Closed-loop Fast Marching Tree (CL-FMT*) with Application to Helicopter Landing Trajectory Planning

2021 ◽  
Author(s):  
Navid Dadkhah Tehrani ◽  
Igor Cherepinsky ◽  
Sean Carlson
Keyword(s):  
Trajectory Planning ◽  
Closed Loop ◽  
Fast Marching ◽  
Helicopter Landing ◽  
Landing Trajectory

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.

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 Collision-free and dynamically feasible trajectory planning for omnidirectional mobile robots using a novel B-spline based rapidly exploring random tree

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110166
Author(s):  
Yuxi Sun ◽  
Chengrui Zhang ◽  
Chang Liu
Keyword(s):  
Mobile Robots ◽  
Trajectory Planning ◽  
Sustainable Growth ◽  
Random Tree ◽  
Rapid Expansion ◽  
Feasible Region ◽  
Fast Marching ◽  
B Spline ◽  
Cluttered Environment ◽  
Experimental Comparisons

Generating a collision-free and dynamically feasible trajectory with a better clearance in a cluttered environment is still a challenge. We propose two dynamically feasible B-spline based rapidly exploring random tree (RRT) approaches, which are named DB-RRT and FMDB-RRT, to achieve path planning and trajectory planning simultaneously for omnidirectional mobile robots. DB-RRT combines the convex hull property of the B-spline and RRT’s rapid expansion capability to generate a safe and dynamically feasible trajectory. Firstly, we analyze the tree’s sustainable growth ability and put forward the dynamically feasible region. A geometric method is proposed to judge whether finding a dynamically feasible trajectory quickly. Secondly, we design two steer functions to guide the tree’s growth, improve efficiency, and decrease the number of iterations. To further increase the clearance and reduce the randomness of the trajectory, we propose FMDB-RRT, which uses the path of fast marching to guide the rapid growth of DB-RRT. Then, assuming that the number of sampled points is sufficient to represent the dynamically feasible region, the DB-RRT is proved to be probabilistically complete. Finally, by conducting experimental comparisons with other algorithms in different environments and deploying the proposed algorithm to an omnidirectional mobile robot, the effectiveness and good performance of the algorithm have been verified.

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.

Research on trajectory planning of closed loop grouting robot

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110534
Author(s):  
Runmei Zhang ◽  
Rui Ren ◽  
Guan Luo ◽  
Shuai Li ◽  
Lijun Bi ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Trajectory Planning ◽  
Closed Loop ◽  
High Efficiency ◽  
Control Method ◽  
Sliding Mode ◽  
Three Dimensional ◽  
Adaptive Sliding Mode Control ◽  
A Algorithm ◽  
Mode Control

In order to promote building intelligence and solve the disadvantages of traditional grouting technology, the trajectory planning of closed-loop grouting robot was designed. The minimumsnap optimization function was used to optimize the A* algorithm to realize the 2D trajectory planning, which could obtain a smooth, continuous route, and planning diagram of time distribution, speed, acceleration, and jerk. Further, the weight function of the improved A* algorithm was adjusted to perform 3D trajectory planning to reduce redundant nodes in the route. A new approaching law adaptive sliding mode control method was used to achieve precise trajectory tracking of the robotic arm and reduce the problem of chattering in sliding mode control. Through the design of closed-loop grouting robot and the research of trajectory planning, the two-dimensional and three-dimensional paths of grouting robot could be optimized. The system could realize automatic grouting operation. It could promote the development of high efficiency and safety in the construction grouting industry.

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