Takanori Fukao

Adaptive tracking control of a nonholonomic mobile robot

A mobile robot is one of the well-known nonholonomic systems. The integration of a kinematic controller and a torque controller for the dynamic model of a nonholonomic mobile robot has been presented (Fierro and Lewis, 1995). In this paper, an adaptive extension of the controller is proposed. If an adaptive tracking controller for the kinematic model with unknown parameters exists, an adaptive tracking controller for the dynamic model with unknown parameters can be designed by using an adaptive backstepping approach. A design example for a mobile robot with two actuated wheels is provided. In this design, a new kinematic adaptive controller is proposed, then a torque adaptive controller is derived by using the kinematic controller.

Image-based visual adaptive tracking control of nonholonomic mobile robots

A novel image-based visual approach for controlling nonholonomic mobile robots to track a moving target is presented. The mobile robot is endowed with a fixed camera, and a visual feedback controller is used to control the mobile robot to track a moving target of interest. A three dimensional state space representation of the camera-target visual interaction model fully defined in the image plane is used. In the case of an unknown height moving target symbol traced by camera, the global stability is proved using an adaptive backstepping control law. Based on the Lyapunov direct method, the closed-loop stability is guaranteed. Experimental results of a mobile robot with two actuated wheels equiped with a fixed camera are provided for illustrating the tracking ability of the controller.

Active Steering Systems Based on Model Reference Adaptive Nonlinear Control

This paper presents a model reference adaptive nonlinear control strategy for active steering of a two wheel steering car which is realized by steer-by-wire technology. The ideal fixed property of a steering system, which is provided by a reference model, is attained by D * control. The proposed method can treat the nonlinear relationships between the slip angles and the lateral forces on tires, and the uncertainties on the friction of the road surface, whose compensations are very important under critical situations. Some results of realtime simulation with a steering equipment show the effectiveness of the proposed method.

Image-based tracking control of a blimp

Image-based tracking control of an aerial blimp is proposed for surveillance systems. The controller is designed by backstepping techniques for underactuated systems. In our framework, only one camera on a blimp is used to control the blimp without the other sensors and to generate a reference trajectory from image information. After a commander sets a target, the blimp flies around it automatically. This image-based approach reduces to utilize the values estimated by a structure-from-motion algorithm. In this research an aerial blimp is used for indoor experiments, and image-based control are compared with position-based control.

An autonomous blimp for a surveillance system

An autonomous blimp for a surveillance system, which is circling around a specified target with only one camera, is designed in this paper. For this purpose, an extension of Lucas-Kanade algorithm for detection and tracking of features with rotation and scaling is provided, and a simplified structure-from-motion algorithm is applied to improve the accuracy of state estimation. A tracking controller is designed for the blimp which is an underactuated system. The desired path of the blimp is also generated from image information of a target. The blimp flies around the target automatically, after a commander sets it. Some experiments are performed indoors by using an aerial blimp.

Inverse optimal tracking control of a nonholonomic mobile robot

A design method of inverse optimal tracking controllers is proposed for nonholonomic mobile robots with two actuated wheels. In the inverse optimal control approach, a controller is designed by using a control Lyapunov function and Sontags formula. The controller minimizes some meaningful cost dependent on the controller which is not given in advance, and the designed system has a stability margin which guarantees robustness with respect to input uncertainties. The robust property is a very important issue for real applications. Several simulation and experimental results show the ability of the proposed controller by comparing with an existing method.

Nonlinear and H/sub /spl infin// control of active suspension systems with hydraulic actuators

H/sub /spl infin// and adaptive nonlinear control technique is provided for the active suspension system which is divided into two parts: the main car body part and the hydraulic actuator part. H/sub /spl infin// control design is used for the body part where the frequency response property is important for the ride quality of the automobile, and adaptive nonlinear control design is worked out for the actuator part which has high nonlinearity and parametric uncertainty. These two design methods are combined by a modified version of backstepping.

Active steering systems based on model reference adaptive nonlinear control

Presents a model reference adaptive control strategy for active steering of 2WS cars which is realized by steer-by-wire technology. The ideal fixed property of a steering system which is provided by a reference model is attained by D* control. The proposed method can treat the nonlinear relationships between the slip angles and the lateral forces on tires, and the uncertainties on the friction of the road surface, whose compensations are proved to be very important under critical situations. Some results of real time simulation with a steering equipment show the effectiveness of the proposed method.

Inverse optimal tracking control of an aerial blimp robot

Inverse optimal tracking control is applied to an aerial blimp which is one of the underactuated systems. In the inverse optimal control approach, a controller is designed by using a control Lyapunov function and Sontags formula. The controller minimizes some meaningful cost dependent on the controller, which is not given in advance, and the designed system has a stability margin which guarantees robustness with respect to input uncertainties. This robust property is a very important issue for a blimp which has large uncertainties. Some experiments are performed by using an indoor blimp.

Hovering control of outdoor blimp robots based on path following

A surveillance system is required to gather information about the stricken area safely and quickly after large-scale disasters. An autonomous blimp is the best option for this purpose. This paper proposes a control design method for automatic hovering of outdoor blimp robots under strong wind by using path following approach. The method consists of inverse optimal path following control in horizontal plane and PID control for altitude and pitching motion of the blimp in longitudinal plane. Some simulations and experiments for an outdoor blimp whose length is 12m are performed to confirm the usefulness of the proposed method.