Automatic cooperative disassembly robotic system: Task planner to distribute tasks among robots Fernando Torres, Santiago Puente à , Carolina Dı ´az Crta San Vicente del Raspeig s/n, PO Box 03080, University of Alicante, 03690 San Vicent del Raspeig, Spain article info Article history: Received 5 July 2006 Accepted 27 May 2008 Available online 7 July 2008 Keywords: Recycling Automatic disassembly Cooperative manipulator Task planner abstract This paper presents a task planner based on decision trees. Two different types of cooperative tasks are described: common task and parallel task. In the first type of task two or more robots are required to accomplish the task. In the second type, several tasks can be performed in parallel by different robots to reduce the total disassembly time. The planner presented is based on a hierarchical representation of the product and performs the distribution of the tasks among robots using decision trees. The system takes into consideration the work area of each robot and its own characteristics. The work cell can be composed of j robotic manipulators. Finally, a practical application of a PC disassembly system is shown. & 2008 Elsevier Ltd. All rights reserved. 1. Introduction Environmental considerations in industrial activities are growing continuously. Governments have therefore proposed regulations in this aspect in different industrial areas. In 1998, the European Community introduced a report that contains regulations and norms on how to treat the waste produced from electrical and electronic devices. These regulations are still in effect (Waste Electrical and Electronic Equipment, Directive, 2003). These norms have implica- tions in the development of products. Environmental considerations must be taken into account in the complete production life-cycle. They are involved in the whole life-cycle of the product; from the design stage through to the delivery to the consumer until the end- of-life stage. This political strategy intends to eliminate the toxic waste generated by a product when its useful life ends, reducing the damage caused to the environment. In the electronics industry the initial responses to this trend was mainly of a defensive nature, directed towards compliance with legislation and towards preventing a negative image from being developed in the press and with the public. Emphasis was therefore on issues such as eliminating banned substances, cleaner production, recycling of packaging, and power manage- ment for the standby mode (ECO-Design Guide, 2002). The automatic disassembly allows (Hesselbach, Friedrich, & Schu ¨ te, 1994):  Elimination of toxic substances: here the restriction of hazar- dous substances (RoHS) directives has been taken into account.  Concentration of valuable materials: for example, metals which are interesting to separate not only for ecological but also for economical reasons.  reuse of components: like energy sources, memory chips, etc. These make the disassembling a profitable process. Companies normally have a distinctive and customized product development process. Therefore, it is necessary to customize the integration of the environment into the process according to the company’s culture, and the characteristics of its products and processes (Parlinkad & McFarlane, 2007). The disassembly process for recycling is introduced in the design of new products, to optimize the resource uses (Kattentidt, Jong, & Dalmijn, 2003; Torres & Puente, 2006). Some objectives for disassembly products are: recovery of pieces, defective pieces elimination, pieces extraction to be reused in the future and diminution of waste that reduce environment contamination (Gu ¨ ngo ¨r & Gupta, 2001). To integrate the environmental concerns in the design process, companies develop design methods (standards) like ISO 9000 norms. Fig. 1 gives an example of such integration. The main reasons for disassembling the products are ecologi- cal, and/or economical (Gu ¨ ngo ¨r & Gupta, 2001; Thomas Hirth, 2005). The ecological reasons are based on the conservation of the environment. When companies use a disassembly process, the ecosystem is being taken care of because toxic substances can be separated; and treated separately, to avoid contamination. The economical reasons are based on the fact that the products disassembly allows companies to recover materials to make new products, with the consequent saving of raw materials. Also, pieces that are in good state can be reused directly. Thus, the value of manufacturing these pieces is completely eliminated (Eckterth, ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/conengprac Control Engineering Practice 0967-0661/$ - see front matter & 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.conengprac.2008.05.013 à Corresponding author. Tel.: +34965903400x2371; fax: +34 965909750. E-mail addresses: Fernando.Torres@ua.es (F. Torres), Santiago.Puente@ua.es (S. Puente), cdiaz@dfists.ua.es (C. Dı ´az). Control Engineering Practice 17 (2009) 112–121