Humanoid robots have great potential in applications in organically dangerous environments. They have advantages like the strength, accuracy, endurance as a machine, and intelligence, agility like humans. The fast development in robotic research and industry in recent years has enlarged the possibility in robot applications especially for humanoids. For example, humanoid robots are considered to be a substitution for humans working on dangerous tasks in radiation environments, like nuclear power plants and reactors which are in radioactive leaking accidents. However, this wonderful idea has not been widely taken into application. The reason is that even the robot components can be damaged in the radiation environment. Although scientists have discovered how electronic circuits are damaged by radiation, radiation damage on mechanical components, like the speed reducer and the motor, has never been well studied. This dissertation, as an addition to this particular field of research, focuses on the joint components of the robot---speed reducer and motor. In this dissertation, the harmonic drive and the brushless DC (BLDC) motor are selected as the targets of research.

This dissertation aims at obtaining radiation effects on the robotic components at the system level. First, we look into the physics principles of radiation damage to the materials on the specific parts of the harmonic drive and the BLDC motor, especially on how feature changes in the materials will affect the performance of the components. We have also developed characterization methods for evaluating radiation damage to the harmonic drive and BLDC motor. Finally, we have designed and performed simulation and experiments to draw a conclusion. Additionally, inspired by the harmonic drive study, we have developed a new structure of the drive such that the flexible materials are substituted by rigid materials. The result could eliminate the cause of radiation to the embrittlement of the flexible materials. As a result, the radiation effect to the materials of the harmonic drive can be eliminated. As the result shows that the motor is the major component that is affected by the irradiation, we also studied how the radiation-affected-robot will perform when such a motor is used in a robot joint servo system.