A new performance index is proposed for evaluating a single manipulator's configuration along a line to be traced. It depends on the manipulator's kinematics and the tracing-line's geometric information. Using this index, another index is proposed for planning cooperative motion sequences among multiple manipulators for a line-tracing task. The usefulness of these indices has been shown by some simulations.
We have been proposing new concept of active endoscope with hyper redundancy. This medical tool named “Hyper Endoscope” for minimally invasive surgery is driven by miniature cybernetic actuators. Dynamical model of the cybernetic actuator taking into account of Piezoelectric effect is proposed and detail performance is analyzed. Based on this result, new technique to minimize the number of lead wires is proposed. The FMVC (Frequency Modulation Velocity Control) with two lead wires as an analogue control method is invented and verified experimentally.
In this paper, we are concerned with the stabilizing control for a vertical mono wheeled servo system based on the disturbance observer compensation. After separating the mono-cycle dynamic structure into a body-frame dynamic system and a mono-wheeled system, the mono-wheeled system is regarded as a main control system and we consider that unstable behavior of the vertical mono-wheeled system because of one supported point body is caused by the virtual disturbance torque. For this purpose, this paper proposes a design method of 2-degrees of freedom control system including disturbance observer for such virtual disturbance torque in feedback loop and evaluates its effec-tiveness by experiment. The main aim of such 2-degrees of freedom control is to accomplish the regulator problem and the servo problem, especially the regulator problem is realized by 2-stage control whose structure has firstly pseudo-stabilization by disturbance observer compensation and secondly output feedback with H∞ controller for whole the system.
As a practical way of athletic Intelligence, we choose the mobile robot which plays soccer to be a theme, and are advancing the research. Then, the dribbling and the shooting actions were achieved by using single robot Nomad200. The purpose of this research is in the relation of the control of feedforward (FF) and feedback (FB) to the achievement of these two kinds of operations respectively, and clarifying the problem how it is necessary to combine. We clarify the combination through operation (shoot and dribble) two kinds of experiments. For the example of kicking the rolling ball, we check whether the robot should have to follow the ball by feedback or move to the position by feedforward which is presumed by the change in the position of the ball. We took the standpoint where the designer has to tune the movement of the robot carefully. The robot first has the target to move so that the robot do actions properly and should repeat the re-calculation of the target. We explains how robot should set the target in the time series or how to approach the target in addition. Dribbling is achieved by feedback control so that the ball keeps existing on the straight line by which this target is connected with the robot. Next, the meandering dribbling is made to be done to the example of the operation that the target changes to the time series. For instance, the action that robot carries the ball to a target between the enemies. In this dribbling, robot first keeps maintaining the ball in front of the body. In a word, it is necessary to decide the direction which should move in the general situation adjusting the rolling condition of the ball. Because the each targets is different from a geostationary ball and the rolling ball, robot switches the shooting actions dependent on the conditions of the ball. To kick a geostationary ball to the direction, robot only has to set the target in the back of the ball seen from the direction. If the ball rolls, the target should also shifts. Then, the robot calculates and renews the target to follow the ball. If the robot follow the ball only by feedback control, robot cannot kick the rolling ball because the delay is taken in the movement. Robot presumes the position where the ball rolls beforehand, and sets the moving target. The target is presumed from the movement of the ball, and the forestalled technique is needed. Robot can move at a stroke earlier than ball moves to the target position for the feedforward control and wait for the arrival of the ball.
A hardware satellite model with thrusters and a control moment gyro (CMG) is constructed to discuss position/attitude control methods for a ground testbed simulating a space robot. A bang-bang position control and two attitude control methods, i.e., a Lyapunov-type controller and an exact-linearization-based controller, are designed. Hardware experiments as well as numerical simulations show the feasibility of the modeling and the controllers. It is also shown that the developed position/attitude control system has enough performance for the ground testbed.
This paper is concerned with an adaptive control of free-flying space robots with uncertain inertial parameters of payloads. It is applicable to control all of the position and attitude of the satellite vehicle as well as that of the manipulator hand if the satellite has position/attitude control devices, e.g., thrusters and control momentum gyros. The proposed adaptive control realizes high control performance by estimating unknown parameters even if a control model has an error to the real plant caused by the payload. Asymptotic stability of the adaptive control is proven by Lyapunov's second method. The effectiveness is examined by numerical simulations for a hardware experimental system.
This paper describes the theory and the experiment of a velocity potential approach for path planning and avoiding standing obstacles and moving obstacles for an autonomous mobile robot by the use of the hydrodynamic potential. This potential function for path planning is feasible for guiding a mobile robot to avoid arbitrarily moving obstacles and to reach the goal in real time. In this theory, a mobile robot should avoid the obstacles even when the robot is trapped in the slit narrower than the diameter of a mobile robot and formed by plural obstacles. The vortex field is introduced for resolving this difficulty. An experiment is conducted to prove the usefulness of this theory. A camera of PSD (Position Sensing Device) is installed at the top of the experimental site. The robot, the obstacles, and the landmark of a crossroads are identified by this camera. A velocity of the obstacles is estimated by proccessing the signal. The path planning is conducted with a computer, and the velocity for avoiding obstacles is sent to a mobile robot. A mobile robot succeed in avoiding the moving obstacles at a crossroads in this experimental systems.
This paper proposes a complementary visual servoing controller of both zoom and arm mechanisms. A camera, which is used as an artificial vision, often has a zoom mechanism. A zoom mechanism cannot realize fast motion while an arm mechanism can do, and it has only one degree of freedom. On the other hand the arm mechanism cannot cover wide range of change in the image while the zoom mechanism can do. First we discuss on a condition that camera position and zoom setting are regarded as redundant. Then a visual servoing controller is proposed making use of complementary characteristics of the both mechanisms. Experimental results demonstrate the effeciveness of the proposed method.
A spatial path generation algorithm and its application to the highreliability seam tracking robotic system which can operate even under poor sensing conditions are proposed. First, the concept of the robotic system with a wrist mounted high performance vision sensor is presented, then an accurate spatial path generation algorithm based on the complementary use of nominal path data and sensory data of an actual path with a reliability coefficient is described. In the algorithm, the modification matrix that maps a nominal path to an actual path is generated by comparing nominal path data with actual path data acquired by a sensor located ahead of an end-effector at certain points. Then an actual path is restored by modifying nominal path data with the modification matrix. Computer simulations and experiments on a spatial path show that the proposed system operates effectively even under disturbances such as burst sensory data missing caused by joint configuration abnormalities like tack welding beads often appearing in practical applications.
This paper discusses the enveloping grasp of multiple objects under rolling contacts. We first provide a general mathematical formulation on the kinematic relationship for multiple objects enveloped by a multi-fingered robot hand, and then derive a condition for judging whether the rolling condition can be satisfied at each contact point. We also show a sufficient condition for shovelling up two objects. Finally, an experimental result is shown to confirm how easily two cylindrical objects can be shovelled up by a simple grasping motion.
We are studying a wheeled robot with the ability of going up and down stairs. We previously developed a wheeled robot called a ‘variable structure type four-wheeled robot’ capable of passing over a single step, but it cannot negotiate the stairs whose tread is short compared with the wheelbase of the robot. In this paper, we propose a ‘biped type leg-wheeled robot’ which has ability to pass over stairs with short treads. We also propose a trajectory planning method which uses a nominal static walking trajectory as a reference for the dynamic control of the robot, and investigate a trajectory control method using computer simulation. We finally confirm the effectiveness of our proposed method with a successful experiment of going up stairs by this robot.