Browsing by Author "Park, Jongho"
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Item Open Access Design framework for optimizing waypoints of vehicle trajectory considering terminal velocity and impact angle constraints(Taylor and Francis, 2021-05-17) Kim, Youngil; Cho, Namhoon; Park, Jongho; Kim, YoudanBallistic missiles often require the terminal velocity and impact angle to be confined to a certain region around a desired value considering a wide variety of uncertain initial conditions and operational ranges. This study presents a design framework to determine optimum waypoints that satisfy constraints for given launch conditions and mission profiles. As a systematic approach to this kinodynamic motion planning problem, the proposed framework deterministically samples the waypoints. The trajectory generated by the determined waypoints in consideration of various conditions satisfies the terminal constraint. Numerical simulations are performed to demonstrate the effectiveness of the proposed method.Item Open Access Online trajectory replan for gliding vehicle considering terminal velocity constraint(IEEE, 2022-08-08) Kim, Youngil; Cho, Namhoon; Park, Jongho; Kim, YoudanControlling the terminal velocity can improve the effectiveness of guided missiles. In particular, a ballistic missile propelled by solid rocket motors can successfully accomplish its mission when it hits the target at an appropriate speed. In this study, a method for modifying the trajectory of gliding vehicle, i.e., gliding ballistic missiles is proposed to meet the terminal velocity constraint by reflecting the effects of the environment during a flight. The proposed framework consisting of trajectory generation and dynamic propagation compensates for errors due to uncertainties in real time. The trajectory generation step provides various trajectories that satisfy the given constraints based on information about the current state. The dynamic propagation step efficiently predicts the terminal velocity for each of the generated trajectories and finds the trajectory with the lowest terminal speed error. A numerical simulation is performed considering various conditions to demonstrate the performance of the proposed method.Item Open Access Unified control parameterization approach for finite-horizon feedback control with trajectory shaping(IEEE, 2022-03-22) Cho, Namhoon; Park, Jongho; Kim, Youdan; Shin, Hyo-SangThis study presents control parametrisation as a unifying framework for designing a linear feedback control law that achieves finite-time transfer of output as well as trajectory shaping. Representing control input as a linear combination of independent basis functions allows wide variability in the resultant feedback control laws through selection of the number and types of basis functions. Given an array of basis functions that meets the trajectory shaping necessities, the unified design approach proceeds with determination of the coefficients so that the predicted trajectory attains the desired output at the final time. The input evaluated with the coefficients found at each instance essentially turns out to be a linear state feedback policy with an additional feedforward term and time-dependent gains which is appropriate for practical use. The unified control parametrisation approach lends itself well to missile guidance applications with the expandability and direct trajectory shaping capability that it provides. To emphasise expandability of the framework, this study revisits the trajectory shaping guidance laws from the control parametrisation viewpoint and shows how the notion of specifying input basis functions not only generalises various existing methods but also enables further extensions. Furthermore, an application to integrated guidance and control illustrates the strength of design process in handling the shaping requirements more directly through construction of appropriate basis.