Temporal calibration and synchronization of robotic total stations for kinematic multi-sensor-systems

Despite the increasing interest in kinematic data acquisition, Robotic Total Stations (RTSs) are still relatively seldom used. No matter if Mobile Mapping Systems or Control & Guidance, GNSS is mostly used as position sensor, which limits the application to outdoor areas. For indoor applications, a combination of relative sensors is usually employed. One reason why RTSs are not used is the challenging time referencing and synchronization. In this work we analyze the challenges of a synchronized kinematic application of RTSs and present solutions.Our approach is based on a wireless network synchronization to establish a precise temporal reference frame. The achievable synchronization quality is thoroughly examined. In addition we develop a kinematic model of spherical measurements, that incorporates timing related parameters. To estimate these parameters we propose a temporal calibration utilizing an industrial robot. Both parts of our approach are evaluated using a test setup of two total stations, proofing an overall synchronization accuracy of 0.2 ms. An overall horizontal kinematic point accuracy of 2.3 mm reveals the potential of sufficiently synchronized RTSs.

Kinetostatic analysis of a scissor jack mechanism powered by a tetrad RRR-Ta-RRR

In a paper previously published by the authors, kinematic analysis of a jack mechanism driven by a motor tetrad was done. For the actual design of the mechanism, the forces and moments acting on the kinematic elements that are part of it must be determined. Also, the driving force in the hydraulic cylinder must be determined, so that the mechanism works in good conditions, for a certain technological task imposed by the design theme. The present paper makes the kinetostatic analysis of the mechanism studied, from the kinematic point of view. Therefore, the reactions in the kinematic couplings of the mechanism, as well as the driving force of the hydraulic cylinder, are determined. In order to determine the reactions of the kinematic couplings, as well as the driving force of the hydraulic cylinder, the masses of the elements, the moments of mechanical inertia, as well as the load force acting on the jack were considered. The results of the calculations were graphically represented, in reaction patterns. In order to verify the correctness of the calculations, the balance force (the hydraulic cylinder motor force) was determined by both the kinetic and the virtual power method, and the results are the same.

Influence of Functional Classification on Skill Tests in Elite Female Wheelchair Basketball Athletes

Background and objectives: Wheelchair basketball players are classified into four functional classes according to the player’s “volume of action”, characterized by trunk movement and stability. As this classification is based on a kinematic point of view, test items might be differentially affected by the functional classification level. We aimed to clarify field-based skill test items closely related to the functional classification level. Materials and Methods: Twenty-six female wheelchair basketball athletes (Japan National Team candidates) completed seven field-based skill tests (20 m sprint, agility T-test, figure-eight with a ball test, the Yo-Yo 10 m recovery test, and three types of maximal passes), and anthropometric measurements were applied. Results: Significant differences among the classification levels were found for one-hand maximal passes (baseball and hook passes) and the figure-eight with a ball test. Furthermore, performance in the 20 m sprint and 10 m Yo-Yo recovery tests significantly differed between classes 1 and 4. Conclusions: The test items most influenced by the classification levels were one-hand passes, which require trunk stability and balance not only in the horizontal plane, but also in the sagittal and frontal planes. Coaches should consider which test items are strongly affected by the functional classification level when assessing a player’s performance.

A derivation of the generalized model of strains during bending of metal tubes at bending machines

According to the postulate concerning a local change of the “actual active radius” with a bending angle in the bend zone, a generalized model of strain during metal tube bending was derived. The tubes should be subjected to bending at tube bending machines by the method of wrapping at the rotating template and with the use of a lubricated steel mandrel. The model is represented by three components of strain in the analytic form, including displacement of the neutral axis. Generalization of the model during bending metal tubes at the tube bending machines as compared with the existing papers (Śloderbach, 1999; Śloderbach and Rechul, 2000) consists in including the neutral axis displacement and possibility of determination of strains at each point along the thickness of the wall of the bent tube in the bending and bend zone. The derived scheme of strain satisfies initial and boundary kinematic conditions of the bending process, conditions of continuity and inseparability of strains. The obtained analytic expressions can be classified as acceptable from the kinematic point of view

SEMILEPTONIC DECAY OF Bc MESON INTO $c\bar c$ STATES IN A QCD POTENTIAL MODEL

The slope and curvature of Isgur–Wise function for Bc meson is computed in a QCD potential model in two different approaches of choosing the perturbative term of the Cornell potential. Based on heavy quark effective theory the exclusive semileptonic decay rates of Bc meson into the [Formula: see text] states are exploited. Spin symmetry breaking effects are ignored up to a particular point and the form factors are connected with Isgur–Wise function for other kinematic point since the recoil momentum of [Formula: see text] from Bc is small due to its heavy mass.

A New Approach to the Classic Structure for Robotic Arc Welding Systems

Starting from the analysis of the modern robotic arc welding system from the kinematic point of view, the paper presents an original concept of the systems structure. Instead a combination of two open chains, as it is generally seen, the author proposes one single closed kinematic chain. The main element of this chain is the electric arc employed for welding, virtually seen as a vector which connects the two open chains, the robot and the part manipulator. This new approach could possibly change and simplify the way arc welding robots are programmed today.

Toward an optimal performance index for neurosurgical robot's design

SUMMARYIn the past years a large number of new surgical devices have been developed to improve the operation outcomes and reduce the patient's trauma. Nevertheless, the dexterity and accuracy required in positioning the surgical tools are often unreachable if the surgeons are not assisted by a suitable system. Since a medical robot works in an operating room, close to the patient and the medical staff, it has to satisfy much stricter requirements with respect to an industrial one. From a kinematic point of view, the robot must reach any target position in the patient's body, being as less invasive as possible for the surgeon's workspace. In order to meet such requirements, the right robot structure has to be chosen by means of the definition of suitable kinematic performance indices.In this paper some task-based indices based on the robot workspace and stiffness are presented and discussed. The indices will be used in a multiobjective optimization problem to evaluate best robot kinematic structure for a given neurosurgical task.