Universität Stuttgart
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Item Open Access Parameter identification for fault analysis of permanent magnet synchronous motors based on transient processes(2024) Wu, Chaoqiang; Verl, AlexanderAs the market for hybrid and electric vehicles expands, electric motor production and testing technology must be continuously improved to meet the cost and quality requirements of mass production. In order to detect faults in motors during the production process, a condition monitoring tool is used for the motor end line. During most condition monitoring, the motor operates in a static state where the speed of the motor remains constant and the voltage/current is recorded for a certain period. This process usually takes a long time and requires a loader to drag the motor to a standstill at a constant speed. In this paper, various transient process testing methods are introduced. For these processes, only transient operation of the motor, such as acceleration, loss, or a short circuit, is required. By analyzing the measurement results and simulation results of motor models, unhealthy motors can be detected more effectively.Item Open Access Efficient combination of topology and parameter optimization(2014) Lin, Yusheng; Sun, Zheng; Dadalau, Alexandru; Verl, AlexanderThis paper presents a combination method of Particle Swarm Optimization (PSO) and topology optimization. With this method a better result can be achieved compared with the sequential ap-plication of the two optimization methods. It inherits the ability in finding global optimum from PSO and also suits for discretized design domain. Some special schemes are used in order to provide higher computation efficiency. This method has only been tested with a convex optimization problem. The application in case of a concave problem will be a future study.Item Open Access Automatic preload adaptation for rack-and-pinion drives to maximize performance and energy efficiency(2024) Steinle, Lukas; Leipe, Valentin; Lechler, Armin; Verl, AlexanderElectrically preloaded rack-and-pinion drives are typically utilized in machine tools to precisely move heavy loads over long travel distances. In the state of the art, the preload torque is commonly set to a constant value during commissioning. This poses a conflict of objectives between maximizing performance and minimizing energy consumption. To resolve this, this publication presents a novel approach to automatically adapt the preload torque during operation. For this purpose, the established preload control is extended by a simple control law that adapts the preload torque to the current operating state within the permissible limits. This way, higher preload torques are only applied, if the resulting higher system stiffness is beneficial for the drive performance. Otherwise, the preload torque is reduced to save energy. The automatic preload adaptation is experimentally validated on a test system with industry standard components. This involves both system-theoretical analyses and practical test scenarios.Item Open Access Model predictive control for compliant feed drives with offset-free tracking behavior(2023) Leipe, Valentin; Hinze, Christoph; Lechler, Armin; Verl, AlexanderIndustrial machine tool feed drives are predominantly controlled by cascade control due to their low tuning complexity and inherent robustness. However, the cascaded structure requires the inner cascades to have higher dynamics than the outer cascades, which limits the achievable dynamic accuracy. Direct control approaches, which substitute the position and velocity cascade, offer the potential to utilize the unused potential. A promising approach is model predictive control (MPC), which optimizes the manipulated variable with a plant model along a prediction horizon. However, model uncertainties between the nominal model and the real plant lead to tracking errors. Therefore, this paper presents, a linear MPC (LMPC) and an adaptive MPC (AMPC) with an additional integral action to robustly compensate for model mismatches. Both controllers use a compliant model, are real-time capable with a sample rate of 2kHzand consider state and input space constraints. The AMPC accounts for position-varying stiffness and friction. The controllers are experimentally compared with classical P-PI cascaded control on a ball screw drive. They show a tracking error reduction of 37%(LMPC) and 44%(AMPC) during a high speed motion profile and an increase in bandwidth of 180%(LMPC) and 184%(AMPC), resulting in significantly improved dynamic accuracy.Item Open Access Strategy for topological reconfiguration of cable-driven parallel robots(2024) Trautwein, Felix; Dietrich, David; Pott, Andreas; Verl, AlexanderItem Open Access Fehlertolerante Sicherheitssteuerung aus der Cloud : Softwarebasierte Sicherheitssteuerungen(2023) Fischer, Marc; Walker, Moritz; Lechler, Armin; Riedel, Oliver; Verl, AlexanderItem Open Access Experimental investigation into the implications of transmission errors for rack-and-pinion drives(2021) Steinle, Lukas; Lechler, Armin; Neubauer, Michael; Verl, AlexanderRack-and-pinion drives are the preferred option in the machine tool sector when long ranges of motion and high loads are involved. However, their shortcomings particularly include deficiencies in the achievable positioning and path accuracy. The backlash as one of the main issues is well described in the literature and numerous solutions to reduce its negative effects exist. In contrast, there is a lack of literature regarding the scientific and systematic analysis of the transmission errors in rack-and-pinion drives. In this paper, the displacements originating in the drive train of a system with industrial components are measured under different operating conditions. The observed transmission errors are thoroughly analyzed in no-load operation and their sources are discussed. Subsequent investigations show significant load-dependent alterations of the transmission errors and direction-dependent characteristics, the causes of which are explained. It is shown, that transmission errors negatively affect the path accuracy of position controlled drives, which is amplified by excitation of the machine structure in certain operating conditions. To address this issue, different error compensation concepts are presented.Item Open Access Konzept zur Testfallgenerierung mittels Mixed Reality : Erweiterung der Testautomatisierung um Methoden der Mixed-Reality-in-the-Loop-Simulation (MRiLS)(2023) Hönig, Jana; Littfinski, Daniel; Schnierle, Marc; Röck, Sascha; Verl, AlexanderItem Open Access Universal and automated approaches for optimising the processing order of geometries in a CAM tool for redundant galvanometer scanner-based systems(2024) Kurth, Daniel; Reiff, Colin; Jiang, Yujiao; Verl, AlexanderThe combination of highly dynamic systems with a limited work envelope with a less dynamic system with a larger working envelope promises to combine the advantages of both systems while eliminating the disadvantages. For these systems, separation algorithms determine the trajectories based on the target geometries. However, arbitrary processing orders of these result in inefficient trajectories because successive geometries may be geometrically far apart. This causes the dynamic system to operate below its potential. Current planning tools do not optimise the processing order for such redundant systems. The aim is to design and implement a planning tool for the application of laser marking. The tool considers the processing order of the 2D geometries from a geometric point of view. The resulting sequenced path data can then be used by trajectory generation algorithms to make full use of the potential of redundant systems. The approach analyses literature on Travelling Salesman Problems (TSP), which is then transferred to the given application. A heuristic and a genetic algorithm are developed and integrated into a planning tool. The results show the heuristic algorithm being faster while still producing solutions whose total path length is similar to that of the genetic algorithm. Even though the solutions don’t meet any optimality standards, the presented automated approaches are superior to manual approaches and are to be seen as a starting point for further research.Item Open Access MoNA - die modulare Werkzeugmaschine : eine offene Forschungsplattform(2024) Dietrich, David; Jud, Oliver; Kurth, Daniel; Lechler, Armin; Leipe, Valentin; Nistler, Maximilian; Reiff, Colin; Schulte, Alexander; Steinle, Lukas; Verl, Alexander