Browsing by Author "Murakami, T"

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Open Access
Control of two wheel mobile manipulator on a rough terrain using reaction torque observer feedback
(Library of Science, 2010-04-01) Abeygunawardhana, P. K. W; Murakami, T
The mobile manipulator has the potential to become an efficient industrial robot due to its mobility and dexterity. Moreover, it has expanded the operational area of the mobile manipulator due to its ability to work in a limited space. However, adaptability to unknown environments has still not been developed to date. Therefore, adaptation of the mobile manipulator for unknown environments especially for rough/irregular terrain is discussed in this paper. Information about the environment, a key factor when aiming for compliance with an unknown and/or unstructured environment, was collected using a reaction torque observer. In order to adapt to the environment, compliance control was applied to the mobile manipulator. In this paper, we present a novel control strategy we have developed that can deal with unknown environments through the effective use of inverted pendulum control. Simulation and experiments were carried out to ensure the validity of the proposed method. The method could be confirmed as effective according to the results obtained.
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Self-sustaining control of two-wheel mobile manipulator using sliding mode control
(IEEE, 2010-03-21) Abeygunawardhana, P. K. W; Defoort, M; Murakami, T
Two wheel mobile manipulator has the potential to become multi-skilled robot in the field of robotics engineering and it is already implemented by using inverted pendulum control. Centre of gravity position is controlled to achieve the balancing of robot. Due to the unbalanced nature and the nonholonomic property of the two-wheel mobile manipulator, balancing is challenging task. On the other hand sliding mode control is a good candidate to address the nonlinear/under actuated system. This paper presents the control methods for balancing of two-wheel mobile manipulator. This paper proposes a novel second order sliding mode controller using twisting algorithm, disturbance observer and dynamics of double inverted pendulum. Dynamics of double inverted pendulum is used to design the control equation of sliding mode controller. Twisting algorithm is used to design the control input. Disturbance observer is compensated model uncertainties and external disturbances. Posture of two wheel mobile manipulator can successfully stabilized by this novel controller.
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Vibration Suppression of Two Wheel Mobile Manipulator using Resonance Ratio Control
(IEEE, 2008-12-02) Abeygunawardhana, P. K. W; Murakami, T
Two wheel mobile manipulator has the potential of becoming a multi-skilled robot in the field of robotics and it is already implemented by using inverted pendulum control. Centre of gravity position (COG) is controlled to achieve the balancing of robot. Since vibration of manipulator arms affect to the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, vibration control of manipulator arms of the mobile manipulator is proposed in this paper. Feedback signal for vibration suppression is introduced to null space of manipulator. Simulation and experiment was carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.
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Vibration suppression of two-wheel mobile manipulator using resonance-ratio-control-based null-space control
(IEEE, 2010-03-01) Abeygunawardhana, P. K. W; Murakami, T
A two-wheel mobile manipulator has the potential to become a multiskilled robot in the field of robotics, and it is already implemented by using inverted pendulum control. The center of gravity (COG) position is controlled to achieve the balancing of the robot. Since the vibrations of manipulator arms affect the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, the vibration control of manipulator arms of the two-wheel mobile manipulator is proposed in this paper. The virtual double-inverted pendulum is modeled using a “4-DOF” manipulator, and it is controlled in work space and null space. Resonance ratio control is utilized for vibration-suppression control. The resonance ratio of a system can be determined arbitrarily by the feedback of reaction torque, and reaction torque observers are implemented for each and every manipulator motor. The feedback signal for vibration suppression is introduced to the null space of the manipulator. Simulations and experiments were carried out to check the validity of the proposed method, and results prove the effectiveness of the proposed vibration controller.
Embargo
Workspace control of two wheel mobile manipulator by resonance ratio control
(IEEE, 2009-07-14) Abeygunawardhana, P. K. W; Murakami, T
Two wheel mobile manipulator has the potential of becoming a multi-skilled robot in the field of robotics and it is already implemented by using inverted pendulum control. Centre of gravity position (COG) is controlled to achieve the balancing of robot. Since vibration of manipulator arms affect to the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, vibration control of manipulator arms of the mobile manipulator is proposed in this paper. Feedback signal for vibration suppression is introduced at work space of manipulator. Simulation and experiment was carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.