Rancang Bangun Grade Monitoring Assist pada D3K Caterpillar Berbasis Mikrokontroler sebagai Akurasi pada Pekerjaan Operator Dozer

In the process of construction work, operators need accuracy in the process of finishing land leveling works such as road highway building, land reclamation, large commercial, landfill installation, so as to increase productivity. Therefore, the purpose of this research is to manufacture and implement a ground leveling finishing tool using Arduino IDE software and Atmega 328 microcontroller on the Dozer D3K Caterpillar heavy equipment unit. The placement of a series of components from the Grade Monitoring Assist includes the ultrasonic sensor on the lift cylinder, gyro and accelerometer at the top center of the blade, as well as a display that displays the results of parameter readings. Connections between components in Grade Monitoring Assist are cables that integrate all installed components. The results of testing the movement of the blade up and down position to get an accuracy value of 97.30% and an error of 2.70%. While the movement of the blade down position has an accuracy value of 96.50% and an error of 2.50%. And Tests by moving the blade according to the implement movement angle at the maximum blade angle position (either side) with an average error value of 1.48o, cutting ditches (angle V) an average error value of 0.676o

An Experimental Evaluation of Particle Impact Dampers Applied on the Tool for Milling of Hardened Steel Complex Surface

In the manufacturing of dies and molds, vibrations may represent serious problems, since the finishing tool used is usually slender (high Length / Diameter ratio) in order to machine deep cavities with complex geometry, typical of these products. Vibration is an undesirable phenomenon in any machining operation as it can lead to poor surface finish, lower material removal rate and increased tool wear. The use of impact dampers in the tool has proven to be an effective method for reducing vibration in machining processes. Damping occurs through energy dissipation and linear momentum exchange during intermittent collisions between the main structure (in this case the milling tool) and a free mass (spheres or cylinders placed within a tool cavity). Although efficient, these types of dampers are highly nonlinear. Thus, the aim of this work is to analyze the effect of different materials and geometries (steel spheres, tungsten spheres and steel cylinders) acting as impact dampers inside a ball nose end milling tool. To do so, milling of a convex D6 steel surface was performed, comparing commercial tool holders with dampened ones. The results showed that the tools with impact dampers generated lower values of roughness in the workpiece (around 30% of the value observed in the conventional steel tool holder for the case of steel cylinders and around 40% for both spheres) and presented lower levels of vibration when compared to the same tool without the impact damper, mainly in the machining of workpiece regions where radial and tangential forces are predominant. The tool which used tungsten spheres generated roughness surfaces similar to those obtained with steel spheres, while the tool that used steel cylinders only generated lower roughness in the regions where the axial force component is not predominant, which shows that their performance is highly dependent on the resulting force direction.

Study on Magnetic Abrasive Finishing Process of AlSi10Mg Alloy Curved Surface Formed by Selective Laser Melting

In this paper, AlSi10Mg alloy powder is selected as the forming powder of Selective Laser Melting technology, and the AlSi10Mg alloy SLM curved surface sample is constructed by setting the internal and external layering parameters. In view of the relatively rough surface roughness of SLM technology molded parts, this paper selects the magnetic finishing technology with higher flexibility characteristics to perform surface finishing and finishing on the formed curved surface samples. Explore the feasibility of magnetic finishing technology on the finishing of SLM shaped curved parts, and test and analyze the surface roughness, surface hardness and hydrophobicity of the finishing permanent magnet tools and the curved surface samples before and after finishing. Finally, it was found that the use of a 75° trapezoidal slotted permanent magnet finishing tool to absorb spherical Al2O3 magnetic abrasives for flexible finishing of AlSi10Mg alloy SLM shaped curved surface samples can achieve better finishing results.In this paper, the orthogonal experiment method is used to optimize the finishing experiment. It is found that the finishing parameters of the spindle speed is 1800 r/min, the feed rate is 5 mm/min, the gap is 2 mm, and the abrasive consumption is 7g to form the AlSi10Mg alloy SLM. The surface roughness Ra=0.279μm can be obtained by magnetic finishing of the curved sample, and the surface morphology of the sample has been greatly improved. At the same time, it is found that the magnetic finishing technology improves the surface roughness of the AlSi10Mg alloy SLM forming surface sample, while it does not change the surface hardness of the sample, but it can significantly improve the hydrophobicity of the sample surface.

Merfin: improved variant filtering and polishing via k-mer validation

Read mapping and variant calling approaches have been widely used for accurate genotyping and improving consensus quality assembled from noisy long reads. Variant calling accuracy relies heavily on the read quality, the precision of the read mapping algorithm and variant caller, and the criteria adopted to filter the calls. However, it is impossible to define a single set of optimal parameters, as they vary depending on the quality of the read set, the variant caller of choice, and the quality of the unpolished assembly. To overcome this issue, we have devised a new tool called Merfin (k-mer based finishing tool), a k-mer based variant filtering algorithm for improved genotyping and polishing. Merfin evaluates the accuracy of a call based on expected k-mer multiplicity in the reads, independently of the quality of the read alignment and variant caller internal score. Moreover, we introduce novel assembly quality and completeness metrics that account for the expected genomic copy numbers. Merfin significantly increased the precision of a variant call and reduced frameshift errors when applied to PacBio HiFi, PacBio CLR, or Nanopore long read based assemblies. We demonstrate the utility while polishing the first complete human genome, a fully phased human genome, and non-human high-quality genomes.

IMPROVEMENT OF TECHNOLOGICAL PROCESS OF MACHINING WITH THE DESIGN OF THE CUTTER FOR FINISH TURNING

The technological process of mechanical processing of composite materials is considered. A brief description of composite materials, their physical and mechanical properties, and their structure is studied. The features of processing of glass-reinforced plastics carbon fiber reinforced plastics, organic plastics and bioplastics are reflected. The processing of composites will be difficult due to reinforcement schemes, different fiber directions and types of continuous fiber laying. All this leads to certain requirements that will be imposed on the tool and its wear rate. Tool wear consists of different types of wear – adhesive, fatigue, abrasive-mechanical, chemical. When carrying out the cutting process, it is necessary to take into account the direction of reinforcement, and therefore the direction of processing of the cutting tool. Depending on the state of the surface layer, the cutting tool required for mechanical processing is considered. The justification of the need to improve the design of the cutting tool is given. The design of the cutting head has been developed for the cutting process. It consists of roughing and finishing cutters. The values of the design parameters of the tool head are considered and selected. The optimal cutting depth for the finishing tool is determined. The geometric parameters of the finishing tool are selected experimentally, the purpose of which is to provide the required quality of processing. Using experiments, the values of the angle of deviation of the main cutting edge from the horizontal plane are found. The design of the finishing tool is described in detail, which largely eliminates the disadvantages of processing. The appearance of a leading crack when turning with a finishing tool is excluded.

Estimating Human Wrist Stiffness during a Tooling Task

In this work, we propose a practical approach to estimate human joint stiffness during tooling tasks for the purpose of programming a robot by demonstration. More specifically, we estimate the stiffness along the wrist radial-ulnar deviation while a human operator performs flexion-extension movements during a polishing task. The joint stiffness information allows to transfer skills from expert human operators to industrial robots. A typical hand-held, abrasive tool used by humans during finishing tasks was instrumented at the handle (through which both robots and humans are attached to the tool) to assess the 3D force/torque interactions between operator and tool during finishing task, as well as the 3D kinematics of the tool itself. Building upon stochastic methods for human arm impedance estimation, the novelty of our approach is that we rely on the natural variability taking place during the multi-passes task itself to estimate (neuro-)mechanical impedance during motion. Our apparatus (hand-held, finishing tool instrumented with motion capture and multi-axis force/torque sensors) and algorithms (for filtering and impedance estimation) were first tested on an impedance-controlled industrial robot carrying out the finishing task of interest, where the impedance could be pre-programmed. We were able to accurately estimate impedance in this case. The same apparatus and algorithms were then applied to the same task performed by a human operators. The stiffness values of the human operator, at different force level, correlated positively with the muscular activity, measured during the same task.