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    So You Want to Design Aircraft: Robots on the Floor
    So You Want to Design Aircraft: Robots on the Floor
    So You Want to Design Aircraft: Robots on the Floor
    Ebook127 pages1 hour

    So You Want to Design Aircraft: Robots on the Floor

    By Jean Broge

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    About this ebook

    It is ironic that as aircraft have gotten more sophisticated, much of their manufacture has remained manual. However, as orders for commercial aircraft have dramatically increased over the past years and are expected to remain on that trajectory, the competition has become not just about how fast new technologies can be put on the aircraft, but

    LanguageEnglish
    PublisherSAE International
    Release dateJul 27, 2017
    ISBN9780768091670
    So You Want to Design Aircraft: Robots on the Floor

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      Book preview

      So You Want to Design Aircraft - Jean Broge

      So You Want to Design Aircraft: Robots on the Floor

      CHAPTER 1: A Human Walks into an Assembly Cell…

      Print ISBN: 978-0-7680-8424-5

      eISBN: 978-0-7680-9167-0

      DOI: 10.4271/SYWD-0001

      CHAPTER 1

      A Human Walks into an Assembly Cell…

      Rickard Olsen and Kerstin Johansen

      Linköping University

      Magnus Engstrom

      Saab AB

      Increased collaboration between humans and robots is considered by many to be the next big challenge to address in manufacturing and assembly operations. As computing power becomes more potent, the possibilities of achieving safer working environments increase, as all safety signals demand fast data management. Such information could be the enabling power that leads to a human working closely or directly with a robot, using the robot as a third hand.

      There are different levels of interaction between humans and machines. The term human-machine interaction (HMI) encompasses all types of interactions. These interactions could be on such a low level where the human performs all actions and decision-making or at the highest level where the machine is autonomous. In this chapter, HMI is used to describe when the operator interacts with a robot.

      Additionally, the term human-robot collaboration (HRC) is used to designate when the operator is using the robot either in a collaborative operation or in a collaborative workspace. Therefore, when implementing HRC, the challenges are safety and dependability.

      1.1 What Is Safety?

      There are a multitude of ways to define safety. In a manufacturing workspace, managing safety means adhering to various standards and regulations, especially regarding machines used in the manufacturing process. These standards and regulations aim to protect the operator from injury. The International Organization for Standardization (ISO) defines a safe state for a machine:

      Condition of a machine or piece of equipment where it does not present an impendent hazard.

      This is important to manage when implementing the next generation of HRC solutions.

      There are different kinds of safety systems, from the classic fence-guarded systems to pre-collision systems and post-collision systems, see Figure 1.1. The classic fence-guarded systems traditionally consists of a robot surrounded by a fence. Here, the fence should be designed to prevent humans from accessing the robot workspace where hazards may be present. The fence should restrict robot motion if or when personnel access the workspace.

      Figure 1.1

      FIGURE 1.1 An overview of different safety control systems is depicted, from the classic fence-guarded systems to pre-collision system and post-collision systems.

      Another way to prevent accidents between humans and robots is to utilize a pre-collision system. This method integrates external support systems with the communication system of a robot to monitor the workspace. Different types of sensors may be used for identifying personnel entering the workspace (e.g., vision systems, force sensors on the floor).

      The third main type of safety system is the post-collision system. Here, integrated sensors, lightweight structures, or software-created barriers are used to prevent or minimize collision damage.

      Regarding ISO, there are three major applicable robotic safety standards, and these three standards cite other standards as well. One of these standards—the Technical Specification (TS) focusing on HRC—is under revision and has not yet been released. Therefore, the content in that TS can only be identified and referred to through other research and work, including interviews with key persons from that TS development workgroup.

      To use a robot in a collaborative mode, a visual indicator and one or more of the following is required:

      Safety-rated monitored stop: A category 0 stop, or a decelerated to a category 2 stop, but with a safety catch that when it doesn't work it automatically goes into a category 0 stop

      Hand guiding: This should be equipped with an emergency stop and an enabling device and it should operate with a safety-rated monitored speed

      Speed and separation monitoring

      Power and force limiting by inherent design or control

      In the robot system, the developer of the robotic cell defines the different requirements to ensure that the environment in the collaborative workspace is safe. A risk analysis is required to identify all the hazards that could be present in each workspace. The ISO standards set the safety limits (i.e., speed limits when the operator enters the robot working area) for an HRC setup.

      There are multiple possible setups for an human-robot collaboration (HRC) cell, with three concepts depicted in Figure 1.2.

      Figure 1.2

      FIGURE 1.2 There are multiple possible setups for an human-robot collaboration (HRC) cell, with three concepts depicted here.

      1.2 Support Systems

      Concerning assembly tasks, HRC is considered mandatory for improved flexibility and adaptability. With the assistance of different support systems, the programming methods can be changed in the future (i.e., a simplified way for teaching the robot different paths). The cooperation between humans and robots will provide new concepts in the design of industrial robots, such as dual-armed robots or light-weighted robots. Today's focus on accuracy could be changed to safety in the future and support systems could help the robot system with both accuracy and safety.

      A 3D vision sensor and a force sensor are two different kinds of support systems. With the 3D vision sensor, positional errors may be identified; it is sensitive to motion and/or parts that are observed in a 3D volume. A computer manages received images from the vision system and then, using algorithms, creates a 3D environment of the vision systems’ subjected area.

      When an object enters the subjected 3D environment, the vision system should react in different ways depending on how close the new object is to the robot and what kind of speed vector it has. On the signal from the vision system, the robot reaction could be a change of path, a category 0 stop, or speed reduction, depending on the situation.

      Force sensors are

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