Design of an Anthropomorphic, Compliant, and Lightweight Dual Arm for Aerial Manipulation

This paper presents an anthropomorphic, compliant and lightweight dual arm manipulator designed and developed for aerial manipulation applications with multi-rotor platforms. Each arm provides four degrees of freedom in a human-like kinematic configuration for end effector positioning: shoulder pitch, roll and yaw, and elbow pitch. The dual arm, weighting 1.3 kg in total, employs smart servo actuators and a customized and carefully designed aluminum frame structure manufactured by laser cut. The proposed design reduces the manufacturing cost as no computer numerical control machined part is used. Mechanical joint compliance is provided in all the joints, introducing a compact spring-lever transmission mechanism between the servo shaft and the links, integrating a potentiometer for measuring the deflection of the joints. The servo actuators are partially or fully isolated against impacts and overloads thanks to the ange bearings attached to the frame structure that support the rotation of the links and the deflection of the joints. This simple mechanism increases the robustness of the arms and safety in the physical interactions between the aerial robot and the environment. The developed manipulator has been validated through different experiments in fixed base test-bench and in outdoor flight tests.Unión Europea H2020-ICT-2014- 644271Ministerio de Economía y Competitividad DPI2015-71524-RMinisterio de Economía y Competitividad DPI2017-89790-

Introduction to Surface-Mount Technology

In chapter 1, the surface-mount technology and reflow soldering technology are overviewed. A brief introduction is presented into the type of electronic components, including through-hole- and surface-mounted ones. Steps of reflow soldering technology are outlined, and details are given regarding the properties of solder material in this technology. The rheological behavior of solder pastes is detailed, and some recent advancements in addressing the thixotropic behavior of this material are summarized. The process of stencil printing is detailed next, which is the most crucial step in reflow soldering technology; since even 60–70% of the soldering failures can be traced back to this process. The topic includes the structures of stencils, discussion of the primary process parameters, and process optimization possibilities by numerical modeling. Process issues of component placement are presented. The critical parameter (process and machines capability), which is used extensively for characterizing the placement process is studied. In connection with the measurement of process capability, the method of Gage R&R (repeatability and reproducibility) is detailed, including the estimation of respective variances. Process of the reflow soldering itself is detailed, including the two main phenomena taking place when the solder is in the molten state, namely: wetting of the liquid solder due to surface tension, and intermetallic compound formation due to diffusion. Solder profile calculation and component movements during the soldering (e.g., self-alignment of passive components) are presented too. Lastly, the pin-in-paste technology (reflow solder of through-hole components) is detailed, including some recent advancements in the optimization of this technology by utilizing machine learning techniques

Overview of Selected Issues Related to Soldering

The formation of defects and imperfections in the soldering process can have many causes, which primarily include a poorly setup technological process, inappropriate or inappropriately used materials and their combinations, the effect of the surroundings and design errors. This chapter lists some examples of errors that can occur in soldering, while review is devoted to selected defects: non-wettability of the solder pads, dewetting, wrong solder mask design, warpage, head-in-pillow, cracks in the joints, pad cratering, black pad, solder beading, tombstoning, dendrites, voids, flux spattering from the solder paste, popcorning and whiskers

Effects of Solder Paste Volume on PCBA Assembly Yield and Reliability

Solder paste printing is the most common method for attaching surface mount devices to printed circuit boards and it has been reported that a majority of all assembly defects occur during the stencil printing process. It is also recognized that the solder paste printing process is wholly responsible for the solder joint formation of leadless package technologies such as Land Grid Array (LGA) and Quad-Flat No-Lead (QFN) components and therefore is a determining factor in the long-term reliability of said devices. The goal of this experiment is to determine the acceptable lower limit for solder paste volume deposit tolerances during stencil printing process to ensure both good assembly yield and reliability expectations. Stencils with modified aperture dimensions at particular locations for LGA and QFN package footprints were designed in order to vary the solder paste volume deposited during the stencil printing process. Solder paste volumes were measured using Solder Paste Inspection (SPI) system. Low volume solder paste deposits were generated using the modified stencil designs to evaluate assemble yield. Accelerated Thermal Cycling (ATC) was used to determine the reliability of the solder joints. For the LGAs, solder joints formed with higher paste volume survived longer in ATC compared to lower volume joints. Low solder paste volume deposits did not affect BGA devices in ATC. Transfer efficiency numbers for both good assembly yield and good reliability are reported for LGA, QFN and BGA devices. This research provides valuable data because, very little data is available on solder paste volume tolerance limits in terms of assembly yield and reliability. Manufacturers often use ±50% of stencil aperture volume with no evidence of its effectiveness in determining yield and reliability of the solder joints

Low energy stage study. Volume 5: Program study cost elements and appendices

The methodology and rationale used in the development of costs for engineering, manufacturing, testing and operating a low thrust system for placing automated shuttle payloads into earth orbits are described. Cost related information for the recommended propulsion approach is included

Validating the Operating Window Concept for Robustness on a Circuit Board Stencil Printing Process

The lifecycle of a system is dependent on the system design. However, the concern with quality has been stressed mostly during its production and use. The understanding of the system variability generated by noise variables shifted the quality focus to the design phase. The development of robustness early on the system lifecycle increases the system reliability through its entire life cycle. Although the robust design approach developed by the Taguchi methods application had a great contribution to this philosophy, there is much criticism of this methodology. One alternative to the Taguchi method is the Operating Window methodology. Its application has successfully been demonstrated as a substitute for the Taguchi methods, especially when the response is not quantitative. However, most of the examples were used repeatedly and the steps on the application of the methodology have not been well detailed. Therefore, this project had the objective of developing a unique application of the methodology with a simple approach. Moreover, with the implementation of the methodology, the project aims to identify the difference between a design with a wide output data distribution and a design with a narrow distribution. The methodology followed the Operating Window methodology steps, applying it to a circuit board printing process. The results have shown that it is possible to have a relationship between the Operating Window range and the distribution variation from the system output