Page 118 - Mechatronics for Safety, Security and Dependability in a New Era

Ch21-I044963.fm Page 102 Tuesday, August 1, 2006 3:30 PM
Ch21-I044963.fm
102
102 Page 102 Tuesday, August 1, 2006 3:30 PM
As the same way as mentioned above, by realizing the path between every adjacent middle
configuration, the total path from the goal configuration to the initial one is obtained, in which the
robot successfully passes through two holes. The path from the initial configuration to the goal one is
easily obtained by tracking the obtained path reversely.

Based on the proposed method, a computer simulator is developed for solving the inverse kinematics
of redundant robot under restraint by obstacles. Windows XP is adopted as an operating system and
Visual C++ is adopted as a programming language. The CPU is Pentium 4 (1.70GHz) and memory is
256 MB. The total computing time for the solution in the case of this paper is about 3 minutes. The
simulation results can be graphically shown in a computer display. An example of the simulation result
is already shown in Fig. 4.

CONCLUSION

For the purpose of collision avoidance, a new efficient method for solving inverse kinematics of a
redundant robot is proposed. The summary is as follows:
1) This method is divided into three procedures, which are position synthesis by 3 joints, orientation
synthesis by 3 wrist joints, and collision avoidance by other remaining joints. Each of these three
procedures can be calculated analytically. After series of three procedures, the positioning error is
occurred, since they are not independent from each other. Therefore, the calculation is carried out
iteratively until sufficient convergence is obtained.
2) As the configuration on which the combination of joint angles for realizing the passage through the
hole can be changed and must be selected, middle configurations are set on the way from a given
initial configuration to the final configuration. The method for selecting the combination of joint
angles is also proposed.
3) A simulator based on this method is developed. A robot of 14 DOF can successfully pass through
two cylindrical holes in two thick walls, while realizing high positioning and orientating accuracy of
its end effector.

ACKNOWLEDGEMENT

This work was partially supported by JSPS (Japan Society for the Promotion of Science).KAKENHI
(16310103), MEXT (Ministry of Education, Culture, Sports, Science and Technology).KAKENHI
(17656090), the Kansai University Special Research Fund, 2004 and 2005.

REFERENCES

[1] Nakamura Y., Hanafusa H. and Yoshikawa T. (1987). Task-Priority Based Redundancy Control of
Robot Manipulators. The International Journal of Robotics Research 6:2, 3-15.
[2] Hirukawa H. and Kitamura S. (1987). A collision Avoidance Method for Robot Manipulators based
on Safety First Algorithm and the Potential Function. Journal of the Robotics Society of Japan 5:3,
3-11.
[3] Takano M. (1958). A New Effective Solution for Inverse Kinematics Problem (Synthesis) of a
Robot with Any Type of Configuration. J. Fac. Eng., Univ. Tokyo (B) 38:2, 107-135.
[4] Kawamoto J., Aoyagi S. and Takano M. (2003). Path Planning of Collision Avoidance for
Redundant Robot -Passage through Hole-. Proceedings of the 21th Annual Conference of the
Robotics Society of Japan, CD ROM no. 2113.