A contact force computation method in forward dynamics simulation of multibody systems is proposed based on a fusion technique of both the microscopic and the macroscopic contact models. The former models microscopic deformation of colliding objects, while the latter models macroscopic uncontinuous change of impulse. The difficulty of the contact dynamics simulation is mainly at numerical ill-posedness which is due to the coexistence of two phenomena with largely different durations. The proposed method resolves this problem by superposing the microscopic models to the macroscopic models in order to complement the drawbacks of each other. As the result, numerical stability, avoidance of chattering, recovery of excessive penetration of colliding objects and easy implementation of static friction model are simultaneously achieved.
This paper introduces a novel multirate feedforward control method for robot manipulators with elastic joints. Perfect tracking control methodology using multirate feedforward control was proposed by H. Fujimoto, et al. Then, A. Shimada, et al. have prsented its application to robot manipulators; however, they only described the controller design process and gave a few simulation results. In addition, they did not provide details on how the state reference should be designed. Even if experiments were attempted, it would be difficult to evaluate control performance since generally manipulators have joint angle sensors mounted on the output side of reduction gears In order to solve this, this paper illustrates the design process for the state reference, and introduces a prototype robot manipulator that has precision rotary encoders installed on the output side of the joints. This means that the manipulator has not only the rotary encoders attached to servo motors but special precision rotary encoders. We describe experimental results obtained by applying this control technique.
RSi (Robot Service Initiative) is a group to develop and promote various services of service robots that use the communication network at the home and the office. RSi developed “RSi Protocol” as a communication protocol specification for the robot service that uses the network. RSi is also intent to promote the RSi platform provided by the RSi Protocol as the common platform for the robot services. This paper describes how RSi protocol resolved the requirements of the common platform for the robot services, and how RSi platform is appropriate as the common platform for the robot services.
We have developed a vocal control method based on forward and inverse model, and new vocal cord mechanism, for anthropomorphic talking robot, Waseda Talker No.7, to produce various kinds of voices. The previous artificial vocal cord model could reproduce human-like vibration, however, the control range of the acoustic parameters are very small. We developed new mechanism could adjust the vocal cords tension effectively and control the glottal opening-closing, to broaden the control range. The control parameters of the vocal cords on WT-7 are vocal cord tension, glottal opening and air pressure, and the acoustic parameters are sound pitch, spectrum tilt and sound pressure. The relations between these parameters are complicated, and hard to modeling. The learning process consists of learning of the NN forward model and learning of the inverse model by using the forward model. In addition, the real-time auditory feedback mechanism is used to reduce the error. By this method, the acoustic parameters could be followed well the target.
In this paper, analysis of locomotive dynamics of the Active Cord Mechanism is described. Lateral undulation of terrestrial snake is a unique locomotion pattern and interesting as a mechanical phenomenon, but the analysis in prior research were not so generalized. For example, sinus-lifting, which is an important locomotion style of snakes, have not been analyzed because the dynamics in sinus-lifting is relatively complex. So we introduce generalized basic equations of the locomotive dynamics of the ACM using equilibrium of external forces, internal forces, and torques acting in a snake's body. Then we show analysis of locomotion in 2 different cases; locomotion with steady resistant force, and locomotion with sinus-lifting. The analysis shows the feature of the phenomena and provides condition of friction necessary for locomotion, and the effectiveness of sinus-lifting is clarified quantitatively for the first time. The results of analysis are verified by experiments of a real snake-like robot, which was newly developed for a measurement of bending torque during lateral undulation.
In the near future, robots are expected to actively participate in our daily lives. Once this time arrives, they will need to be socially accepted by people in various communities. However, the issues remain unknown that must be solved to make robots socially accepted. We have conducted a long-term experiment that a communication robot interacts people daily in an office. From the questionaire answers for the experiment, we have found that three fundamental issues, offering familiarity, reading the situation, and playing a social role, are required for a robot that is socially accepted. In this paper, we propose a hypothesis that three fundamental issues must be fulfilled by a socially accepted robot. Then, we tested our hypothesis through a six-week experiment in an office. We present the details of the experimental results and discuss what is the most important issue among them for a socially accepted robot.
This paper describes the development of a guide robot for a shopping center, which attempts to build rapport with customers while providing route guidance and other shopping information. A field trial was conducted at a shopping mall for 25 days to study the possible role of a robot in a shopping center. Since a shopping center is a place where local people repeatedly visit, it is important for the robot to interact with people multiple times. Using passive RFID tags to identify customers, and using the WOZ method to overcome difficulties in speech recognition, the robot built rapport with customers through a series of interactions based on a set of four design principles. During each day of the field trial, the robot interacted with approximately 200 customers, and the robot was able to sustain customers' interest throughout multiple interactions. The robot also provided shopping information through natural conversation with the customers, and the experimental results revealed that 63 out of 235 people in fact went shopping based on advice from the robot. These results seem to demonstrate a promising potential for guide robots designed to build rapport with customers in a shopping mall.
As jumping is an effective method of moving over rough terrain, there is much interest in building robots that can jump, and deformation of a soft robot's body is an effective method to induce jumping. Our aim was to investigate the effect of the initial deformed shape of deformation of a circular shell made of spring metal. The dish shape jumped the highest in the initial shapes of deformation, with the dish jumping twice as high as the cap. A simulation of a model was in good agreement with the observations. We showed that the jumping height is determined by impulse, time and the center of gravity until taking off from the ground.
With aging, human skin develops a dry condition called senile xerosis. The skin lesion can be prevented by daily skin care, for example, by applying an ointment containing moisturing factors several times a day. Aged persons, however, have difficulties in accessing their back and rely therefore on nursing care for such treatment. But note that in underpopulated areas such nursing care may not always be available. To tackle this problem, the concept of a skincare robot is first proposed. The feasibility of the concept is then confirmed by designing a real skincare robot and by performing experiments for applying ointment to a human's back. The developed system is able to recognize the shape of the body, to plan the appropriate motion paths for the end-effector, and to execute the task without applying any excessive forces.
This paper proposes a new method of geometry modeling for robotic applications. We utilized visual ID-tags to acquire the tangent planes of objects, and generated polyhedral approximate models of the environment. We developed the optimization algorithm for estimating the tag configuration and the method for forming polyhedral models of objects. Our approach enables an easy modeling using a single camera without pose information. The geometry models can be superimposed onto the real environment, and robots use the models in their tasks. We examined the performance of our modeling method, and demonstrated the availability of the models to robotic applications.