6 results
Filters
Settings
Now showing1 - 6 of 6
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Cooperative distributed MPC via decentralized real-time optimization: Implementation results for robot formationsDistributed model predictive control (DMPC) is a flexible and scalable feedback control method applicable to a wide range of systems. While the stability analysis of DMPC is quite well understood, there exist only limited implementation results for realistic applications involving distributed computation and networked communication. This article approaches formation control of mobile robots via a cooperative DMPC scheme. We discuss the implementation via decentralized optimization algorithms. To this end, we combine the alternating direction method of multipliers with decentralized sequential quadratic programming to solve the underlying optimal control problem in a decentralized fashion with nominal convergence guarantees. Our approach only requires coupled subsystems to communicate and does not rely on a central coordinator. Our experimental results showcase the efficacy of DMPC for formation control and they demonstrate the real-time feasibility of the considered algorithms.Publicationtype: Journal Article5 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Trajectory tracking with collision avoidance for a parallel robot with flexible links(2021-06); ; End-effector trajectory tracking of a highly flexible three-link parallel robot is combined with collision avoidance in real-time. Typical real-time collision avoidance algorithms issue commands on actuator level which can cause large oscillations within flexible robots. Thus, the needed evasive motion at the points which are about to collide is used to adapt the desired end-effector trajectory of the underactuated system, even for actuator limits and points other than the end-effector. In contrast to existing real-time collision avoidance concepts, which are essentially completely based on rigid models, a dynamic flexible model inversion is then used for tracking. Thereby, output redefinition leads to a minimum phase system. The presented computationally efficient concepts, being actuator limit and obstacle collision avoidance, use sigmoid functions providing smooth trajectories. The former calculates a braking factor for the end-effector when an actuator approaches its limit. The latter avoids external dynamic obstacles based on repulsive vectors. Experiments validate both concepts with a flexible model inversion which clearly outperforms the classical rigid body approach.Publicationtype: Journal Article82 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Robust autopilot design for landing a large civil aircraft in crosswind(2018-07); ; ; A comprehensive autolanding design for a representative model of a twin-engined commercial aircraft is presented in this paper. To facilitate the design task and minimize control law switching, a cascaded control structure is selected which resembles integrator chains. Classical loopshaping and robust control techniques are used to design the individual control loops. The emphasis is on providing a complete and comprehensive qualitative design strategy. The control system's ability to safely land the aircraft despite strong crosswind in a variety of possible scenarios is demonstrated in an industry-grade verification campaign. Nonlinear Monte Carlo simulations of the airliner model are used to assess the risk of unsafe landing conditions and provide insight into the performance characteristics and limitations of the proposed control system.Publicationtype: Journal Article177 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Distributed identification and control of spatially interconnected systems with application to an actuated beamThis paper presents a case study on modelling and control of spatially interconnected systems. Considered is a vibration control problem, with experimental results on a flexible beam that is equipped with an array of piezo sensors and actuators. The sensor-actuator array induces a spatial discretization of the beam into an array of interconnected subsystems. Models are experimentally identified that have the structure of spatially interconnected systems. Based on the identified models, distributed control schemes are designed by solving a linear matrix inequality (LMI) problem that has the size of a single subsystem. Modelling and control is considered for both spatially invariant and spatially varying systems; in the latter case the system is represented as linear parameter-varying (LPV) system that is scheduled not over time but over space. Simulation and experimental closed-loop results demonstrate the practicality and efficiency of the underlying framework.Publicationtype: Journal Article79 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Subsynchronous damping controller design for high voltage DC links using linear matrix inequalitiesA systematic tuning procedure of a subsynchronous damping controller for a high voltage DC link is presented. Linear matrix inequality (LMI) techniques are utilized combining pole region assignment with H-infinity constraints. The controller is tuned to damp subsynchronous torsional (7-40 Hz) and electromechanical oscillations (<3 Hz) as present with a thermal generator located near to an AC/DC rectifier and a weak electrical link to the rest of the AC system. A linearized state space model is used for the control design and the performance and robustness is demonstrated by simulation using the software package EMTDC representing detailed non-linear and time varying characteristics.Publicationtype: Journal Article22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Robust control of a laboratory aircraft model via fast output samplingA new multimodel approach to robust controller design is illustrated by a practical application: for a laboratory aircraft model, a robust controller is designed for acceptable performance, in normal operating conditions and under propeller failure, simultaneously. Based on a linear model for each operating mode, linear matrix inequality (LMI) formulation of the problem and convex programming are used to search for a state feedback controller that achieves the objective. This state feedback design is then realized simultaneously in both operating modes by a controller that is based on fast output sampling. Robust performance is demonstrated by experimental results.Publicationtype: Journal Article17