Terminal Area Energy Management Trajectory Planning for an Unpowered Reusable Launch Vehicle with Gliding Limitations

2013 ◽  
Vol 446-447 ◽  
pp. 611-615
Author(s):  
Min Zhou ◽  
Jun Zhou ◽  
Jian Guo Guo
Keyword(s):  
Trajectory Planning ◽  
Closed Loop ◽  
Dynamic Pressure ◽  
Open Loop ◽  
Bank Angle ◽  
Reference Velocity ◽  
Reusable Launch Vehicle ◽  
Planning Algorithm ◽  
Constant Maximum ◽  
Terminal Area

RLVs' gliding capability, determined by its maximum dive and maximum range, provided a significant restriction in TAEM trajectory planning in this paper. The maximum-dive trajectory was generated based on Eq.(3) for a constant maximum dynamic pressure. In the guidance, it was optimized to be Eq.(13) for the open-loop command of bank angle in HAC segment. The simplified closed-loop command of angle of attack contained errors of altitude and path angle except the controlled velocity. Energy propagating as Eq.(8) calculated the reference velocity for the speed brake to track. Finally, an illustrative example was given to confirm the efficiency of the trajectory planning algorithm and optimized command. The simulation results in Fig.2 and Fig.3 indicate the proposed trajectory planning algorithm and guidance method are useful for the gliding capability limited RLV's TAEM with initial deviations.

scholarly journals Rapid trajectory planning of a reusable launch vehicle for airdrop with geographic constraints

2019 ◽  
Vol 16 (1) ◽  
pp. 172988141881797 ◽  
Author(s):  
Xing Wei ◽  
Xuejing Lan ◽  
Lei Liu ◽  
Yongji Wang
Keyword(s):  
Trajectory Planning ◽  
Planning Process ◽  
Launch Vehicle ◽  
Search Problem ◽  
Quasi Equilibrium ◽  
Bank Angle ◽  
Weighted Interpolation ◽  
Reusable Launch Vehicle ◽  
Terminal Constraints ◽  
Planning Algorithm

Online feasible trajectory generation for an airdrop unpowered reusable launch vehicle is addressed in this article. A rapid trajectory planning algorithm is proposed to satisfy not only the multiple path and terminal constraints but also the complex geographic constraints of waypoints and no-fly zones. Firstly, the lower and upper boundaries of the bank angle that implement all the path constraints are obtained based on the quasi-equilibrium glide condition. To determine the bank angle directly, a weighted interpolation of the boundaries is then developed, which provides an effective approach to simplify the planning process as a one-parameter search problem. Subsequently, three types of lateral planning algorithms are designed to determine the sign of the bank angle according to the requirements of waypoints passage, no-fly-zones avoidance, and terminal constraints in the airdrop process, and the convergence of these methods for passing over the waypoints and meeting the terminal conditions has been clarified and formally demonstrated. Considering the constraints in the actual airdrop flight missions, the planning trajectory is divided into several subphases to facilitate the application of corresponding algorithms. Finally, the performance of the proposed algorithm is assessed through three airdrop missions of reusable launch vehicle with different geographic constraints. Besides, the effectiveness of the algorithm is demonstrated by the Monte Carlo simulation results.

scholarly journals Guidance Law Design for Terminal Area Energy Management of Reusable Launch Vehicle by Energy-to-Range Ratio

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Wen Jiang ◽  
Zhaohua Yang
Keyword(s):  
Energy Management ◽  
Trajectory Planning ◽  
Launch Vehicle ◽  
Reference Trajectory ◽  
Tracking Errors ◽  
Guidance Law ◽  
Reusable Launch Vehicle ◽  
Planning Algorithm ◽  
Flight Profile ◽  
Terminal Area

A new guidance scheme that utilizes a trajectory planning algorithm by energy-to-range ratio has been developed under the circumstance of surplus energy for the terminal area energy management phase of a reusable launch vehicle. The trajectory planning scheme estimates the reference flight profile by piecing together several flight phases that are defined by a set of geometric parameters. Guidance commands are readily available once the best reference trajectory is determined. The trajectory planning algorithm based on energy-to-range ratio is able to quickly generate new reference profiles for testing cases with large variations in initial vehicle condition and energy. The designed flight track has only one turn heading, which simplifies the trajectory planning algorithm. The effectiveness of the trajectory planning algorithm is demonstrated by simulations, which shows that the guided vehicle is able to successfully dissipate energy and reach the desired approach and landing glideslope target with small tracking errors.

Optimal attitude trajectory planning method for CMG actuated spacecraft

2017 ◽  
Vol 232 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Lijun Zhang ◽  
Chunmei Yu ◽  
Shifeng Zhang ◽  
Hong Cai
Keyword(s):  
Trajectory Planning ◽  
Closed Loop ◽  
Pseudospectral Method ◽  
Linear Quadratic Regulator ◽  
Fixed Time ◽  
Open Loop ◽  
Planning Method ◽  
Global Perspective ◽  
Linear Quadratic ◽  
Loop Control

This paper presents an optimal attitude trajectory planning method for the spacecraft equipped with control moment gyros as the actuators. Both the fixed-time energy-optimal and synthesis performance optimal cases are taken into account. The corresponding nonsingular attitude maneuvering trajectories (i.e. open-loop control trajectories) with the consideration of a series of constraints are generated via Radau pseudospectral method. Compared with the traditional steering laws, the optimal steering law designed by this method can explicitly avoid the singularity from the global perspective. A linear quadratic regulator closed-loop controller is designed to guarantee the trajectory tracking performance in the presence of initial errors, inertia uncertainties and external disturbances. Simulation results verify the validity and feasibility of the proposed open-loop and closed-loop control methods.

scholarly journals Accurate predictor–corrector skip entry guidance for low lift-to-drag ratio spacecraft

2018 ◽  
Author(s):  
Y. Enmi ◽  
W. Qian ◽  
K. He ◽  
D. Di
Keyword(s):  
Trajectory Planning ◽  
Closed Loop ◽  
Initial Value ◽  
Bank Angle ◽  
Air Density ◽  
Entry Guidance ◽  
Skip Entry ◽  
Predictor Corrector ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper develops numerical predictor–corrector skip en try guidance for vehicles with low lift-to-drag L/D ratio during the skip entry phase of a Moon return mission. The guidance method is composed of two parts: trajectory planning before entry and closed-loop gu idance during skip entry. The result of trajectory planning before entry is able to present an initial value for predictor–corrector algorithm in closed-loop guidance for fast convergence. The magnitude of bank angle, which is parameterized as a linear function of the range-to-go, is modulated to satisfy the downrange requirements. The sign of the bank ang le is determined by the bank-reversal logic. The predictor-corrector algorithm repeatedly applied onboard in each guidance cycle to realize closed-loop guidance in the skip entry phase. The effectivity of the proposed guidance is validated by simulations in nominal conditions, including skip entry, loft entry, and direct entry, as well as simulations in dispersion conditions considering the combination disturbance of the entry interface, the aerodynamic coefficients, the air density, and the mass of the vehicle.

Motion Planning for Industrial Mobile Robots With Closed-Loop Stability Enhanced Prediction

2019 ◽  
Author(s):  
Jessica Leu ◽  
Masayoshi Tomizuka
Keyword(s):  
Motion Planning ◽  
Closed Loop ◽  
Dynamic Environments ◽  
Open Loop ◽  
Human Robot Interaction ◽  
Planning Problem ◽  
Prediction Horizon ◽  
Robot Systems ◽  
Planning Algorithm ◽  
Loop Stability

Abstract Real-time, safe, and stable motion planning in co-robot systems involving dynamic human robot interaction (HRI) remains challenging due to the time varying nature of the problem. One of the biggest challenges is to guarantee closed-loop stability of the planning algorithm in dynamic environments. Typically, this can be addressed if there exists a perfect predictor that precisely predicts the future motions of the obstacles. Unfortunately, a perfect predictor is not possible to achieve. In HRI environments in this paper, human workers and other robots are the obstacles to the ego robot. We discuss necessary conditions for the closed-loop stability of a planning problem using the framework of model predictive control (MPC). It is concluded that the predictor needs to be able to detect the obstacles’ movement mode change within a time delay allowance and the MPC needs to have a sufficient prediction horizon and a proper cost function. These allow MPC to have an uncertainty tolerance for closed-loop stability, and still avoid collision when the obstacles’ movement is not within the tolerance. Also, the closed-loop performance is investigated using a notion of M-convergence, which guarantees finite local convergence (at least M steps ahead) of the open-loop trajectories toward the closed-loop trajectory. With this notion, we verify the performance of the proposed MPC with stability enhanced prediction through simulations and experiments. With the proposed method, the robot can better deal with dynamic environments and the closed-loop cost is reduced.

Chord Error Closed-Loop Controlled NURBS Interpolator and Trajectory Planning

2009 ◽  
Vol 16-19 ◽  
pp. 925-929
Author(s):  
Yu Liu ◽  
Jie Liu
Keyword(s):  
Trajectory Planning ◽  
High Speed ◽  
Closed Loop ◽  
Time Characteristic ◽  
Maximal Velocity ◽  
Nurbs Curve ◽  
Chord Error ◽  
Curve Interpolation ◽  
Planning Algorithm ◽  
Braking Distance

Focusing on the problem of NURBS curve interpolation in high speed manufacture, a new trajectory planning algorithm, which is suitable for chord error closed loop controlled interpolator is proposed. This tragjectory can determine accelerating, decelerating or maintenance last velocity in the next period via judging the braking distance. By the way of testing different calculating time under different CPU core, the real-time characteristic is validated. The simulation shows that chord error closed loop interpolator can automatically adjust the velocity to satisfying the precision demand, through calculating the curvature. In addition, it can assure that the maximal velocity and the acceleration were equal to the referenced parameters and machine runs with the dynamic characteristic of operator set completely.

Joint Rotation Space, Workspace, and Singularity-Free Workspace of Parallel Five-Bar Manipulators

2000 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Yi Zhang
Keyword(s):  
Trajectory Planning ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parallel Manipulators ◽  
Extensive Study ◽  
Open Loop ◽  
Joint Rotation ◽  
One To One ◽  
The One

Abstract Closed-loop manipulators, while offering some advantages over the open-loop manipulators, also introduce new topics of study such as their joint rotation space (JRS) and workspace. In the previous studies, the concept of JRS was very effective in the study of the allowable inputs of five-bar linkages[11], and the concepts of sheet and side[7] were later introduced for the purpose of clearly describing all of the joint rotation spaces associated to a parallel manipulator with two degrees of freedom. However, of the two types of singularity of parallel manipulators, only the uncertainty singularity was considered in the aforementioned studies. The stationarity singularity was not indicated in the JRS of the manipulators, which would not be sufficient in the design and trajectory planning of parallel manipulators where the one-to-one correspondence between the JRS and the wrist point workspace would be required. This paper reports an extensive study on the JRS and singularity-free workspace of the parallel five-bar manipulators. The objective of the study is to establish a one-to-one corresponding relationship between the JRS and singularity-free workspace. A concise and sufficient way is proposed to thoroughly recognize the JRS and workspace of the parallel five-bar manipulators. The result can be applied in the design and trajectory planning of parallel five-bar manipulators, and the concepts can be extended to other parallel manipulators.

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