Mechanical system of a small biped entertainment robot

SDR-4X is the latest prototype model, which is a small humanoid type robot. We reported the outline of this robot last year. In this paper we discuss more about mechanical system, which is important and original for a small biped entertainment robot, which will be used, in home environment. One technology is the design of actuators alignment in the body, which enables dynamic motion performance. Another technology is the actuator technology, which we originally developed, named intelligent servo actuator (ISA). We explain the specification and the important technical points. Next technology is the sensor system, which supports the high performance of the robot, especially the detection of outside objects, ability of stable walking motion and safe interaction with human. The robot is used in normal home environment, so we should strongly consider the falling-over of the robot. We propose the ideas against falling-over which makes the robot as safe as possible.