外文翻譯-機械模具自動化【期刊】線性速率估計和成像導引頭在戰(zhàn)術導彈中通過比例導引的線性化控制-外文文獻

1、556 IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, VOL. 10, NO. 4, JULY 2002Line-of-Sight Rate Estimation and Linearizing Control of an Imaging Seeker in a Tactical Missile Guided by Proportional NavigationJacques Wald

2、mann, Member, IEEEAbstract—Acceleration commands in missiles guided by proportional navigation require the measurement of line-of-sight (LOS) rate. It is often obtained by filtering the output of a two-degree-of-freedom

3、(2-DOF) rate gyro mounted on the inner gimbal of the seeker. This paper describes the modeling of an imaging seeker and the formulation of an extended Kalman filter (EKF) for the estimation of LOS rate from measurements

4、of relative angular displacement between seeker gimbals and a low-cost strapdown inertial unit. The approach aims at circum- venting the need for the rate gyro on the seeker. A linearizing feedback control law for decoup

5、ling missile motion from that of the seeker is proposed based on the filter model and its estimates. Additionally, the control law uses visual information from the image sequence for target tracking. Seeker dynamics and

6、control are then integrated into a dynamic model of a cruciform missile equipped with canards and rollerons and guided by proportional navigation in three-dimensional (3-D) interception tasks. Monte Carlo simulation is e

7、mployed to evaluate the overall system accu- racy subject to different initial conditions—lateral and head-on engagements—and the impact of rolling motion during high- maneuvers on miss distance. The validation model inc

8、ludes noise in the various sensors, coupled inertia of the seeker gimbals, signal saturation at various subsystems, optical geometric distortion, and target segmentation errors in the image plane. Initial engagement geom

9、etry and roll-rate damping at high incidence angles have been observed to have a significant impact on miss distance.Index Terms—Image sequence analysis, Kalman filtering, ma- chine vision, missile guidance, nonlinear es

10、timation and control, optical distortion, pointing systems.I. INTRODUCTION GIMBALLED seekers are often utilized in contemporary tactical missiles. They should provide rapid and accurate tracking of boresight error signal

11、s generated by the target de- tector located in the inner gimbal. The demands on seeker con- trol become more severe at the endgame portion of the engage- ment. Inadequate performance results in large miss distances and

12、thus reduces the probability of a successful interception. A two-degree-of-freedom (2-DOF) rate gyro is usually mounted on the inner gimbal and feeds inertial angular rate directly to the torquers to provide boresight er

13、ror tracking and stabiliza- tion against base motion [1], [2]. The latter is a consequenceManuscript received December 11, 2000; revised November 9, 2001. Man- uscript received in final form February 22, 2002. Recommende

14、d by Associate Editor S. Banda. The author is with the Centro Técnico Aeroespacial, Instituto Tecnológico de Aeronáutica, Department of Systems and Control, 12228-900 São José dos Campos SP, Braz

15、il (e-mail: jacques@ele.ita.cta.br). Publisher Item Identifier S 1063-6536(02)05356-3.of the missile angular and linear motion during the engagement and is transmitted to the gimbals by mechanical means. Accu- rate stabi

16、lization of imaging seekers is critical to reduce image smearing which in turn impacts adequate target acquisition, seg- mentation, and tracking. Additionally, minor mass unbalances add to the disturbances acting upon th

17、e gimbals as the missile suffers accelerations. The packaging of subsystems in tactical missiles is seriously affected by volume and aerodynamic constraints that ulti- mately dictate maneuverability. Gimballed seekers ar

18、e usually positioned at the front tip of the missile. Not rarely the size of the seeker and its supporting systems dictates the shape of the front tip of the missile. In such cases, the bulkier the shape, the more intens

19、e become the generated shock waves which degrade missile performance. Seeker volume can be reduced by removing the rate-gyro from the gimballed assembly and using a strapdown configuration. However, the approach calls fo

20、r the estimation of the inner gimbal angular rate relative to the missile body. Differentiation of the relative angular rate of the gimbals and further matched filtering to reduce noise has been used in a linearized appr

21、oach [3] to stabilize a single-axis gim- balled imaging seeker disturbed by missile motion. Incorrect output by the image segmentation algorithm was neglected. Sliding mode control has been used [4]—under the assumption

22、of uncoupled identical pitch and yaw channels—again with a single-axis gimballed seeker and evaluated against a repre- sentative command signal. The proposed control law required the computation of first and second time

23、derivatives of the command signal as well as perfect measurements of gimbal angular displacement and rate relative to the missile body. This paper proposes to extend the above formulation to cope with the dynamics of a y

24、aw- and pitch-controlled imaging seeker. The approach is based on modeling the nonlinear seeker dynamics with its time-varying inertia for use in an extended Kalman filter (EKF), aiming at the estimation of relative angu

25、lar displacement of the gimbals. Furthermore, image sequence analysis—assuming that target segmentation has been solved and a noisy estimate of its centroid location in the image plane is available—is addressed in terms

26、of optical flow [21] estimation for visual feedback to the torquers. The approach is evaluated by assessing the miss distance statistics via Monte Carlo simulation of the closed-loop comprising seeker control and the dyn

27、amic model of a tactical cruciform missile. The missile is guided by pure proportional navigation in three-dimensional (3-D) engagements against one nonma- neuvering target.1063-6536/02$17.00 © 2002 IEEE558 IEEE TRA

28、NSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, VOL. 10, NO. 4, JULY 2002dynamics of the last two components in (1b) when excited by torque from the actuators. The first component refers to the reaction torque of the missile bo

29、dy acting upon the outer gimbal and hence is not considered in the ensuing model. On one hand, torque component is applied to the outer gimbal along thedirection and affects the angular momentum component of both gimbals

30、 given by . Torque component , on the other hand, is applied to the inner gimbal along the direction by an actuator located in such way at the outer gimbal that its action is perpendicular to . Therefore, only affects th

31、e angular momentum component of the inner gimbal alongdirection, given by(4)Substituting (2)–(4) in (1b) produces the following:(5a)(5b)which yields after some algebraic manipulation(6a)(6b)(6c)(6d)(6e)(6f)(6g)(6h)(6i)(6

32、j)(6k)The dynamic model of seeker motion relative to then be- comes (7a) and (7b) at the bottom of the page and the dynamiccoupling arising from the inertia products becomes apparent. Torquer dynamics is modeled by(8)whe

33、re , are current signals applied to each torquer and, are constant gains. The current signals to the torquers must drive the seeker, aiming at base motion stabilization and target tracking. Inertia moments and products o

34、f both gimbals and electroop- tical payload ; are known along torquer axes prior to seeker assembly. The torquer axes are aligned with the coordinate frame. Therefore, the inertia parameters of the inner gimbal assembly

35、and its payload rela- tive to the frame vary in time during seeker operation due to the occurrence of relative motion in elevation, given by and. The inertia moments and products of the inner gimbal and electrooptical pa

36、yload in the frame, along with the respec- tive time rates, are computed as(9)Equations (6)–(9) compose the dynamic model relating the input driving the torquers to the output, which is the seeker motion relative to thec

37、oordinate frame. In order to stabilize the seeker in inertial space and track the target while performing proportional navigation, the inertial LOS rate from seeker to target has to be estimated from available missile an

38、gular rate and relative gimbal angle measurements in order to circumvent the need for a 2-DOF rate gyro mounted on the inner gimbal. Section III describes the formulation of an EKF for this purpose.III. LOS RATE ESTIMATI