Koichi Osuka

Stability analysis of passive-dynamic-walking focusing on the inner structure of Poincare map

The purpose of this paper is to analyze the stability of passive dynamic walking using an approximate analytical Poincare map of the impact point, which is the state of walking robot at the collision between a swing leg and ground. Especially, in this paper, we focus on the feedback structure in equations which are used to get the Poincare map, and consider the relationship between stability of passive-dynamic-walking and the feedback structure. In this process, we derive a control method of quasi passive-dynamic-walking which utilizes the inner structure of Poincare map and confirm the effectiveness of the control method via several simulations

Demonstration and Analysis of Quadrupedal Passive Dynamic Walking

Animals, including human beings, can travel in a variety of environments adaptively. Legged locomotion makes this possible. However, legged locomotion is temporarily unstable and finding out the principle of walking is an important matter for optimum locomotion strategy or engineering applications. As one of the challenges, passive dynamic walking has been studied on this. Passive dynamic walking is a walking phenomenon in which a biped walking robot with no actuator walks down a gentle slope. The gait is very smooth (like a human) and much research has been conducted on this. Passive dynamic walking is mainly about bipedalism. Considering that there are more quadruped animals than bipeds and a four-legged robot is easier to control than a two-legged robot, quadrupedal passive dynamic walking must exist. Based on the above, we studied saggital plane quadrupedal passive dynamic walking simulation. However, it was not enough to attribute the result to the existence of quadrupedal passive dynamic walking. In this research, quadrupedal passive dynamic walking is experimentally demonstrated by the four-legged walking robot Quartet 4. Furthermore, changing the type of body joint, slope angle, leg length and variety of gaits (characteristics in four-legged animals) was observed passively. Experimental data could not have enough walking time and could not change parameters continuously. Then, each gait was analyzed quantitatively by the experiment and three-dimensional simulation.

On the embodiment that enables passive dynamic bipedal running

The control and mechanical systems of an embodied agent should be tightly coupled so as to emerge useful functionalities such as adaptivity. This indicates that the mechanical system as well as the control system should be responsible for a certain amount of computation for generating the behavior. However, there still leaves much to be understood about to what extent computational offloading from the control system to the mechanical system should be achieved. In order to effectively consider this, here we particularly focus on a passive dynamic running biped whose behavior is generated purely from its mechanical system, and investigate how the bodys properties influence the resulting behavior. Through the numerical simulations, we have found that two elastic parameters of its body, leg spring constant and hip coil spring constant, play a crucial role, and depending on which various kinds of stable gait patterns are generated. To the best of our knowledge, this has not been explicitly addressed so far. The results obtained are expected to shed a new light on to what extent the mechanical system should be responsible for generating the behavior.

Design and control of a heavy material handling manipulator for agricultural robots

In this paper, we propose a manipulation system for agricultural robots that handle heavy materials. The structural systems of a mobile platform and a manipulator are selected and designed after proposing new knowledge about agricultural robots. Also, the control systems for these structural systems are designed in the presence of parametric perturbation and uncertainty while avoiding conservative results. The validity of both the structural and control systems is confirmed by conducting watermelon harvesting experiments in an open field. Furthermore, an explicit design procedure is confirmed for both the structural and control systems and three key design tools are clarified.

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.

Image-based path following control of mobile robots with central catadioptric cameras

The research of image-based control for nonholonomic mobile robots is a recent topic of mobile robots. There are few researches about image-based control of mobile robots with central catadioptric cameras. A central catadioptric camera is very effective to keep target objects in the camera field of view because of its wide area view. In this paper, a new image-based path following control method for a nonholonomic mobile robot with a central catadioptric camera is proposed in the image parameter space. It is confirmed by several simulation, indoor and outdoor experiments that the designed system has high performance and robustness in real world.

Hierarchical implicit feedback structure in passive dynamic walking

The purpose of this paper is to analyze the stability of Passive Dynamic Walking (PDW) using a linearized analytical Poincare map. In particular, in this paper, we focus on a bifurcation phenomenon in PDW. Although the bifurcation of the walking period is one of the well-known features of PDW, it have not been studied sufficiently so far. Using techniques similar to our previous research, we derive an analytical Poincare map for 2-period walking and discuss the stability of PDW with this map. In addition, we point out that there is a similar interesting structure in this Poincare map.

Inverse Optimal Velocity Field Control of an Outdoor Blimp Robot – Blimp Surveillance Systems for Rescue –

Abstract: A surveillance system is required to gather the suffering information in the stricken area safely and quickly after natural disasters. An autonomous blimp is the best option for this purpose. Inverse optimal velocity field control is proposed for the blimp to keep a desired trajectory. The desired trajectory based on velocity field is designed, and inverse optimal tracking control is applied to be robust to input uncertainties. The transient performance to the desired trajectory is very important to fly smoothly along the contour, because the blimp is affected by wind easily. The inverse optimal control is expected to improve the robustness to uncertainties of various dynamic parameters. Some experiments are performed to confirm the usefulness of the proposed method by using an outdoor blimp whose length is 12.2m.

Passivity-based Adaptive Nonlinear Control for Active Steering

Many researches of active steering systems have been proceeding to improve the driving safety of automobiles. The authors proposed a design method of model reference adaptive nonlinear controllers to treat uncertainties and non-linearities of tires lateral forces directly. But the designed controller is very complicated because it has many estimated parameters for adaptive control. In this research, a design method of passivity-based adaptive nonlinear controllers is proposed for active steering systems. The designed controller is robust to uncertainties and nonlinearities of tires lateral forces. Furthermore, the controller is much simpler than the existing ones. Some simulation results are provided to confirm the usefulness of the proposed method.

Tracking Control of an Aerial Blimp Robot Based on Image Information

An autonomous surveillance blimp system is provided with only one camera as a sensor. Motion segmentation is used to improve automatic detection and tracking of point features on a target object. Inverse optimal tracking control is applied to an aerial blimp which is one of the underactuated systems. 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. Some experiments are performed by using an indoor blimp.