Jurek Z. Sasiadek
Carleton University
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Publication
Featured researches published by Jurek Z. Sasiadek.
IEEE Transactions on Control Systems and Technology | 2003
Ignacy Duleba; Jurek Z. Sasiadek
Discusses a modification of the Newton algorithm applied to nonholonomic motion planning with energy optimization. The energy optimization is performed either by optimizing motion in the null space of the Jacobian matrix derived from the nonholonomic system or coupling this motion with movement toward the goal. Resulting controls are smooth and easily generated by motors or thrusters. The two methods can be used, when kinematics are considered, to steer any driftless nonholonomic systems particular free-floating objects, underactuated manipulators, mobile robots (with trailers). Similarities and differences are also discussed in the Newton algorithm for holonomic and nonholonomic systems.
Journal of Guidance Control and Dynamics | 2012
Steve Ulrich; Jurek Z. Sasiadek; Itzhak Barkana
DOI: 10.2514/1.54083 This paper addresses the problem of adaptive trajectory control of space manipulators that exhibit elastic vibrations in their joints and that are subject to parametric uncertainties and modeling errors. First, it presents a comprehensive study of rigid and linear flexible-joint stiffness models, to propose a dynamic formulation that includes nonlinear effects such as soft-windup and time-varying joint stiffness. Second, it develops an adaptive composite control scheme for tracking the end effector of a two-link flexible-joint manipulator. The control scheme consists of a direct model reference adaptive system designed to stabilize the rigid dynamics and a linear correction termtoimprovedampingofvibrationsatthejoints.Numericalsimulationscomparetheperformanceoftheadaptive controllerwithitsnonadaptiveversioninthecontextofa12:6 12:6 msquaretrajectorytracking.Resultsobtained withtheadaptivecontrolstrategyshowanincreasedrobustnesstomodelingerrorsanduncertaintiesinjointstiffness coefficients, and greatly improved tracking performance, compared with the nonadaptive strategy.
Journal of Vibration and Control | 2004
Anthony Green; Jurek Z. Sasiadek
Operational problems with robot manipulators in space relate to several factors, most importantly, structural flexibility and subsequent difficulties with their position control. In this paper we present control methods for endpoint tracking of a 12.6 × 12.6m2 trajectory by a two-link robot manipulator. Initially, a manipulator with rigid links is modeled using inverse dynamics, a linear quadratic regulator and fuzzy logic schemes actuated by a Jacobian transpose control law computed using dominant cantilever and pinned-pinned assumed mode frequencies. The inverse dynamics model is pursued further to study a manipulator with flexible links where nonlinear rigid-link dynamics are coupled with dominant assumed modes for cantilever and pinned-pinned beams. A time delay in the feedback control loop represents elastic wave travel time along the links to generate non-minimum phase response. A time delay acting on control commands ameliorates non-minimum phase response. Finally, a fuzzy logic system outputs a variable to adapt the control law in response to elastic deformation inputs. Results show greater endpoint position control accuracy using a flexible inverse dynamics robot model combined with a fuzzy logic adapted control law and time delays than could be obtained for the rigid dynamics models.
Journal of Guidance Control and Dynamics | 2004
Anthony Green; Jurek Z. Sasiadek
Operational problems with robot manipulators in space relate to several factors, one most importantly being structural flexibility and subsequently significant difficulties with the control systems, especially, for endpoint position control. Elastic vibrations of the links coupled with their large rotations and nonlinear dynamics is the primary cause. This paper presents a control scheme for tracking the endpoint of a two-link flexible robot. The dominant assumed modes of vibration for Euler-Bernoulli cantilever and pinned-pinned beam boundary conditions are coupled with the nonlinear dynamics for rigid links to form an Euler-Lagrange inverse flexible dynamics robot model. A Jacobian transpose control law actuating the robot joints is adapted by a fuzzy logic system (FLS) with link deformation inputs and a single variable output. Results obtained with an FLS adaptive control strategy show significantly diminished vibration amplitudes for both cantilever and pinned-pinned link dynamics and greatly improved control performance compared to the nonadaptive strategy.
Journal of Guidance Control and Dynamics | 2014
Steve Ulrich; Jurek Z. Sasiadek; Itzhak Barkana
Growing research interest in space robotic systems capable of accurately performing autonomous manipulation tasks within an acceptable execution time has led to an increased demand for lightweight materials and mechanisms. As a result, joint flexibility effects become important and represent the main limitation to achieving satisfactory trajectory-tracking performance. This paper addresses the nonlinear adaptive output feedback control problem for flexible-joint space manipulators. Composite control schemes in which decentralized simple adaptive control-based adaptation mechanisms to control the quasi-steady-state robot model are added to a linear correction term to stabilize the boundary-layer model are proposed. An almost strictly passivity-based approach is adopted to guarantee closed-loop stability of the quasi-steady-state model. Simulation results are included to highlight the performance and robustness of the proposed adaptive composite control methodologies to parametric and dynamics modeling unce...
Annual Reviews in Control | 2006
A. Ollero; S. Boverie; Roger M. Goodall; Jurek Z. Sasiadek; Heinz-Hermann Erbe; Detlef Zuehlke
This paper presents a general overview of the technological fields of mechatronic, robotic, components for automation and control. Five technical areas are considered: component and instruments, mechatronic, robotics, cost oriented automation and human-machine systems. The paper addresses their current key problems and the recent major accomplishments. At last the most promising forecasted development and applications are considered.
IEEE Transactions on Control Systems and Technology | 2006
Anthony Green; Jurek Z. Sasiadek
A ratio is identified as a heuristic to assist in designing fuzzy logic system (FLS) controllers with a low number of membership functions (MFs), high tracking precision, and fast execution time for the control of a two-link flexible space robot. Comparing simulation results for an FLS with three, five, seven, and nine triangular and Gaussian membership functions provides a combination of type and number of MF for optimal tracking control and execution time. Optimal control occurs when the ratio of the FLS output scaling gain to the number of MFs is equal to the output variable universe of discourse. The optimal FLS design is chosen with three triangular membership functions at an output scaling gain of 15, giving a design ratio of five and execution time of 1 min 40 s while tracking a square trajectory
advances in computing and communications | 2010
Steve Ulrich; Jurek Z. Sasiadek
An adaptive control scheme is proposed for tracking a 12.6 × 12.6 m square trajectory by the endpoint of a two-link rigid joint space robot. The adaptive controller is based on the classical Transpose Jacobian control law where the controller gains are adapted using a modified version of the Simple Adaptive Control (SAC) adaptation law. The formal Lyapunov proof of stability for the adaptive control system is derived. Simulation results show that the proposed adaptive control methodology is a promising concept when applied to space robots and yields improved tracking results compared to a nonadaptive control strategy.
mediterranean conference on control and automation | 2008
Jurek Z. Sasiadek; Amir Monjazeb; Dan S. Necsulescu
This paper presents a navigation of an autonomous robot using simultaneous localization and mapping (SLAM) in outdoor environments. SLAM is a method in which localization and mapping are done simultaneously in an unknown environment without an access to a priori map. This paper introduces a probabilistic approach to a SLAM problem under Gaussian and non-Gaussian conditions and offers alternative solutions. First, an extended Kalman filter algorithm for the SLAM problem under Gaussian condition will be shown. Also, an alternative way of dealing with SLAM problem with assumption of non-Gaussian and called FastSLAM will be analyzed. FastSLAM is an algorithm that using Rao-Blackwellised method for particle filtering, estimates the path of robot while the landmarks positions which are mutually independent and with no correlation, can be estimated by EKF. This is done using a factorization that fits very well into SLAM problem based on a Bayesian network. In this paper, a real outdoor autonomous robot is presented and several experiments have been performed based on both methods. The experimental results are discussed and compared.
AIAA Guidance, Navigation, and Control Conference and Exhibit | 2003
Anthony Green; Jurek Z. Sasiadek
rigid Euler-Lagrange dynamics model but are extended here to a flexible dynamics model based on the first assumed mode calculated using Euler-Bernoulli pinnedpinned beam theory. A square trajectory presents an ideal case for studying intense vibration effects and their control at the four orthogonal direction switches. 7 Operational problems with robots in space relate to several factors. One most important is the structural flexibility problem of a robot manipulator and subsequently significant difficulties with its control systems, especially, position control. Typically, small elastic vibrations of the links coupled with their large rigid link rotations and non-linear dynamics primarily cause these difficulties. This paper presents a control scheme for positioning the endpoint of a two-link robot manipulator modeled with assumed modes flexible dynamics while tracking a square trajectory. The dominant assumed mode vibration is derived for an Euler-Bernoulli pinned-pinned beam to model link flexibility then, coupled with nonlinear dynamics for large rotations of rigid links to formulate an EulerLagrange inverse dynamics robot model. A control law derived using the Jacobian transpose provides joint actuation for both rigid and flexible dynamics. Comparison of output trajectories shows some differences in control performance between the rigid and flexible dynamics models with the transient response characteristics demonstrating a reduction in maximum overshoot for the flexible dynamics over the rigid dynamics models but a lengthier settling time with a consistent albeit slight oscillation about the entire desired steady-state ttrajectory .