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...on. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task completion time. In this paper, we aim to design a compact work cell consisting of a 6-DOF robot arm and a 1-DOF positioning table, as shown in Figure 1. This study is unique from previous studies in two aspects: 1) the evaluation of a compact work cell and 2) the incorporation of a task completion time constraint in the optimization. We evaluate the compactness of a work cell on the basis of the ...

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...hrough simulations. I. INTRODUCTION OBOT arm with positioning table is an important system applied in manufacturing work cells such as in inspection and welding. It is widely-used due to its flexibility, reliability, and efficiency in the use of robot arm workspace [1]. Since a work cell is the basic manufacturing unit, this system has to be compact and be able to execute task in minimal time. In previous studies, the facility layout problem, a nondeterministic polynomial time-complete problem, deals with the placement of several machines. A comprehensive survey of this problem is provided in [2]. In [3] and [4], a layout is designed to minimize the traveled path of a robot arm by determining the relative position and orientation of machines in a work cell. To save space, machines are represented as squares instead of super-shapes like circles enclosing machines [3]. Such representation allows the machines to be compactly located in a floor area. Since exact or linear programming methods are computationally inefficient for large number of machines, heuristics are used, e.g., machines with high frequency of interaction are placed near to each other [3]. Commonly, an area is divided int...

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...imulated annealing (SA). The SA, which is based on a stochastic local neighbor search method, can be robust and capable of avoiding local minima by selecting a solution that can be worse than a current solution (i.e., a base placement design with a work cell size larger than that of the previous design). The probability of accepting a worse solution is too high at the start and is subsequently reduced as the optimization proceeds. In this paper, we define a neighborhood as a set of solutions found by incrementing or decrementing the design variables by a constant step size (i.e. 10 [mm]). See [16] for detailed discussion on SA. C. Goal Rearrangement We briefly describe the algorithm for the goal rearrangement in this section. See [15] for details. To reduce the calculation time, the goals are clustered into groups based on their locations on the planar boundaries defined by the approximate box enclosing object AO. With the clustering, the algorithm derives (a) the order of clusters and (b) the goal order in every cluster. The order of clusters (a) is solved using the 2-opt algorithm, which exchanges the order of two clusters, while (b) is derived using the Lin-Kernighan algorithm. The ...

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... be easily calculated since a machine once it is assigned a placement in the layout can be treated as a static goal of the robot arm. In this paper, however, goals can be repositioned by a positioning table making the problem complicated. Some studies provide solutions for component arrangement, motion programming, and layout optimization in the form of interactive software [5], which may require some user skills to generate a good layout. In the above-mentioned studies, the layout is focused on two-dimensional (2D) floor area. A related study dealing with 3D layout of objects is evaluated in [6]. In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimizatio...

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...od for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task completion time. In this paper, we aim to design a compact work cell consisting of a 6-DOF robot arm and a 1-DOF positioning table, as shown in Figure 1. This study is unique from previous studies in two aspects: 1) the evaluation of a compact work cell and 2) the incorporation of a task completion time constraint in the optimization. We evaluate the compactness of a work cell on the basis of the size and the swept volume of work cell components. This evaluation has two merits: (a) it extends the facility layout problem into 3 dim...

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...poral requirements, we propose the integration of the base placement optimization, goal rearrangement, and motion coordination between the robot arm and the positioning table. Furthermore, we introduce two motion coordination schemes based on the spatial and temporal requirements. We showed the effectiveness of the proposed method through simulations. I. INTRODUCTION OBOT arm with positioning table is an important system applied in manufacturing work cells such as in inspection and welding. It is widely-used due to its flexibility, reliability, and efficiency in the use of robot arm workspace [1]. Since a work cell is the basic manufacturing unit, this system has to be compact and be able to execute task in minimal time. In previous studies, the facility layout problem, a nondeterministic polynomial time-complete problem, deals with the placement of several machines. A comprehensive survey of this problem is provided in [2]. In [3] and [4], a layout is designed to minimize the traveled path of a robot arm by determining the relative position and orientation of machines in a work cell. To save space, machines are represented as squares instead of super-shapes like circles enclosing mac...

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...ling with 3D layout of objects is evaluated in [6]. In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task complet...

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... Hino-shi, Tokyo, Japan, 191-0065. (email: rchiba@sd.tmu.ac.jp). T. Ueyama is with DENSO WAVE INCORPORATED, 1, Yoshiike, Kusaki, Agui-cho, Chita-gun, Aichi, Japan, 470-2298. as a distance between blocks. These distances can be easily calculated since a machine once it is assigned a placement in the layout can be treated as a static goal of the robot arm. In this paper, however, goals can be repositioned by a positioning table making the problem complicated. Some studies provide solutions for component arrangement, motion programming, and layout optimization in the form of interactive software [5], which may require some user skills to generate a good layout. In the above-mentioned studies, the layout is focused on two-dimensional (2D) floor area. A related study dealing with 3D layout of objects is evaluated in [6]. In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed su...

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...r the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task completion time. In this paper, we aim to design a compact work cell consisting of a 6-DOF robot arm and a 1-DOF positioning table, as shown in Figure 1. This study is unique from previous studies in two aspects: 1) the evaluation of a compact work cell and 2) the incorporation of a task completion time constraint in the optimization. We evaluate the compactness of a work cell on the basis of the size and the swept volume of work cell components. This evaluation has two merits: (a) it extends the facility layout problem into 3 dimensio...

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...imulations. I. INTRODUCTION OBOT arm with positioning table is an important system applied in manufacturing work cells such as in inspection and welding. It is widely-used due to its flexibility, reliability, and efficiency in the use of robot arm workspace [1]. Since a work cell is the basic manufacturing unit, this system has to be compact and be able to execute task in minimal time. In previous studies, the facility layout problem, a nondeterministic polynomial time-complete problem, deals with the placement of several machines. A comprehensive survey of this problem is provided in [2]. In [3] and [4], a layout is designed to minimize the traveled path of a robot arm by determining the relative position and orientation of machines in a work cell. To save space, machines are represented as squares instead of super-shapes like circles enclosing machines [3]. Such representation allows the machines to be compactly located in a floor area. Since exact or linear programming methods are computationally inefficient for large number of machines, heuristics are used, e.g., machines with high frequency of interaction are placed near to each other [3]. Commonly, an area is divided into blocks...

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...ns. I. INTRODUCTION OBOT arm with positioning table is an important system applied in manufacturing work cells such as in inspection and welding. It is widely-used due to its flexibility, reliability, and efficiency in the use of robot arm workspace [1]. Since a work cell is the basic manufacturing unit, this system has to be compact and be able to execute task in minimal time. In previous studies, the facility layout problem, a nondeterministic polynomial time-complete problem, deals with the placement of several machines. A comprehensive survey of this problem is provided in [2]. In [3] and [4], a layout is designed to minimize the traveled path of a robot arm by determining the relative position and orientation of machines in a work cell. To save space, machines are represented as squares instead of super-shapes like circles enclosing machines [3]. Such representation allows the machines to be compactly located in a floor area. Since exact or linear programming methods are computationally inefficient for large number of machines, heuristics are used, e.g., machines with high frequency of interaction are placed near to each other [3]. Commonly, an area is divided into blocks and the...

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...ensional (2D) floor area. A related study dealing with 3D layout of objects is evaluated in [6]. In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, t...

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...with 3D layout of objects is evaluated in [6]. In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task completion t...

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...In that study, components are packed into a container with the objective of maximizing packing density. In this paper, however, the work cell components are moving (e. g., the robot arm and the positioning table simultaneously move to execute task). A problem similar to the facility layout design is the robot arm base placement optimization. Several methods are proposed such as employing a random method for the base placement optimization with a probabilistic roadmap method for the motion planning [7], optimization of some kinematic criteria [8], [9], and the task completion time minimization [10]. In [10], it is shown that in order to reduce the task completion time, a robot arm must be placed afar from its goals to achieve few joint motions; this, however, results into a large occupied floor area. Several studies focused on the motion planning of robot arms. A comprehensive literature for the motion planning can be found in [11]. In multiple-goal tasks (e.g., inspection and welding), motion planning has been dealt with in combination with goal rearrangement [12]-[15]. In those studies, the emphasis is on minimizing the task completion time. In this paper, we aim to design a compact w...