International Journal of Humanoid Robotics

This paper studies real-time gait planning for a humanoid robot. By simultaneously planning the trajectories of the COG (Center of Gravity) and the ZMP (Zero Moment Point), a fast and smooth change of gait can be realized. The change of gait is also realized by connecting the newly calculated trajectories to the current ones. While we propose two methods for connecting two trajectories, i.e. the real-time method and the quasi-real-time one, we show that a stable change of gait can be realized by using the quasi-real-time method even if the change of the step position is significant. The effectiveness of the proposed methods are confirmed by simulation and experiment.

This paper elaborates a generalized approach to the modeling of human and humanoid motion. Instead of the usual inductive approach that starts from the analysis of different situations of real motion (like bipedal gait and running; playing tennis, soccer, or volleyball; gymnastics on the floor or using some gymnastic apparatus) and tries to make a generalization, the deductive approach considered begins by formulating a completely general problem and deriving different real situations as special cases. The paper first explains the general methodology. The concept and the software realization are verified by comparing the results with the ones obtained by using "classical" software for one particular well-known problem: biped walk. The applicability and potentials of the proposed method are demonstrated by simulation using a selected example. The simulated motion includes a landing on one foot (after a jump), the impact, a dynamically balanced single-support phase, and overturning (falling down) when the balance is lost. It is shown that the same methodology and the same software can cover all these phases.

This paper describes in detail the control architecture of an anthropometric robotic leg. It contains a brief description of the mechanical structure of the prototype and a kinematical structure overview. The aim of this project is the development of new technologies for the implementation and realization of bio-mechanical limbs for motoric gait rehabilitation, as well as for human gate study and analysis. In particular, a detailed description of the pneumatic control architecture is provided, together with some design considerations. Moreover, a platform for walking trajectory generation is presented, and some experimental results are reported. In order to assure a proper stability control during the gait, a center of pressure sensor has been specifically designed and placed onboard the robot. A detailed description on the sensor mechanism is also provided.

This paper reports on the control structure of the pneumatic biped "Lucy." The robot is actuated with pleated pneumatic artificial muscles which have interesting characteristics that can be exploited for legged machines. They have a high power-to-weight ratio, an adaptable compliance and they can reduce impact effects.

The current control architecture focuses on the trajectory generator and the tracking controller, which is divided into a computed torque controller, a delta-p unit, a PI position controller and a pressure bang-bang controller. The trajectory generator provides polynomial joint trajectories while the computed torque, combined with the delta-p unit, calculates the required muscle pressure levels. The PI and bang-bang controller work at a pressure level to cope with modeling errors and to set the pressures in each muscle. The control design is divided into single support and double support, where specifically the computed torque differs for these two phases.

The proposed control architecture is evaluated with a full hybrid dynamic simulation model of the biped. This simulator combines the dynamical behavior of the robot with the thermodynamical effects that take place in the muscle-valves system. The observed hardware limitations of the real robot and expected model errors are taken into account in order to give a realistic qualitative evaluation of the control performance and to test the robustness.

A preliminary implementation of the presented controller on the real biped, representing a walking motion of the robot while both feet are in the air, is discussed. This first implementation shows already promising results concerning tracking performance of the proposed control architecture. It confirms that the pneumatic tracking system can be used for a dynamic application such as a biped walking robot.

Recently, a lot of research has been conducted in the area of biped walking robots that could be compared to human beings. The aim of this article is to control a new planar biped robot by means of an adaptive procedure. The newly designed robot is able to move on its heel like a human. After derivation of dynamic equations of motion for two states of the robot, namely, "supporting leg and trunk" and "swing leg" separately, the stability of robot is achieved by locating the zero moment point (ZMP). A dynamic modification is developed for ZMP positioning. For motion control of the robot, the physical parameters (such as mass, link length and geometry) are estimated (identified) by adaptive methods. A Matlab based software simulation is also conducted.