Low-Cost Automation for Aircraft Assembly

<div class="htmlview paragraph">Automation in manufacturing is not a new idea. Automation remained simple until computers became available. The design, deployment, and utilization of cheap, simple automation became a lost art. We have begun to rediscover this art-“low cost automation,” or LCA, at NMMC.</div> <div class="htmlview paragraph">There is no textbook definition of LCA. One must consider LCA versus high-cost automation (HCA) from the perspective of the budget approval process, anticipated life cycle, complexity of control mechanism, and whether it is a general- or specific-purpose item.</div> <div class="htmlview paragraph">There isn't a specific dollar figure as a cutoff. HCA is a capital spending item. LCA shouldn't be. Low cost also refers to the life cycle maintenance costs of the item. HCA items may fill a wide variety of applications over a long life cycle. An LCA device at the end of its utilization cycle would be recycled for use in next-generation LCA applications. The true LCA device has a very simple guidance or control system, or even none at all. Expect the line between HCA and LCA to blur as HCA costs decrease while LCA complexity and capability increases. LCA items are intended to solve a specific problem. HCA items are more generalized in their application.</div> <div class="htmlview paragraph">The most important step is to design and build LCA items in-house. It encourages ingenuity in the use of salvaged components. This will hold down the costs and promote the use of LCA. At Nissan, we initially “spec'ed out” LCA items to a vendor. By establishing our own fabrication shop we were able to make LCA affordable. We still maintain relationships with vendors for complicated LCA projects.</div> <div class="htmlview paragraph">LCA, like HCA can be adaptable, and can grow and develop over time. Lineside space, particularly in our Trim & Chassis plant, has been converted from pallet footprints to shooter racks. A shooter rack uses gravity to feed parts to the line. Shooter racks themselves have evolved from a standard size of 42 inches to 68 inches to 90 inches. Tilt tables, turn tables, and lift tables are all examples of simple LCA devices. The trend has been toward turntables for ease of resupply, tilt or lift tables for ergonomic efficiency, or turn-and-lift tables for both. A more typical example of LCA is the lineside limo. LCA applications are usually employed to gain some advantage in quality, cost, delivery, or safety. Many LCA devices are “fail-safes” or “goof-proofs.”</div> <div class="htmlview paragraph">Some of the advantages gained from LCA projects are intangible. LCA devices can reduce fatigue and cumulative trauma. LCA devices can make the job adjustable and adaptable for a wide variety of body sizes and strength ranges. The design, construction, and application of LCA items constitute the perfect mental gymnasium for engineers and first-line managers. Look for a project that would have a high “payoff,” such as an ergonomic project or a chronic quality problem. Document the project carefully, and then use the participants to help teach others about the process. You'll find that this process will soon become part of the essential development of an engineer in your organization. LCA is not intended to replace HCA. There remains a need for both approaches to problem solving. Using a mixture of the two approaches will help to provide you with greater flexibility.</div>

<div class="htmlview paragraph">This paper describes work being conducted by OC Robotics and Airbus to develop snake-arm robots to conduct assembly tasks within wing boxes - an area currently inaccessible for automation.</div> <div class="htmlview paragraph">The composite, single skin construction of aircraft structures presents new assembly challenges. Currently during box close-out it is necessary for aircraft fitters to climb into the wing box through small access panels and use manual or power tools to perform a variety of tasks. In future wing designs it may be that certain parts of the wing do not provide adequate access for manual assembly methods. It is also known that these manual interventions introduce health and safety concerns with their associated costs.</div> <div class="htmlview paragraph">Snake-arm robots provide a means to replace manual procedures by delivering the required tools to all areas of the wing box.</div> <div class="htmlview paragraph">Such a development has broader implications for aircraft design and assembly. There is potential for considerable cost savings for the aerospace industry through reduced weight, improved aerodynamics, standardisation of assembly processes, increased rate and reduced health and safety costs.</div> <div class="htmlview paragraph">This paper presents early results of the demonstration snake-arm robot and outlines expectations for future development. It also identifies critical design parameters for the snake-arm and considers the tools and processes delivered by the snake-arm.</div>

<div class="section abstract"><div class="htmlview paragraph">Developing the most advanced wing panel assembly line for very high production rates required an innovative and integrated solution, relying on the latest technologies in the industry.</div><div class="htmlview paragraph">Looking back at over five decades of commercial aircraft assembly, a clear and singular vision of a fully integrated solution was defined for the new panel production line. The execution was to be focused on co-developing the automation, tooling, material handling and facilities while limiting the number of parties involved. Using the latest technologies in all these areas also required a development plan, which included pre-qualification at all stages of the system development.</div><div class="htmlview paragraph">Planning this large scale project included goals not only for the final solution but for the development and implementation stages as well.</div><div class="htmlview paragraph">The results: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Design/build philosophy reduced project time and the number of teams involved. This allowed for easier communication and extended development time well into the project.</div></li><li class="list-item"><div class="htmlview paragraph">All design teams (machine, tooling, automation, controls) collocated and worked together on integration during all stages of development and implementation for the highest level of integration.</div></li><li class="list-item"><div class="htmlview paragraph">Innovative integration of the tooling and the automated equipment evolved throughout project with the teams working as one group.</div></li><li class="list-item"><div class="htmlview paragraph">Latest fastening technology using all electric, ball-screw squeeze riveting was developed for high-speed and robust automated fastening.</div></li><li class="list-item"><div class="htmlview paragraph">Latest mobilization technology was used to make the automated fastening machines interchangeable to reduce MTTR and to enable more PPM activities offline without affecting production.</div></li><li class="list-item"><div class="htmlview paragraph">More automation was also introduced for tool changing and to the material handling systems for more consistent processing and to reduce operator intervention.</div></li><li class="list-item"><div class="htmlview paragraph">All systems were developed together for full integration and to enable more safety interlocks and HMI for simplified operation.</div></li><li class="list-item"><div class="htmlview paragraph">A 30 month schedule for the complete large scale assembly line was maintained to support the new aircraft launch schedule.</div></li></ul></div><div class="htmlview paragraph">The final solution was a coherent, streamlined and efficient assembly line capable of very high aircraft production rates (<span class="xref">Figure 1</span>).</div><div class="htmlview paragraph"><figure id="F1" class="figure"><div class="graphic-wrapper"><img class="article-figure figure" src="2015-01-2492_fig0001.jpg" alt="PAL, automation cell, Line 4, Position 1 (L4P1)"/></div><span class="label">Figure 1</span><figcaption class="caption"><span class="title">PAL, automation cell, Line 4, Position 1 (L4P1)</span></figcaption></figure></div></div>

<div class="section abstract"><div class="htmlview paragraph">Within the current part production of carbon fiber parts a lot of manual work is included for sorting and kitting of automatic cut plies. This is required due to the high raw material costs and enables a good utilization of the materials. Automation of this non-value adding process will be a big benefit for the part production. The high variety of shapes and the different materials to be processed are complex boundary conditions, which are to be overcome.</div><div class="htmlview paragraph">Broetje is in development of handling systems and automation solutions, which are used for a high variety of materials as well as for a high variety of shapes. These systems are meant to be an add-on for existing cutting tables as well as for fully integrated production systems with downstream automation equipment like draping hoods.</div><div class="htmlview paragraph">Mayor challenges to overcome are safe gripping capabilities, detection of non-cut fibers, high variety of shapes, complex logistic management. These challenges are addressed with Broetje’s ASK solution.</div><div class="htmlview paragraph">This paper will focus on the innovative ASK solution invented by Broetje-Automation.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Pilot injections are normally used for the reduction of diesel engine emissions and combustion noise. Nonetheless, with a penalty on the indicated thermal efficiency. The cost is reduced by the minimization of the pilot mass, which on its counterpart increases the risk of pilot misfire. Pilot misfire can have a higher penalty on the indicated efficiency if it is not compensated adequately. This paper investigates how in-cycle closed-loop combustion control techniques can reduce the effects of pilot misfire events.</div><div class="htmlview paragraph">By closed-loop combustion control, pilot misfire can be detected and counteracted in-cycle. Two injection strategies are investigated. The first is the control of the main injection, the second includes an additional second pilot injection. Based on the in-cycle misfire diagnose, two architectures are investigated. The first uses a cycle-to-cycle controller to set the main injection under each scenario. The second is a fully in-cycle controller with feedback from predictive models. All the algorithms were tested experimentally in a Scania D13 engine.</div><div class="htmlview paragraph">The results confirmed that in-cycle closed-loop combustion control can effectively reduce the effects of pilot misfire. An error of +1.5CAD on the main SOC and −0.5bar IMEP on the engine load was reduced to 0±0.6CAD and 0±0.4bar IMEP using the cycle-to-cycle architecture. The predictive in-cycle control can further reduce the error of the main SOC to 0±0.4CAD and 0±0.2bar IMEP for the engine load. These two approaches had one degree of freedom, and therefore only one of the combustion timing parameters (SOC or CA50) was regulated successfully. With the additional degree of freedom of the second pilot injection, the misfire effects were not only reduced, but also fully counteracted.</div><div class="htmlview paragraph">The methods are limited by the time window where pilot misfire observability and controllability overlap. This is set by the injections’ separations and the respective ignition delays. The second pilot injection can be further improved by the regulation of its injection timing and duration. The results can enhance the nominal set-up optimization by including the in-cycle controllability and regulation performance in the constraints.</div></div>

<div class="section abstract"><div class="htmlview paragraph">In order to be more competitive, aerospace industries have to continually improve product's cost, quality and cycle time. One way to perform all three at once is to manage product's variations, as variations are responsible for waste, rework and delay. There are only three ways to reduce product's variation: improve manufacturing capability, improve assembly capabilities and manage assembly sequence. Generally, variation reduction programs tackle only manufacturing capabilities. Unfortunately this solution is by far the most expensive one. We propose in this article to reduce variation first by selecting best assembly sequences or eliminating assembly tools and only after if there is no other way by reducing manufacturing capabilities. With this aim, we have defined an assembly analysis method. This method studies for each assembly sequence how variations are flowed from part to part through the assembly joints. Two types of assembly joint have been defined: mates that pass positional variation from part to part and contact that merely provide support and block variations. To represent variation flow down, we propose to use an “Assembly-Oriented Graph” and a “Datum Flow Chain”. First one captures the assembly sequence and allows us to identify which joints are mates and which ones are contacts. The second represents where variations are driven in the product. Datum Flow Chains assess assembly families and best ones are selected. This method can be used from the preliminary design allowing validating assembly sequence and design principles without serious investment. This method has been applied with success at Aerospatiale-Matra on various aircraft assemblies.</div></div>

<div class="htmlview paragraph">This paper describes the development process for acceleration sensors used on automobiles and acceleration evaluation system especially for the acceleration in super low range frequency.</div> <div class="htmlview paragraph">Acceleration sensor is indispensable not only for good vehicle motion control system, for example, active suspension control system, antiskid control system and four wheel steering control system, but also for safety system like air bag control system. This work focused on the development process of acceleration sensor which applied piezo ceramics.</div> <div class="htmlview paragraph">Features of newly developed sensor are as follows.</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1)</span> <div class="htmlview paragraph">Achievement of self-diagnostic function to detect sensor failure utilizing the characteristics of piezo ceramics</div> </li> <li class="list-item"> <span class="li-label">2)</span> <div class="htmlview paragraph">Addition of piezo ceramic to cancel the pyro-effect achieved stabilization of sensor characteristics and enabled to detect acceleration of 0.0025G in super low range frequency of 0.05Hz.</div> </li> <li class="list-item"> <span class="li-label">3)</span> <div class="htmlview paragraph">Incorporates impedance conversion, filtering and temperature characteristics compensation circuitry.</div> </li> </ol> </div> <div class="htmlview paragraph">Frequency range of acceleration for good vehicle motion control is considered to be from DC to about 50Hz.</div> <div class="htmlview paragraph">But the measurement of acceleration in thus super low range frequency near DC had been difficult because of its mechanical and electrical noise interruption.</div> <div class="htmlview paragraph">This had delayed the development of acceleration sensor for automotive use.</div> <div class="htmlview paragraph">We succeeded in the development of acceleration measurement system for super low range frequency from 0.01Hz to 2Hz with detecting acceleration range from 0.0002 (0.2 gal) G to 1G as well as the development of piezo type acceleration sensor for automotive use.</div>

<div class="htmlview paragraph">Emissions optimization, particularly for complex engines, relies on developing mathematical correlations or ‘Response Surface Models’ of engine outputs. There is a clear tradeoff between the complexity of the model and its usefulness for a range of optimization tasks.</div> <div class="htmlview paragraph">Several current SI engine management systems use a ‘Spark efficiency curve’ to elegantly describe the response of engine torque to spark advance using a prescribed characteristic line that is fitted to a spark sweep with only two degrees of freedom. This provides a powerful method of data reduction.</div> <div class="htmlview paragraph">A similar technique has been developed to characterize engine emissions data. A single efficiency curve with only two degrees of freedom can be used to accurately describe the response of, say, hydrocarbon emissions to spark over a wide range of engines and operating conditions. The technique offers similar data reduction advantages for engine management system developers and those optimizing engines using high DoF models. The form and application of the efficiency curves is discussed and examples of application to tasks such as engine emission optimization are discussed.</div>

<div class="htmlview paragraph">Cycle-resolved numerical and experimental analyses were carried out to study the dynamics of an automotive diesel injection system with a distributor-type pump during transient control phases. The investigation had the following main objectives: to assess a flexible and efficient simulation program of high-pressure fuel-injection systems in unsteady operating conditions; to examine the system response to rapid load or speed variations, regardless of the control device which may cause them. The program, based on a fast implicit numerical algorithm with second-order accuracy, was an extension of the computational code NAIS which had been previously developed and validated for stationary operating conditions. The experiments were made on a test bench usually used by industry to evaluate diesel injection equipment.</div> <div class="htmlview paragraph">A nonlinear system numerical model with two degrees of freedom, developed for the pump speed-governor, was set up and included in a library containing a variety of system component models so as to give a modular structure to the NAIS code. Comparison between computed and measured static characteristics of the governor was made in order to assess the model of this system component.</div> <div class="htmlview paragraph">Experimental tests were carried out by rapidly moving the pump control lever from its idle position to the full-load position at two constant pump speeds, in the low and high-speed range, respectively. During these transient operations pressure time-histories were gauged and simulated cycle-by-cycle in the pumping chamber and at the distribution-pipe ends. In-cycle fuel-injected quantities were also measured and computed. Results were compared and discussed.</div> <div class="htmlview paragraph">The dynamic system behavior under assigned transient load or speed phases was then theoretically analyzed by computing local-pressure, needle-lift and injection-rate time histories. Besides, experimental steady-state distributions of the injection rate and injection pressure, that is the pressure in the sac chamber, were compared to the simulation results during an acceleration phase at full load.</div>

<div class="htmlview paragraph"> </div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">This paper describes a fundamental design for a riding simulator of two wheeled vehicle which is used to analyze the human factor of riders. At the first step of this research, the relationship between the movement of rider and behavior of a two wheeled vehicle is inquired with experiments on a proving ground. Based on the results, the degrees of freedom which is required by simulator and main input of rider are settled. This study goes along examination of the expression method of simulated movements, and production of the riding simulator.</div> <div class="htmlview paragraph"> </div>

<div class="htmlview paragraph">Submarining is a common cause of injury in severe frontal crashes. Furthermore, submarining protection may limit lap-belt designs, in that it restricts the range of usable lap-belt angles. Therefore a method to assess how close the occupant substitute is to submarining in a crash test is desirable.</div> <div class="htmlview paragraph">In this paper the hypothesis was that the maximum value of the angle, in the x-z plane, between the lap-belt and the pelvis during the time-period when the belt force exceeds 3 kN is a measure of the lap-belt slipping off the pelvis in a frontal impact. In order to obtain this angle with high precision, five mechanical sled-tests with the Hybrid-III dummy was transferred into MADYMO. In MADYMO belt slip over the dummy pelvis was modeled by means of two orthogonal, translational joints (i. e. joints with one-dimensional translation as their only degree of freedom) on the right and left Anterior Superior Iliac Spine (A.S.I.S., also called iliac crest wing) and thus bilateral and unilateral belt slip could be assessed.</div> <div class="htmlview paragraph">The results support the hypothesis. Thus a belt-to-pelvis angle of 11 degrees in the simulations corresponded to observed lap-belt slippage in the sled tests, whereas the lap-belt acted on the pelvic structures throughout those tests in which the belt-to-pelvis angle did not exceed eight degrees. Results from subsequent simulations point out belt-slack, velocity change (Δv), and initial knee angle as factors strongly related to the tendency for submarining.</div> <div class="htmlview paragraph">The conclusion is that the maximum belt-to-pelvis angle during the time-span when the lap-belt force exceeds 3 kN can be used to estimate the tendency for belt slip onto the abdomen and submarining in mathematical simulations of frontal impacts.</div>

<div class="section abstract"><div class="htmlview paragraph">In recent years, internal-combustion engines have been required to satisfy various performance standards against emission regulations and fuel-efficiency targets. To this end, accurate measurement of piston temperature under various engine operating conditions is important.</div><div class="htmlview paragraph">Some studies reported the use of wireless methods to confirm the reliability of the measurement system at the highest engine speed and create a piston temperature map under all operating conditions. However, previous case studies only considered relatively large displacement engines, and the advantage of wireless methods—a high degree of freedom for design—was not used. In terms of engine operating conditions, few cases focus on the piston to cylinder wall clearance during engine warm-up conditions. Thus, wireless methods are still space to use their features.</div><div class="htmlview paragraph">In this study, we develop and implement a telemetry-type method for a motorcycle engine, which has smaller displacement and is therefore more restrictive relative to measurement system design than past case studies. The temperature distribution in the entire piston is measured, considering the temperature distribution of a cylinder bore wall surface during the period between a cold start and the completion of the warm-up. Temperature measurement data are continuously obtained under transient operating conditions. In addition, the measurement results are input to a model that simulates piston behavior to improve the calculation results of piston slap noise.</div></div>

<div class="htmlview paragraph">Many manufacturers utilize statistical methods to control product characteristics during processing. Often traditional x charts are utilized. This method is appropriate when examining characteristics with one degree of freedom. For features with two or more degrees of freedom, traditional x charts may be misleading. Techniques for controlling characteristics with multiple degrees of freedom, however, have not been developed.</div> <div class="htmlview paragraph">The purpose of this paper is to present a method of statistical analysis using radial type charting techniques for characteristics with multiple degrees of freedom. Included in this paper is a detailed discussion of the steps to prepare and interpret radial type charts. These techniques are applied to true position measurements as a specific example.</div>

<div class="htmlview paragraph">The goal of this paper is to present an innovative yet practical approach to automated aircraft assembly which meets the evolving aerospace industry requirements for flexibility and modularity.</div> <div class="htmlview paragraph">Adaptive Robotized Multifunction Assembly cell -ARMA is then described in two different vantage points:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"> <div class="htmlview paragraph"><u>as a concept:</u> a description of the philosophy which led to the development of automated assembly cells is offered</div> </li> <li class="list-item"> <div class="htmlview paragraph"><u>as a practical solution</u>: a description of the modular hardware and the powerful information processing system, that supports the individual cells is provided.</div> </li> </ul> </div> <div class="htmlview paragraph">The configuration which results in the most productive and effective cell while keeping the cost of equipment as low as possible is described. The ability of the cell to adapt to new requirements, as they evolve, is also described.</div>

<div class="section abstract"><div class="htmlview paragraph">This paper presents a methodology to represent automatic transmission clutch-to-clutch shift dynamics with a two degree of freedom, lumped inertia model. The method of reducing the automatic transmission to a lumped, two inertia model as a function of shift and input shaft acceleration is detailed using a full kinematic representation of the automatic transmission. For a given clutch-to-clutch shift maneuver there are two dependent equations that utilize the two lumped inertias and represent the response of the transmission system from input to output shaft. Applicability of the method is shown for planetary automatic and layshaft dual clutch transmissions. Typical clutch-to-clutch shift maneuvers are illustrated with the two inertia model for power on upshifts and downshifts. The simplification of automatic transmission shift dynamics using this method enables rapid synthesis of a given transmission powerflow for estimation of shift quality potential, required clutching torques, inertia phase engine torque intervention and output torque through all phases of a shift event.</div></div>