Vol.4 No.2 2011

Research paper : Toward the use of humanoid robots as assemblies of content technologies (S. Nakaoka et al.)−91−Synthesiology - English edition Vol.4 No.2 (2011) between the robot and the floor was the SDR Motion Creating System[19] that enabled various movements in a small, 58-cm-tall biped humanoid QRIO[20]. However, in this system, movements could be made from the key poses only for the upper body, and the movement of the lower body could be set only by the specific command and the parameters provided by the system. In this case, the movement of the lower body was limited to the ones allowed by the preset commands, and the task of creating the movement of the whole body was complex. In another light, the fact that a stable movement could be possible only by such a method highlighted the difficulty of the problem.Until now, the system that allowed the creation of whole body motion of a life-size bipedal humanoid in a way similar to the key frame animation did not exist. We thought such a system would be the fundamental technology for the motion expression of humanoids, and set our topic as the integration of the key frame animation technology and the bipedal robot technology.4.2 Development of the whole body motion choreography systemAs a technology to solve the aforementioned issues, we succeeded in developing the whole body motion choreography system for bipedal humanoids[21]. The interface for the system and the example of the motion created by this system are shown in Fig. 5.The interface of the system handles the whole body, without dividing the body into the upper and lower parts. As shown in the middle row of Fig. 5, the user can set the key poses on the CG model of the robot. The result will be a stable movement where the robot keeps balance on its feet. The robot can execute the motion without falling as long as there is no self-collision or exceeding of the limits of the joint angle speed (the user will be prompted to correct them when such events occur).To realize this, we devised an interface design never seen before. The greatest characteristic is that the system determines the horizontal position of the hips at each key pose so the robot can stay in balance. This determination is done instantly as the user enters or corrects the key pose. The result is presented on the spot to the user in the form of the correction of the hip position in the key pose. The supplementation between the key poses is also done to generate a balanced movement. In another word, the system allows only well-balanced choreography. While this maneuver is done, the user does the same operation as in the ordinary key frame animation, and the robot can be choreographed in a manner just like a CG character. It is also possible for the user to explicitly indicate the weight placement of the robot to the floor as the ZMP between the sole and the floor in the key pose, to obtain the desired horizontal movement of the hips within the balanced range.Such design was not self-evident, and the fact that we reached this design was important in overcoming the issue. Also, implementation of this design was difficult. While providing a simple interface to the user, the system must integrate various complex computations such as the detection of sole landing status, the transition of target ZMP, the transition of supplementary space, the addition of supplementary key poses, and the calculation of center of gravity path that matches the target ZMP. Moreover, these have to be done at high speed.In overcoming such implementation issues, we were able to utilize the technology of OpenHRP3[22], the dynamics simulator for robots that we have been developing. The various calculation processes for robotics implemented in the simulator were developed to handle practical simulation in terms of execution speed and precision, and it was useful for the implementation of this system. The dynamics simulation method that we developed for OpenHRP3[23] could accurately verify the behavior of the bipedal robot on the floor. By incorporating this into our system, we could directly verify the adequacy of the implementation to the system, and were able to increase the development efficiency.This system was confirmed to be effective for HRP-4C. By combining the whole body motion created with the walking stabilization system[18] mentioned in subchapter 3.3, stable execution was confirmed to be possible for HRP-4C, as in the example of Fig. 5. To be able to construct such complex movements in a life-size humanoid with small soles, as in HRP-4C, was a major accomplishment. Also, as shown in Fig. 6, it was possible to create the changes in facial Fig. 5 Editing screen for the whole body choreography system and examples of the created key posesIn this example, eight patterns of key poses are needed to create an action of about 7 seconds where the robot makes the pose, takes a step, and does a kicking motion.0.0[s]2.3[s]3.1[s]1.7[s]4.1[s]6.0[s]6.7[s]4.8[s]


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