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In this paper, a real-time laser based gap finding obstacle avoidance algorithm is presented. This algorithm layers on top of a global planner to maintain the overall goal of a given task. In the presence of an unknown obstacle, the algorithm computes a trajectory toward a gap that is wide enough and is closest to the path pre-planned by the global planner. In order to achieve this result, a four-stage...
Mobile Robots are robots that can move from one place to another autonomously, ie. without external human assistance. Proper control methods are to be used for autonomously controlling the motion of these robots. As these robots are to be utilized in real-world situations, the controller used should be promising and robust in nature. In this paper, the tracking control of a Non-holonomous Differential...
We present a distributed on-line coordinated motion planning approach for a group of mobile robots moving amidst dynamic obstacles. The objective for the motion planning is to minimize the total distance traveled by the robots as well as the danger of deadlock. Kinematic constraints, robot-obstacle collision avoidance constraints, and velocity/acceleration constraints are explicitly considered in...
This paper studies trajectory tracking control of unicycle-type mobile robots with longitudinal slippage in kinematic level. By introducing a parameter, called “Slipping ratio”, into the steering system, an adaptive controller different from [8] is designed. All the tracking errors are guaranteed to converge to zero asymptotically using the proposed controller. At the meantime, with some limitations...
This paper studies the issue of input saturation in tracking control of differential drive robots. Although the structure of control strategy is a determinant factor for the occurrence of saturation phenomena, having a trajectory for the robot that is compatible with the bounds on the inputs is a necessary condition for avoiding saturation. In this study, analytic conditions for determining the compatibility...
We provide a new adaptive controller for curve tracking in the plane under unknown curvature. We prove a global asymptotic stability theorem that ensures tracking of the curve and convergence of the curvature estimate to the unknown curvature. Our curvature identification result is an improvement over the known adaptive curve tracking results, which do not ensure parameter identification, or which...
This paper presents the development and trajectory tracking control of a nonholonomic mobile robot with differential drive. The used control system is composed of two loops cascaded, with internal PID controlling the speed of the two wheels and an external loop controlling the robot position and orientation. The second one is a feedfoward kinematics controller which is tuned according to desired closed-loop...
For the formation and obstacle avoidance problems of wheeled mobile robot, a multi-robot formation algorithm of trajectory tracking based on fabrication method is presented. First kinematics model is transformed into a chained form, and then through the canonical coordinate transform, the form error of the system is transformed into a series of nonlinear system, then Lyapunov function of the wheeled...
We are addressing the problem of designing an autonomous feedback control for a group of robots moving in the environment with obstacles and avoiding collisions. A robotic team with full information is considered. We propose a two-stage numerical approach for control synthesis. On the first stage a stabilizing control about some point in the state space is produced. On the second stage optimal trajectories...
An adaptive modified dynamic surface tracking controller for a nonholonomic wheeled mobile robot (WMR) with parametric uncertainties is proposed. The dynamic surface control (DSC), with Levant's differentiator instead of the commonly adopted first-order filter, is incorporated to alleviate the so-called explosion of complexity problem. The major advantage is its finite-time convergence which in turn...
This paper addresses the formation control problem of a multi-agent system (MAS) under the leader-follower scheme. Thus, the followers must to keep a desired relative distance with respect to the leader trajectory against known and constant communication delay. Thus, in order to ensured the coordinated behavior and formation control against parametric uncertainties and external disturbances, a decentralized...
In this paper is presented an algorithm for trajectory-tracking and obstacle avoidance for wheeled mobile robots (WMR). The proposed algorithm creates a trajectory composed of a global trajectory generated off-line and local obstacle avoidance trajectories that are created when an obstacle is detected by the sonar and laser sensors. Only one discrete-time sliding-mode controller is required to track...
Local trajectory is the base of motion UGV and several algorithms used to calculate desired land robot path. A common approach is to use a 2-D grid based algorithm, such a well-known A*. But problems arise due to specific kinematic of ground vehicle and nonideal movement realisation. In this paper presented an approach to local trajectory planning on base 2-D passability map with considering UGV kinematic...
This paper investigates forest monitoring and fire detection strategies using a team of unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs). UAVs have great advantages in forest fire detection and fighting. However they have limited running time and payload capabilities, therefore UGVs are paired with UAVs to avoid their demerits. First, UGVs are used to transport the UAVs to the nearest...
This paper investigates three-dimensional dynamic model of underactuated spherical wheel mobile robot (Ballbot) in the presence of input coupling and friction. The way of how such a robot moves is considered and an approach is proposed for accurate trajectory generation for linear and circular paths. Due to the high reliability of the approach, no position feedback is used and it is simulated open-loop...
A trajectory tracking problem for wheels mobile robot is presented in this paper. The central concept is based on the kinematics model of a two degree of freedom wheeled mobile robot, the fractional calculus is designed in the Backstepping control method. Using the idea of fractional Backstepping, a time-varying fractional order trajectory tracking feedback control law is proposed by constructing...
This work focus on the application of Fuzzy-Backstepping controller, based on optimization method, for trajectory tracking problem. The control algorithm based on the errors in postures of mobile robot which feed to the Fuzzy-Backstepping controller to generate correction signals that transport to torque for each driven wheel. By means of dynamic model of mobile robot, these torques are used to compute...
In order to achieve a continous lateral acceleration profile for moving objects — like robots — clothoids as a part of the pathplanning are important. This paper describes the implementation of a local planning algorithm for a partly autonomnous wheelchair with clothoids as integral part. Further the integration into the ROS framework as main aspects of the development and limitations of the algorithm...
A wireless navigation mobile robot system is proposed in this paper for both path planning and trajectory execution. It should be within an indoor maze environment. The system consists of some device like a mobile robot, motion controller, visual sensor, ZigBee wireless communication device and a maze terrain to capture images of the mobile robot. The camera is used within the maze. To determine the...
Much robotics research has focused on intent-expressive (legible) motion. However, algorithms that can autonomously generate legible motion have implicitly made the strong assumption of an omniscient observer, with access to the robot's configuration as it changes across time. In reality, human observers have a particular viewpoint, which biases the way they perceive the motion. In this work, we free...
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