Hayato Kaetsu

Development of an omni-directional mobile robot with 3 DOF decoupling drive mechanism

A new driving mechanism for holonomic omnidirectional mobile robots is designed, which enables 3 DOF motion control by three correspondent actuators in a decoupled manner with no redundancy. A prototype of the omnidirectional mobile robot with the driving mechanism is developed including a parallel link suspension mechanism. The kinematics of the omnidirectional mobile robot is also analyzed, and simulation for velocity control of the robot is performed by a method for velocity modulation with interpolation to achieve the given target position and velocity.

Self-organizing collective robots with morphogenesis in a vertical plane

This paper presents a novel concept of self-organizing collective robots with morphogenesis in a vertical plane. It is potentially applicable to autonomous mobile robots. For physical reconfiguration of a swarm of robots against gravity, new types of mechanisms and control strategies are proposed and demonstrated. Prototype robots have been fabricated in order to confirm the basic feasibility of the mechanisms. Each robot is composed of a body and a pair of arms. The body can be regarded as a cube with edge length of 90 mm, and is equipped with permanent magnets for bonding with another robot. The arms change the bonding configuration by rotating and sliding motions. As for the control strategies, we proposed the algorithms which can locally generate specific global formations of robots, with minimum interactions between neighboring robots. The overall scheme is similar to cellular automata. The control algorithms proposed have been tested by simulations.

Motion control of multiple autonomous mobile robots handling a large object in coordination

In, this paper, we discuss a problem relating to the force/moment transformation for the handling of a large object by multiple mobile robots in coordination. We propose a control algorithm using geometrical constraints among the grasping points and the representative point of the object, which reduce the effect of noise amplified by force/moment transformation. We extend this algorithm to the decentralized control algorithm of multiple robots handling an object in coordination. The proposed control algorithm is experimentally applied to the mobile robots. Experimental results illustrate the validity of the proposed control algorithm.

Synchronized motion by multiple mobile robots using communication

This paper addresses a method for synchronizing motion by multiple autonomous mobile robots using radio communication. The autonomous and decentralized robot system, ACTRESS, is a multi-agent robotic system including multiple autonomous mobile robots. The autonomous mobile robots are developed so as not only to act individually, but also to cooperate with the other robots if they cannot accomplish the task alone. The synchronized motion is sometimes required to execute such cooperative tasks. Every agent of ACTRESS is equipped with the communication system, which enables a message passing between any robotic agents. The prototype ACTRESS system is introduced, and cooperation among multiple robotic agents is discussed. A method for synchronization using the communication system is proposed. The method is applied to the prototype system, and side-by-side motion on the actual mobile robots is implemented as a example of synchronized motion.

Mutual transportation of cooperative mobile robots using forklift mechanisms

A concept of mutual transportation by cooperative multiple mobile robots is proposed in this paper, which enables robots to process complicated or heavy-duty tasks, and overcome the large obstruction in an environment. A method of mutual transportation utilizing forklift mechanisms is introduced with discussion on the lifting process and moving process. Cooperative mobile robots including a holonomic omni-directional platform and a forklift mechanism are developed. Finally, as an example of applications of mutual transportation, step-climbing motion is presented, and the motion realized by the developed mobile robots is shown.

Force assistance system for standing‐up motion

In our current research, we are developing a force assistance system for standing up motion. Our developing system realizes the standing up motion using the support bar with two degrees of freedom and the bed system which can move up and down. In this paper, we develop the force assistance system which realizes the natural standing up motion using remaining strength of the patient. Our key ideas are two topics. The first topic is distributed system which controls the support bar and the bed system with coordination among them. The second topic is the combination of force and position control. According to the patients posture during standing up, our control system selects more appropriate control method from them. We use the reference of standing-up motion which is based on the typical standing up motion by nursing specialist for realizing the natural assistance. The performance of our proposed control scheme is experimented by computer simulations

An infra-red sensory system with local communication for cooperative multiple mobile robots

Distributed autonomous robotic systems which are composed of multiple robotic agents have been attracted the attention of many researchers as a new strategy for flexible and robust robotic systems. For cooperative multiple mobile robots in distributed autonomous robotic systems, recognition of the dynamic environment is required. In this paper, a new sensory system with local communication functionality is developed utilizing infra-red devices. Based on the discussion on sensing and communication for cooperative multiple mobile robots, requirements for the sensory system are derived. Then, the infra-red sensory system is designed and developed taking account of the required function. This system enables not only detection of collisions against obstacles or other robots but also local communication between robots. This system can also detect interference of plural infra-red signals. Finally the developed system as introduced, and its performance obtained as a results of experiments is shown.

Collision avoidance among multiple autonomous mobile robots using LOCISS (locally communicable infrared sensory system)

Collision avoidance is an essential problem for applications of multiple mobile robots. The authors have proposed new sensor system called LOCISS (Locally Communicable Infrared Sensory System) to detect robots and obstacles using infrared local communication. Robots mounting LOCISS can exchange useful information for collision avoidance such as speed and moving direction. In this paper, a set of rules for collision avoidance among multiple autonomous mobile robots using LOCISS is proposed. Each robot mutually carries out collision avoidance using the proposed rule. The validity of this set of rules is shown through a series of experiments using mobile robots.

Adaptive behavior acquisition of collision avoidance among multiple autonomous mobile robots

We discuss adaptive behavior acquisition for collision avoidance among multiple autonomous mobile robots which are equipped with the locally communicable infrared sensory system (LOCISS). The LOCISS is a local sensing device for collision avoidance by which robots can detect other robots and obstacles and discriminate them by exchanging relevant information. We (1996) reported previously a collision avoidance method between two robots based on the predetermined rules using LOCISS. It is, however, difficult to realize collision avoidance among three or more robots by the predetermined rules only because situations around the robots become more complicated as the number of robots increases. Thus, it is desirable for the robots to have an adaptive capability for acquisition of the behaviors to avoid collision with other robots and obstacles. To acquire the adaptive behavior, the reinforcement learning is introduced in this paper. It is shown that appropriate behaviors for collision avoidance can be successfully acquired through the proposed learning process.

Development of a control system for an omni-directional vehicle with step-climbing ability

This paper proposes a control method for wheels to pass over rough terrain. In our previous work, we have developed a holonomic mobile mechanism capable of running over steps. The mechanism realizes omni-directional motion on a flat floor and passes over uneven ground in forward and backward directions. The vehicle has seven special wheels with cylindrical free rollers and two passive body axes that can adapt to rough terrain. Seven actuators are located in each wheel; therefore, our vehicle system requires the rotation velocity of each wheel to be coordinated. However, it is difficult to keep such coordination among the wheels — as the vehicle passes over the step, the load applied to the wheel tends to heavy and irregular. Therefore, we propose a new control system for synchronization among the wheels. In this paper, the following two topics are discussed: the load adjustment so as not to exceed the maximum torque of the actuator in some of the wheels and keeping the balance of rotation velocity among the wheels. Our novel control method adjusts the output value by referring to the state of the other wheels. The performance of our system is investigated by means of computer simulations and experiments using our prototype vehicle.