Development of a drive mechanism for a robot with a cyclo gear reducer, and its application to a semi-continuous variable transmission gear

Rapid prototyping is a technology using a CAD/CAM, and a molding machine, which manufactures a prototype model rapidly. Since it can make products with complex shapes of three dimensions, the cost and time for development is reduced. It is convenient in the production of a wide range of prototypes, particularly in a product´s development. The purpose of our research was to manufacture an effective motor reducer to develop a robot with high mobility. To achieve this, it was necessary both to reduce the weight of the robot using a 3D processing machine and a 3D molding machine, and to develop a robot with high rigidity. In this paper, a cyclo gear reducer was developed using the rapid prototyping. The cyclo gear reducer has a deceleration ratio of engagement that is two and three times higher than the usual involute gears. Also, the transmission efficiency of the cyclo gear reducer is usually designed to be high, which means that it is usually difficult to achieve precision in gear teeth, such as those of the spur wheel and involute gear of the planetary gear, using resin material. Since the curved shape of the teeth used in an epitrochoid gear are not sharp, the gear and gear box can be made using a simple 3D processing machine even if the material has low rigidity, as in the case of plastics. Furthermore, we are planning to develop the cyclo gear reducer that can semi-continuously change the deceleration ratio by installing the mechanism where the slide moves along the direction of the rotation axis in the epitrochoid gear, as one of the applications of the cyclo gear reducer.