In this paper, we propose a new collision avoidance method among multiple autonomous mobile robots. Generally, it is difficult to apply conventional collision avoidance methods to robots in multi-robot environment because those methods are only applicable to a single robot environment. For this problem, we propose a new method using the LOCISS (LOcally Communicable Infrared Sensory System) by which a robot is able to communicate with other robots locally to exchange information necessary for their mutual collision avoidance. To realize the collision avoidance based on these information, we introduce a learning method by which a robot is able to acquire the behavior adaptively and autonomously. A learning curriculum is divided into multiple layers to reduce a number of situation for the learning. Finally, we implemented this system to execute acquired behaviors, so that robots can avoid other robots and obstacles at the same time. It is confirmed by conducting experiments that this method is effective in the multi-robot environment.
Generation of a stationary environmental map is one of important tasks for robot navigation. Under the assumption of a known motion of a robot, environmental maps of a real scene are successfully generated by monitoring azimuth changes in an image. However, it is difficult to observe the exact motion parameters of the robot because of measurement error of the encoder of the robot. Therefore, observational errors in the generated environmental map accumulated in long movements of the robot. Furthermore, the exact stationary map generation is difficult because of ambiguity of correspondence caused by occlusion. In this paper, we propose a method to generate a stationary environmental map and estimate the egomotion of a robot, recursively, by using an omnidirectional image sensor. And the method can find mismatching and bring to right correspondence by evaluating estimation error of each objects location.
In the biotechnology field, it is very difficult to manipulate microscopic material through human handling. There is a great need for a new experiment system that is easy to operate. In this paper, we show a three dimensional calibration technique for reducing positional errors of a glass pipette tip, attached to a micro-manipulator. We then propose a method of observing the manipulator tip with sub-micron order accuracy using a newly developed lighting method with an optical fiber. We also take into account the influence of the positional error of z-axis introduced by the microscopic optical system.
In this paper, we discuss on robustness of manipulators. The main result of this paper is the following. We showed that the property of passivity is satisfied in case of one link flexible manipulator. That is, if we regard the joint angular velocity as the output variable and the joint torque as the input valuable, then the system from the input to the output becomes passive. For n-link-flexible manipulator we showed the similar result using an approximated model.
A danger evaluation method of various kind of control strategy for human-care robot is first proposed. The impact force and impact stress are chosen as evaluation measures. The danger-index is defined to make quantitative evaluation of the effectiveness for each safety strategy in control strategy. As same as previous paper on safety design, this proposed method enables us to know the contribution of each safety control strategy to the overall safety performance of welfare robot. In addition, new type of robot simulation system for dangerous evaluation is first constructed on workstation. The system simplifies to evaluate the danger about both design and control of human-care robots to quantify the effectiveness of various safety strategies. As a result, the control optimization of the safety robot is described successfully.
Fingers of human allow an object to be lifted using adequate grasping force and without slippage, even when the weight and friction coefficient of the object are unknown. Grasping force is controlled by detecting complex response of the skin using tactile receptors incorporated in the finger tissue. In this study, we propose a method for controlling the grasping force when objects are grasped by artificial elastic fingers in which many sensors are incorporated. First the relationship between the stick area and internal strain distribution of the finger is calculated in detail by using FE (finite element) analysis. The quantitative relationship between the stick area in the contact surface and the velocity of internal strain distribution is obtained. From these, we propose a method for controlling the grasping force by decreasing the increasing ratio of the tangential force when the stick area is decreasing. Finally, the grasping force is controlled by using the actual elastic finger made of silicorn rubber in which strain gages are incorporated. It is confirmed that objects can be grasped using adequate grasping force without complete slippage even when the weight and the friction coefficient of the objects are unknown.
Visual tracking plays an important role in various robotic tasks such as monitoring an object in the manipulation or tracking a target in navigation of a mobile robot. This paper presents a view-based visual tracking system. The view-based systems are more general than the other approaches which require analysis of 2D image features and the matching with the 3D models. For the image correlation, we use a visual tracking hardware based on a template matching algorithm. One problem of the view-based visual tracking is how to cope with the changes of the template's appearance in the 3D environment. Consequently, the system generates affine transformed templates corresponding to various orientation of the target image plane. We use geodesic domes not only for an uniform sampling of the 3D orientations of the template image plane, but also for dynamic transition in groups of the candidate templates to utilize the latest matching results. Experimental results demonstrate the usefulness of the proposed system.
We propose a quasi-static trajectory tracking control method for the general flexible manipulators which have a flexible-macro/rigid-micro structure. We derive the quasi-static control schemes without considering the dynamics of the manipulator. The purposes of these schemes are position error compensation and vibration suppression for both macro and micro part. We consider the combination of the error compensation control and the vibration suppression control for the macro part and the error compensation control for the micro part and consider the combination of the error compensation control and the vibration suppression control for the macro part and the active mass damper for the micro part. The former combination is called the trajectory tracking mode and the latter is called the vibration suppression mode. These two proposed modes are easy to implement. It is shown by experiments that the trajectory tracking mode realizes the high performance of the trajectory tracking, the vibration suppression mode realizes the high performance of the vibration suppressing, and the switching of these two control modes is effective.
Sensory-motor integration is one of the key issues in robotics. In this paper, we propose an approach to rhythmic arm movement control that is synchronized with an external signal based on exploiting a simple neural oscillator network. Trajectory generation by the neural oscillator is a biologically inspired method that can allow us to generate a smooth and continuous trajectory. The parameter tuning of the oscillators is used to generate a synchronized movement with wide intervals. We adopted the method for the drumming task as an example task. By using this method, the robot can realize synchronized drumming with wide drumming intervals in real time. The paper also shows the experimental results of drumming by a humanoid robot.
Mechatronic servo system design for industrial robot manipulators and NC machine tools are usually carried out by engineers based on their experiences in cut and try techniques and/or intuitive methods. This paper describes the relationship between the inertia of the servo motor and the load for the optimum selection of motor and servo controller parameters. The method is based on the sixth order model of the industrial servo systems with torque filter. The proposed method was experimentaly evaluated by use of an industrial DC servo motor.
For the speedup of robot's task, authors have already proposed STS (State to State) control, which deals with a state (a pair of position and velocity) as a controlled variable and transfers a robot arm's tip from an initial state to a final state in a specified time. In order to realize STS control, the method based on the combination of the trajectory planning and trajectory update is newly proposed in this paper. Since the initial reference trajectory can be planned mathematically and the influence of the robot dynamics is eliminated by the on-line trajectory update, repeated trials for obtaining the series of command positions prior to the task are not needed. Moreover, this method can cope with the change of the final state during the task. A practical STS control system is constructed by employing an open architecture articulated robot and a pin insertion experiment to a moving hole on a belt conveyer is carried out. The accuracy of the final state in the case of applying the proposed method is fairly good compared with that applying the method without updating the trajectory. A pin insertion task under the clearance of ±0.25[mm] is succeeded with almost 100% probability by applying the proposed method.
This paper deals with the turning motion mechanism of a brush-type micro robot using cyclic centrifugal forces. Many wheeled type robots may turn usually along the tangential velocity generated by the rolling wheels. However, the micro robot proposed here has different turning property from the usual mobile robots. First, we derive a two dimensional rolling model of the brush-type robot accompanied with cyclic centrifugal forces, and indicate the existence of the lateral force toward the robot by the computer simulations and the simple mathematical analysis. Next, to confirm the turning motion mechanism caused by the lateral force, we have experiments of the turning motion using some kinds of prototype, and then acquire some experimental data concerned with circle trajectories. Finally, we conclude the validity of the turning motion mechanism caused by the lateral forces which the cyclic centrifugal force generates.