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In this paper we present a viability-based formulation for the stabilization of an underactuated underwater vehicle under the influence of a known, constant current and state constraints. The stabilization problem is described by three problems in terms of viability theory. We present a solution to the first problem which addresses the safety of the system, i.e. guarantees that there exists a control...
Receding Horizon (RH) control is an established control methodology which has been used successfully for many control applications. More recently it has been applied for autonomous vehicle guidance. Its successful implementation, in particular for applications involving agile vehicles like rotorcraft, hinges on two critical factors: (1) adequately accounting for the vehicle dynamics to guarantee that...
This paper considers the formation control problem of a group of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAV) in SE(3). The vehicles among the team are required to track a reference velocity signal and maintain a desired formation. For each vehicle in the formation, we propose a design methodology based on the separation of the translational and the rotational dynamics, using...
In this paper, the trajectory-tracking control problem of an omnidirectional mobile robot (also known as a type (3,0)) is addressed and solved. The proposed controller takes into account the mobile robot dynamic model and it is based on a particular passivity-based control formulation, widely applied in power electronics, resulting in linear time-varying controllers. It is formally proved that the...
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...
Our aim is to explore the fundamental stability issues of a robotic vehicle carrying out localization, mapping, and feedback control in a perturbation-filled environment. Motivated by the application of an ocean vehicle performing an autonomous ship hull inspection, our planar vehicle model performs localization using point features from a given map. Cases in which the agent must update the map are...
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...
Coordination of autonomous non-point agents in four-way crossings is studied in this work. A control scheme based on artificial potential functions is proposed in order to coordinate holonomic agents whose aim is to pass through an intersection while avoiding collisions. To do so, the agents are provided with a decentralized navigation function in which the goal and collision functions are decoupled...
Special Automatic Guided Vehicles (AGVs) equipped with at least three omnidirectional wheels may be very useful tools in industrial applications because -in contrast to the Ackerman engines- their position and orientation with respect to the plane of operation can simultaneously be prescribed. So they have the ability for smart and precise navigation in a crowded environment. In the present constructions...
Conventionally, caster wheels are placed underneath a vehicle to provide passive support. The caster wheels do not additionally restrict the vehicle's mobility. Inspired by the success of a commercial funboard RipStik, we explore the use of actively driven caster wheels within autonomous mobile robots. Specifically, we explore the nature of the governing equations of a vehicle with caster wheels having...
A viability algorithm is developed to compute the constrained minimum time function for general dynamical systems. The algorithm is instantiated for a specific dynamics (Dubin's vehicle forced by a flow field) in order to numerically solve the minimum time problem. With the specific dynamics considered, the framework of hybrid systems enables us to solve the problem efficiently. The algorithm is implemented...
This paper describes a general framework for the study of multiple vehicle, time-coordinated path following (TC-PF) control problems. An example is the situation where a group of vehicles is tasked to maneuver and arrive at pre-assigned final positions at the same time in a collision-free manner, while reducing some optimality criterion. The time of arrival is not fixed a priori, and the vehicles...
In this paper, a computationally effective trajectory generation algorithm of omnidirectional mobile robots is proposed. The algorithm plans a reference path based on Bezier curves, which meet obstacle avoidance criteria. Then the algorithm solves the problem of motion planning for the robot to track the path in a short travel time while satisfying dynamic constraints and robustness to noise. Accelerations...
This paper describes a vehicle stability control (VSC) system using a yaw inertia and mass independent adaptive control law. As a primary vehicle active control system, VSC can significantly improve vehicle driving safety for passenger cars and enhance trajectory tracking accuracy for other applications such as autonomous, surveillance, and wheeled mobile robot vehicles. For the designs of vehicle...
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...
In this paper, a non-time based action executor is proposed for the Coordinated Hybrid Agent (CHA) framework for the control of multi-agent systems. The non-time based agent is designed for multiple intelligent vehicles. Non-time based motion controllers have been successfully applied to many areas such as robot motion control, multi-robot coordination, force and impact control, robotic teleoperation...
In this paper, we investigate the leader-follower formation control of underactuated autonomous underwater vehicles (AUVs). By using position measurements from the leader, we design a virtual vehicle such that the trajectory of the virtual vehicle converges to the reference trajectory of the follower. A position tracking control is designed for the follower to track the virtual vehicle using Lyapunov...
This paper presents Tiji, a trajectory generation scheme, ie an algorithm that computes a feasible trajectory between a start and a goal state, for a given robotic system. Tiji is geared towards complex dynamic systems subject to differential constraints, such as wheeled vehicles, and its efficiency warrants it can be used in real-time. Above all, Tiji is able to compute a trajectory that reaches...
This paper describes an autonomous driving control algorithm based on skid steering for Robotic Vehicle with Articulated Suspension (RVAS). The driving control algorithm consists of four parts; speed controller for following a desired speed, trajectory tracking controller which computes a yaw moment input to track a desired trajectory, longitudinal tire force distribution which determines an optimal...
In this work we concentrate on the problem of path planning in a scenario in which two different vehicles with complementary capabilities are employed cooperatively to perform a desired task in an optimal way. In particular we consider the case in which a vehicle carrier, typically slow but with virtually infinite operativity range, and a carried vehicle, which on the contrary is typically fast but...
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