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A symmetry position/force hybrid control framework for cooperative object transportation tasks with multiple humanoid robots is proposed in this paper. In a leader-follower type cooperation, follower robots plan their biped gaits based on the forces generated at their hands after a leader robot moves. Therefore, if the leader robot moves fast (rapidly pulls or pushes the carried object), some of the follower humanoid robots may lose their balance and fall down. The symmetry type cooperation discussed in this paper solves this problem because it enables all humanoid robots to move synchronously. The proposed framework is verified by dynamic simulations. [ABSTRACT FROM AUTHOR]

In this paper, an imitation learning framework that includes an evolutionary process based on principal component analysis (PCA) is presented. The framework comprises offline and online processes. In the offline process, human demonstrations are used to develop a motion database. The database covers the workspace and includes robot properties. The evolved database has a clustered structure for efficiency. In the online process, a robot can generate desired motions using a real-time motion reconstruction method based on PCA. The performance of this method is verified through two case studies. The proposed framework is applied to the generation of reaching motions to an object on a table and a shelf. [ABSTRACT FROM PUBLISHER]

Most of the studies on biped walking on even or uneven terrain have assumed stiff ground. This paper proposes a dynamic contact model between foot and loose soil. The proposed contact model provides sinkage of the foot, slip of the sole and reactive force acting on the foot on loose soil. Sinkage of the foot and slip of the sole are calculated utilizing terramechanics model, which are important characteristics for biped robot to walk on loose soil. Reactive force acting on the foot on loose soil is calculated using spring-damper model between the foot and the deformed ground. By applying the proposed contact model to a usual dynamics simulator, dynamic sinkage and slip phenomenon during biped walking on loose soil are simulated. Additionally, in order to verify the simulation result, experiments were carried out using a humanoid robot. [ABSTRACT FROM AUTHOR]

When a human needs to generate a large force, they will try to apply an impulsive force with dynamic cooperation of the whole body. In this paper we first discuss impact dynamics of humanoid robots and then propose a way to generate impact motions for a humanoid robot to exert a large force while keeping a balance. In the impact motion generation, Sequential Quadratic Programming (SQP) is used to solve a non-linear programming problem in which an objective function and constraints may be non-linear functions of the motion parameters. Impact motions are generated using SQP so that the impact force is maximized while the angular momentum is minimized. Breaking wooden boards with a Karate chop is taken as a case study because it is a typical example of tasks that utilize impulsive force. A humanoid robot motion for the Karate chop is generated by the proposed method. In order to validate the designed motion, experiments are carried out using a small humanoid robot Fujitsu HOAP-2. The Karate-chop motion generated by the proposed method is compared with the motion designed by a human. The results of breaking the wooden boards experiments clearly show the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

Humanoid robots posses the unique ability to cross obstacles by stepping over or upon them. However, conventional 2D methods for robot navigation fail to exploit this ability and thus design trajectories only by circumventing obstacles. Recently, global algorithms have been presented that take into account this feature of humanoids. However, due to high computational complexity, most of them are very time consuming. In this paper, we present a novel approach to footstep planning in obstacle cluttered environments that employs a human-like strategy to terrain traversal. Design methodology for obstacle stepping over motion designed for use with this algorithm is also presented. The paper puts forth simulation results of footstep planning as well as experimental results for the stepping over trajectory designed for use with hardware execution of the footstep plan. [ABSTRACT FROM AUTHOR]