一、伺服系統是什么意思
伺服系(xi)(xi)(xi)統(tong)(tong)(tong)(servomechanism)又稱(cheng)隨動(dong)系(xi)(xi)(xi)統(tong)(tong)(tong),是(shi)(shi)(shi)用(yong)來精確地跟隨或(huo)復現(xian)某個過程的(de)(de)反(fan)饋控(kong)(kong)(kong)制(zhi)系(xi)(xi)(xi)統(tong)(tong)(tong)。伺服系(xi)(xi)(xi)統(tong)(tong)(tong)使(shi)物體的(de)(de)位(wei)置(zhi)、方位(wei)、狀態(tai)等(deng)輸(shu)(shu)(shu)出被控(kong)(kong)(kong)量能(neng)夠跟隨輸(shu)(shu)(shu)入目標(biao)(或(huo)給定(ding)值)的(de)(de)任(ren)(ren)意變化的(de)(de)自動(dong)控(kong)(kong)(kong)制(zhi)系(xi)(xi)(xi)統(tong)(tong)(tong)。它的(de)(de)主要(yao)任(ren)(ren)務(wu)是(shi)(shi)(shi)按(an)控(kong)(kong)(kong)制(zhi)命令(ling)的(de)(de)要(yao)求、對功率(lv)進行放大(da)、變換(huan)與調控(kong)(kong)(kong)等(deng)處(chu)理(li),使(shi)驅動(dong)裝置(zhi)輸(shu)(shu)(shu)出的(de)(de)力(li)矩、速度(du)和位(wei)置(zhi)控(kong)(kong)(kong)制(zhi)非(fei)常靈活方便。在很多情況下,伺服系(xi)(xi)(xi)統(tong)(tong)(tong)專指被控(kong)(kong)(kong)制(zhi)量(系(xi)(xi)(xi)統(tong)(tong)(tong)的(de)(de)輸(shu)(shu)(shu)出量)是(shi)(shi)(shi)機(ji)械位(wei)移或(huo)位(wei)移速度(du)、加(jia)速度(du)的(de)(de)反(fan)饋控(kong)(kong)(kong)制(zhi)系(xi)(xi)(xi)統(tong)(tong)(tong),其(qi)(qi)作用(yong)是(shi)(shi)(shi)使(shi)輸(shu)(shu)(shu)出的(de)(de)機(ji)械位(wei)移(或(huo)轉角(jiao))準(zhun)確地跟蹤(zong)輸(shu)(shu)(shu)入的(de)(de)位(wei)移(或(huo)轉角(jiao)),其(qi)(qi)結構組(zu)成和其(qi)(qi)他形(xing)式的(de)(de)反(fan)饋控(kong)(kong)(kong)制(zhi)系(xi)(xi)(xi)統(tong)(tong)(tong)沒(mei)有(you)原(yuan)則上的(de)(de)區別。伺服系(xi)(xi)(xi)統(tong)(tong)(tong)最初用(yong)于國防(fang)軍工,如火炮的(de)(de)控(kong)(kong)(kong)制(zhi),船艦、飛(fei)機(ji)的(de)(de)自動(dong)駕駛(shi),導彈發射等(deng),后來逐漸(jian)推廣到國民經濟的(de)(de)許多部門,如自動(dong)機(ji)床、無(wu)線跟蹤(zong)控(kong)(kong)(kong)制(zhi)等(deng)。
二、伺服系統由哪幾個部分組成
伺(si)服(fu)系統主要(yao)由三部分組成:控制器,功率驅(qu)動(dong)(dong)(dong)裝置(zhi)和電(dian)動(dong)(dong)(dong)機(ji)(ji)。控制器按(an)(an)照數控系統的(de)給定(ding)值和通過反(fan)饋(kui)裝置(zhi)檢測(ce)的(de)實際運行值的(de)差,調節控制量;功率驅(qu)動(dong)(dong)(dong)裝置(zhi)作(zuo)為(wei)系統的(de)主回路,一(yi)方面按(an)(an)控制量的(de)大(da)小(xiao)將(jiang)電(dian)網中(zhong)的(de)電(dian)能作(zuo)用(yong)到電(dian)動(dong)(dong)(dong)機(ji)(ji)之上(shang),調節電(dian)動(dong)(dong)(dong)機(ji)(ji)轉(zhuan)矩的(de)大(da)小(xiao),另(ling)一(yi)方面按(an)(an)電(dian)動(dong)(dong)(dong)機(ji)(ji)的(de)要(yao)求把恒壓(ya)恒頻的(de)電(dian)網供電(dian)轉(zhuan)換為(wei)電(dian)動(dong)(dong)(dong)機(ji)(ji)所(suo)需的(de)交流(liu)電(dian)或直(zhi)流(liu)電(dian);電(dian)動(dong)(dong)(dong)機(ji)(ji)則按(an)(an)供電(dian)大(da)小(xiao)拖動(dong)(dong)(dong)機(ji)(ji)械運轉(zhuan)。
三、伺服系統的主要作用
1、以(yi)小功率指令信號去(qu)控(kong)制大功率負(fu)載(zai)。
2、在沒有(you)機(ji)械連(lian)接的情況下,由(you)輸入軸控(kong)制位(wei)于遠處(chu)的輸出軸,實現遠距同步(bu)傳動。
3、使輸(shu)出機械(xie)位移精確地跟蹤電(dian)信號,如記錄和指示儀表等(deng)。
四、伺服系統的類型有哪些
1、從系統組成元件的性質來(lai)看,有電氣(qi)伺服系統、液壓伺服系統和電氣(qi)-液壓伺服系統及(ji)電氣(qi)-電氣(qi)伺服系統等。
2、從系統輸出量(liang)的物理性(xing)質來(lai)看,有速(su)度或加速(su)度伺(si)服(fu)(fu)系統和(he)位(wei)置伺(si)服(fu)(fu)系統等。
3、從系(xi)(xi)統(tong)(tong)中所包(bao)含的元件特性和(he)信(xin)號作用特點(dian)來看,有模擬(ni)式伺(si)服(fu)系(xi)(xi)統(tong)(tong)和(he)數字式伺(si)服(fu)系(xi)(xi)統(tong)(tong)。
4、從系(xi)統(tong)的結構(gou)特點來看,有(you)單回(hui)伺(si)服(fu)(fu)系(xi)統(tong)、多回(hui)伺(si)服(fu)(fu)系(xi)統(tong)和開(kai)環(huan)伺(si)服(fu)(fu)系(xi)統(tong)、閉環(huan)伺(si)服(fu)(fu)系(xi)統(tong)。
5、伺(si)服系(xi)統(tong)按其驅動元件劃分,有步進式(shi)伺(si)服系(xi)統(tong)、直流電(dian)動機(ji)(簡稱(cheng)直流電(dian)機(ji))伺(si)服系(xi)統(tong)、交流電(dian)動機(ji)(簡稱(cheng)交流電(dian)機(ji))伺(si)服系(xi)統(tong)。
五、伺服系統的主要特點
1、精(jing)確的檢測裝置:以(yi)組(zu)成速度和位(wei)置閉環控制;
2、有多種反饋比較原理與方法:根據檢測裝置實現信息反饋的原理不同,伺服系統反(fan)饋比(bi)較(jiao)的(de)方法也不(bu)相同。常用的(de)有(you)脈(mo)沖(chong)比(bi)較(jiao)、相位比(bi)較(jiao)和幅值比(bi)較(jiao)3種;
3、高(gao)性能(neng)的伺服電動(dong)(dong)機(ji)(ji)(ji)(簡稱伺服電機(ji)(ji)(ji)):用于(yu)高(gao)效和復(fu)雜型面加工的數控(kong)機(ji)(ji)(ji)床,伺服系(xi)統將經常處于(yu)頻繁的啟(qi)動(dong)(dong)和制動(dong)(dong)過程中。要求電機(ji)(ji)(ji)的輸出(chu)力(li)矩與(yu)轉(zhuan)動(dong)(dong)慣量(liang)的比(bi)值大,以產(chan)生足夠大的加速(su)或制動(dong)(dong)力(li)矩。要求伺服電機(ji)(ji)(ji)在低速(su)時有足夠大的輸出(chu)力(li)矩且運轉(zhuan)平穩(wen),以便(bian)在與(yu)機(ji)(ji)(ji)械運動(dong)(dong)部分連(lian)接(jie)中盡量(liang)減少中間環節;
4、寬(kuan)調(diao)速(su)(su)范圍的速(su)(su)度(du)(du)調(diao)節(jie)系(xi)(xi)統(tong)(tong)(tong),即速(su)(su)度(du)(du)伺(si)服(fu)系(xi)(xi)統(tong)(tong)(tong):從系(xi)(xi)統(tong)(tong)(tong)的控制結構看,數控機床的位(wei)(wei)置閉環(huan)系(xi)(xi)統(tong)(tong)(tong)可看作是位(wei)(wei)置調(diao)節(jie)為(wei)外環(huan)、速(su)(su)度(du)(du)調(diao)節(jie)為(wei)內環(huan)的雙閉環(huan)自動控制系(xi)(xi)統(tong)(tong)(tong),其內部的實際(ji)工作過程(cheng)是把位(wei)(wei)置控制輸入(ru)轉換成相應(ying)的速(su)(su)度(du)(du)給定(ding)信號后,再通過調(diao)速(su)(su)系(xi)(xi)統(tong)(tong)(tong)驅(qu)動伺(si)服(fu)電機,實現(xian)實際(ji)位(wei)(wei)移。數控機床的主運動要求調(diao)速(su)(su)性(xing)能(neng)也比較高,因此要求伺(si)服(fu)系(xi)(xi)統(tong)(tong)(tong)為(wei)高性(xing)能(neng)的寬(kuan)調(diao)速(su)(su)系(xi)(xi)統(tong)(tong)(tong)。
六、伺服系統的性能要求
對伺服系統的基本要求有穩定性、精度、快速響應(ying)性和節能。
1、穩定性好
作(zuo)(zuo)用在系(xi)統上的(de)擾(rao)(rao)動消(xiao)失后,系(xi)統能(neng)夠(gou)恢復到(dao)原來的(de)穩定(ding)(ding)狀(zhuang)(zhuang)態(tai)下運行或(huo)者在輸入指令信號作(zuo)(zuo)用下,系(xi)統能(neng)夠(gou)達(da)到(dao)新的(de)穩定(ding)(ding)運行狀(zhuang)(zhuang)態(tai)的(de)能(neng)力,在給定(ding)(ding)輸入或(huo)外界干擾(rao)(rao)作(zuo)(zuo)用下,能(neng)在短暫的(de)調節過程后到(dao)達(da)新的(de)或(huo)者回復到(dao)原有平衡狀(zhuang)(zhuang)態(tai)。
2、精度高
伺服系統的(de)精(jing)度(du)(du)是指輸出量能跟隨(sui)輸入量的(de)精(jing)確程度(du)(du)。作(zuo)為精(jing)密加(jia)(jia)工(gong)(gong)的(de)數(shu)控機(ji)床(chuang),要求的(de)定位精(jing)度(du)(du)或輪廓加(jia)(jia)工(gong)(gong)精(jing)度(du)(du)通(tong)常都(dou)比較高,允許的(de)偏差一般都(dou)在0.01~0.001mm之間。
3、快速響應性好
有兩方面(mian)含(han)義(yi),一(yi)(yi)是指(zhi)動態(tai)響(xiang)應過(guo)程(cheng)中,輸出(chu)量(liang)隨輸入指(zhi)令信號變化的迅(xun)速(su)程(cheng)度(du),二是指(zhi)動態(tai)響(xiang)應過(guo)程(cheng)結束的迅(xun)速(su)程(cheng)度(du)。快速(su)響(xiang)應性是伺服系統動態(tai)品質的標志之一(yi)(yi),即要(yao)(yao)求(qiu)跟蹤(zong)指(zhi)令信號的響(xiang)應要(yao)(yao)快,一(yi)(yi)方面(mian)要(yao)(yao)求(qiu)過(guo)渡(du)過(guo)程(cheng)時(shi)間短(duan),一(yi)(yi)般在200ms以內,甚至小(xiao)于幾十毫(hao)秒;另(ling)一(yi)(yi)方面(mian),為(wei)滿足(zu)超調要(yao)(yao)求(qiu),要(yao)(yao)求(qiu)過(guo)渡(du)過(guo)程(cheng)的前沿陡(dou),即上升率(lv)要(yao)(yao)大。
4、節能高
由于(yu)伺服系統的(de)快速相應,注(zhu)塑(su)機(ji)能夠根據自(zi)身(shen)的(de)需要對供給(gei)進行快速的(de)調整,能夠有效提高注(zhu)塑(su)機(ji)的(de)電能的(de)利用率,從(cong)而達到(dao)高效節能。