Satoshi Okabayashi

Waseda University, Edo, Tōkyō, Japan

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Publications (9)3.8 Total impact

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    ABSTRACT: We developed a novel small rat-like robot called Waseda Rat No. 4 (WR-4) to interact with real rats. WR-4 can perform both rearing (rising up on its hind limbs) and rotating (body bending during movement) actions faster than live mature rats. After robot–rat interaction involving rearing and body grooming (body cuddling and head curling) actions of WR-4, real rats showed more activity and greater interest in the robot. Similar results evident from rat–rat interaction suggest that a rat-like robot is able to interact with rats in the same way as real rats. Furthermore, lower variances between the rat subjects in robot–rat interaction reveals that a rat-like robot can more effectively impact rat's behavior in a controllable, predictable way.
    Robotica 12/2013; 31(08). · 0.88 Impact Factor
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    ABSTRACT: In this paper, we study the response of a rat to a rat-like robot capable of generating different types of behaviour (stressful, friendly, neutral). Experiments are conducted in an open-field where a rat-like robot called WR-4 is put together with live rats. The activity level of each rat subject is evaluated by scoring its locomotor activity and frequencies of performing rearing (rising up on its hind limbs) and body grooming (body cuddling and head curling) actions, whereas the degree of preference of that is indicated by the robot-rat distance and the frequency of contacting WR-4. The moving speed and behaviour of WR-4 are controlled in real-time based on the feedback from rat motion. The activity level and degree of preference of rats for each experimental condition are analysed and compared to understand the influence of robot behaviour. The results of this study show that the activity level and degree of preference of the rat decrease when exposed to a stressful robot, and increase when the robot exhibit friendly behaviour, suggesting that a rat-like robot can modulate rat behaviour in a controllable, predictable way.
    Bioinspiration &amp Biomimetics 10/2013; 8(4):046002. · 2.41 Impact Factor
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    ABSTRACT: In animal behavior research, rat models of mental disorders (RMMDs) are developed to screen psychotropic drugs and to clarify the mechanism of mental disorders. Meanwhile, interaction between real rats is used to evaluate the RMMD. However, since rat-rat interaction is hard to control and quantify, we have adopted a bio-inspired robot to interact with real rats owing to its programmability and reconfigurability in testing different models. We have developed several rat-like robots before, however, these robots still can not fully satisfy the requirement of animal experiment. As an improvement, the newest generation rat-like robot called WR-5 is developed. WR-5 can perform mounting and grooming actions naturally as live mature rat owing to adopted differential gear in its waist. Preliminary SIT between WR-5 and mature rats have been conducted strictly following psychological rules. Experimental results show that rats are more active and have fewer frequencies of grooming and rearing actions when WR-5 performs mounting action periodically. The rat-like robot is therefore able to make the anxiety level of rats high by means of performing mounting action.
    Robotics and Biomimetics (ROBIO), 2012 IEEE International Conference on; 01/2012
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    ABSTRACT: The number of patients with mental disorders is increasing in advanced countries, hence more effective psychotropic drugs are recently desired. In process of development of psychotropic drugs, animal experiments have been playing a very important role. Mental disorder model animals which exhibit behavior disorder like patients with mental disorders are used in these experiments. These animals are normally developed by genetic manipulation, surgical operation in their brain or drug administration. A candidate for a new drug is administrated in these animals to evaluate its effect. However, we have some doubts about conventional mental disorder model animals because they are induced these disorders by using methods which are quite different from causes of mental disorder of human beings. Therefore, the purpose of this study is to develop an novel methodology to create mental disorder model animals. We then developed a small mobile robot and a control system for it. Using them, we have performed some experiments to create a mental disorder model rat. We had then succeeded in developing a mental disorder model rat by exposing stress using the robot during immature period. This rat exhibits low activity in some behavior tests during mature period. For better understanding of how stress exposure induces mental disorder in a rat, we conducted another experiment based on stress vulnerability hypothesis. In this experiment, stress was exposed during both immature and mature period while that had been exposed only during immature period. We prepared several conditions of stress exposure by changing robot behavior pattern to find the one to induce much stress in a rat. From a result of experiment, we found that a rat which received gentle chase by the robot during immature period was induced much stress when it received robot attack during mature period. Thus, we consider that this rat is more appropriate to the mental disorder model than that was developed in our past experi- ent.
    Biomedical Robotics and Biomechatronics (BioRob), 2012 4th IEEE RAS & EMBS International Conference on; 01/2012
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    ABSTRACT: This paper proposes the use of a specific mathematical model to represent the relationship between rat behavior and sociality (degree of friendliness with the robot) in the robot-rat interaction system. To validate the model, we conducted social interaction test between a rat-like robot and real, live rats. A rat-like robot called WR-4 capable of generating friendly or neutral behaviors among rats serves as partner to the rats in the interaction. Meanwhile, we performed Principal Component Analysis to specify the mathematical model. The experimental results show that this mathematical model allows quantitative estimation of rat sociality. Likewise, the results reveal that rat sociality can be analyzed and modified in this robot-rat interaction system.
    Intelligent Robots and Systems (IROS), 2012 IEEE/RSJ International Conference on; 01/2012
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    ABSTRACT: This paper presents the design and development of a bio-inspired mobile robot called WR-3 (Waseda Rat no. 3). The purpose of the robot is to work as an experimental tool to study social interaction between rats and robots. According to the results of the analysis of the motion of rats, their behavior can be divided into two phases: movement and interaction. Therefore, a novel hybrid mechanism that uses wheels during the movement phase and legs while interacting has been designed to actuate WR-3. Consequently, the robot can move at a high speed using its wheels, and reproduce the rat's interaction behavior using its legs and other parts. Based on body structure of a mature rat, WR-3 has been designed with similar dimensions and shape as a mature rat, and the quality of the shape imitation has been verified by the experiments of a rat's interestingness to the robot and stuffed rat. Evaluation experiments show that WR-3 is capable of reproducing a rat's actions such as chasing, rearing, grooming, mounting, etc., similar to a real rat. Furthermore, preliminary social interaction tests with living rats reveal that WR-3 is to some extent able to evoke natural reactions form a real rat and is therefore able to perform a certain level of realistic interaction.
    Advanced Robotics 01/2011; 25:2255-2272. · 0.51 Impact Factor
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    ABSTRACT: This research proposes to design and develop a novel robot involved in the general and famous animal experimental method called Social Interaction Test (SIT). Aiming at increased movement range of the waist and improved interoperability, we have developed a novel small animaroid robot WR-4 (Waseda Rat No.4). The waist of WR-4 endowed with a multi-bendable 6-bar linkage mechanism makes the robot able to rotate around ±130° horizontally, meeting required movement range. Integrating with a 4-bar linkage mechanism in the neck, this 6-bar linkage mechanism achieves the bending posture as living rats, allowing the imitation of behavior such as rotating. Furthermore, ultrasonic motors (USM) used to drive forelegs greatly reduce the weight of upper body, resulting in quicker acting of rearing behavior. WR-4 consists of 10 active DOFs (two 1-DOF wheels for locomotion, two 2-DOF forelegs for interaction, one 1-DOF neck for swing, one 2-DOF waist for rearing and body grooming and one 1-DOF reserved for tail) and 2 passive DOFs in the paws. The evaluation tests on motion performance show that WR-4 could act both rearing (reaching 60°) and rotating (reaching ±100° respectively) behaviors approximately 0.1s quicker than mature rats. Preliminary SIT between WR-4 and mature rats have been conducted strictly following psychological rules. Experimental results reveal that the frequencies of rearing behavior in rats were increased significantly when WR-4 reared periodically, and the activities of rats were decreased after WR-4 reared.
    01/2011;
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    ABSTRACT: The number of patients with mental disorders is increasing in advanced countries. Many researchers are working to develop mental disorder model animals that contribute to development of new psychotropic drugs. However, we have some doubts about conventional mental disorder models. Therefore, the purpose of this study is to develop an experimental setup to create novel mental disorder model animals. We then developed a small mobile robot and a control system for the robot. Using them, we performed an experiment to develop a mental disorder model rat. In the experiment, we succeeded in developing a new depression model rat and also high activity model rat. These disorder models must be useful in the screening of new psychotropic drugs. In addition, the methodology we developed in this research will contribute to clarifying mechanisms of mental disorders.
    2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, October 18-22, 2010, Taipei, Taiwan; 01/2010
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    ABSTRACT: In psychology and basic medical science, many studies have been performed with experiments on animals such as rats and mice, to clarify mechanisms of mental disorders. With this aim, several ldquomental disorder modelrdquo rats and mice have been developed by genetic manipulation, giving psychotropic drugs, injuring their brain or breeding under special conditions. ldquoSocial interaction testrdquo is one of the experimental protocols to evaluate their appropriateness. However, this test is not popular because of lack of reproducibility. Thus, we consider the robotic agent that interacts with a rat/mouse in the social interaction test provides new opportunities to perform it under more strict conditions. We have then developed a quadruped animaroid, WR-1. WR-1 has four 3-DOF legs, 2-DOF waist and 1-DOF neck. WR-1 walks with both crawl and trot gait. WR-1 also reproduces rearing and head shake behavior. Size of WR-1 is larger and motion performance lower than those of a mature rat. However, in a social interaction test with a rat and WR-1, some social interactions were observed between them.
    Advanced Intelligent Mechatronics, 2009. AIM 2009. IEEE/ASME International Conference on; 08/2009