This paper proposes an effective walking system for a hexapod robot on uneven terrain. To overcome the deficiencies of two-pair walking systems, which are effective on even terrain, the use of only three legs changes the steps required for movement. The proposed system receives feedback data from switches attached to the bottom of the legs and gyro sensor to carry out stable walking using the Bezier curve algorithm. From the coordinates of the Bezier curve, which guarantees the circular motion of legs, the motor's angle value can be obtained using inverse kinematics. The angle values are sent to each motor though RS-485 communication. If a switch is pushed by the surface during navigation in the Bezier curve pattern, the robot is designed to change its circular course. Through the changed course, each leg can be located on an optimal surface and the wobble phenomenon is reduced by using a normal vector algorithm. The simulation and experiment results show the efficiency of the proposed algorithm.
탐사로봇이란 인간이 근접하기 힘든 환경에 접근하여 자원, 환경, 상태 등을 조사하는 로봇이다. 로봇이 처음 접하는 환경 속에서 자신의 위치를 인지하고, 주변을 정확하게 탐색하기 위해서는 높은 지능이 필요하지만, 탐사로봇의 지능만큼 중요한 부분을 차지하는 것은 이동성이다. 실제 대부분의 지면은 불규칙적인 모양을 하고 있으며, 얼마나 효과적으로 이동하느냐에 따라서 탐사로봇의 임무수행능력이 결정된다.
G.-B. Han, C.-I. Yang, and Y.-S. Baek, "Analysis on the walking volumes of a hexapod system with general 3R link legs," Transactions of the Korean Society of Mechanical Engineers, A, vol. 20, no. 7, pp. 2205-2212, 1996.
S.-G. Lee, Y.-T. Do, C.-Y. Lee, and J.-W. Lee, "Introduction to Robotics," SciTech, 2008.
Y.-K. Yoo, J.-S. Kong, and J.-G. Kim, "Implementation of transformable hexapod robot for complex terrains," Journal of the Korean Society for Precision Engineering, vol. 25, no. 12, pp. 65-74, 2008.
G. Endo and S. Hirose, "Study on roller-walker," IEEE International Conference on Robotics & Automation, vol. 3, pp. 2032-2037, 1999.
K. Tabata, A. Inaba, and H. Amano, "Development of a transformational mobile robot to search victims under debris and rubble-2and report: Improvement of mechanism and interface," IEEE International Workshop on Safety, Security and Rescue Robotics, pp. 19-24, 2005.
R. C. Dorf and R. H. Bishop, Modern Control System, Prentice-Hall, 2008.
J.-W. Choi, R. E. Curry, and G. H. Elkaim, "Continuous curvature path generation based on bezier curves for autonomous vehicles," IAENG International Journal of Applied Mathematics, vol. 40, no. 2, 2010.
J. Choi and G. H. Elkaim, "Bezier curves for tra-jectory guidance," Lecture Notes in Engineering and Computer Science: Proceedings of the World Congress on Engineering and Computer Science 2008, pp. 625-630, Oct. 2008.
C.-N. Ko, T.-L. Lee, H.-T. Fan, and C.-J. Wu, "Genetic autotuning and rule reduction of fuzzy PID controllers," 2006 IEEE Intl. Conf. on System, Man, and Cybernetics, vol. 2, pp. 1096-1101, 2006.
S. Kucuk and Z. Bingul, "The inverse kinematics solutions of industrial robot manipulators," IEEE Conferance on Mechatronics, pp. 274-279, Jun. 2004.
D. Terzopoulos and A. Witkin, "Physically based models with rigid and deformable components," Computer Graphics and Applications, IEEE, vol. 8, no. 6, pp. 41-51, Nov. 1988.
D. M. Bourge, Physics for Game Developers, OReilly, Nov. 2011.
D. Metaxax and D. Terzopoulos, "Dynamic 3D models with local and global deformations:deformable superquadrics," Pattern Analysis and Machine Intelligence, IEEE Transactions, vol. 13, no. 7, pp. 703-714, Jul. 1991.