This paper describes a novel non-contact manipulation system using on-chip magnetically driven micro-tools (MMT). This system has sorting function of particles one by one with MMT. It has unique feature of installation of MMT directly in a microchannel which is unlike to the conventional cell sorter systems. The drive unit was remarkably downsized by using an amplification mechanism of magnetic power actuated by electromagnets. We have demonstrated sorting of micro-beads automatically based on trigger signals generated by real-time image recognition. The proposed method can be extended to the environmental particulate analysis, cell sorting system and so on.
This paper presents omnidirectional control and prototyping of a new type of electric wheelchair with four-wheel drive (4WD) mechanism for improving traction on the slippery surface and enhancing mobility on rough terrain of standard wheelchairs. The 4WD mechanism equips four wheels, two omni-wheels in front and two normal tires in rear. The normal wheel and the omni-wheel, mounted on the same side of the base, are interconnected by belt transmissions to rotate in unison with a drive motor, i.e. a synchro-drive transmission. To rotate a chair at the center of the 4WD about vertical axis, the third motor is installed on the platform. For omnidirectional control of the 4WD mechanism, two wheel motors are coordinated to translate the center of the chair in an arbitrary direction while the chair orientation is controlled by the third motor separately. Thus a wheelchair with proposed 4WD mechanism can move in any direction without changing the chair orientation and turn in a place, namely holonomic. In the paper, motion analysis of the 4WD mechanism and the omnidirectional control method are presented followed by prototype design for verification of the proposed 4WD omnidirectional wheelchair system.
This paper proposes a sound source localization method which is robust for multiple sound sources and sound pressure difference. We propose the Main-Lobe Fitting algorithm using the directional pattern of a microphone array to reduce localization error in reverberant environments and noisy conditions such as a robot moving. The localization method is a post process of beam forming and it filters out reflected or interfered signals by selecting spectra which are fitted with the main-lobe model. We implemented the method on our 32ch microphone array mounted on a mobile robot, and evaluated the performance in different conditions. The experimental results show that the system provides accurate and robust sound localization for multiple different sound sources during robot motion.
A standing style transfer system, ABLE, is designed to assist a person with disabled lower limbs to travel in a standing position, to sit down in and stand up from a chair, and to go up and down a step. ABLE comprises three modules: a pair of telescopic crutches, a powered lower extremity orthosis, and a pair of mobile platforms. In this system, the telescopic crutches are useful not only to maintain the body stability in a standing position, but to supply power when standing up from a chair, going up a step, and so forth. The powered lower extremity orthosis has an actuator on each hip and knee joint. This module actively fixes, bends, and stretches each joint. The mobile platforms use crawlers to enable the person to travel even on uneven ground. These platforms also enable the user to turn on a rotation board mechanism. In this paper, we mainly discuss the chair and step motions. Experimental results related to these motions confirm the design’s effectiveness.
Holonomic omnidirectional mobile robot is useful with its high mobility in narrow or crowded place, and omnidirectional robot equipped with normal tires is desired for difference excess, vibration suppression and riding comfort. Caster-drive mechanism using normal tire has been developed to realize a holonomic omnidiredctional robot, however, there remains some problems. This paper presents effective systems to control the caster-drive wheels of omnidirectional mobile robot. Two kinds of Differential-Drive Steering System (DDSS) are proposed to improve the operation ratio of motors. One is using bevel pair gear and the other is using planetary gear to generate driving and steering torque effectively from two motors. Simulation results show the proposed system is effective for holonomic omnidirectional mobile robots.
Existing reinforcement learning approaches have been suffering from policy alternation by others in multi-agent dynamic environments that may cause sudden changes in state transition probabilities of which constancy is needed for behavior learning to converge. A typical example is the case of RoboCup competitions because behaviors of other agents may change the state transition probabilities. A modular learning system would be able to solve this problem if we can assign each module to one situation in which the module can regard the state transition probabilities as constant. Scheduling for learning is introduced to avoid the complexity in autonomous situation assignment. Furthermore, introduction of macro actions reduces the exploration space and it would enable agents to learn competitive behaviors simulaneously in such an adversary environment. This paper presents a method of modular learning in a multi-agent environment in which the learning agents can learn their behaviors and adapt themselves to the resultant situations by the others’ behaviors.
This paper provides a new approach of manipulability for general grasping system. While conventional manipulability is the analysis in velocity domain and can not include force effect such as gravitational force, the proposing approach can include the force effect to keep grasping. For the purpose, an operation range is introduced. The operation range is for actuator attached with every joint of robot and provides generable joint torque and velocity and their relation (between generating torque/velocity and addable velocity/torque). Using the operation range, we derive manipulability set and measure in velocity domain, including force effect. The proposing method can evaluate not only the performance in velocity domain but also effects of friction, contact state, and external forces, which were not obtained in conventional studies.