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This paper proposes the emulation of the socalled kingpin mechanism in order to reduce the off-tracking effects exhibited by the standard and generalized n-trailer systems. In turn, both systems are emulated by a group of differential-drive mobile robots trough time-varying relative position vectors using the leader-follower scheme. A control law is proposed which involves the position of the virtual...
In this note, the tracking trajectory problem for a wheeled mobile base has been solved using the robot dynamical model. The proposed solution is based on sliding mode control. The asymptotic vanishing of the tracking errors has been theoretically proved, and simulation results have been reported, showing the effectiveness of the proposed control law.
In this note the trajectory tracking problem for a wheeled mobile base has been addressed, considering the presence of uncertainties in the dynamical model. The proposed solution is based on discrete sliding mode control, in order to ensure both robustness and implementability of the controller. The asymptotic boundedness of the tracking errors has been theoretically proved. The proposed discrete...
Conventional agricultural fields are sprayed uniformly to control weeds, insects, and diseases. To reduce cultivation expenses, to produce healthier food and to create more environmentally friendly farms, chemicals should only be applied to the right place at the right time and exactly with the right amount. In this article, a task and motion planning for a team of autonomous vehicles to reduce chemicals...
We present a real-time optimization method for autonomous vehicle motion planning. Trajectory optimization is essential for autonomous vehicle motion planning, due to its non-holonomic motion. Conventional way of optimization is by trajectory smoothing. In this paper, we use differential dynamic programming (DDP) to optimize the trajectory. The key advantage of DDP is that it not only smoothes the...
This paper presents two contributions for the path planning for motion, and convergent global trajectory tracking, which assistance to autonomous vehicle. The path planning for motion is processed by two stages: road network detection and the shortest path estimation for vehicle motion. A road network is detected using the road map images based on image-processing techniques such color filter, segmentation...
This paper discusses a new path tracking controller strategy for autonomous vehicle. Preliminary works done by researchers shows that most of the controller performs well in a straight path and normal curve. However, the problem arises in tight curve or discontinuous path. Therefore, this work aims to reduce the gap on the tight corner problem. The controller is designed based on the dynamic curvature...
This paper presents a flexible virtual structure formation keeping control design for nonholonomic mobile robots that are driven by low-level velocities control systems that possess non-trivial dynamical effects. The formation is flexible in the sense that the formation configuration is defined based on a set of curvilinear relative separations instead of commonly used rectilinear relative separations...
This research work introduces a new method for feedback control of nonlinear dynamical systems and considers as application example the problem of trajectory tracking for autonomous robotic vehicles. The control method consists of a repetitive solution of an H-infinity control problem for the mobile robot, that makes use of a locally linearized model of the robot and takes place at each iteration...
While decades of work and hundreds of research papers exist on unicycle robot control, the control of skid-steer robots is not yet as standardized due to the complexity of wheel slipping behavior. This work presents a method of utilizing the track or wheel Instantaneous Centers of Rotation (ICRs) on a skid-steer vehicle to map skid-steer dynamics to an equivalent time-varying model of unicycle dynamics...
The ability to employ autonomous vehicles to find and track the boundary between two different water masses can increase the efficiency in waterborne data collection, by concentrating measurements in the most relevant regions and capturing detailed spacial and temporal variations. In this paper we provide a guidance mechanism to enable an autonomous vehicle to find and track the steepest gradient...
This paper proposes a trajectory generation method for high-speed autonomous vehicles in a structured on-road environment, such as a highway. The proposed method generates a smooth trajectory using G2 cubic Bézier spiral smoothing, based on the current trajectory and the centerline model of a desired lane, and the velocity profile of the trajectory. Using the proposed method, an on-road vehicle can...
The presence of autonomous vehicles on public roads is becoming a reality. In the last 10 years, autonomous prototypes have been confined in controlled or isolated environments, but new traffic regulations for testing and direct automotive companies interests are moving autonomous vehicles tests on real roads. This paper presents a test on public urban roads and freeways that was held in Parma on...
In this paper, we propose a control law for navigating a robot along the boundary of a stationary obstacle, where the only sensor information available is the minimum distance to the obstacle. Using a particle filter, the curvature profile of the obstacle around the observed point is estimated on-line. Safety is ensured by performing local path planning inside an area guaranteed to be safe. The method...
In this paper, we propose a novel planning framework that can greatly improve the level of intelligence and driving quality of autonomous vehicles. A reference planning layer first generates kinematically and dynamically feasible paths assuming no obstacles on the road, then a behavioral planning layer takes static and dynamic obstacles into account. Instead of directly commanding a desired trajectory,...
In this paper, we employ the hybrid automata theory combined with the longitudinal dynamics model of autonomous vehicle for model to solve collaborative problems between vehicles at intersections. By virtue of order-preserving property of the model, we can divide the danger zone on the displacement coordinate plane of the two vehicles depending on the speed of the two vehicles, and take different...
In this paper a control strategy for a mobile robot enabling to track a manually driven vehicle or a moving target is proposed in the context of natural environment. In such a context, the motion does not meet classical assumptions usually proposed for mobile robots, since the terrain geometry is not necessarily flat and wheels are subject to sliding. As a result, in order to preserve the accuracy...
We present a novel biased sampling technique, Cloud RRT∗, for efficiently computing high-quality collision-free paths, while maintaining the asymptotic convergence to the optimal solution. Our method uses sampling cloud for allocating samples on promising regions. Our sampling cloud consists of a set of spheres containing a portion of the C-space. In particular, each sphere projects to a collision-free...
In this paper, an improved trajectory tracking control law is proposed for a four-wheel differential nonholonomic drive intelligent vehicle. Based on the kinematics model and Euler-Lagrange (EL) system of the vehicle, the control laws adopt an improved typical backstepping method to design the kinematics controller and a fast terminal sliding mode technique to devise the dynamic control law, which...
To generate local trajectory between initial states and target states for autonomous vehicles, a feasible trajectory generation algorithm based on quartic Bézier curve is proposed. The problem of trajectory generation is firstly seperated into generating continuous and bounded curvature profile to shape the trajectory and generating linear velocity profile to execute the trajectory. The curvature...
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