Proposal for Advancements to the Llsf in 2014 and Beyond
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PROPOSAL FOR ADVANCEMENTS TO THE LLSF IN 2014 AND BEYOND T. Niemueller and G. Lakemeyer∗ A. Ferreiny fniemueller,[email protected] [email protected] S. Reuter, D. Ewert, and S. Jeschkez D. Penskyx [first.last]@ima-zlw-ifu.rwth-aachen.de [email protected] U. Karras{ [email protected] ∗Knowledge-based Systems Group, RWTH Aachen University, Germany yElectrical Engineering Department, Aachen University of Applied Sciences, Germany zInstitute Cluster IMA/ZLW & IfU, RWTH Aachen University, Germany xFesto Didactic, Denkendorf, Germany {Organization Committee, Logistics League Sponsored by Festo ABSTRACT physical processes. They include embedded computers and net- works which monitor and control the physical processes and The Logistics League Sponsored by Festo (LLSF) is a RoboCup have a wide range of applications in assisted living, advanced au- league focusing on in-factory logistics applications involving tomotive systems, energy conservation, environmental and crit- task-level planning, scheduling, and automation in an industrial ical infrastructure control, or manufacturing (Lee, 2008). In the production workflow scenario. It is meant to spawn interest in LLSF, this is mapped onto a mobile robot logistics task. Issues industry for current robotics research and to provide a bench- of particular relevance are task-level planning and production marking domain for such applications. In this paper, we first de- scheduling, dealing with incomplete knowledge during produc- scribe the current set of rules used for the competition in 2013, tion, coping with limits to the on-robot computational resources outlining several advancements like variant production and (al- shared among all software and planning components, and han- most) autonomous judging through a referee box. We describe dling uncertainty, e.g., due to machines which are undergoing and propose changes for 2014, including doubling the field-size, maintenance or have failures at unknown times. multiple teams competing on the field at the same time, and the introduction of physical processing machinery replacing the sig- In 2012 the LLSF was officially founded. The task is to fetch nal light metaphor used so far, addressing the recommendations raw materials (symbolized by pallet carrier pucks) from an input by RoboCup community members and casual visitors alike. storage, move them in a particular sequence by machines with RFID readers, and finally deliver them. It builds on the Festo 1 INTRODUCTION Robotino robot platform (Weinert and Pensky, 2011). In 2013, the dynamicity and complexity were increased by changing the The RoboCup vision is to create a team of humanoid robots rules to demand for more variable production plans. This also re- which can compete with the then-to-be human world champion quired the introduction of an autonomous referee box, a program by 2050. Various soccer leagues have been created to work that controls, monitors, and instructs the game in a knowledge- on different aspects to reach this goal. But the people driving based manner. Additionally, limits regarding the computational RoboCup have also come to realize that the sustainability of this hardware were lifted allowing to foster the integration of more vision depends on support and cooperation with parties inter- robotic techniques like self-localization and navigation with col- ested in real-world robotic applications. Additionally, already lision avoidance. This was done to pave the way from a league today there are technologies developed and tested in the compe- with an automation background towards a production planning titions useful enough to transfer them into such out-of-lab sce- and scheduling scenario. narios. This is where the Logistics League Sponsored by Festo The major criticism about the LLSF is that it is virtually impos- (LLSF) fits in. It focuses on the logistics aspect of an industrial sible to understand the game by watching it. We tried to alle- production workflow, using coordinated teams of autonomous viate the problem in the 2013 competitions by visualizing the mobile robots building on technologies also developed in robot game from the perspective of the referee box along with expla- soccer leagues like self-localization, navigation, or perception. nations. But discussions with members of the RoboCup commu- In industry, cyber-physical systems (CPS) have received a lot of nity and casual visitors revealed that the problem remains—even attention recently. They strive to combine computational with got worse with the more flexible production plans. Therefore, in 1 R2 T M10 M7 T3 T2 Type Name M9 M6 M2 T1 T3 T2 D1 M5 D2 T3 D3 Input Storage Delivery Zone M8 M4 M1 T1 T2 T1 Machine Space Machine M3 Facing Robot Insertion T1 Direction R1 (a) LLSF Competition Area 2013 (b) Competition in 2013 Figure 1: LLSF competition area and field machine in 2013 this paper we outline changes that we, (some) members of the ing sensors or computing power. Fig. 2(c) shows the modified Technical Committee (TC), the Organization Committee (OC), version of the Carologistics RoboCup team1 (Niemueller, Ewert, and Festo, the League’s sponsor, envision to improve in partic- Reuter, Ferrein, Jeschke and Lakemeyer, 2013b), which has an ular on this situation, but also to gradually increase the game’s omni-directional camera system, which allows for a 360◦ view complexity and thus challenge the participating teams. The main around the robot. An additional 2D Hokuyo URG laser scanner idea is to replace the signal lights representing machines by ac- provides data for collision avoidance and self-localization. tual machines that carry out physical actions. Also, we propose to step away from a single product for which only the referee On the field (cf. Fig. 1(a)) two margin areas on opposite sides box knows the actual state, to multiple similarly shaped but dif- contain the puck input storage, delivery zone, and several signal ferently colored products, to make it easy to observe the trans- lights that deal as delivery gates for the final products or as recy- formations along the production chain. We describe the (already cling stations. Each puck has a programmable radio frequency made) decision of the LLSF to combine the two playing fields identification (RFID) chip with which the different product states into one, on which two teams compete at the same time. This S0, S1, S2, and P1, P2, P3 are distinguished. Initially, all pucks will require the avoidance of other agents in the environment are in state S0. In the enclosed inner field, ten signals equipped during locomotion, much like humans or equipment from an- with an RFID device mounted on its front represent production other manufacturer would have to be avoided in a real factory. machines. Each machine is assigned a random but defined type We outline some of the implications for robot systems and re- out of the types T1–T5, which is initially unknown to the robots. quired developments for the referee box. The type determines the input and output of a machine. Pucks transition through their states by being processed through ma- On a related note, we report on some first discussion between the chines. The complete production tree is shown in Fig. 3. Cir- LLSF and members of the RoboCup@Work Technical Commit- cular nodes indicate a puck’s state and rectangular nodes show tee regarding possible connections and cooperation in the future. the respective machine type. For example, the T1 machine in the upper branch takes an S0 puck as input with an S1 puck as The rest of the paper is structured as follows. In Sect. 2 we de- output. If a machine, like T2, requires multiple inputs, these can scribe the rules and objectives of the game in 2013. The au- be presented to the machine in any order. However, until the tonomous referee box is detailed in Sect. 3. With this back- machine cycle completes, all involved pucks must remain in the ground knowledge, we propose the envisioned changes for 2014 machine space. The last input puck will be converted to the out- in Sect. 4. In Sect. 5 we report on our discussion with members put puck, all others become junk and must be recycled at a recy- of the RoboCup@Work TC. We conclude in Sect. 6. cling station. The machines indicate their state after processing a puck using light signals which the robots need to perceive and 2 GAME RULES AND OBJECTIVES IN 2013 act upon. The general intention for the LLSF is to create a simplified fac- Besides typical robotics tasks such as motion planning or self- tory automation scenario with an emphasis on logistics applica- localization, the robot needs to plan an efficient sequence of ac- tions. The goal is to complete production chains that require to tions to produce as many products as possible in a fixed amount move workpieces to a varying sequence of machines. Some in- of time. Moreover, the robot has to deal with incomplete knowl- termediate steps and the delivery of final products are awarded edge as it is not known in advance what machine has which type. with points. Uncertainties are introduced by randomized product Thus, the robots need to combine sensing and reasoning to in- demands and machine down times. crementally update their belief about the world. Based on the knowledge gained, it has to find a strategy to maximize its pro- In 2013 teams of up to three robots operated in a fenced duction output, ideally minimizing costs such as travel distance. area of about 5:6 m × 5:6 m as shown in Fig. 1. The Festo Robotino (Karras et al., 2011) is the sole platform at this time. 3 AUTONOMOUS REFEREE BOX Fig. 2(a) and (b) show the original Robotino 2 used in 2013, and the upcoming Robotino 3. The Robotino features omni- Games in RoboCup in general involve machines playing a game directional locomotion, twelve infrared distance sensors, and against each other or solving real-world tasks withing certain bumpers mounted around the base, a gyroscope, and a webcam facing forward.