Computer simulation and dynamic modeling of a quadrupedal pronking gait robot with SLIP model q Servet Soyguder ⇑ , Hasan Alli Department of Mechanical Engineering, Fırat University, Elazig 23279, Turkey article info Article history: Received 22 October 2010 Received in revised form 11 November 2011 Accepted 11 November 2011 Available online 3 December 2011 abstract In this study, a quadrupedal pronking gait robot modeling was carried out with Spring Loaded Inverted Pendulum model in stance phase. This is achieved by solving a natural problem in which the main goal is to enable the robot to walk and run in a stable condition regardless of the environmental conditions. In order to solve this problem, dynamic model and control of a quadrupedal robot were realized for a pronking gait. The stance and flight phase dynamic structures were solved in a sequential closed loop to obtain the equation of motion for pronking gait. Spring Loaded Inverted Pendulum model was used as a dynamic model to simplify the simulation, dynamic locomotion and experimental works of the sys- tem, and also to simplify the pronking gait concept. The quadrupedal robot with pronking gait was controlled by proportional-derivative control algorithm. As a result, all computer simulations have shown that the proposed control actions and methods are more effective and make the system control quite easy and successful. Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. 1. Introduction In recent years, numerous studies on legged robots have been reported [1–15]. Scientists and engineers have taken an interest in constructing legged robots with biologically-based designs [7,12]. Son et al. have tried on gait planning based on kinematics for a quadruped being inspired by gecko lizard [12]. Furthermore, Yi has tired on gait planning and control for miniaturized quadruped robot [13]. Besides, Yang has studied about two-phase discontinuous gaits for quadruped walk- ing machines [14]. Ho and Lee have carried out biomimetic self-contained quadruped bounding robot [15]. The main advan- tage of legged robots is their ability to access places impossible for wheeled robots. Therefore, the legged robots have received great attention in robotics literature because the most of the studies on mobile robots have been related to legged robots in the last years. In order to maintain the stability of the legged robot, the location of the center-of-mass (COM) must be kept within the polygon of support excited by the stance legs [16]. In an other example, the leg is represented by a four bar mechanism exist- ing in Rhex robots [5]. Furthermore, Raibert performed very important research on dynamic legged locomotion at the Car- negie Mellon University (CMU) and Massachusetts Institute of Technology (MIT) Leglabs in the 1980s and 1990s [17]. The fundamental areas of his research were the main control principles of hopping height, forward speed, body posture and forming possible different gaits on monopedal, bipedal and quadrupedal robots for stable locomotion. Furthermore, the control algorithms in these studies make stable dynamic locomotion at very high speeds possible for various gait characters such as the trot, pace and bound. Besides, there are a lot of quadruped robot studies having various leg mechanisms and 0045-7906/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.compeleceng.2011.11.007 q Reviews processed and approved for publication by Editor-in-Chief Dr. Manu Malek. ⇑ Corresponding author. E-mail addresses: ssoyguder@firat.edu.tr (S. Soyguder), halli@firat.edu.tr (H. Alli). Computers and Electrical Engineering 38 (2012) 161–174 Contents lists available at SciVerse ScienceDirect Computers and Electrical Engineering journal homepage: www.elsevier.com/locate/compeleceng