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We propose a model predictive control approach to path-following problems of constrained nonlinear systems. We directly consider input and state constraints. Furthermore, we introduce an extended corridor path-following problem, which allows to add spatial degrees of freedom to the path formulation.We give sufficient stability conditions for predictive solutions to 1d and corridor path-following problems...
We present a robust motion planning algorithm for a holonomic mobile robot that incorporates the risk of collisions directly in the cost function. This deterministic algorithm uses analytic predictions of the path-following error statistics to quickly calculate the collision risk. The A* search algorithm is used to find motion plans that optimally balance the plan duration with the collision risk,...
We consider a variation of the classical Markov-Dubins problem dealing with curvature-constrained, shortest paths in the plane with prescribed initial and terminal positions and tangents, when the lower and upper bounds of the curvature are not necessarily equal. The motivation for this problem stems from vehicle navigation applications when the vehicle may be biased in taking turns at a particular...
Precise control of Automatic Guided Vehicles (AGVs) navigating between the aisles of manufacturing systems by the use of local markers is an important task. On the basis of the geometric model of the workspace and the vehicles and that of the sensor uncertainties precise trajectories were recently generated along which the vehicle safely can move. In order to achieve precise trajectory tracking the...
A new, simple, and fast method to compute the sharpness and curvature of a clothoid segment of a continuous curvature path is presented. When generating continuous curvature paths, clothoid segments are needed to connect straight segments to perfect arc segments. This algorithm is part of a new trajectory generator and motion planner that generates smooth, natural, drivable paths, using a minimal...
For an autonomous vehicle navigating in a static environment for which an a priori map is inaccurate, we propose a hybrid receding horizon control method to determine optimal routes when new obstacles are detected. The hybrid method uses the level sets of the solution to either a global or local Eikonal equation in the formulation of the receding horizon control problem. Whenever an obstacle is detected...
Coordination of autonomous non-point agents is studied in this work. Interactions between vehicles together with their internal dynamics have been modeled as a continuous, unconstrained differential game. In particular, collision prediction is shown to be achievable in a cooperative scheme through solving the boundary value equation associated with the dual problem. Optimal control formulation has...
Most autonomous mobile agents operate in a highly constrained environment. Despite significant research, existing solutions are limited in their ability to handle heterogeneous constraints within highly dynamic or uncertain environments. This paper presents a novel maneuver selection technique suited for both 2D and 3D environments with highly dynamic maneuvering constraints and multiple mobile obstacles...
We present a method for motion planning in the presence of moving obstacles that is aimed at dynamic on-road driving scenarios. Planning is performed within a geometric graph that is established by sampling deterministically from a manifold that is obtained by combining configuration space and time. We show that these graphs are acyclic and shortest path algorithms with linear runtime can be employed...
This paper proposes a solution to a door crossing problem in unknown environments for an autonomous wheelchair. The problem is solved by a dynamic path planning algorithm implementation based on successive frontier points determination. An adaptive trajectory tracking control based on the dynamic model is implemented on the vehicle to direct the wheelchair motion along the path in a smooth movement...
This paper addresses the problem of path generation and motion control for the autonomous maneuvers of a farm vehicle in headland. A reverse turn planner is firstly investigated, based on primitives connected together to easily generate the reference motion. Then, both steering and speed control algorithms are presented to accurately guide the vehicle. They are based on a kinematic model extended...
By combining a low-order model of forecast errors, the extended Kalman filter, and classical continuous optimization, we develop an integrated methodology for planning mobile sensor paths to sample continuous fields. Agent trajectories are developed that specifically take into account the fact that data collected will be used for near real-time assimilation with large predictive models. This aspect...
Various "Urban Transportation Systems" are currently in developing, in order to put forward solutions to congestion and pollution in dense areas. Autonomous electric vehicles in free-access can be seen as an attractive approach, in view of the large flexibility that can be expected. One instrumental functionality linked to this solution is platoon motion: several autonomous vehicles accurately...
This paper studies the tracking problem for an underactuated underwater vehicle moving in 6-degrees of freedom under environmental disturbances. By application of Lyapunov's direct method and parameter projection techniques, A robust adaptive continues controller is proposed to force the vehicle follow any smooth time-varying bounded trajectory, despite of the uncertainty of the vehicle's environmental...
The problem of robot navigation is treated under constraints of limited perception horizon in complex, cluttered, natural environments. We propose a solution based on our previous work in fast constrained motion planning, where arbitrary mobility constraints could be satisfied while the planning problem is reduced to unconstrained heuristic search in state lattices. By trading off optimality, we improve...
Path planning is basis for any autonomous underwater vehicle to implement completely cruising in subsea environment and path tracking is important technology as well, especially for multi-AUV (Autonomous underwater vehicle) cruising with a fleet formate. In this paper, algorithms path planning and path tracking are addressed for an open frame AUV. Fast Marching algorithm is applied to solve problems...
This paper derives a control law to steer the dynamic model of an underactuated autonomous underwater vehicle (AUV) along a predefined path. We describe the path to be followed by the movement of a virtual AUV and drive the actual AUV on the desired path through following this virtual AUV. Furthermore, it overcomes a singular point that are presented in a number of path following control strategies...
Recently, the problem of autonomous navigation of automobiles has gained substantial interest in the robotics community. Especially during the two recent DARPA grand challenges, autonomous cars have been shown to robustly navigate over extended periods of time through complex desert courses or through dynamic urban traffic environments. In these tasks, the robots typically relied on GPS traces to...
Path planning algorithms that incorporate risk and uncertainty need to be able to predict the evolution of path-following error statistics for each candidate plan. We present an analytic method to predict the evolving error statistics of a holonomic vehicle following a reference trajectory in a planar environment. This method is faster than integrating the plant through time or performing a Monte...
This paper presents an algorithm for real-time sensor-based motion planning under kinodynamic constraints, in unknown environments. The objective of the trajectory-generation algorithm is to optimise a cost function out to a limited time horizon. The space of control trajectories is searched by expanding a tree using randomised sampling, in a manner similar to an RRT. The algorithm is improved by...
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