Page - 139 - in Proceedings - OAGM & ARW Joint Workshop 2016 on "Computer Vision and Robotics“

(a) Baxter with its inbuilt and additional mounted sen- sor. (b) Environment in which Baxter performs the order picking task. Figure1: Robot Baxter and theenvironment it operates in. 4. Architecture In Figure 2 the conceptional overview of the proposed 3-TIER architecture is shown. The 3 layers for planning, executive and behavioral control are separated. The communication is clearly defined. The top layer represents the planning layer. The planner uses the information of the domain and the problem to generate a plan. The plan is a sequence of skills that have to be executed to reach a given goal. The plan is forwarded to the next layer. The executive layer takes care of the execution of each skill. It knows about the composition of the skill primitives. The primitives are located in the behavioral layer. Theadvantageof thisabstraction is itsclearstructureanditsmodularity. For further readingabout the3-TIER architectureplease see [8,p. 244–277]. Figure2: Overviewofproposedsystem’sarchitecture. 4.1. PlanningLayer The top layer of the 3-TIER architecture is the planning layer. The planning layer uses a domain and problemdescriptionof thegivenenvironmentandtask. It isbasedonthePlanningDomainDefinition Language (PDDL) modeling the system capabilities (further on called skills), the current state of the environment and the goal state. The authors of [6] showed that PDDL is an appropriate choice for 3 139