**6. Conclusion**

94 The Future of Humanoid Robots – Research and Applications

( )( )

The 6*l* is the designed value and *P*3 can be known by forward kinematics from <sup>2</sup>*J* . These formulas are also solved by Matlab, because they are too complicated to solve by hand.

6 32 32

7 43 43

*xx yy l PP PP*

( )( )

Even if the complicated kinematics was solved, it was not used to operate hand except for

This hand was made for gestures like human hand not grasping, so experiments are very simple. From this purpose, the experiments were taken to check how this hand can realize gestures like the one of human similarly and verify the torque of hand is enough or not to move under the resistance of skin. Even if some experiments were taken to know the resistance of skin by pieces of silicon, there are great differences between pieces of skin and hand shaped skin. The exact experiments can be taken by material engineering area, so it was not efficient way to check the resistance of skin, tests to the real model was taken. The performed experiments to gestures are basically to express rock-paper-scissors posture. The 6 postures are performed including rock-paper-scissors and during these postures, how the shapes are natural like the shape of hand of human in same posture was checked. The tearing and wrinkle at the surface, adequateness of torque are also checked. Fig. 12 shows 6 postures with the completed hand. The gear ratio was 1/30 at first, but it is not enough to bend the finger fully, so the gear ratio was changed to 1/50 and it worked well. In addition to change of the gear ratio, the thickness of skin was thinner and this made problem. Because the transmittance becomes high, the inner mechanical part can be shown even if there is make-up to the skin. The mixture ratio among silicon, pigments and an emulsion should be more researched. There are no barometers for a point of similarity between presented hand and human hand, so the evaluation of this hand is subjectively. The esthetic valuation basis should be needed as future works. There are some needs of improvement after experiments. Firstly, the exact measure of the resistance of skin is needed. It is not easy to know the resistance of the real shape, but trial-error ways are not efficient. Secondly, the cost of hand is too expensive. This hand is not just for researches, the cost is one of the most important factors. The small and exquisite parts caused high cost, so the more simple structure and parts should be designed. Thirdly, the 1 D.O.F thumb finger and no spread of fingers are not enough to gesture like human. Even if there are not enough spaces in hand, the spread fingers and abduction-adduction motion of thumb finger should be added to

*xx yy l PP PP*

3 2

5 3

*P fJ*

( )

*P fJ*

The structure of distal joint is simple 4 bar linkage, so the

3 is known by solving simultaneous equations (4).

How to get unknown values is same to get unknown in

The 

calculating

1 .

**5. Experiment and discussions** 

make natural gestures like human.

( )

2 2

2 2

<sup>2</sup> . (3)

(4)

1 ,<sup>2</sup> .

3 can be solved easier than

In this paper, 5 D.O.F hand for an android robot with an artificial skin was presented. The hand of an android robot required human like appearance because of an android robot is the nearest robot to human. The presented robotic hand has 5 D.O.F fingers and its shape and size are based on Korean young woman. There are three design policies which are size, shape and skin to make this hand and these are for the closest realization of human hand. The finger used D.C motor, screw-nut and liner potentiometer and linkage structure as a power transmission. The characteristic of mechanical design is a modular structure. Each finger module has its own power and sensor independently, so this design can bring easy maintenance by changing modules. The finger module was designed to suit the shape which is based on 3D data from human hand. The hand is just combination of each finger module and palm part. The palm part decides the shape of hand by arrangement of finger modules and it is also designed by 3D data based on human hand. The artificial skin was made of silicon complex which was selected as the nearest material to human skin. To make this silicon complex, mock-up and mold and mixture of materials are needed. After these processes, the closest android hand to real human hand can be produced. This hand is not for grasping but gesture, so experiments are for evaluation how it has similar appearance to human hand and can make variable gestures. In experiments, this hand can express variable postures include rock-paper-scissors and its appearance is similar to human hand. There are some improvements to this hand. The 5 D.O.F is not enough to realize variable gestures of human hand especially spread of fingers and adduction-abduction. In addition, the exact valuation standard of similarity in appearance should be researched. These should be the future works in this research.

**6** 

*Kobe University* 

*Japan* 

**Development of Multi-Fingered** 

Wataru Fukui, Futoshi Kobayashi and Fumio Kojima

Today, various industrial robots are developed and used all over the world. However, these industrial robots are specialized in particular operations. In fact, one industrial robot is not able to be designed for operating various tasks. One of the causes is that general-purpose and multifunctional robot hands substituted human manual-handling task are not brought to realization. If these robot hands like human hands are consummated, the applicable field of industrial robots is extended, and the utilization efficiency is improved very much. A human hand has mechanical handling function such as grab, grip, pinch, push and pull. In addition, it can sense the feeling such as configuration, hard, flexible, smoothness and asperity. In other words, a human hand is a multifunctional and a universal end effector. Many research works on robot hand have been studied all over the world in order to imitate human hand and achieve the similar function to human hand. However, it is not attained that a robot hand system has the coordinative function to human hand's one yet. For resolving this problem, it is necessity that software system processes various sensors' information effectively. Additionally, it is also necessity that hardware system has drive mechanism, multi Degrees Of Freedom (DOFs) linkage mechanism and some sensors that allocated in limited spatial restrictions. Consequently, we produced the Universal Robot Hand I as shown in Fig.1. The robot hand system has tactile sensors, joint torque sensors, joint angle sensors and the similar structure to human hand's one. We have studied on the robot hand's mechanism, the sensory information processing and the kinematic control.

**1. Introduction** 

Fig. 1. Universal robot hand I

**Universal Robot Hand with** 

 **Torque Limiter Mechanism** 

### **7. References**

