Development of a Biped Robot Based on Dynamic Walking

Abstract —In this research project we present the design and construction of a biped robot based on dynamic walking. The main objective of this research is the assimilation of technology in the field of dynamic walking robots; therefore, we built a prototype based on a previously built robot developed at Delft University created by Martjin Wisse. The reason for performing this research is to have a starting point in the development of bipedal robots and human prostheses. The robot was built under a mechatronic approach, i.e. with a synergical relationship between the mechanical, electronics and programming constituent parts. The prototype performes dynamic walking analogous to the locomotion of humans. It was concluded that these technologies can be used for the design, simulation and construction of dynamic walking robots. Keywords-Passive dynamic walking; bipedal walking; Design; Simulation; Construction. I. I NTRODUCTION For many years, humans have tried to create human-like robots. Create a humanoid robot is difficult due to the complex design. Research has shown that the morphology of the human being is one of the best for use in legged robots [1]. The trend of mobile robotics is to develop robots that can be transported with only two legs. The advantage of using robots with legs is the ease of transportation in places that are designed for humans. Biped robots are a topic of interest because in the near future they may possibly serve as assistants in daily tasks. Human locomotion is a series of alternating rhythmic movements of limbs and trunk that determine a forward shift of the center of gravity. Biomechanical investigations have provided several suggestions to dynamic passive movements in human walking. Many robot designs are based on human locomotion, using only two legs. The term dynamic walking was introduced in 1990 by Tad McGeer [2]. He was inspired by a simple toy and passive mechanisms that were capable of walking on a downhill slope. The benefits of using an approach based on passive dynamic walking are efficiency and simplicity. On the other hand, the development of such robots is attractive because of the natural look in their movements when they walk. Diverse research on the topic of dynamic walking has been developed before McGeer, starting with simulations and simple principles of passivity [3], [4], [5], [6], [7]. It has been shown that toys are passive devices that can perform a natural walking [8]. Depending on the size and distribution of masses it is possible to know the natural speed of a walking robot [9]. The first dynamic walking robots were machines that walked in 2 dimensions on a downhill slope. In [10] and [11] it began to simulate passive biped robots in 3-dimensional dynamics walking on a floor with irregularities. In [12] the first passive dynamic walking machine in 3dimensions using two legs was built, making it possible the design of such robots. In [13] the robot was improved by adding another degree of freedom in the hip, allowing the addition of an upper body. A current problem of dynamic walking is falling forward [13], which can occur depending on the position of the robot's legs. Walking dynamic principles can be obtained by different forms of actions such as electrical, hydraulic and pneumatic (Fig. 1). The design procedure of a biped robot can be similar. The type of actuators does not affect the gait of the robot [14] (Fig.1). The collision of the leg on the floor provides stability while walking. The impact may have positive effects on walking because it stabilizes the center of mass when the robot makes contact with the ground [15], [16], [17]. The study of the addition of an upper body in a dynamic walking robot is studied, because it provides a more human appearance. When an extra mass is added on the hip of a robot, an improvement in the robot stabilization is obtained while walking [18]. In [19] it is presented the construction of a dynamic walking biped based on a human appearance and driven by