**2.2.2 Shape**

84 The Future of Humanoid Robots – Research and Applications

The goal of this design is to make a human like hand as possible. To achieve this goal, the design policies are established and those are about size, shape and skin. The priority of these

The size of the hand is based on an android robot which was already mentioned, EveR 3. The model of an android robot EveR 3 is Korean young woman whose height is 165cm and weight is 50kg. When humanoid robots which use real human as model are designed, they use only size like height, length of the limb etc. in general. However, android robots need more strict observation of size not only height, length of joint but also circumference of joint, each part. To make exact reference of model, the original model was scanned by 3D scanner and the scanned data was handled by 3D MAX. From this process, the data which can be used CAD program (Solid works) was earned. This data contained all information of size of original model and this can measure exactly by CAD. The size of hand from original model can be measured exactly, too. The required size data which is needed to realize same size of original model is length of each finger, length of each joint of finger, circumference of each finger, thickness of palm and length of palm. Of course, it is hard to realize exact size of each factor of original model, but this process can help to make a robot hand which is the nearest to human hand than any other existing hands. Fig. 2 shows the real size of robotic hand especially mechanical structure and comparison with real human hand whose is the designer of this hand (168cm, Korean man). Even if this man's hand is small, the robotic hand is smaller than

his one. Table.1 shows parameters of main factor which are considered to design.

Fig. 2. Mechanical part of robotic hand and comparison with real human hand.

**2.2 Design policies** 

**2.2.1 Size** 

policies focused on appearance but not performance.

The consideration of shape of an android robot hand is as important as one of its size. There are many humanoid robot hands whose size satisfy human like size, because humanoid robots are designed as real human size. However, most of their designs are not like real human hand especially shape. Even if humanoid robots have similar appearance to human, its design is based on robot basically, so shape of human is curved but one of humanoid robots is angulate (AKACHI K. et al., 2005) (Ill-Woo Park. et al., 2005) (Jun-Ho Oh. et al., 2006). The android robot hand should have curved design and it make hard to design, because most of mechanical parts are angulate, so the space which can be used is very narrow. To design human like curved shape, 3D scanned hand data which was already mentioned was used. There is consideration to use that data. The shape of this data is full straightened, so it is hard to know the shape when the finger bended. Some processing was applied to original data to make bended shape by 3D graphics program (Maya). Fig. 3 shows variable shape of finger to check. From these processes, the nearest reference 3D data to real human hand can be obtained.

Fig. 3. The handled 3D data to check shape by graphics program.

Design of 5 D.O.F Robot Hand with an Artificial Skin for an Android Robot 87

finger has 3 D.O.F at proximal joint, middle joint and distal joint to bend or stretch and 1 D.O.F to spread, so there are 4 D.O.F in each finger basically. In case of thumb finger, there is no middle joint, so it has 3 D.O.F (proximal, distal and 1 D.O.F for abduction and adduction). There are at least 25 D.O.F in real hand, so it is very hard to realize by robotic hands, because there are not enough spaces to install actuators in hand. For this reason, most of humanoid or android hands have smaller number of D.O.F than one of human. Of course, there are some hands which have many D.O.F like one of human, but their size are bigger than human hands (H. Liu. et al., 2008) or they have other large spaces which have a lot of actuators instead (Yuichi Kurita. et al., 2009). For these reasons, the hands for humanoid robots or android robots should have less D.O.F than one of human hand. In this research, the 5 D.O.F hand is designed to express fundamental motion of human hand like straightening – bending of each finger. The best feature of this hand is that the each finger was made as a modular structure independently. Most of robotic hands have their actuators like motors in palm or forearm and their finger is connected to palm, but the finger of this hand has an actuator (DC motor), sensor and gears as its own components. The combination of these components becomes independent finger module. Why this finger was designed as a module is for easy maintenance. The android robot EveR 3 which this hand is applied to was designed for stage performance especially commercial performances not just using in the laboratory for researches, so reliability and maintenance is one of the most important factors. The modular structure can give fast and easy maintenance of hardware. For example, when the middle finger breaks down, replacing of the middle finger module is the only maintenance of all. It is fast, easy and low cost. Fig. 5 shows the disassembled hand by

each module.

Fig. 5. The disassembled hand by each module (fingers and palm).
