Browsing by Author "Lechler, Armin"

Now showing 1 - 11 of 11

Open Access
Acceleration-based disturbance compensation for elastic rack-and-pinion drives
(2021) Brenner, Felix; Lechler, Armin; Verl, Alexander
Rack-and-pinion drives are mainly used for large machine tools and are often operated with indirect position control. Due to the lack of state information on the output side, this results in reduced accuracy regarding the table position. In addition, the system can only react inadequately to disturbances outside the control loop, meaning that often insufficient results can be achieved in typical application scenarios such as milling. To meet the increasing dynamic and accuracy requirements of the modern manufacturing industry, this paper presents a highly dynamic acceleration-based disturbance compensation method. For this purpose, the table acceleration is estimated using a dynamical model of the drive train and compared to the signal from an additional acceleration sensor attached to the machine table. Based on the resulting difference, an additional compensation torque is provided, which suppresses the disturbance in counterphase. The approach is tested experimentally on an open control platform with industrial drive components and the behavior is investigated based on compliance frequency responses and externally applied milling forces. At the same time, a standardized parametrization methodology is developed and the robustness is evaluated by varying table masses. In summary, a considerable improvement of the dynamic disturbance behavior can be achieved compared to the conventional system without compensator.
Open Access
Experimental investigation into the implications of transmission errors for rack-and-pinion drives
(2021) Steinle, Lukas; Lechler, Armin; Neubauer, Michael; Verl, Alexander
Rack-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.
Open Access
Fehlertolerante Sicherheitssteuerung aus der Cloud : Softwarebasierte Sicherheitssteuerungen
(2023) Fischer, Marc; Walker, Moritz; Lechler, Armin; Riedel, Oliver; Verl, Alexander
Open Access
Hybrid manufacturing of topology optimized machine tool parts through a layer laminated manufacturing method : practical validation using the example of a bearing block
(2021) Helfesrieder, Nico; Neubauer, Michael; Lechler, Armin; Verl, Alexander
Load-oriented lightweight structures are commonly designed based on topology optimization. For machine tool parts, they enable the reduction of moving masses and therefore increase the resource and energy efficiency of production systems. However, this usually results in complex part structures that are difficult or impossible to produce using conventional manufacturing methods. In this paper, a hybrid layer laminated manufacturing (LLM) method is proposed enabling manufacturing of topology-optimized machine tool parts. The method is referred to as hybrid, as the subtractive structuring of metal sheets is combined with the additive joining of the sheets by adhesive bonding. This enables enclosed inner cavities without support structures, which are used to approximate the optimal density distribution from a topology optimization via manufacturing. The proposed LLM method is validated on the basis of a bearing block of a ball screw feed drive. A experimental study in the time and frequency domain on a test rig confirms the principle suitability of the LLM method for the production of industrial applicable lightweight components.
Open Access
Kompensation fehlender Komponenten in der Simulation : Konzept KI-basierte Assistenzsysteme zum beschleunigten Einstieg in die virtuelle Inbetriebnahme
(2023) Tinsel, Erik-Felix; Lechler, Armin; Riedel, Oliver
Open Access
Konzeption einer funktional einheitlichen Applikationsschnittstelle für Ethernet-basierte Bussysteme
(2011) Lechler, Armin; Verl, Alexander (Prof. Dr.-Ing. Dr. h.c.)
Die Wandlungsfähigkeit der Produktionstechnik hat neben maschinenbaulichen und organisatorischen Veränderungen insbesondere Auswirkungen auf die Systemarchitektur von Maschinen und Anlagen. Aktuelle Systemarchitekturen zeichnen sich durch Dezentralisierung und vernetzte mechatronische Module aus. Der Trend in der Automatisierungstechnik zur Dezentralisierung und zu mechatronischen Systemen führt zu einem erhöhten Kommunikationsaufwand innerhalb solcher Systemarchitekturen. Der Zugriff auf die Kommunikationssysteme aus der Applikation heraus unterscheidet sich grundlegend zwischen den einzelnen existierenden Bussystemen. Dies führt dazu, dass busspezifische Informationen in den Applikationen selbst enthalten sind. Applikation sind dadurch vom verwendeten Kommunikationssystem abhängig und können nicht ohne aufwändige Anpassung über ein anderes Bussystem kommunizieren. Ziel der vorliegenden Arbeit ist es Automatisierungssysteme und insbesondere Anwendungsprogramme sowie Applikationen zu schaffen, die unabhängig von der eingesetzten Kommunikationstechnik sind. Dazu wird die Konzeption einer funktional einheitlichen Applikationsschnittstelle für Ethernet-basierte Bussysteme betrachtet. Es wird mit Hilfe der Objektorientierten Analyse eine geeignete Sichtweise in Form einer Schnittstelle für industrielle Kommunikationssysteme abgeleitet. Dazu werden die in der Produktionstechnik relevanten Ethernet-basierten Bussysteme und deren zugehörige Applikationsprofile betrachtet. Es wird zunächst durch Abstraktion eine Struktur definiert anhand derer die einzelnen Systeme durch Spezialisierung verglichen und daraus eine einheitliche Applikationsschnittstelle abgeleitet werden kann.
Open Access
Model predictive control for compliant feed drives with offset-free tracking behavior
(2023) Leipe, Valentin; Hinze, Christoph; Lechler, Armin; Verl, Alexander
Industrial 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.
Open Access
OPC UA Tests im Kontext einer Dateninfrastruktur : Aussagekraft von OPC UA Testfällen für die innerbetriebliche Dateninfrastruktur
(2023) Heinemann, Tonja; Ajdinović, Samed; Lechler, Armin; Riedel, Oliver
Open Access
Process-integrated computerized numerical control : an analysis on process-machine coupling and feed scheduling
(2024) Elser, Anja; Lechler, Armin; Verl, Alexander
Computerized numerical controls (CNCs) have been invented for the automation of industrial processes. They are used, when the process to be automated is required to be exact and fast with repeatable quality. Originally, the use of CNCs was primarily focused on milling and drilling processes. Today, CNCs are utilized in a wide range of industrial processes due to the growing importance of automation. However, the integration of process information or adaptation to the needs of these processes to achieve advanced manufacturing with CNCs is difficult: Industrial CNCs are rather closed real-time machining systems. Today, process integration is possible, when the interaction between the process and the machine is decoupled in view of the bandwidth of machine dynamics and process dynamics. There are interfaces that allow for process-motivated control loops that are realized on top of the machine control loop (e.g. chatter control). Then, machine-integrated real-time control is not the focus. Besides, it is often possible to change desired values inside the control loop (position, velocity, acceleration) on an axes basis. In this case, adaptation to the process can be realized in each computation cycle. However, process dynamics and machine axes dynamics are generally treated separately. The same holds for extra actuators (e.g., in the spindle) for position control. This paper has two goals. First, it wants to create an understanding for different levels of process-machine coupling. Second, the problem of direct coupling of process dynamics and machine dynamics is focused. Machining systems design propositions as well as some examples for the coupling of process and machine dynamics in the CNC are given.
Open Access
Prozessmodellierung für das Rührreibschweißen : semi-analytisches Prozessmodell für das roboterbasierte Rührreibschweißen
(2023) Kamm, Valentin; Mesmer, Patrick; Lechler, Armin; Verl, Alexander
Open Access
Updating the Linux TAPRIO scheduler in deterministic time
(2022) Arnim, Christian von; Gessner, Gernot; Jarwitz, Michael; Lechler, Armin; Riedel, Oliver
In flexible production systems with distributed control systems which communicate with each other via a real time network, changes in the requirements for real time communication during operation must not lead to a temporary failure of the deterministic communication. Rather, the changes of the network configuration must become active at exactly predictable times in order to guarantee the functionality of the deterministic communication all the time. This paper shows a realization of how the configuration of a real time network schedule under Linux can be adjusted at predetermined times without interrupting the communication. For this purpose, the real time scheduler TAPRIO is integrated into the library libnl, and the performance of this extension is evaluated in a test case. It is shown that the modification of the network configuration is reliably possible in several successive communication cycles.