2.1.4. Hardware Structure of the ARS

A/D/RML is served by an ARS, used for the recovery and transport/return operation of the dismantled components, which is a RM-equipped WMR. The ARS, shown in Figure 8, is composed of the following elements:


**Figure 6.** Five-part workpiece components.

**Figure 7.** Assembled workpieces: (**a**) workpiece with metal cylinders; (**b**) workpiece with plastic cylinders and (**c**) workpiece with different cylinders.

**Figure 8.** Real-time control of the ARS with RM Cyton.

The ARS is used to pick-and-place the recovered pieces with the help of Cyton 1500 RM in the appropriate storage depots if the assembled workpiece has failed the quality test and has been disassembled or repaired. The control of the ARS is carried out wirelessly using a router that is placed inside the WMR through dedicated functions from Mobile Robots ARIA (Advanced Robotic Interface for Applications), running on the same Remote PC where Cyton RM is connected to.

#### 2.1.5. Eye-in-Hand VSS

In case workparts should be recuperated from the processed bad products, in disassembly and repair, synchronized tasks for pick-and-place actions are executed by ARS by grabbing the recovered dismantled components from the FC station trays. Therefore, ARS is equipped with an RM Cyton 7-DOF (degrees of freedom) with a gripper paddle and HD video camera on the end effector (Figure 8), connected both via Wi-Fi USB with the Remote PC.

For the moving and manipulation of the RM Cyton 7-DOF, signals from gripper video camera are processed, using eye-in-hand VSS technology. RM Cyton, ARS, HD camera and workparts (in this case, cylinders to be recovered) are shown in Figure 8. The eye-in-hand VSS is a system where the HD camera sensor is placed on the last link of the RM, also known as the end effector [1,2,12]. For this type of VSS, real-time computer vision information is processed with OpenCV on the Remote PC to control the motion of the robot in the workspace [16,17]. The objects tracking and the robots positioning are achieved using the comparison between the current visual features, extracted from the images captured by the camera, and the desired visual features. The obtained difference is used to minimize the error the actual configuration of the visual features, the real and the desired features extracted by the video sensor. VSS technology can make robots "smarter" and help to expand their fields of application. Rotational motions influence global image features, translating movements of the end effector result in movements in the eye-in-hand image. Therefore, image moments for the object detection algorithm are used in the Robot Vision fields due to its simplicity and efficiency in implementation. The image moments contain information about the target, the object to be handled, during the positioning task. Thus, ARS localizes and identifies defined objects in advance and decides by itself how to move the WMR on the spot and how to grip the respective part from the FC station trays.

#### *2.2. Modeling the A/D/RML Assisted by ARS*

The assembly, disassembly and repair automatic operations can be split up into a logical sequence of basic operational tasks, as seen in the figures below, algorithms that run parallel and synchronized with ARS transportation and positioning tasks assignments along the A/D/RML process. The technology on A/D/RML assisted by ARS and eye-inhand VSS's basic design approach depends on aspects such as operation modes, operation lengths, distances and manufactured product types [3,5,6]. External events will be interfaced for synchronization between ARS and VSS. Therefore, prior to task scheduling, some assumptions have to be made for FC, A/DML, ARS and VSS in order to control the whole system. For each of the above-mentioned operations, a separate task scheduling strategy has been implemented. The hybrid aspect of the model (A/D/RML assisted by ARS) is given by the continuous aspect, variables associated with the distances covered by the movement of the ARS [2,18,19].

#### 2.2.1. Assembly Process Task Planning

The A/D/RML, as seen in Figure 9, due to the flexibility characteristic, can assemble and process two different products, referred to as workpiece type 1 (WP1) and workpiece type 2 (WP2). WP1 is the workpiece with the top part having triangular edges (Figure 6) and is assembled in the FC station with the ABB IRM. WP2 is the workpiece with top part having round edges (Figure 7a–c) and is assembled on the Hera&Horstmann ML.

The assembly of WP1 is made by the ABB IRM from the FC, picking and placing components in the right order (Figure 6): Base, Body, Top and two cylinders: metal type. Finally, WP1 moves along the Hera&Horstmann ML and is stored on the left side of the

WS6—this product is always considered to be good, with no quality check to perform, although HMI allows operator selection for assembly between plastic and metal cylinders.

**Figure 9.** Assembly task planning.

The WP2 product is assembled with randomly picked cylinders and is subjected to the quality test (in mechatronics line, WS4 location, inductive proximity sensor for detecting metal cylinder). To evaluate the quality for the WP2 product, the convention is that an assembled product with both metal cylinders, it is considered of good quality and it is stored on the left side of the WS6 station. The WP2 product that contains both plastic cylinders (Figure 7b) is considered a bad product, unrepairable, and it is stored on the right of the WS6 station. This WP2 will be disassembled for component recovery. The WP2 product with different cylinder types (Figure 7c) is also stored on the right side of the Storage Rack and it will be repaired by replacing the plastic cylinder with a metal one.
