手腕要與末端執(zhí)行器相聯(lián)，因此，要有標準的聯(lián)接法蘭，結構上要便于裝卸末端執(zhí)行器。
4.機器人的手腕機構要有足夠的強度和剛度，以保證力與運動的傳遞。
5.要設有可靠的傳動間隙調整機構，以減小空回間隙，提高傳動精度。
6.手腕各關節(jié)軸轉動要有限位開關，并設置硬限位，以防止超限造成機械損壞。
2.4.2設計具體采用方案
通過對數(shù)控機床上下料作業(yè)的具體分析，考慮數(shù)控機床加工的具體形式及對機械手上下料作業(yè)時的具體要求，在滿足系統(tǒng)工藝要求的前提下提高安全和可靠性，為使機械手的結構盡量簡單，降低控制的難度，本設計手腕不增加自由度，實踐證明這是完全能滿足作業(yè)要求的，3個自由度來實現(xiàn)機床的上下料完全足夠。具體的手腕（手臂手爪聯(lián)結梁）結構見圖8。
圖8 車床上料機械手手指
2.5機械手末端執(zhí)行器（手爪）的結構設計
2.5.1機械手末端執(zhí)行器的設計要求
機器人末端執(zhí)行器是安裝在機器人手腕上用來進行某種操作或作業(yè)的附加裝置。機器人末端執(zhí)行器的種類很多，以適應機器人的不同作業(yè)及操作要求。末端執(zhí)行器可分為搬運用、加工用和測量用等。
搬運用末端執(zhí)行器是指各種夾持裝置，用來抓取或吸附被搬運的物體。
加工用末端執(zhí)行器是帶有噴槍、焊槍、砂輪、銑刀等加工工具的機器人附加裝置，用來進行相應的加工作業(yè)。
測量用末端執(zhí)行器是裝有測量頭或傳感器的附加裝置，用來進行測量及檢驗作業(yè)。
在設計機器人末端執(zhí)行器時，應注意以下問題；
1.機器人末端執(zhí)行器是根據(jù)機器人作業(yè)要求來設計的。一個新的末端執(zhí)行器的出現(xiàn)，就可以增加一種機器人新的應用場所。因此，根據(jù)作業(yè)的需要和人們的想象力而創(chuàng)造的新的機器人末端執(zhí)行器，將不斷的擴大機器人的應用領域。
2.機器人末端執(zhí)行器的重量、被抓取物體的重量及操作力的總和機器人容許的負荷力。因此，要求機器人末端執(zhí)行器體積小、重量輕、結構緊湊。
3.機器人末端執(zhí)行器的萬能性與專用性是矛盾的。萬能末端執(zhí)行器在結構上很復雜，甚至很難實現(xiàn)，例如，仿人的萬能機器人靈巧手，至今尚未實用化。目前，能用于生產的還是那些結構簡單、萬能性不強的機器人末端執(zhí)行器。從工業(yè)實際應用出發(fā)，應著重開發(fā)各種專用的、高效率的機器人末端執(zhí)行器，加之以末端執(zhí)行器的快速更換裝置，以實現(xiàn)機器人多種作業(yè)功能，而不主張用一個萬能的末端執(zhí)行器去完成多種作業(yè)。因為這種萬能的執(zhí)行器的結構復雜且造價昂貴。
4.通用性和萬能性是兩個概念，萬能性是指一機多能，而通用性是指有限的末端執(zhí)行器，可適用于不同的機器人，這就要求末端執(zhí)行器要有標準的機械接口（如法蘭），使末端執(zhí)行器實現(xiàn)標準化和積木化。
5.機器人末端執(zhí)行器要便于安裝和維修，易于實現(xiàn)計算機控制。用計算機控制最方便的是電氣式執(zhí)行機構。因此，工業(yè)機器人執(zhí)行機構的主流是電氣式，其次是液壓式和氣壓式（在驅動接口中需要增加電-液或電-氣變換環(huán)節(jié)）。
2.5.2機器人夾持器的運動和驅動方式
機器人夾持器及機器人手爪。一般工業(yè)機器人手爪，多為雙指手爪。按手指的運動方式，可分為回轉型和移動型，按夾持方式來分，有外夾式和內撐式兩種。
機器人夾持器（手爪）的驅動方式主要有三種
1.氣動驅動方式這種驅動系統(tǒng)是用電磁閥來控制手爪的運動方向，用氣流調節(jié)閥來調節(jié)其運動速度。由于氣動驅動系統(tǒng)價格較低，所以氣動夾持器在工業(yè)中應用較為普遍。另外，由于氣體的可壓縮性，使氣動手爪的抓取運動具有一定的柔順性，這一點是抓取動作十分需要的。
2.電動驅動方式電動驅動手爪應用也較為廣泛。這種手爪，一般采用直流伺服電機或步進電機，并需要減速器以獲得足夠大的驅動力和力矩。電動驅動方式可實現(xiàn)手爪的力與位置控制。但是，這種驅動方式不能用于有防爆要求的條件下，因為電機有可能產生火花和發(fā)熱。
3.液壓驅動方式液壓驅動系統(tǒng)傳動剛度大，可實現(xiàn)連續(xù)位置控制。
2.5.3機器人夾持器的典型結構
1.楔塊杠桿式手爪
利用楔塊與杠桿來實現(xiàn)手爪的松、開，來實現(xiàn)抓取工件。
2.滑槽式手爪
當活塞向前運動時，滑槽通過銷子推動手爪合并，產生夾緊動作和夾緊力，當活塞向后運動時，手爪松開。這種手爪開合行程較大，適應抓取大小不同的物體。
3.連桿杠桿式手爪
這種手爪在活塞的推力下，連桿和杠桿使手爪產生夾緊（放松）運動，由于杠桿的力放大作用，這種手爪有可能產生較大的夾緊力。通常與彈簧聯(lián)合使用。
4.齒輪齒條式手爪
這種手爪通過活塞推動齒條，齒條帶動齒輪旋轉，產生手爪的夾緊與松開動作。
5.平行杠桿式手爪
采用平行四邊形機構，因此不需要導軌就可以保證手爪的兩手指保持平行運動，比帶有導軌的平行移動手爪的摩擦力要小很多。
2.5.4設計具體采用方案
結合具體的工作情況，本設計采用連桿杠桿式的手爪。驅動活塞往復移動，通過活塞桿端部齒條，中間齒條及扇形齒條使手指張開或閉合。手指的最小開度由加工工件的直徑來調定。本設計按照工件的直徑為80--130mm來設計。手爪的具體結構形式如圖9所示：
圖9 手爪的具體結構
2.6機械手的機械傳動機構的設計
2.6.1工業(yè)機器人傳動機構設計應注意的問題
機器人是由多級聯(lián)桿和關節(jié)組成的多自由度的空間運動機構。除直接驅動型機器人以外，機器人各聯(lián)桿及各關節(jié)的運動都是由驅動器經過各種機械傳動機構進行驅動的。機器人所采用的傳動機構與一般機械的傳動機構相類似。常用的機械傳動機構主要有螺旋傳動、齒輪傳動、同步帶傳動、高速帶傳動等。由于傳動部件直接影響著機器人的精度、穩(wěn)定性和快速響應能力，因此，應設計和選擇滿足傳動間隙小，精度高，低摩擦、體積小、重量輕、運動平穩(wěn)、響應速度快、傳遞轉矩大、諧振頻率高以及與伺服電動機等其它環(huán)節(jié)的動態(tài)性能相匹配等要求的傳動部件。
在設計機器人的傳動機構時要注意以下問題：
1.為了提高機器人的運動速度及控制精度，要求機器人各運動部件的重量要輕，慣量要小。因此，機器人的傳動機構要力求結構緊湊，重量輕，體積小。
2.在傳動鏈及運動副中要采用間隙調整機構，以減小反向空回所造成的運動誤差。
3.系統(tǒng)傳動部件的靜摩擦力應盡可能小，動摩擦力應是盡可能小的正斜率，若為負斜率則易產生爬行，精度降低，壽命減小。因此，要采用低摩擦阻力的傳動部件和導向支承部件，如滾珠絲杠副、滾動導向支承等。
4.縮短傳動鏈，提高傳動與支承剛度，如用預緊的方法提高滾珠絲杠副和滾動導軌副的傳動和支承剛度；采用大扭矩、寬調速的直流或交流伺服電機直接與絲杠螺母副連接，以減小中間傳動機構；絲杠的支承設計采用兩端軸向預緊或預拉伸支承結構等。
5.選用最佳傳動比，以達到提高系統(tǒng)分辨率、減少等效到執(zhí)行元件輸出軸上的等效轉動慣量，盡可能提高加速能力。
6.縮小反向死區(qū)誤差，如采取消除傳動間隙、減少支承變形等措施。
7.適當?shù)淖枘岜?，機械零件產生共振時，系統(tǒng)的阻尼越大，最大振幅就越小，且衰減越快；但大阻尼也會使系統(tǒng)的失動量和反轉誤差增大，穩(wěn)態(tài)誤差增大，精度降低。故在設計時要使傳動機構的阻尼合適。
2.6.2工業(yè)機器人常用的傳動機構形式
1.齒輪傳動機構
在機器人中常用的齒輪傳動機構有圓柱齒輪，圓錐齒輪，諧波齒輪，擺線針輪及蝸輪蝸桿傳動等。
機器人系統(tǒng)中齒輪傳動設計的一些問題
齒輪傳動形式及其傳動比的最佳匹配選擇。齒輪傳動部件是轉矩、轉速和轉向的變換器用于伺服系統(tǒng)的齒輪減速器是一個力矩變換器。齒輪傳動比應滿足驅動部件與負載之間的位移及轉矩、轉速的匹配要求，其輸入電動機為高轉速，低轉矩，而輸出則為低轉速，高轉矩。故齒輪傳動系統(tǒng)要有足夠的剛度，還要求其轉動慣量盡量小，以便在獲得同一加速度時所需的轉矩小，即在同一驅動功率時，其加速度響應最大。齒輪的嚙合間隙會造成傳動死區(qū)（失動量），若該死區(qū)是閉環(huán)系統(tǒng)中，則可能造成系統(tǒng)不穩(wěn)定，常使系統(tǒng)產生低頻振蕩，因此要盡量采用齒側間隙小，精度高的齒輪；為盡量降低制造成本，要采用調整齒側間隙的方法來消除或減小嚙合間隙，從而提高傳動精度和系統(tǒng)的穩(wěn)定性。
2.3 manipulator arm structure design
According to the requirement, lathe to grab workpiece material arm has three degrees of freedom of the manipulator arm, and adjustable, turning around and drop (or pitch) movement.Turn and lifting movement of the arm is realized by pillar, column the lateral movement known as the shifting arm. Different campaigns have cylinder arm to realize.
2.3.1 manipulator arm design requirements
The robotic arm role, it is in a certain load and a certain speed, realize the work required in robot in space sport. When designing the robotic arm, follow the following principles;
1. Should as far as possible make the robotic arm each joint axis parallel; Perpendicular axis should as far as possible fellowship in a bit, so can make the robot kinematics inverse robot control simplifies, helps.
2. The robotic arm structure size should satisfy the requirements of robots work space. Working space shapes and sizes and robot arm length, arm joint rotation range have close relationship. But the robotic arm end work space does not consider the space robot wrist gesture requirements, if robot wrist gesture to specific request, it can realize space arms ends to less than the above did not consider the wrist gesture work space.
3. In order to improve the robot movement speed and control accuracy, should keep the robotic arm have enough under the condition of the strength and stiffness, as far as possible on the structure, material manage to reduce the weight of his arm. Strive to choose high intensity of lightweight materials, usually choose high-strength aluminum alloy manufacture a robotic arm. At present, in a foreign country, is also studying with carbon fiber composite materials manufacturing robot arm. Carbon fiber composite materials tensile strength, high ant-vibration sex good, small proportion (its proportion of 1/4 quite to steel, equivalent to aluminum alloy 2/3), but it is expensive, and in the performance stability and manufacturing complex shape workpiece exist problems of technology, it is not in application in practical production. At present more effective method is to use the finite element method for the optimization design of the robotic arm structure. The intensity and stiffness in ensuring the required under the weight of his arm, reduce the robot.
4. The robot of each joint bearing clearance as small as possible, in order to reduce to mechanical clearance error motion caused. Therefore, the joints should have reliable operation, easy adjustment bearing clearance adjustment institutions.
5. The robot arm relative to rotate the joints should as far as possible under the weight of the balance, the mechanical load and enhance decreases the response speed of the robotic arm movement is very favorable. In the design of robot arm, should as far as possible use in the robot of mechanical and electronic components and devices installed the weight of robotic arm to reduce weight, the unbalanced balancing mechanism when necessary to balance design remnants of unbalanced weight arm.
6. The robotic arm on the structure to consider all the joints with certain limit switches and buffering mechanical set blocks, and driving device, transmission mechanism and other components installed.
2.3.2 Design specific using scheme
Manipulator arm (arm) vertical lifting and level of arm (forearm) for linear motion telescopic movement. Linear motion realization is generally pneumatic transmission, hydraulic transmission and motor drive the ball screw to achieve. Considering the weight of carrying workpieces larger, consider the machining quality reaches the 30KG, belong to medium weight of the manipulator, and considering the stability of the dynamic performance and movement of the arm, the stiffness of safety, have higher demand. Comprehensive consideration, two arms driver all choose hydraulic drive mode, through hydraulic cylinder of direct drive, hydraulic cylinder is drive component and executive moving parts, and not to design another executive pieces; And the hydraulic cylinder realizing linear motion control simple, easy to realize the computer control.
For hydraulic system can provide great motivation, so in driving force and structural strength are relatively easy to implement, and the key is manipulator of stability and stiffness of the sports meet. Therefore the arm hydraulic cylinder of design principle is the diameter of the cylinder made great point (in overall structure's permission), then a nuclear strength.
manipulator arm cannot too big, if only by increasing the hydraulic cylinder of cylinder size to increase stiffness, cannot satisfy the system is the rigidity requirement. Therefore, in the design of the additional guide-bar mechanism, forearm add two guide bar, and piston rod together constitute an equilateral triangle section form, try to increase its stiffness; Big arms add four guide bar, a positive quadrilateral layout, to reduce the quality, each guide bar adopts hollow structure. By adding a guide bar, can significantly improve the stability and stiffness of the manipulator movement, good solve structure, reliability problems.
2.4 structure design of robot wrist
Robot arm movement (including the waist of the seat, and gives the rotary motion) robot end actuators in its working space position, which the movement in the end of the installation of robotic arm, then gives the wrist robot end actuators in the motion of its working space gesture. CaoZuoJi robot wrist is the end of the robot, and the robotic arm with exercise, realize the end of installation of wrist of actuators space with movement trajectory posture, finish the homework action needed.
2.4.1 The robot wrist structure design requirements
1. Freedom of robot wrist readings, should according to assignments need to design. The more robot wrist freedom, the number of each joint Angle, the robot wrist the greater flexibility of the robot is higher, the adaptability also rightness homework more strong. However, the increase of freedom, also will make the wrist structure more complex, robot control more difficult, costs will increase. Therefore, the wrist of freedom, should according to actual operation degree is required to determine. In meet operational requirements of the premise, should make free degree as less. General robot wrist freedom for 2 to 3 degree, some needs more freedom, and some robot wrist don't need freedom, with only the movement by the arm and waist can achieve operational requirements of the task. Therefore, to the concrete analysis of multiple layouts, consider robot, sports scheme, choose the simplest satisfy the requirements of the plan.
2. Robot wrist installed in the end of robot arm robot wrist, in the design, should strive to reduce the weight and volume to compact structure. In order to reduce the weight of robot wrist, wrist institutions drive sperating transmission. Wrist drive general installation in the arm, and do not adopt direct drive, and choose high-strength aluminum alloy manufacture.
3. Robot wrist to and end actuators connected, accordingly, want to have the standard connection to facilitate the flange, structure of loading and unloading end actuators.
4. Robot wrist institutions should have enough strength and stiffness, strength and movement to ensure the relay.
5. To have reliable transmission gap adjusting mechanism, to minimize returned empty clearance, improve the transmission precision.
6. The wrist of each joint axis rotation to limited a switch, and set limit to prevent hard out-of-gauge cause mechanical damage.
2.4.2 design specific adopts plan
Through the nc machine tools for feeding and unloading operations, considering the concrete analysis of concrete form CNC machine processing and manipulator up-down material operations in the specific requirements, and technological requirements of meet the system under the premise of improving safety and reliability of the structure of the manipulator, to make as far as possible simple, reduce the difficulty of the design and control of freedom, not to increase his wrist proved it is fully meet operational requirements of the three degrees of freedom, to realize the up-down material completely enough machine. Specific wrist (arms PAWS coupling beam) structure see figure 8.
Figure 8 . Lathe feeding manipulator finger
2.5 manipulator actuators (PAWS) structure designing
2.5.1 manipulator actuator design requirements
Robot end actuator is installed on the robot wrist used for an operation or additional device homework. Robot end, many different kinds of actuators, in order to adapt to the different assignments and operation robot requirements. End actuators can be divided into move use, processing with with and measurement etc.
Move use end actuators refers to all clamping device used to grab or adsorption transported objects.
Processing with end actuators with gun, welding torch is milling cutter, grinding wheel, such as the robot machining tool, used for additional device corresponding processing work.
With end actuator is measured with the additional head or sensors measuring device used to measuring and test operations.
In design robot end actuators, should pay attention to the following questions;
1. The robot end actuator is designed according to the operation requirement robot. A new terminal actuators occurrence, can increase a robotic new application places. Accordingly, according to the needs of the homework with people and create a new robot imagination, will continue at actuators expansion of the application field of robot.
2. The weight of the robot end actuators to grab objects and the sum of weight and operating force the load force. The robot allow Therefore, request the end-effector actuators small volume, light weight, compact structure.
3. The end-effector actuators with specificity is universal sexual paradox. Universal end actuators on the structure is complex, and even harder to achieve, for example, the universal humanoid multisensory dexterous robot hand yet practional utilization. At present, can be used to produce or those simple structure, universal sex not strong robot end actuators. Starting from the industrial application, should focus on the development of special, efficient robot end actuators, plus end actuators, in order to achieve the fast changing device of function, the robot is not advocated homework with a universal end actuators to complete variety of homework. Because this kind of everything the implementation of the structure is complex and expensive.
4. Versatility and universal sex are two concepts, universal sex machine, and refers to the multi-energy refers to the end of generality, limited actuators, suitable for different robots, which requires the end actuators have standard machine interface (such as flange), make end actuators realizes standardization and blocks digestion.
5. The end-effector actuators to facilitate installation and maintenance, easy to realize the computer control. Use computer control the most convenient is electric type actuator. Therefore, the industrial robot actuators mainstream is electric type, followed by the hydraulic and pneumatic type (in driving interface to increase electricity - liquid or electricity - air transform link).
2.5.2 robot grippers sports and drive mode
Robot grippers and machine hand claw. General industrial machine hand for double refers to how claws, PAWS. According to finger movement way, can be divided into back transformation and mobile type, press clamping way to points, within the clip type and supporting type two kinds.
Robot grippers (PAWS) drive mode basically has 3 kinds
1. Pneumatic drive mode this drive system is by electromagnetic valve to control the movement direction of the PAWS, with air regulator to adjust its movement speed. The pneumatic drive system of lower prices, so pneumatic grippers are widely used in industry. In addition, because gas compressibility, contentious hands-on claw grab motion has certain compliant sex, it is very need to grab action.
2. Electric drive mode of electric drive PAWS application also more widely. The PAWS, generally USES the dc servo motor or stepping motor, and need to get enough gear reducer driving force and torque. Electric drive mode can realize the force PAWS with position control. But this cannot be used for driving way under the condition of a explosion-proof requirements, because motor may produce sparks and fever.
3. Hydraulic drive mode hydraulic drive system transmission can achieve great stiffness.wherever continuous position control.
2.5.3 The typical structure robot grippers
1. Leveraged wedge PAWS
Using wedge block and levers to realize the pine, open PAWS, come to grab workpiece.
2. Slide groove PAWS
When the pistons forward movement, sliding channel through the pin PAWS merger, pushing produce clamping action and clamping force, when the pistons backward motion, PAWS loosen. This trip is larger, PAWS switching to grab different sizes of the object.
3. Connecting rod leveraged PAWS
The PAWS in Detroit, connecting rod and leverage thrust PAWS produce clamped to relax) movement, because (the force-magnifying function, leverage the PAWS might produce larger clamping force. Usually use a combination of and the spring.
4. Rack-and pinion type PAWS
The PAWS through the pistons pushing rack, rack driving gear rotating, produce the clamping PAWS with loosen action.
5. Parallel leveraged PAWS
Adopt parallelogram frame, so there is no need to guide can guarantee to keep the two fingers PAWS with parallel movement, the parallel rails than PAWS friction move to smaller.
2.5.4 design specific adopts plan
Combined with concrete works, this design USES the connecting rod of lever PAWS. Driven by piston, piston rod ends move, the middle rack and rack is fan rack makes the fingers open or closed. The minimum opening finger by machining diameter to the setting. This design according to the workpiece diameter of 80-130mm to design. The concrete structure form PAWS shown as shown in figure 9:
Figure 9 The specific structure PAWS
2.6 manipulator mechanical transmission design
2.6.1 industrial robot transmission mechanism design problems should be paid attention to
Robot is by multistage league stem and joint space composed of multi-degree-of-freedom sports organization. In addition to direct drive robot, robot outside each league rod and exercise is of each joint by drive through all kinds of mechanical transmission mechanism driven. Robot adopted the transmission mechanism
收藏