The rotation accuracy evaluation methods for the high-speed spindle of machining robots
High speed machining robots is designed for a number of high speed machining applications, the precision of which is one of the essential features. To increase precision of the robots, the study of accuracy evaluation methods is important. First, according to the demands for robots, key information of high-speed spindle of machining robots is determined, then it will be extracted by sensors and data acquisition card. Second, four different evaluating methods are introduced to assess the rotation accuracy, the results respectively solved by which are compared in detail. Furthermore, the particle swarm algorithm based on simulated annealing (SA-PSO) is introduced and theory analysis about the impact of simulated annealing factor is carried on to provide basis for giving the parameter better value. Finally, through the contrast between the evaluation results obtained by the proposed method and other optimization methods, the availability and precision of the SA-PSO is verified.
Dynamic Behavior Analysis for a Six Axis Industrial Machining Robot
The six axis robots are widely used in automotive industry for their good repeatability (as defined in the ISO92983) (painting, welding, mastic deposition, handling etc.). In the aerospace industry, robot starts to be used for complex applications such as drilling, riveting, fiber placement, NDT, etc. Given the positioning performance of serial robots, precision applications require usually external measurement device with complexes calibration procedure in order to reach the precision needed. New applications in the machining field of composite material (aerospace, naval, or wind turbine for example) intend to use off line programming of serial robot without the use of calibration or external measurement device. For those applications, the position, orientation and path trajectory precision of the tool center point of the robot are needed to generate the machining operation. This article presents the different conditions that currently limit the development of robots in robotic machining applications. We analyze the dynamical behavior of a robot KUKA KR240-2 (located at the University of Bordeaux 1) equipped with a HSM Spindle (42000 rpm, 18kW). This analysis is done in three stages. The first step is determining the self-excited frequencies of the robot structure for three different configurations of work. The second phase aims to analyze the dynamical vibration of the structure as the spindle is activated without cutting. The third stage consists of vibration analysis during a milling operation.
Investigation of scatter radiation of non-circular X-ray scan trajectories
Modern interventional X-ray devices are highly maneuverable and allow complex 3D imaging trajectories. New scan trajectories enable not only optimized object sampling but also introduce new approaches for dynamic 3D imaging. In this paper, we investigated the scatter radiation of two different scan trajectories. The scatter radiation was sampled by a rail setup with dosimeters at defined positions. After data analysis, contour maps were generated which show for four exemplary heights the scatter radiation distribution. The alternative scan trajectory showed smaller dose exposures at heights correlated to upper torso and head areas of a model physician. Keywords—Image acquisition, alternative scan trajectory, circular tomosynthesis, scatter radiation distribution