A teleoperation system in a dynamic environment with varying communication time delay is proposed, which consists of three subsystems; a bilateral teleoperation subsystem, a visual information subsystem, and an environment predictive display subsystem. The bilateral teleoperation subsystem is stabilized using the virtual time delay method. The visual information subsystem transfers the visual information in the remote site to the operator's site using the computer network. The environment predictive display subsystem estimates the behaviour of the environment and gives the predicted behaviour to the operator. An experimental system is developed and several experiments illustrate the effectiveness of the proposed system.

We propose a decentralized control algorithm for transporting a single object by two nonholonomic mobile robots driven by two wheels. We extend the leader-follower type control algorithm, proposed by Kosuge and Oosumi (1996) for holonomic robots, to mobile robots by introducing the dual caster action. The extended control algorithm is applied to two experimental tracked mobile robots, and the experimental results illustrate the validity of the control algorithm.

Proposes an alternative control algorithm for a scaled teleoperation system. In a micro environment, since the force acting on the environment as well as its dimension is small, the appropriate size or precision of the force sensor for controlling the manipulator is not always available. So, it is important to implement a bilateral scaled teleoperation system without using force sensors in a micro environment. The proposed algorithm utilizes the mass property of the slave manipulator and it could be implemented without using slave-side force sensors. The stability of the system is also guaranteed based on passivity properties of the system, for any scaling ratio between master and slave. The proposed algorithm is applied to an experimental micro-macro teleoperation system and experimental results illustrate the validity of the system.

In this paper, we discuss a problem relating to the force/moment transformation for the handling a large object by multiple robots in coordination. Three control algorithms, based on impedance control of each manipulator, are then proposed so as to lessen the effect of the transformation. The algorithms are implemented in dual manipulator system, which consists of two industrial robots. Experimental results illustrate the validity of the proposed control algorithms.

This paper proposes a force control algorithm for Stewart platform type of parallel link manipulators with velocity controlled hydraulic actuators. First, we design a control scheme for one degree-of-freedom, hydraulic actuator then we extend the control scheme to the parallel link manipulator. The hybrid force/position control scheme for parallel link manipulator is also proposed. The control scheme is designed based on velocity based force control algorithm, so that we can apply it to the parallel link manipulators with velocity controlled hydraulic actuators. The proposed algorithm is applied to the experimental system with six degrees of freedom and the experimental results illustrate the validity of the system.

Providing force information do a human operator improves the reality of teleoperation. When the communication block between a master and a slave has a transmission time delay, the bilateral feedback system is easily destabilized. Anderson and Spong (1989) guaranteed passivity in the communication block by using scattering transformation and overcame this instability caused by the time delay. This method can be applied to the communication block with constant time delay. Different from traditional teleoperation systems, the transmission time delay irregularly changes in a computer network. This paper reveals that the variable time delay destabilizes bilateral master slave manipulator with scattering transformation and proposes the virtual time delay method, that keeps the apparent time delay constant. This new compensation method has been implemented in a single axis master slave manipulator system connected to a computer network and experimental results illustrate the validity of the proposed method.

In this paper, we design a control system so that the dynamic characteristics of the teleoperation system is specified appropriately for the task execution and the extraction of the operator's skill. We define such dynamic characteristics as "reference dynamics" for the task. We consider to design a control algorithm for the master arm manipulating the virtual environment so that the system has the reference dynamics. Then we consider to design a control algorithm for the teleoperation system so that the system has the reference dynamics given to the manipulator of the virtual environment. By designing the control scheme so that the master and slave arm has the same dynamic characteristics, the skill extracted from the operation of the virtual environment would be applied to the real task directly. The proposed system is applied to experimental manipulator system and experimental results illustrate the validity of the system.

This paper proposes an alternative control scheme for a teleoperation system which consists of a master arm, a slave arm and a virtual environment. For a given task, the operator manipulates a virtual environment and executes the task, a skill for the task is extracted through the manipulation, and the skill is transferred to the remote site to execute the task in real. First, the authors consider the design of a control algorithm for a master arm manipulating the virtual environment so that the system has a given dynamics for the operator and the environment. Then the authors consider the design of a control algorithm for the master-slave system manipulating the real environment so that the system has the same dynamics given to the manipulator of the virtual environment. By designing a control scheme, with which the master arm with a real environment and the master arm with a virtual environment have the same dynamics, the skill extracted from the operation of the virtual environment would be applied to the real task using the slave arm. The proposed control system is applied to an experimental master-slave manipulator and experimental results illustrate the effectiveness of the system.>