Deformable Virtual Zone Research Articles

A Robot Architecture for Outdoor Competitions

Autonomous navigation in unstructured environments is a common topic of research, being motivated by robotic competitions and involving several sets of skills. We present a modular architecture to integrate different components for path planning and navigation of an autonomous mobile robot. This architecture was developed in order to participate in the RoboMagellan competition hosted by RoboGames. It is divided in the organizational, functional and executive levels in order to secure that the developed system has programmability, autonomy, adaptability and extensibility. Global and local localization strategies use unscented and extended Kalman filters (UKF and EKF) to fuse data from a Global Positioning System (GPS) receiver, inertial measurement unit (IMU), odometry and camera. Movement is controlled by a model reference adaptive controller (MRAC) and a proportional controller. To avoid obstacles a deformable virtual zone (DVZ) approach is used. The architecture was tested in simulated environments and with a real robot, providing a very flexible approach to testing different configurations.

Autonomous wheelchair navigation with real time obstacle detection using 3D sensor

Autonomous wheelchairs operating in dynamic environments need to sense its surrounding environment and adapt the control signal, in real-time, to avoid collisions and protect the user. In this paper we propose a robust, simple and real-time autonomous navigation module that drives a wheelchair toward a desired target, along with its capability to avoid obstacles in a 3D dynamic environment. To command the mobile robot to the target, we use a Fuzzy Logic Controller (FLC). For obstacle avoidance, we use the Kinect Xbox 360 to provide an actual map of the environment. The generated map is fed to the reactive obstacle avoidance control Deformable Virtual Zone (DVZ). Simulations and real world experiments results are reported to show the feasibility and the performance of the proposed control system.

Adaptive Shared Control for a Novel Mobile Assistive Robot

This paper presents a new adaptive servo-level shared control scheme for a mobile assistive robot that aims at assisting senior and disabled people to transport heavy objects in a complex environment with obstacles. Several technical problems and challenges related to the assistive robotic system and the shared controller are addressed. Specifically, a nonlinear tracking controller is developed for the robot to follow the user. An obstacle avoidance controller is developed based on the deformable virtual zone principle for the robot to avoid obstacles. The adaptive servo-level shared controller utilizes the tracking controller and the obstacle avoidance controller’s outputs to generate a new shared control output to command the robot. Experiments show that the user can guide the movement of the robot safely and smoothly in the complex environment with the developed controllers.

Combination of the DVZ Method, Particle Filter, and Fuzzy Controller for Electric Wheelchair Navigation

Electric wheelchair is one of the many engines used for the movement of aged and disabled people. This paper introduces an obstacle avoidance using deformable virtual zone (DVZ), particle filter to improve localization and fuzzy controller to join desired target. This controller is developed to increase the independence of disabled and aged people, specifically those who suffer not only disability in the lower limbs but also visual disturbances. To overcome these problems, different perceptive abilities or sensors were introduced. In this context, we developed a control system composed by fuzzy controller to join a target, DVZ method for obstacle avoidance, and particle filter for localization. Also, we present the simulation results of the wheelchair navigation system.

Combined Path-following and Obstacle Avoidance Control of a Wheeled Robot

This paper proposes an algorithm that drives a unicycle type robot to a desired path, including obstacle avoidance capabilities. The path-following control design relies on Lyapunov theory, backstepping techniques and deals explicitly with vehicle dynamics. Furthermore, it overcomes the initial condition constraints present in a number of path-following control strategies described in the literature. This is done by controlling explicitly the rate of progression of a “virtual target” to be tracked along the path; thus bypassing the problems that arise when the position of the path target point is simply defined as the closest point on the path. The obstacle avoidance part uses the Deformable Virtual Zone (DVZ) principle. This principle defines a safety zone around the vehicle in which the presence of an obstacle induces an “intrusion of information” that drives the vehicle reaction. The overall algorithm is combined with a guidance solution that embeds the path-following requirements in a desired intrusion information function, which steers the vehicle to the desired path while the DVZ ensures minimal contact with the obstacle, implicitly bypassing it. Simulation and experimental results illustrate the performance of the control system proposed.

DVZ-based collision avoidance control of non-holonomic mobile manipulators

This paper addresses the problem of collision avoidance control of mobile manipulators evolving in unknown and dynamic environments. The proposed approach is based on Deformable Virtual Zone (DVZ) paradigm. The formulation of this method is given for mobile bases and its extension to mobile manipulators is detailed. This approach allows to implement fast control laws and can be seen as an efficient low level algorithm for controlling motions to avoid unscheduled obstacles. Simulation results are discussed, showing the effectiveness of the proposed method.

Reactive behaviors of fast mobile robots

AbstractThis article addresses the modeling of the reactive behaviors of a mobile robot moving in unstructured and dynamic environments. The main focus is on the software structure devoted to obstacle avoidance when geometric models do not exist and when obstacles can be dynamic. The first part concerns the model of the robot/environment interaction. This model is based on the definition of the interaction component (deformable virtual zone) of an internal state of the robot and leads to avoidance‐oriented control laws. The second part describes the derivation of the state equation and one of its implementations on a fast outdoor mobile robot. © 1994 John Wiley & Sons, Inc.