In this paper, the effects and the experimental method of difficulties of actions and the essential body parts provided on observing and imitating actions are discussed. Difficulties of actions are represented by complexity of postures, power, and difficulties of expression of the subject toward the observed actions. The body parts are represented by the number of end points shown to the subject. An experiment on imitating daily life actions was conducted. Many kinds of short actions according to the difficulties of actions were displayed to the subjects. The number of displayed human figures' body parts was changed for each action. After observing each action, the subjects imitated the observed action. The imitated actions were monitored by the mechanical motion capture. Similarities between the imitated and displayed actions are evaluated by using DP matching. If these actions are similar, the subject is thought to succeed to imitate the displayed action. The result shows that (1) imitation becomes difficult with the increase of complexity of posture, (2) power of action has weak effects on imitation, (3) the increase in displaying body parts does not necessarily improve the subject's success rate of imitation, and (4) the decrease in difficulties for expression does not improve imitation.
We analyze the stability of dynamic object manipulation through asoft interface, the viscoelastic material between a manipulating finger and manipulated object. First, we model a dynamic object manipulation system through a soft interface. The system is described in continuous-discrete time. Second, we formulate the dynamics using the modified z-transform in the continuous-discrete time system for feedback and feedforward control. Thus, we show that the stability of the system depends on viscoelasticity of the soft interface for feedback control. In particular, we point out that, in critical stability, the relationship between material viscosity and sampling time is not monotonous. We also analyze this phenomenon by the root locus method. Next, we compare the stability analysis by the modified z-transform and a regular z-transform. Thus, we demonstrate that the relationship is specific to the continuous-discrete time system. Finally, we confirm the relationship experimentally.
This paper studies the rescue robots to rescue people in an area polluted with radioactive leakage in nuclear power institutions. In particular, we propose the rescue system which consists of a group of small mobile robots. First, small traction robots set the posture of the fainted victims to carry easily, and carry them to the safety space with the mobile robots for the stretcher composition. In this paper, we confirm that the stretcher component robots could transport and convey a 40 [kg] dummy doll. And, we also show an application usage of stretcher robot.
This paper proposes the Non-contact Stiffness Imager that can provide us with the pattern of stiffness distribution of environment. While there are four combinations between the force applying method and the way for capturing the displacement, we pick up the combination in which the force is given to the environment at a local point and the displacement of environment is measured over the neighboring area where the force is given. We confirm the basic idea by utilizing the experiment system composed of an air supply system and a line laser sensor. We apply the idea to an endoscope camera, so that we can obtain the pseudo-stiffness pattern as well as the visual pattern. We also show a couple of experimental results exhibiting the pattern.
In this paper, we design a feed-forward trajectory following controller by using optimal preview control theory for a helicopter, based on its transition model and an LQI position controller derived from previous work. In order to apply optimal preview control theory to trajectory following control at any given yaw angle, we propose a correction method for eliminating disturbances due to attitude perturbations on the magnetic direction sensor. We show the axis transform of position and velocity has a problem and as a result it can not be applied to optimal preview control at any given yaw angle. To solve it, we propose alternative axis transform method. Finally, the performance of the designed preview controller and the proposed axis transform were verified by“circular”and“S character”trajectory following experiments.
We describe crawling and jumping by the deformation of a soft robot. Locomotion over rough terrain has been achieved mainly by rigid body systems including crawlers and leg mechanisms. This paper presents an alternative method, one that uses deformation of a robot body. We employ soft actuators to controllably deform a robot body, enabling it to crawl and jump on terrain via charge and release of elastic potential energy of the body. We experimentally show that circular soft robots and spherical soft robots, which consist of an elastic shell made of rubber or spring steel and SMA (shape memory alloy) coils, can crawl on a flat terrain, climb up a slope, and jump over a terrain. We also apply a particle-based modeling to simulate the behavior of a circular soft robot.
In this paper, we propose a method that enables a biped humanoid robot to reproduce human dance motions with its whole body. Our method is based on the paradigm ofLearning from Observation. In this study, a robot uses its own legs to support the body during a dance performance. We proposeleg task models, which can solve the problems caused by severe constraints in adapting human motions to the legs of a robot. First, elements of the leg task models are recognized from motion data captured from human performances. Then motion data of a robot is regenerated from the recognized elements so that the motion is stably executable on the robot. Our method was verified by experiments on a humanoid robotHRP-2using a traditional folk dance. HRP-2 successfully performed dance motions that were automatically reproduced from motion data captured from human dance performances.
In this paper, we derive a dynamic model and a control law for cooperative task of two snake-like robots which have wheeled links and demonstrate the validity of proposed controller by simulation and experiment. First, we derive a dynamic model of single snake-like robot with redundancy by introducing the shape controllable points. Next, we extend it to the model for the cooperative task of two redundant snake-like robots and propose a control law to accomplish this task. Finally, in order to demonstrate the validity of the derived model and effectiveness of the proposed control law, simulation and experiment are carried out.
We propose a new tactile sensor utilizing piezoelectric vibration. This tactile sensor has a high sensitivity, wide measurement range, pressure resistance, flexibility, and self-sensing function. This tactile sensor comprises two piezoelectric materials. One is used for the vibration of the sensor element and the other is used for the measurement of the change in mechanical impedance induced by an external force. We achieved the wide measurement range by implementing two ideas. One was to apply the external force to the sensor element through an elastic body and the other was to use two or more modes of vibration. Moreover, for the elastic body, it is preferable to use a material whose elasticity and viscosity are easily changed by an external force, such as a gel. In this study, first, this tactile sensor was analyzed, and then its characteristics were derived. The analytical results qualitatively corresponded to the experimental results. Next, a prototype tactile sensor was fabricated and evaluated. The evaluation results showed that this tactile sensor can measure a pressure of 2.5 [Pa] or less and a pressure of 10 [kPa] or more and its pressure resistance is 1 [MPa] or more.
In this paper, characteristics of freely frictional sliding motion is investigated. With physical concept and results of numerical computation, we clarify the fact that the trajectories of non-rotationally symmetric objects are nearly straight lines. Further, we expend the results that the translational and rotational motions come to stop simultaneously from the rotationally symmetric objects to the non-rotationally symmetric objects; meanwhile we point out that the radius of instantaneous rotation of the object at final stage is dependent on the final configuration and geometric properties of the object, but independent of its initial velocities. Further, we develop one approximate approach to simplify the analysis of the complex frictional motion for one extreme case, initially translation-dominant motion. Consequently, a series of important properties and motion monotonicity of the frictional sliding motion are obtained. With the above results, an inverse problem that is to determine the necessary initial translational and rotational velocities of the object, is got very easy and straightforward.