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Messschraube zur Ermittlung von Schraubenbelastungen, die einen Schraubenkopf (8) und einen Schraubenschaft (9) mit einem oberen Schaftbereich (7) aufweist, der bei bestimmungsgemäßer Benutzung der Schraube nicht an einem Objekt anliegt, wobei mindestens zwei Dehnungsmesssensoren so im Schraubenschaft (9) angeordnet und dehnungskinematisch mit dem Schraubenschaft (9) gekoppelt sind, dass sie Dehnungswerte im Schraubenschaft (9) erfassen, aus denen über konstitutive Materialgesetze Belastungen in mehr als einer Achse im oberen Schaftbereich (7) bestimmt werden können, wobei die Dehnungsmesssensoren als faseroptische Sensoren an mehreren Stellen entlang mindestens einer optischen Faser (1) ausgebildet sind.
Die vorliegende Erfindung betrifft eine Messchraube zur Ermittlung von Schraubenbelastungen sowie ein Verfahren zu deren Herstellung. Die Messschraube umfasst mindestens zwei Dehnungsmesssensoren, die so im Schraubenschaft angeordnet und dehnungskinematisch mit dem Schraubenschaft gekoppelt sind, dass sie Dehnungswerte im Schraubenschaft erfassen, aus denenüber konstitutive Materialgesetze Belastungen in mehr als einer Achse im oberen freien Schaftbereich bestimmt werden können. Durch Möglichkeit der Bestimmung mehrachsiger Belastungen lassen sich Schrauben sachgerechter auslegen, so dass die Gefahr von Schraubenbrüchen reduziert wird.
Maintaining stability while walking on arbitrary surfaces or dealing with external perturbations is of great interest in humanoid robotics research. Increasing the system’s autonomous robustness to a variety of postural threats during locomotion is the key despite the need to evaluate noisy sensor signals. The equations of motion are the foundation of all published approaches. In contrast, we propose a more adequate evaluation of the equations of motion with respect to an arbitrary moving reference point in a non-inertial reference frame. Conceptual advantages are, e.g., getting independent of global position and velocity vectors estimated by sensor fusions or calculating the imaginary zero-moment point walking on different inclined ground surfaces. Further, we improve the calculation results by reducing noise-amplifying methods in our algorithm and using specific characteristics of physical robots. We use simulation results to compare our algorithm with established approaches and test it with experimental robot data.
Sweaty has already participated several times in RoboCup soccer competitions (Adult Size). Now the work is focused coordinating the play of two robots. Moreover, we are working on stabilizing the gait by adding additional sensor information. An ongoing work is the optimization of the control strategy by balancing between impedance and position control. By minimizing the jerk, gait and overall gameplay should improve significantly.
This paper describes the new Sweaty humanoid adult size robot trying to qualify for the RoboCup 2014 adult size humanoid competition. The robot is built from scratch to eventually allow it to run. One characteristic is that to prevent the motors from overheating, water evaporation is used for cooling. The robot is literally sweating which has given it its name. Another characteristic is, that the motors are not directly connected to the frame but by means of beams. This allows a variable transmission ratio depending on the angle.
An analytical and numerical study of the wobbling dynamics of friction disks is presented. Of particular interest is the excitation mechanism taking into account two contrarian effects both originating in dry friction: the circulatory terms describing the energy input due to the sliding contacts and the friction induced damping which stabilizes the system. Balance of these terms determines the instability domain in the parameter space. It is shown that there is a slip threshold so that, if the slip is under this limit, the system remains stable. If the slip is larger than this limit, then the criterion of stability is determined by the relation between the friction coefficient and the internal damping. The limit cycle appearing in the unstable domain is also investigated. It is shown that the limit cycle can be described as a kind of a regular reverse precession of the wobbling disc. Its amplitude is limited by the geometric nonlinearity and partial contact loss. Analytic results are compared with numeric simulations.