As the complexity of flight tasks increases , the linearized equation based on the small disturbance theory is no longer adequate for the design of control systems , and the necessity of exploring a nonlinear approach seems increasingly obvious 隨著飛機(jī)飛行任務(wù)不斷趨向復(fù)雜化,基于小擾動(dòng)線性化方程的線性系統(tǒng)設(shè)計(jì)方法已經(jīng)難以滿足現(xiàn)代飛機(jī)飛控系統(tǒng)的設(shè)計(jì)要求。這就迫使我們研究飛機(jī)的非線性控制律的設(shè)計(jì)方法。
As the complexity of flight tasks increases , the linearized equation based on the small disturbance theory is no longer adequate for the design of control systems , and the necessity of exploring a nonlinear approach seems increasingly obvious 隨著飛機(jī)飛行任務(wù)不斷趨向復(fù)雜化,飛機(jī)的動(dòng)態(tài)模型具有顯著的非線性,基于小擾動(dòng)線性化方程的線性系統(tǒng)設(shè)計(jì)方法已經(jīng)難以滿足系統(tǒng)設(shè)計(jì)的要求。這就迫使我們研究飛機(jī)的非線性設(shè)計(jì)方法。
In chapter 3 , the non - linear equation was linearized with the jacobi matrix , and then the linearized equation was transformed into fixed frame to analyze the stability problem with eigenvalue method ( on - ground or hovering ) or floquet theory ( forward flight ) . meanwhile , the equation was perturbed by sweep frequency excitation from steady state to get transit decay of lag response which was then transformed into fixed frame with a numerical fourier coordination transformation ( fct ) . the fixed frame response along with the body response was analyzed via an fft to determine modal frequencies 然后,在穩(wěn)態(tài)響應(yīng)的基礎(chǔ)上利用雅各比矩陣對(duì)非線性方程進(jìn)行了線化,線化后的方程利用多槳葉坐標(biāo)變換轉(zhuǎn)換到固定系下后,利用直接特征值分析(地面、懸停)或floquet理論(前飛)對(duì)系統(tǒng)進(jìn)行了穩(wěn)定性分析;同時(shí),對(duì)系統(tǒng)進(jìn)行了瞬態(tài)響應(yīng)分析;在系統(tǒng)達(dá)到穩(wěn)態(tài)的基礎(chǔ)上進(jìn)行掃頻激勵(lì),用fft變換求得系統(tǒng)頻率,進(jìn)而用移動(dòng)矩形窗方法分析得到系統(tǒng)的阻尼。