Design of a Biped Toy Robot with an Automatic Center of Gravity Shifting Mechanism

The design of the biped toy robot in this study, presents a brand new concept compared to that of the conventional mechanical biped robots on the market. These conventional mechanical products rely mainly on a large sole area to stabilize the wobbling movement during walking. In this design walking stability is not achieved by large sole areas, but by having more degrees of freedom and automatically shifting the center of gravity as the robot walks. A single motor is used to drive the biped toy robot trunk so that the center of gravity is automatically shifted to achieve walking stability. The two feet are driven by four connecting rods for striding and leg-lifting action. More particularly, an equal parallel crank mechanism is provided that uses a single motor to drive the connecting rods, thereby swinging the center of gravity of the toy robot in time with striding frequency. In addition, the concept of the zero moment point is utilized in the shifting of the center of gravity allowing the biped robot to lift its legs, change step, and move forward in balance. This study also discusses the use of the four connecting rods, and the shifting of the center of gravity of the robot, as an alternative to the servomotors commonly used in conventional robots which are bulky, expensive and hard to control.