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Nagata F.,Tokyo University of Science, Yamaguchi | Mizobuchi T.,Tokyo University of Science, Yamaguchi | Tani S.,Tokyo University of Science, Yamaguchi | Hase T.,Meiho Co. | And 4 more authors.
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2010

In this paper, a new desktop orthogonal-type robot, which has abilities of compliant motion and stick-slip motion, is first presented for lapping small metallic molds with curved surface. The robot consists of three single-axis devices with a high position resolution of 1μm. A thin wood stick tool is attached to the tip of the z-axis. The tool tip has a small ballend shape. The control system is composed of a force feedback loop, position feedback loop and position feedforward loop. The force feedback loop controls the polishing force consisting of tool contact force and kinetic friction forces. The position feedback loop controls the position in pick feed direction, e.g., z-direction. The position feedforward loop leads the tool tip along a desired trajectory called cutter location data (CL data). The CL data are generated from the main-processor of a CAM system. The proposed robot realizes a compliant motion required for the surface following control along a spiral path. In order to improve the lapping performance, a small stick-slip motion control strategy is further added to the control system. The small stick-slip motion is orthogonally generated to the direction of the tool moving direction. Generally, the stick-slip motion is an undesirable phenomenon and should be eliminated in precision machineries. However, the proposed robot employs a small stick-slip motion to improve the lapping quality. The effectiveness of the robot is examined through an actual lapping test of an LED lens mold with a diameter of 4 mm. ©2010 IEEE.


Nagata F.,Tokyo University of Science, Yamaguchi | Mizobuchi T.,Tokyo University of Science, Yamaguchi | Hase T.,Meiho Co. | Haga Z.,Meiho Co. | And 2 more authors.
Proceedings of the 15th International Symposium on Artificial Life and Robotics, AROB 15th'10 | Year: 2010

In manufacturing industries of metallic molds, various NC machine tools are used. We have already proposed a desktop NC machine tool with compliance control capability to automatically cope with the finishing process of LED lens molds. The NC machine tool has an ability to control the polishing force acting between an abrasive tool and a workpiece. The force control method is called impedance model force control. The most effective gain is the desired damping of the impedance model. Ideally, the desired damping is calculated from the critical damping condition in consideration of the effective stiffness in force control system. However, there exists a problem that the effective stiffness of the NC machine tool has undesirable nonlinearity. The nonlinearity gives bad influences to the force control stability. In this paper, a fine tuning method of the desired damping is considered by using neural networks. The neural networks acquire the nonlinearity of effective stiffness. The promise is evaluated through an experiment. © 2010 ISAROB.


Nagata F.,Tokyo University of Science, Yamaguchi | Mizobuchi T.,Tokyo University of Science, Yamaguchi | Tani S.,Tokyo University of Science, Yamaguchi | Hase T.,Meiho Co. | And 3 more authors.
Proceedings of the 15th International Symposium on Artificial Life and Robotics, AROB 15th'10 | Year: 2010

In this paper, a new desktop orthogonal-type robot, which has abilities of compliant motion and stick-slip motion, is presented for lapping small metallic molds with curved surface. The robot consists of three single-axis devices with a high position resolution of 1 μm. A thin wood stick tool is attached to the tip of the z-axis. The tool tip has a small ball-end shape. In order to improve the lapping performance, a small stick-slip motion control is considered in the control system. The small stick-slip motion is orthogonally generated to the direction of the tool's moving direction. The effectiveness of the stick-slip motion control is examined through an actual lapping test of an LED lens mold with a diameter of 4 mm. © 2010 ISAROB.


Nagata F.,Tokyo University of Science, Yamaguchi | Mizobuchi T.,Tokyo University of Science, Yamaguchi | Hase T.,Meiho Co. | Haga Z.,Meiho Co. | And 2 more authors.
Artificial Life and Robotics | Year: 2010

In industries manufacturing metallic molds, various NC machine tools are used. We have already proposed a desktop NC machine tool with compliance control capability to automatically cope with the finishing process of LED lens molds. The NC machine tool has the ability to control the polishing force acting between an abrasive tool and a work piece. The force control method is called impedance model force control. The most effective gain is the desired damping of the impedance model. Ideally, the desired damping is calculated from the critical damping condition after considering the effective stiffness in the force control system. However, there is a problem in that the effective stiffness of the NC machine tool has undesirable nonlinearity. The nonlinearity has a bad influence on the force control stability. In this article, a fine tuning method of the desired damping is considered using neural networks. The neural networks acquire the nonlinearity of effective stiffness. The promise is evaluated through an experiment. © 2010 International Symposium on Artificial Life and Robotics (ISAROB).


Nagata F.,Tokyo University of Science, Yamaguchi | Mizobuchi T.,Tokyo University of Science, Yamaguchi | Tani S.,Tokyo University of Science, Yamaguchi | Hase T.,Meiho Co. | And 3 more authors.
Artificial Life and Robotics | Year: 2010

In this article, a new desktop orthogonal-type robot, which has the capacity of stick-slip motion control based on cutter location data, is presented for lapping small metallic molds with a curved surface. The robot consists of three single-axis devices with a high position resolution of 1 μm. A thin wooden stick tool with a ball-end shape is attached to the tip of the z-axis. In order to improve the lapping performance, a novel stick-slip motion control method is developed in the control system. The small stick-slip motion is orthogonally generated in the direction of the tool's movement. The effectiveness of stick-slip motion control is examined through an actual lapping test of an LED lens cavity. © 2010 International Symposium on Artificial Life and Robotics (ISAROB).

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