Rescue operation is one of the most effective applications of snake-like robots, because it is very dangerous for human beings to locate survivors in collapsed buildings and, in addition, snake-like robots can move into narrow spaces to find survivors. However, previous rescue systems that use robots have a significant problem that is shortage of professional operators. To solve the problem, we have focused on volunteer non-professional staffs as operators of the rescue robots, and have developed a three dimensional snake-like robot that can be controlled easily. In this paper, we extend our previous works, and propose new snake-like robot which can be controlled easily by using simple steering wheel without losing mobility.

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In this paper, indeterminate contact forces in robotic grasping and manipulation are investigated. Previous studies by Omata et al. showed that static friction forces in power grasps were constrained by rigid-body contact kinematics. The set of possible contact forces can be calculated using the constraint on static friction. However, their formulation generates paradoxical results on contact forces in some cases. In this paper, we study this problem and propose a modified method to calculate the set of possible contact forces, which can be applied to not only power grasps but also other robotic manipulation. The method excludes the above-mentioned paradoxical results successfully. In addition, a sufficient condition to reduce the computation for the method is derived.

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This paper proposes a piercing based grasping by using the self-tightening effect of objects with elasticity. We suppose a piercing hand with palm where the piercing motion by needle can be independently achieved irrespective of the palm motion. The palm first approaches and touches with the object, with a slight pushing motion. This motion produces an increase of potential energy of object. After the motion, needles pierce the object. When the object is lifted up, the accumulated potential energy is released and the object tries to recover the original shape under the piercing condition. We found a particular mechanical configuration between the object and the needle arrangement, under which the constraint of object is tightened due to the object deformation during the release of potential energy. In order to confirm the robustness of the proposed method, we have done a couple of experiments. The results show that the proposed method keeps an extremely high robustness compared with the other piercing methods.

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To introduce a passive compliant mechanism for robot joints is an effective way for impact absorption. However, because robot joints also require high torque transmission characteristic, the simultaneous implementation of stiffness and softness is a significant issue. In this paper, we develop a torque transmission mechanism with nonlinear passive stiffness that realizes from zero to extremely high stiffness based on mechanical singularity. The analysis of nonlinearity of the stiffness is established and the experimental evaluations are shown. A four-legged robot with the proposed mechanism is designed and the effectiveness of high nonlinearity of the proposed mechanism is illustrated.

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For a robot providing services to people in a public space such as a train station or a shopping mall, it is important to distinguish potential customers, such as window-shoppers, from other people, such as busy commuters. In this paper, we present a series of techniques for anticipating people’s behavior in a public space, mainly based on the analysis of accumulated trajectories, and we demonstrate the use of these techniques in a social robot. We placed a ubiquitous sensor system consisting of six laser range finders in a shopping arcade. The system tracks people’s positions as well as their local behaviors such as fast walking, idle walking, or stopping. We accumulated people’s trajectories for a week, applying a clustering technique to the accumulated trajectories to extract information about the use of space and people’s typical global behaviors. This information enables the robot to target its services to people who are walking idly or stopping. The robot anticipates both the areas in which people are likely to perform these behaviors, and also the probable local behaviors of individuals a few seconds in the future. In a field experiment we demonstrate that this system enables the robot to serve people efficiently.

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Internally-balanced Magnetic Unit (IB Magnet) has been developed as a fundamental technique of wall climbing robots. This unit comprises of a permanent magnet which generates a strong sticking force, and a spring unit which cancels the internal force so that the unit can provide easy sticking and releasing actions. In this paper, the authors aim to enlarge usefulness of IB Magnet by several approaches. At first, two novel methods to design nonlinear springs which canceled the internal force of IB Magnet were proposed, and two types of IB Magnets which comprised the nonlinear spring designed by each method of them were developed. Effects of the design methods were confirmed by comparing control forces of the units and magnetic forces. Next, two evaluation methods for nonlinear springs were also proposed. By using the evaluation methods, we can choose the appropriate type of nonlinear spring in various conditions. In addition, a middle yoke that increases the adhering force of the magnet and protects the magnet from dusts, and a mechanism that adjusts the balance force of the nonlinear spring in order to adapt to painted walls were discussed. At last, it was concluded that these studies enlarged usefulness of IB Magnet for various situations.

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We introduce a large scaled 6 legged walking machine. It was developed to realize a solid and reliable walking vehicle for practical uses in forestry steep terrain with spread mechanical elements those used in usual construction machines. It weighs about 4,000[kg] with aluminum structure. Owing to a mounted diesel engine of output 11[kW] and hydraulic drive systems, it can walk around on a soft soil terrain and climb the steep slope of inclination up to about 30[deg], and walk along contour line of lateral inclination up to about 40[deg]. Finally it walked and worked well, despite it was tested on severe steep terrain where a lot of shrubs and stumps exist.

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