This paper describes a novel method of path following by a wheeled mobile robot. A number of virtual manipulators mounted on the robot are used to make the robot poses which satisfy both of path following and collision avoidance. This method can calculate robot poses by using a single jacobi matrix despite of coping with several manipulators. We also present about the method of tracking stabilization by using a singularity-avoiding criteria. Effectiveness of the proposed method is proven by means of simulation in both cases of omnidirectional wheelbase and 2 wheeled mobile base.
It is important for robots that act in human-centered environment to manipulate objects using visual information, where adaptability to unknown factors such as properties of robot body and objects is required. In this paper, we propose a learning method to acquire visual representation of robot body and object that is suitable for motion learning in a bottom-up manner. An advantage of the proposed framework is that it does not require specific hand-coding depending on the visual properties of objects or the robot, such as colors, shapes and sizes. Objects are extracted by a subtraction technique and the state space is constructed by SOM based on the images of extracted objects. Motion of the robot is planned based on reachable set that expresses a region where the object can reach. The task to move an object to a target position is divided into two phases, one to reach a position that is suitable for starting pushing and pulling motion and the other to push and pull the object to the target. The proposed method is verified by experiment of pushing and pulling manipulation of an object with a robot arm.
This paper describes that a proposal of link composition for a parallel mechanism with pin joints. The maximum angle of inclination by the general parallel mechanism with ball joints is about 55 degrees because of limitations of angle of those joints. Therefore, a novel parallel mechanism that replaced ball joints by the pin joints with wide movable angle is proposed. Moreover, three kinds of link composition that are an outside type, an inside type and a combination type are proposed. The transmission index is investigated about these three types, therefore it has been understood that the combination type is able to move in the widest area. It was confirmed to be able to move the inclination angle of the end effector to 90 degrees by simulations and experiments, and showed the effectiveness.
The paper presents a three DOF mechanical wrist that is capable to control its joint stiffness as well as joint angle by using the ANLES (Actuator with Non-Linear Elastic System). First it describes the structure of the ANLES followed by the designing method of the non-linear elasticity. Subsequently it shows the second machine of the wrist joint controlled by the ANLES of which size and weight are downsized nearly a half compared to the first machine. Next it presents a new ANLES (we call V-ANLES) that has a viscosity to suppress vibrations caused by the elasticity. It follows the experimental results of the step-response of the joint to show the V-ANLES successfully diminishes the overshoot. Finally it shows the experimental results to rotate the wrist joint about Z-axis by using the four ANLES.
The purpose of our study is to realize an active vision capable of casting its gaze in any desired direction in ms-order. It is, however, difficult even if a vision sensor itself is controlled directly by high-speed actuators. Therefore, we propose a high-speed gaze control subsystem, called “Saccade Mirror.” Using this system and a high-speed vision, image sequences that each image has different direction of gaze in msorder has been successfully obtained. Measuring the frequency response of the gaze control, this result has exceeded the preceding study. That is to say, the utility of our proposal has been ascertained.
This paper is concerned with a gait generation framework for legged robots based on iterative learning control (ILC) of Hamiltonian systems. This method allows one to obtain solutions to a class of optimal control problems by iteration of laboratory experiments and, furthermore, precise knowledge of the plant model is not required for it by taking advantage of a symmetric property of Hamiltonian systems. Generally in walking motion, there are discontinuous state transitions caused by collision between the foot and the ground. The proposed framework can also deal with such state transitions without using the parameters of the transition model by combining ILC method and the least-squares. It is applied to a compass-like biped robot to generate optimal gait on the level ground. Some numerical examples demonstrate the effectiveness of the proposed method.