Bipedal Walking Machine Research Articles

Using Neural Networks to Predict the Normal Reactions of a Walking Robot

Purpose of reseach . This work is devoted to solving one of the problems associated with the control of walking robots based on their dynamic mathematical model − the presence in it of obvious mechanical bonds due to reactions of bonds with the supporting surface. To solve this problem, it is proposed to use a fully connected neural network to evaluate the forces of normal reactions between the surface and the feet of a bipedal walking machine during its implementation of one step. Methods. The paper considers two neural network architectures based on fully connected layers with ReLU activation functions. The architecture of the neural network includes five fully connected layers (input, output and three hidden), and an alternative architecture includes a thinning layer after each fully connected layer. The input data for the network are the state of the robot and the required control actions, and the output is the predicted reaction forces. The training sample is generated by modeling a complete dynamic model of the robot. The network is built and trained using machine learning libraries Keras and TensorFlow. Results. The generation of training sample for neural network is described here, and it is carried out the training of two architectures of neural networks. Based on the simulation data, it was established that both trained neural networks are able to accurately predict the values of normal reactions using the values of generalized coordinates and velocities, as well as control actions as input, however, a static prediction error is observed. Conclusion . The results obtained within the framework of the article can be further used to control the movement of bipedal walking machines on various types of surfaces.

Обзор способов реализации ходьбы двуногого шагающего робота

Обзор способов реализации ходьбы двуногого шагающего робота

Minimally Actuated Walking: Identifying Core Challenges to Economical Legged Locomotion Reveals Novel Solutions.

Terrestrial organisms adept at locomotion employ strut-like legs for economical and robust movement across the substrate. Although it is relatively easy to observe and analyze details of the solutions these organic systems have arrived at, it is not as easy to identify the problems these movement strategies have solved. As such, it is useful to investigate fundamental challenges that effective legged locomotion overcomes in order to understand why the mechanisms employed by biological systems provide viable solutions to these challenges. Such insight can inform the design and development of legged robots that may eventually match or exceed animal performance. In the context of human walking, we apply control optimization as a design strategy for simple bipedal walking machines with minimal actuation. This approach is used to discuss key facilitators of energetically efficient locomotion in simple bipedal walkers. Furthermore, we extrapolate the approach to a novel application—a theoretical exoskeleton attached to the trunk of a human walker—to demonstrate how coordinated efforts between bipedal actuation and a machine oscillator can potentially alleviate a meaningful portion of energetic exertion associated with leg function during human walking.

Constrained robot dynamics II: Parallel machines

Part I of this two-part article considered the dynamics of serially connected robot arms with holonomic end-effector constraints. Here, the work is extended to parallel linkages by first finding the dynamic equations for general tree and star structured mechanisms. Parallel linkages are then formed by applying constraints to the terminal links of the tree or star. The formalism is illustrated with two examples: bipedal walking machines and the Stewart platform.

Control Method of Biped Locomotion Giving Asymptotic Stability of Trajectory

This paper deals with a control method of a biped locomotion by utilizing a dynamical system having a stable limit cycle and presents the recent results of an experimentally constructed bipedal walking machine. The control method is discussed for a walking model having four-degrees-of freedom and separately studied for the double support phase and the single support phase. The control strategy makes use of the bifurcation of a coupled van der Pol1s equation, which is one of the dynamical system having a. stable limit cycle. Analysis and computer simulations have proved the validity of the control method.