In this paper we propose a calculation method for the optimal trajectory of a biped locomotion ma... more In this paper we propose a calculation method for the optimal trajectory of a biped locomotion machine which is based on inverse kinematics and inverse dynamics. First, the trajectory of the waist is expressed by a Fourier series, where the bases are selected appropriately so that the periodic boundary conditions are strictly satisfied. A biped locomotion machine establishes optimal walking by using kicking forces to the ground at the moment of switching legs. In order to include the effecs of the kicking forces, additional terms that indicate the impulsive forces at the moment of switching legs are included in the formulation. Then the angles of each joint are determined by inverse kinematics, and using inverse dynamics, the input torques of each joint are expressed in terms of Fourier coefficients. By defining the performance index as a quadratic form of the input torques, the motion planning problem is formulated as an optimization problem of the trajectory of the waist, whose paramaters are Fourier coefficients of the trajactory of the waist. Using the successive quadratic programming (SQP) method, the optimal trajectory of a biped locomotion machine is obtained.
This article deals with the design of a control system for a quadrupedal locomotion robot. The pr... more This article deals with the design of a control system for a quadrupedal locomotion robot. The proposed control system is composed of a leg motion controller and a gait pattern controller within a hierarchical architecture. The leg controller drives actuators at the joints of the legs using a high-gain local feedback control. It receives the command signal from the gait pattern controller. The gait pattern controller, on the other hand, involves nonlinear oscillators. These oscillators interact with each other through signals from the touch sensors located at the tips of the legs. Various gait patterns emerge through the mutual entrainment of these oscillators. As a result, the system walks stably in a wide velocity range by changing its gait patterns and limiting the increase in energy consumption of the actuators. The performance of the proposed control system is verified by numerical simulations.
Decentralized Autonomous Control of a Myriapod Locomotion Robot Ahmet Onat Sabanci University, Tu... more Decentralized Autonomous Control of a Myriapod Locomotion Robot Ahmet Onat Sabanci University, Turkey onat@sabanciuniv.edu Kazuo Tsuchiya Kyoto University, Japan tsuchiya@kuaero.kyoto-u.ac.jp Katsuyoshi Tsujita Kyoto University, Japan tsujita@kuaero.kyoto-...
In our previous work, we developed a locomotion control system of a biped robot which is composed... more In our previous work, we developed a locomotion control system of a biped robot which is composed of nonlinear oscillators and realized a stable straight walk of the biped robot against the changes of the environments. Then, we revealed that the adaptability to the changes of the environments is realized as the straight walk results in the change of the period of the motions of the legs. In this paper, we realize a turning walk of the biped robot by using the developed locomotion control system. First, we provide analysis of the turning behavior of the biped robot and reveal that, in this case, the turning behavior leads to the change of the duty ratios of the legs. Moreover, we realize the task that the robot pursues a target on the floor moving along a corner and it demonstrates that the robot can turn a corner successfully in the real world.
We discuss the motion control of a two-wheeled mobile robot. In the design of a controller for th... more We discuss the motion control of a two-wheeled mobile robot. In the design of a controller for the system, a kinematic model is usually used; the wheels do not skid at all and the mobile robot is regarded as a 3D 2-input nonholonomic system without drift. Many controllers based on the kinematic model have been proposed. However, in a real world, the wheels may skid on the ground or float away from the ground according to the rolling motion of the body. Therefore, we derive a dynamic model of a two-wheeled mobile robot which implies the translational motion with 3 degrees-of-freedom and the rotational motion with 3 degrees-of-freedom of the body and the rotational motion with one degree-of-freedom of each wheel, and then reduce the dynamic model to the kinematic model under certain assumptions. We design a controller based on the kinematic model by extending the Lyapunov control and analyze whether the designed controller works well in a real world by numerical simulations based on the dynamic model
This paper proposes the locomotion control system for a biped locomotion robot. The propose contr... more This paper proposes the locomotion control system for a biped locomotion robot. The propose control system is composed of motion generator system and motion control system. Motion generator system is composed of nonlinear oscillators, which generate the commanded trajectories of the joints as functions of phases of oscillators. Motion control system is composed of motors with controllers installed at joints, which control motions of joints. The oscillators tune the phases through the mutual interactions and the feedback signals from the touch sensors at the tips of the legs. As a result, the robot with the controller walks stably by changing its period of locomotion in a changing environment. The performance of the proposed control system is verified by numerical simulations and experiments.
An oscillator-type gait controller for a quadruped robot with antagonistic pairs of pneumatic act... more An oscillator-type gait controller for a quadruped robot with antagonistic pairs of pneumatic actuators is proposed. By using the controller, a feasibility study on the stability of gait patterns with changeable body stiffness is reported. The periodic motions of the legs are generated and controlled by an oscillator network with state resetting. This type of controller has robustness in its gaits against variation in walking conditions or changes of environment. However, it sometimes loses robustness under conditions of actuation delay, decrease of actuator accuracy, etc. We investigated whether an oscillator-type controller with phase resetting is also effective under such conditions. The stability of locomotion also strongly depends on the mechanical properties of the body mechanism, especially the joint stiffness. In this report, the muscle tone of the robot on the pitching motion at the trunk is changeable by using the changeable elasticity of the pneumatic actuators. The stability of quadruped locomotion in walk and trot patterns with changeable body stiffness was evaluated with numerical simulations and hardware experiments.
The development of an oscillator controller for a bipedal robot with antagonistic pairs of pneuma... more The development of an oscillator controller for a bipedal robot with antagonistic pairs of pneumatic actuators is reported. Periodic motions of the legs switch between the swinging and supporting stages based on the phase of the oscillators. The oscillators receive touch sensor signals at the end of the legs as feedback when the leg touches the ground and compose a steady limit cycle of the total periodic dynamics of bipedal locomotion. The effectiveness and performance of the proposed controller were evaluated with numerical simulations and experiments with the hardware.
In this paper we propose a calculation method for the optimal trajectory of a biped locomotion ma... more In this paper we propose a calculation method for the optimal trajectory of a biped locomotion machine which is based on inverse kinematics and inverse dynamics. First, the trajectory of the waist is expressed by a Fourier series, where the bases are selected appropriately so that the periodic boundary conditions are strictly satisfied. A biped locomotion machine establishes optimal walking by using kicking forces to the ground at the moment of switching legs. In order to include the effecs of the kicking forces, additional terms that indicate the impulsive forces at the moment of switching legs are included in the formulation. Then the angles of each joint are determined by inverse kinematics, and using inverse dynamics, the input torques of each joint are expressed in terms of Fourier coefficients. By defining the performance index as a quadratic form of the input torques, the motion planning problem is formulated as an optimization problem of the trajectory of the waist, whose paramaters are Fourier coefficients of the trajactory of the waist. Using the successive quadratic programming (SQP) method, the optimal trajectory of a biped locomotion machine is obtained.
This article deals with the design of a control system for a quadrupedal locomotion robot. The pr... more This article deals with the design of a control system for a quadrupedal locomotion robot. The proposed control system is composed of a leg motion controller and a gait pattern controller within a hierarchical architecture. The leg controller drives actuators at the joints of the legs using a high-gain local feedback control. It receives the command signal from the gait pattern controller. The gait pattern controller, on the other hand, involves nonlinear oscillators. These oscillators interact with each other through signals from the touch sensors located at the tips of the legs. Various gait patterns emerge through the mutual entrainment of these oscillators. As a result, the system walks stably in a wide velocity range by changing its gait patterns and limiting the increase in energy consumption of the actuators. The performance of the proposed control system is verified by numerical simulations.
Decentralized Autonomous Control of a Myriapod Locomotion Robot Ahmet Onat Sabanci University, Tu... more Decentralized Autonomous Control of a Myriapod Locomotion Robot Ahmet Onat Sabanci University, Turkey onat@sabanciuniv.edu Kazuo Tsuchiya Kyoto University, Japan tsuchiya@kuaero.kyoto-u.ac.jp Katsuyoshi Tsujita Kyoto University, Japan tsujita@kuaero.kyoto-...
In our previous work, we developed a locomotion control system of a biped robot which is composed... more In our previous work, we developed a locomotion control system of a biped robot which is composed of nonlinear oscillators and realized a stable straight walk of the biped robot against the changes of the environments. Then, we revealed that the adaptability to the changes of the environments is realized as the straight walk results in the change of the period of the motions of the legs. In this paper, we realize a turning walk of the biped robot by using the developed locomotion control system. First, we provide analysis of the turning behavior of the biped robot and reveal that, in this case, the turning behavior leads to the change of the duty ratios of the legs. Moreover, we realize the task that the robot pursues a target on the floor moving along a corner and it demonstrates that the robot can turn a corner successfully in the real world.
We discuss the motion control of a two-wheeled mobile robot. In the design of a controller for th... more We discuss the motion control of a two-wheeled mobile robot. In the design of a controller for the system, a kinematic model is usually used; the wheels do not skid at all and the mobile robot is regarded as a 3D 2-input nonholonomic system without drift. Many controllers based on the kinematic model have been proposed. However, in a real world, the wheels may skid on the ground or float away from the ground according to the rolling motion of the body. Therefore, we derive a dynamic model of a two-wheeled mobile robot which implies the translational motion with 3 degrees-of-freedom and the rotational motion with 3 degrees-of-freedom of the body and the rotational motion with one degree-of-freedom of each wheel, and then reduce the dynamic model to the kinematic model under certain assumptions. We design a controller based on the kinematic model by extending the Lyapunov control and analyze whether the designed controller works well in a real world by numerical simulations based on the dynamic model
This paper proposes the locomotion control system for a biped locomotion robot. The propose contr... more This paper proposes the locomotion control system for a biped locomotion robot. The propose control system is composed of motion generator system and motion control system. Motion generator system is composed of nonlinear oscillators, which generate the commanded trajectories of the joints as functions of phases of oscillators. Motion control system is composed of motors with controllers installed at joints, which control motions of joints. The oscillators tune the phases through the mutual interactions and the feedback signals from the touch sensors at the tips of the legs. As a result, the robot with the controller walks stably by changing its period of locomotion in a changing environment. The performance of the proposed control system is verified by numerical simulations and experiments.
An oscillator-type gait controller for a quadruped robot with antagonistic pairs of pneumatic act... more An oscillator-type gait controller for a quadruped robot with antagonistic pairs of pneumatic actuators is proposed. By using the controller, a feasibility study on the stability of gait patterns with changeable body stiffness is reported. The periodic motions of the legs are generated and controlled by an oscillator network with state resetting. This type of controller has robustness in its gaits against variation in walking conditions or changes of environment. However, it sometimes loses robustness under conditions of actuation delay, decrease of actuator accuracy, etc. We investigated whether an oscillator-type controller with phase resetting is also effective under such conditions. The stability of locomotion also strongly depends on the mechanical properties of the body mechanism, especially the joint stiffness. In this report, the muscle tone of the robot on the pitching motion at the trunk is changeable by using the changeable elasticity of the pneumatic actuators. The stability of quadruped locomotion in walk and trot patterns with changeable body stiffness was evaluated with numerical simulations and hardware experiments.
The development of an oscillator controller for a bipedal robot with antagonistic pairs of pneuma... more The development of an oscillator controller for a bipedal robot with antagonistic pairs of pneumatic actuators is reported. Periodic motions of the legs switch between the swinging and supporting stages based on the phase of the oscillators. The oscillators receive touch sensor signals at the end of the legs as feedback when the leg touches the ground and compose a steady limit cycle of the total periodic dynamics of bipedal locomotion. The effectiveness and performance of the proposed controller were evaluated with numerical simulations and experiments with the hardware.
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