Ostrowski, James P.
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Publication Motion Planning in Humans and Robots(1997-10-01) Kumar, R. Vijay; Ostrowski, James P.; Zefran, MilosWe present a general framework for generating trajectories and actuator forces that will take a robot system from an initial configuration to a goal configuration in the presence of obstacles observed with noisy sensors. The central idea is to find the motion plan that optimizes a performance criterion dictated by specific task requirements. The approach is motivated by studies of human voluntary manipulation tasks that suggest that human motions can be described as solutions of certain optimization problems.Publication Steering for a Class of Dynamic Nonholonomic Systems(1999) Ostrowski, James P.In this paper we derive control algorithms for a class of dynamic nonholonomic steering problems, characterized as mechanical systems with nonholonomic constraints and symmetries. Recent research in geometric mechanics has led to a single, simplified framework that describes this class of systems, which includes examples such as wheeled mobile robots; undulatory robotic and biological locomotion systems, such as paramecia, inchworms, and snakes; and the reorientation of satellites and underwater vehicles. This geometric framework has also been applied to more unusual examples, such as the snakeboard robot, bicycles, the wobblestone, and the reorientation of a falling cat. We use this geometric framework as a basis for developing two types of control algorithms for such systems. The first is geared towards local controllability, using a perturbation approach to establish results similar to steering using sinusoids. The second method utilizes these results in applying more traditional steering algorithms for mobile robots, and is directed towards generating more non-local control methods of steering for this class of systems.Publication Special Issue on the Grand Challenges of Robotics(2007-03-01) Ostrowski, James; Yim, Mark; Tapus, AdrianaPublication Hybrid Control of Formations of Robots(2001-05-21) Das, Aveek K.; Kumar, R. Vijay; Fierro, Rafael; Ostrowski, James P.We describe a framework for controlling a group of nonholonomic mobile robots equipped with range sensors. The vehicles are required to follow a prescribed trajectory while maintaining a desired formation. By using the leader-following approach, we formulate the formation control problem as a hybrid (mode switching) control system. We then develop a decision module that allows the robots to automatically switch between continuous-state control laws to achieve a desired formation shape. The stability properties of the closed-loop hybrid system are studied using Lyapunov theory. We do not use explicit communication between robots; instead we integrate optimal estimation techniques with nonlinear controllers. Simulation and experimental results verify the validity of our approach.