Hironori Adachi

Mechanism and control of a leg-wheel hybrid mobile robot

Describes the mechanism and control of a leg-wheel hybrid mobile robot. Legged locomotion has high adaptability for rough terrain, and wheeled locomotion possesses speed and efficiency. A locomotion mechanism that combines legs and wheels is proposed, and a prototype mobile robot that adopts the mechanism is introduced. The robot has four legs, and a wheel is attached at the end of each leg. The front leg has three joints and a passive wheel. The rear leg has one joint and an active wheel. In order to make the best of the mechanism, three locomotion modes, wheel mode, hybrid mode, and step mode, are developed. In the wheel mode, four wheels are used on flat terrain. On rough terrain, the hybrid mode is selected, and two legs and two active wheels are used for locomotion. To climb or descend a large step, the step mode is used.

Design, analysis and construction of a prototype parallel link manipulator

The paper discusses characteristics mechanism analysis, a design method and an overview of a prototype parallel link manipulator. An evaluation criteria is introduced by analyzing the manipulator statics using the singular value decomposition to realize a well balanced parallel mechanism. Based on this criteria a new configuration is proposed and the basic characteristics of a prototype manipulator are discussed.<<ETX>>

Control of walk and manipulation by a hexapod with integrated limb mechanism: MELMANTIS-1

Describes dual mode control of walk and manipulation of a prototype hexapod with integrated limb mechanism, named MELMANTIS-1. MELMANTIS-1 uses six-bar linkages with four degrees-of-freedom as an integrated limb mechanism with dual use for a leg and for an arm. Omni-directional drive control is introduced to the hexapod walk with alternative tripod gait. The transformation from hexapod walking style into the combination of dual arms and quadruped platform is introduced. A remote control to handle an object by dual arms is experimented with in a simple application of a trash pitcher.

Mechanical design of hexapods with integrated limb mechanism: MELMANTIS-1 and MELMANTIS-2

This paper describes the mechanical design and basic control of prototype hexapods with integrated limb mechanism, named MELMANTIS-1 and MELMANTIS-2. MELMANTIS-1 and MELMANTIS-2 use a six-bar linkage with four degrees-of-freedom as an integrated limb mechanism with dual use for leg and for arm. The mechanical design of MELMANTIS-1 is based on kinematic analysis of the six-bar linkage. MELMANTIS-2 is designed and manufactured to improve mechanical stiffness and to reduce position control errors of arms, based on the result of basic experiments of MELMANTIS-1.

Study on Underground Space Excavating Machine

A National Research and Development Program on Underground Space Development Technology has started in 1989. In this program, an automated excavating machine will be developed to construct an underground dome. This paper describes three basic studies, locomotion system, manipulation system, and task planning system, which are required for the excavating machine. For the locomotion system, a pair of crawler and four legs are provided to perform the effective locomotion on the unstructured terrain. Parallel link mechanism is applied to the manipulation system since it has advantages such as large load capacity, simple mechanism, and good durability. Appropriate task planning including real-time prediction of soil behavior is effective for automated excavation.

Terrain following control of self-contained semi-fixed gait hexapod walking robot

The paper provides a control algorithm for terrain following of the self-contained semi-fixed gait hexapod walking machine MELCRAB-2. MELCRAB-2 uses decoupled freedoms of the leg mechanism for the body-propelling motion and the terrain-adapting motion. The mechanism simplifies the drive and control of the walking machine over rough terrain. The geometry of the leg mechanism is described, and its inverse kinematics is solved analytically. An algorithm for following the terrain and adjusting the body altitude is introduced.<<ETX>>

Spatial image model for manipulation of shape variable objects and application to excavation

Proposes a spatial image model which expresses the physical characteristics of an object whose shape may vary. This model consists of a mass of particles to represent the shape of the object and a set of production rules to predict the change of the objects shape. Models to represent gas, liquid and soil are described. A three-dimensional model for sand is used to describe the planning method based on the model. Finally, this planning method is applied to an experimental excavation of sand using an industrial manipulator with a six-axis force/torque sensor.<<ETX>>

Application of locomotive robot to rescue tasks

The research aim is to apply locomotive robots to rescue tasks, such as searching for sufferers and removing obstacles to save sufferers. The paper discusses the exploitation of arm and leg integrated robots and basic experiments of infrared probing sensor, in the application of rescue tasks. First, the limb mechanism is introduced and discussed in the aspect of locomotion capability and stability in rough terrain of disaster area. Then, the probing sensor is evaluated in the aspect of its detection range and capability. Assuming the sensor is mounted on the tip of robot arm for probing, the probing algorithm is proposed to find quickly and locate precisely a sufferer. The basic experiments have been carried out using a parallel arm to confirm the applicability and the usefulness of the proposed rescue system.

Human-operated walking control of a quadruped by event-driven method

This paper describes a walking control scheme for a quadruped robot. In conventional walking control scheme, the leg motion is generated from the robot moving trajectory beforehand and it is difficult to control in real time. The proposed control scheme employs a real time command from a human operator instead of the moving trajectory. The operator gives a current planar moving velocity command to the robot. Body propulsive action is basically continued according with the command unless a problem arises. When a foot reaches the border of the work space of the leg, the body propulsive actions is interrupted and a supporting foot pattern is changed. That is, a foots arrival at the border is considered as an event to trigger a recovery action for the body propulsion. The recovery actions are decided to converge to the intermittent crawl gait when straight walking command is continued. The proposed control scheme is evaluated using actual walking robot.

Control of a manipulator mounted on a quadruped

This paper describes a control method of a manipulator mounted on a quadruped walking robot. One of the advantages of legged robots is the capability to change the body position and posture without changing the foot points. When a manipulator is mounted on a legged robot, it obtains extra motion from the body. By coordinating leg motion and manipulator motion, the end-effector has more sophisticated motion. When six degrees of freedom velocity command of the end-effector is supplied the proposed control method gives each joint velocity of the manipulator and the legs. This control method is experimentally evaluated using actual robot.