1. Field
This disclosure relates to a face robot which is operated similarly to the motion of a human head and a multi-joint manipulator which supports a robot's face, and more particularly, to a structure which may compensate an influence caused by the gravity and exerted on rotation parts rotating about its axes.
2. Description of the Related Art
In recent years, various kinds of robots have been developed so as to make the human's living environment more convenient or assist work in industrial fields. Especially, developed are many robot arms which are utilized in various industrial fields such as painting and welding. It is very important that the robot arms need to produce high torque, since such industrial multi-joint robot arms need to transfer and support a heavy load.
The multi-joint robot arm receives load torque due to the own weight thereof or the weight of the load, and the load torque directly affects the design of a driving unit such as a driving motor. In particular, the proportion of the torque element generated by the own weight of the robot arm in the load exerted on the driving motor is considerably high.
In the case where the capacity of the driving unit of the robot arm is determined in the related art, not only the torque generated by the load but also the gravity torque generated by the own weight of the robot arm need to be taken into consideration, which has a disadvantage in that the capacity of the power source for driving the robot arm inevitably increases.
Even in a robot face which is developed so as to move similarly to the motion of the human head, the proportion of the torque element generated by the own weight of the head is considerably high, which also causes a problem in that the capacity of a power source for driving a neck part needs to be increased.
In addition, simple ideas having a concept of theoretically compensating the gravity generated by the own weight of the robot arm or the like have been proposed, but any mechanism practically adopting the ideas cannot be developed yet. Furthermore, in the face robot, the structure of the neck joint is complex and the installation space thereof is not sufficiently ensured, which hinders the application example that employs the gravity compensation.