Grasp planning for a reconfigurable parallel robot with an underactuated arm structure

In this paper, a novel approach of grasp planning is applied to find out the appropriate grasp points for a reconfigurable parallel robot called PARAGRIP (Parallel Gripping). This new handling system is able to manipulate objects in the six-dimensional Cartesian space by several robotic arms using only six actuated joints. After grasping, the contact elements at the end of the underactuated arm mechanisms are connected to the object which forms a closed loop mechanism similar to the architecture of parallel manipulators. As the mounting and grasp points of the arms can easily be changed, the manipulator can be reconfigured to match the user's preferences and needs. This paper raises the question, how and where these grasp points are to be placed on the object to perform well for a certain manipulation task. <br><br> <i>This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.</i&gt

Методы автоматического поиска неисправностей и контроля сложных систем: обзор

In the face of continuously increasing cost pressure, a wide range of product versions and shorter innovation cycles, the demand for more versatile assembly and handling systems is steadily growing. Co-operating robots represent a suitable approach for this purpose. However, reconfiguring a multi-device robot cell usually involves a certain programming effort and unfavorable down times. By integrating self-optimizing functions, the complex task of reconfiguration is substantially simplified in order to make economic use not only of the referenced co-operating robotic systems. Therefore, several self-optimizing functions for different stages of production have been developed and applied to various production tasks. The implemented functions comprise self-optimizing planning and commissioning as well as a self-optimizing joining process. Based on the experience gained from these examples, the self-optimizing functions will be similarly applicable to various cases with rel atively small additional effort

Simulation of Integrated Actuators for Electrostatic Self-Assembly

Die Montage ist ein Kostentreiber in der Produktion, insbesondere wenn die Anforderungen an die Präzision stei-gen. Ein Ansatz für die kostengünstige Feinpositionierung von planaren Bauteilen ist die elektrostatische Self-Assembly, bei dem Aktoren in die Bauteile integriert werden. In diesem Artikel werden die Grundlagen des Designs solcher Systeme thematisiert, da diese Ausschlaggebend für die resultierenden Positionierkräfte sind. Zum Feststellen der Zusammenhänge werden Simulationen für einzelne Elektrodenpaare durchgeführt, wobei die Geometrien Kreis, Quadrat, Rechteck, Sechseck und Dreieck miteinander verglichen werden. Die Auswertung erfolgt mit der simulierten Maximalkraft und der Kraftverteilung innerhalb der xy-Ebene. In Hinblick auf die Prozessgrößen Präzision und maximalen Wirkbereich werden die Ergebnisse interpretiert und Rückschlüsse auf die sinnvolle Gestaltung von Self-Assembly Systemen gezogen. Abschließend erfolgt ein Ausblick auf weitere Forschungen zu elektrostatischen Self-Assembly Systemen.Assembly is a high-cost process in production, especially when the precision requirements are high. One approach for cost-effective fine positioning of planar components is electrostatic self-assembly. Therefore, actuators are integrated into the components. This paper deals with the fundamental design principles of such systems, because they are significantly influencing the alignment force. This paper presents simulations of individual electrode pairs, comparing the geometries circle, square, rectangle, hexagon and triangle. The evaluation shows the results of the simulated maximum force and the force distribution within the xy-plane. Aiming for high precision and a wide range of force distribution, conclusions are made about the appropriate design of self-assembly systems. In conclusion, there is an outlook on additional research into electrostatic self-assembly systems

Automation of flexible handling of hot forged Tailored Forming components

Universalgreifer sind flexibel einsetzbar und können sich an verschiedene Situationen und Objekte anpassen. Aktuelle formvariable Universalgreifer bestehen überwiegend aus monolithischen polymeren Werkstoffen, deren maximale Einsatztemperaturen bei 300 °C liegen. Somit kann von der Formflexibilität nicht in Bereich profitiert werden in denen höhere Temperaturen vorherrschen und die zu handhabenden Objekte Umformungsprozesse durchschreiten. Solch ein Bereich ist der Schmiedesektor, bei dem die Objekte Temperaturen von bis zu 1250 °C erreichen. Die vorliegende Diskrepanz zwischen der Formvariabilität der Greifer und den Prozesstemperaturen im Schmiedesektor versuchen wir zu schließen. In dieser Arbeit stellen wir das von uns entwickelte Konzept eines formvariablen hochtemperaturbeständigem Handhabungssystem und deren praktische Umsetzung vor, sowie die noch zu lösenden Herausforderungen.Universal grippers are flexible and can adapt to different situations and objects. The shape variability has limitations, for example, the temperature. For manufacturing such shape variable grippers, elastic polymer materials are used. The material has an upper limit of the operating temperature of 300 °C. In the forging sector, the manufactured object change their geometry during the process and reaches temperature up 1250 °C. Here, we see the potential of the utilization of shape variable grippers. Therefore, we developed a system that overcomes the gap between the temperature limitation of current shape variable grippers and the high temperature in forging environments. This paper presents our gripper and the task to be solved in future works

Benefit of extra sensors for distinguishability of models of electric power trains in structure und parameter identification

Für viele Fragestellungen aus Reglerauslegung, Vorsteuerung und Zustandsüberwachung werden Prozessmodelle mit korrekter und physikalisch interpretierbarer innerer Struktur benötigt (phenomenologische Modelle). Die modellbasierten Ansätze werden in der Industrie vielfach noch nicht angewandt, weil die Modellerstellung ein hohes Maß an Expertenwissen und die langwierige Programmierung von Experimenten erfordert. Eine automatischen Struktur- und Parameteridentifikation ist dadurch bebrenzt, dass anhand des Ein-/Ausgangsverhaltens häufig die Unterscheidbarkeit von Modellen nicht gegeben ist. In dieser Veröffentlichung liegt der Fokus auf industriellen Anlagen mit elektrischem Antriebsstrang und einfacher Kinematik wie Regalbediengeräten, Werkzeugmaschinen und Positionierantrieben. Diese Systeme haben häufig nur einen Positions- und einen Stromsensor. Es wird in Experimenten gezeigt, dass durch Hinzunahme von einfach zu installierenden Zusatzsensoren wie Beschleunigungssensoren oder Drehratensensoren in einigen Fällen eine eindeutige Strukturidentifikation ermöglicht wird, auch wenn nur wenig Vorwissen über den Sensorort vorliegt

Adaptive approximation control of biped robots: a low-level tracking control layer

The adaptive approximation control is a powerful tool for controlling robotic systems with unmodeled dynamics. The local (partitioned) approximation-based adaptive control includes representation of the uncertain matrices and vectors in the robot model as finite combinations of basis functions. Update laws for the weighting matrices are obtained by the Lyapunov-like design. However, one of the inherent limitations of this category of approximation is curse dimensionality associated with the approximation of uncertain matrix. There are three possible representations for the approximation of the uncertain matrix: Kronecker product, sparse matrices, and GL operator. Both Kronecker product and sparse matrices can grow exponentially with the dimension of the target matrix, whereas GL operator can grow linearly but without the use of conventional operations of matrices. In light of the above, this report proposes a simple representation for the approximation of the uncertain matrix. The proposed representation is directly linear concerning the dimension of the target matrix using the conventional operations of matrices. Two case studies are simulated which are: two-link manipulator and 6-link biped robots during the complete gait cycles (single support phase SSP and double support phase DSP). Biped robot has different configurations during the walking cycle; it is considered as an open-chain mechanism with a fixed-base stance foot during the SSP and as a closed constrained mechanism during the DSP.The results show that for low dimension robotic manipulators, all representations can be conducted equivalently. There is no large difference in simulation time, whereas for higher degrees of freedom robots the GL operator and the proposed representation are superior in simulation time

Adaptive approximation control of biped robots: a low-level tracking control layer

The adaptive approximation control is a powerful tool for controlling robotic systems with unmodeled dynamics. The local (partitioned) approximation-based adaptive control includes representation of the uncertain matrices and vectors in the robot model as finite combinations of basis functions. Update laws for the weighting matrices are obtained by the Lyapunov-like design. However, one of the inherent limitations of this category of approximation is curse dimensionality associated with the approximation of uncertain matrix. There are three possible representations for the approximation of the uncertain matrix: Kronecker product, sparse matrices, and GL operator. Both Kronecker product and sparse matrices can grow exponentially with the dimension of the target matrix, whereas GL operator can grow linearly but without the use of conventional operations of matrices. In light of the above, this report proposes a simple representation for the approximation of the uncertain matrix. The proposed representation is directly linear concerning the dimension of the target matrix using the conventional operations of matrices. Two case studies are simulated which are: two-link manipulator and 6-link biped robots during the complete gait cycles (single support phase SSP and double support phase DSP). Biped robot has different configurations during the walking cycle; it is considered as an open-chain mechanism with a fixed-base stance foot during the SSP and as a closed constrained mechanism during the DSP.The results show that for low dimension robotic manipulators, all representations can be conducted equivalently. There is no large difference in simulation time, whereas for higher degrees of freedom robots the GL operator and the proposed representation are superior in simulation time

Design of a Two-DOFs driving mechanism for a motion-assisted finger exoskeleton

© 2020 by the authors. This paper presents a novel exoskeleton mechanism for finger motion assistance. The exoskeleton is designed as a serial 2-degrees-of-freedom wearable mechanism that is able to guide human finger motion. The design process starts by analyzing the motion of healthy human fingers by video motion tracking. The experimental data are used to obtain the kinematics of a human finger. Then, a graphic/geometric synthesis procedure is implemented for achieving the dimensional synthesis of the proposed novel 2 degrees of freedom linkage mechanism for the finger exoskeleton. The proposed linkage mechanism can drive the three finger phalanxes by using two independent actuators that are both installed on the back of the hand palm. A prototype is designed based on the proposed design by using additive manufacturing. Results of numerical simulations and experimental tests are reported and discussed to prove the feasibility and the operational effectiveness of the proposed design solution that can assist a wide range of finger motions with proper adaptability to a variety of human fingers