日本无码免费高清在线|成人日本在线观看高清|A级片免费视频操逼欧美|全裸美女搞黄色大片网站|免费成人a片视频|久久无码福利成人激情久久|国产视频一二国产在线v|av女主播在线观看|五月激情影音先锋|亚洲一区天堂av

  • 手機站
  • 小程序

    汽車測試網

  • 公眾號

    • 汽車測試網

    • 在線課堂

    • 電車測試

極限工況下的無人駕駛路徑跟蹤 | 斯坦福大學團隊最新研究成果

2018-09-26 23:56:49·  來源：集成與控制研究室 同濟智能汽車研究所  
　
5、試驗結果
 
試驗車輛安裝了普利司通的Potenza S-04輪胎來測試新的控制系統(tǒng)。斜坡轉角輸入的測試結果表明車輛的前后軸輪胎的等效側偏剛度分別為220kN/rad和240kN/rad，附著系數分別為0.99和1.04。直線制動測試結果表明前后軸的有效縱向剛度為450kN?？刂破髦械膮礨LA=10m，kp=1/s，kspeed=1000Ns/m。參考路徑設為一個半徑突變的逆時針圓周，從而驗證車輛的路徑跟蹤性能。試驗場地路面為向西傾斜2.5度的干凈柏油路面。
 圖8分別是路面附著系數的估計結果和輪胎側偏角跟蹤目標值，圓周半徑在77.5s的時候從18m變?yōu)?0m?；诠烙嫷妮喬担逯祩绕菫?.4度。測量的側偏角比目標值稍大，可能是由于側偏角控制器中轉向力矩的建模存在一定誤差，但是前軸的輪胎力也得到了充分的利用（如圖 6所示）。估計器的路面附著系數估計結果在1和1.1之間，與轉角斜坡輸入工況下的估計結果一致。
圖7是車輛跟蹤路徑時的車速目標值和測量值。較小的kp和較大的kspeed參數對車速跟蹤控制效果更好。如圖 9所示，側向位移誤差在轉向半徑突變后逐漸收斂，并最終穩(wěn)定在1m左右，車輛在目標軌跡的外側。而這部分偏差還需要更深入的研究。
圖8 路面附著系數估計結果（左）和路徑跟蹤的前軸側偏角的目標值和測量值（右）
圖9 路徑跟蹤結果（俯視）
 
6、結論
試驗數據表明在路徑跟蹤過程中的速度跟蹤控制和轉角控制需要路面附著系數的估計誤差在大約2%以內。然而，基于輪胎側偏角設計的轉角控制能夠有效降低系統(tǒng)對于路面附著系數估計結果精度的依賴。采集到的專業(yè)賽車駕駛員數據指出通過側偏角控制能夠使得不足轉向的車輛更充分地利用輪胎的附著能力，并且可以通過速度反饋來實現路徑跟蹤。
為了驗證這一理念，設計了根據虛擬橫擺角速度控制輸入得到的速度控制量來進行路徑跟蹤。貝葉斯濾波在線估計器和試驗數據表明，即使在路面附著系數不確定的條件下，控制器也能夠很好地跟蹤上圓周路徑。
不管是在賽道競速或者公路上的緊急工況，文章設計的控制架構在極限工況下的無人駕駛都能夠有很好地應用前景。未來的研究將進一步考慮縱向車速控制的建模、不同控制系統(tǒng)對附著系數的靈敏度、變曲率的路徑跟蹤、地形和輪胎的影響、以及路面附著系數不一致的情況。
 
7、參考文獻
[1] K. Kritayakirana, “Autonomous vehiclecontrol at the limits of handling,” Ph.D. dissertation, Stanford University,2012.
[2] C. E. Beal and J. C. Gerdes, “Modelpredictive control for vehicle stabilization at the limits of handling,” IEEETransactions on Control Systems Technology, vol. 21, no. 4, pp. 1258–1269,2013.
[3] Y.-H. J. Hsu, S. M. Laws, and J. C.Gerdes, “Estimation of tire slip angle and friction limits using steeringtorque,” IEEE Transactions on Control Systems Technology, vol. 18, no. 4, pp.896–907, 2010.
[4] J.-O. Hahn, R. Rajamani, and L.Alexander, “GPS-based real-time identification of tire-road frictioncoefficient,” IEEE Transactions on Control Systems Technology, vol. 10, no. 3,pp. 331–343, 2002.
[5] L. R. Ray, “Nonlinear estimation ofvehicle state and tire forces,” in American Control Conference, 1992. IEEE,1992, pp. 526–530.
[6] L. R. Ray, “Real time determination ofroad coefficient of friction for IVHS and advanced vehicle control,” inAmerican Control Conference, Proceedings of the 1995, vol. 3. IEEE, 1995, pp.2133–2137.
[7] L. R. Ray, “Nonlinear state and tireforce estimation for advanced vehicle control,” Control Systems Technology,IEEE Transactions on, vol. 3, no. 1, pp. 117–124, 1995.
[8] L. R. Ray, “Nonlinear tire forceestimation and road friction identification: Simulation and experiments,”Automatica, vol. 33, no. 10, pp. 1819–1833, 1997.
[9] L. R. Ray, “Experimental determinationof tire forces and road friction,” in American Control Conference, 1998.Proceedings of the 1998, vol. 3. IEEE, 1998, pp. 1843–1847.
[10] J. Subosits and J. C. Gerdes, “Asynthetic input approach to slip angle based steering control for autonomousvehicles,” in 2017 American Control Conference (ACC). IEEE, 2017 (in press).
[11] N. R. Kapania and J. C. Gerdes,“Design of a feedback-feedforward steering controller for accurate pathtracking and stability at the limits of handling,” Vehicle System Dynamics,vol. 53, no. 12, pp. 1687– 1704, 2015.
[12] H. Pacejka, Tyre and Vehicle Dynamics,3rd ed. Butterworth- Heinemann, 2012.
[13] R. Y. Hindiyeh, “Dynamics and controlof drifting in automobiles,” Ph.D. dissertation, Stanford University, 2013.
[14] C. Voser, R. Y. Hindiyeh, and J. C.Gerdes, “Analysis and control of high sideslip manoeuvres,” Vehicle SystemDynamics, vol. 48, no. S1, pp. 317–336, 2010.
[15] P. A. Theodosis and J. C. Gerdes,“Nonlinear optimization of a racing line for an autonomous racecar usingprofessional driving techniques,” in ASME 2012 5th Annual Dynamic Systems andControl Conference joint with the JSME 2012 11th Motion and VibrationConference. American Society of Mechanical Engineers, 2012, pp. 235–241.
[16] J. Subosits and J. C. Gerdes,“Autonomous vehicle control for emergency maneuvers: The effect of topography,”in 2015 American Control Conference (ACC). IEEE, 2015, pp. 1405–1410.
[17] N. R. Kapania, J. Subosits, and J. C.Gerdes, “A sequential two-step algorithm for fast generation of vehicle racingtrajectories,” Journal of Dynamic Systems, Measurement, and Control, vol. 138,no. 9, p. 091005, 2016.
[18] J. Y. Goh and J. C. Gerdes,“Simultaneous stabilization and tracking of basic automobile driftingtrajectories,” in 2016 IEEE Intelligent Vehicles Symposium (IV). IEEE, 2016,pp. 597–602.
 
智能汽車研究所聯系方式
聯系電話：021-69589225
聯系郵箱：11666104@#edu.cn
聯系人：李老師 
分享到：
 
反對 0 舉報 0 收藏 0 評論 0
廣告
滬ICP備11026917號-25