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This book provides a comprehensive presentation of issues and challenges faced by researchers and practicing engineers in motion planning and hybrid control of dynamical legged locomotion. The major features range from offline and online motion planning algorithms to generate desired feasible periodic walking and running motions and tow-level control schemes, including within-stride feedback laws, continuous time update laws and event-based update laws, to asymptotically stabilize the generated desired periodic orbits. This book describes the current state of the art and future directions across all domains of dynamical legged locomotion so that readers can extend proposed motion planning... 

Recently, it has been proved that a different switching surface can preserve the walking trajectory while varying the walking stability [1], [2]. In this paper, by employing the simplest passive dynamic biped, we optimize the switching surface to maximize the robot's stability. Here, the stability measure is preferably the size of the basin of attraction, i.e. the collection of all possible initial conditions leading to the system's equilibrium point. Numerical investigations indicate that the maximum stability is obtained for neither the highest nor the lowest walking speed  

A novel Locomotion and gait planning method for a surface walking/climbing robot based on sequential 4-bar mechanism motions is presented. The robot moves on a surface through decoupled transverse gaits and turning gaits with desired length and angle. For implementation of turning gaits three methods of Simulated Annealing Accurate Planning (SAAP), Gradient Based Planning (GBP) and Hybrid Accurate Planning (HAP) are studied. Where the last method was found the most effective approach  

The use of active modes of travel in school trips has sharply declined for a number of reasons, some of which are rooted in urban design, location of schools, and parental reservations. Thus, policy makers are keen to find practical ways to promote active modes of travel, particularly walking. This study was an effort to determine a tolerable walking distance for school trips and identify factors that made walking trips more reasonable for students. In the vein of understanding the tolerable walking distance, a two-step framework encompassing a random utility method and a hazard-based model was introduced. This framework was applied to a set of data that were collected from middle and high... 

Inspired by the effects of a switching surface on the stability of passive dynamic walking (Safa and Naraghi in Robotica 33(01):195–207, 2015; Safa et al. in Nonlinear Dyn. 81(4):2127–2140, 2015), this paper suggests a new control strategy for stabilization of dynamic bipedal locomotion. It verifies that the stability improvement of a dynamic walking system is feasible while preserving the speed, step-length, period, natural dynamics, and the energy effectiveness of the gait. The proposed control policy goes behind the three primary principles: (i) The system’s switching surface has to be replaced by a new one if an external disturbance is induced. (ii) The new switching surface has to be... 

Free gait becomes necessary in walking robots when they come to walk over discontinuous terrain or face some difficulties in walking. A basic gait generation strategy is presented here using reinforcement learning and fuzzy reward approach. A six-legged (hexapod) robot is implemented using Q-learning algorithm. The learning ability of walking in a hexapod robot is explored considering only the ability of moving its legs and using a fuzzy rewarding system telling whether and how it is moving forward. Results show that the hexapod robot learns to walk using the presented approach properly  

The majority of the people with incomplete spinal cord injury lose their walking ability, due to the weakness of their muscle motors in providing torque. As a result, developing assistive devices to improve their conditionis of great importance. In this study, a combined application of the saddle-assistive device (S-AD) and mechanical medial linkage or thosis was evaluated to improve the walking ability in patients with spinal cord injury in the gait laboratory. This mobile assistive device is called the saddle-assistive device equipped with medial linkage or thosis (S-ADEM). In this device, a mechanical orthosis was used in a wheeled walker as previously done in the literature. Initially,... 

Background The aim of this study was to develop a new stance control knee-ankle-foot orthosis (SCKAFO) and determine its efficacy on specific spatiotemporal and kinematic parameters. Method Seven healthy volunteer subjects participated in this study. After orthotic gait training, subjects participated in a four-part data collection session that consisted of gait evaluation with normal walking, SCKAFO with locked knee joint, SCKAFO without initial flexion (IF) mode, and SCKAFO with IF mode. Results Walking with any of the control knee-ankle-foot orthoses (KAFOs) produced a significant reduction in walking speed compared with normal walking. There was no significant difference in walking speed... 

A passive bipedal walking robot can descend down a small slope without any exertion of external force and only by using the gravity force. By exerting a proper energy to a passive biped robot, its walking speed can be controlled and also it can be forced to walk on flat planes and ascending slopes. In this paper, the proper energy is applied to the robot in three different methods: applying a proper moment to the robot joints, applying a proper moment to the robot’s stance leg, and applying a proper movement to the robot’s upper body. It is found that the first method is not practical, but the second and third methods enhance the stability and speed regulation of the robot. Additionally, the... 

Background and aim: Most currently-available stance control knee ankle foot orthoses (SCKAFOs) still need full knee extension to lock the knee joint, and they are still noisy, bulky, and heavy. Therefore, the aim of this study was to design, construct, and evaluate an original electromechanical SCKAFO knee joint that could feasibly solve these problems, and thus address the problems of current stance control knee joints with regards to their structure, function, cosmesis, and cost. Method: Ten able-bodied (AB) participants and two (knee ankle foot orthosis) KAFO users were recruited to participate in the study. A custom SCKAFO with the same set of components was constructed for each... 

Limit cycle walkers are known as a class of walking robots capable of presenting periodic repetitive gaits without having local controllability at all times during motion. A well-known subclass of these robots is McGeer’s passive dynamic walkers solely activated by the gravity field. The mathematics governing this style of walking is hybrid and described by a set of nonlinear differential equations along with impulses. In this paper, by applying perturbation method to a simple model of these machines, we analytically prove that for this type of nonlinear impulsive system, there exist different switching surfaces, leading to the same equilibrium points (periodic solutions) with different... 

By employing a few simple models of passive dynamic walking mechanism, we have shown the possibility of extending the boundaries of the maximum stable speed of these autonomous robots merely by changing their terrain. The replaced terrain consists of a series of parallel local slopes and is recognized as a general form of a ramp-stair surface. Although here, the mechanism of stabilization of the unstable locomotion patterns is not clearly known, the technique is quite simple and works effectively. The merit to the method over other strategies, could be described in two separate aspects: First, it is still completely passive; so we do not need any external energy to control the robot. Second,... 

Inspired by the effects of a switching surface on the stability of passive dynamic walking (Safa and Naraghi in Robotica 33(01):195–207, 2015; Safa et al. in Nonlinear Dyn. 81(4):2127–2140, 2015), this paper suggests a new control strategy for stabilization of dynamic bipedal locomotion. It verifies that the stability improvement of a dynamic walking system is feasible while preserving the speed, step-length, period, natural dynamics, and the energy effectiveness of the gait. The proposed control policy goes behind the three primary principles: (i) The system’s switching surface has to be replaced by a new one if an external disturbance is induced. (ii) The new switching surface has to be... 

The aim of this paper is to simulate numerically the airflow induced by a walking visitor and its effects on the contaminant transport and ventilation system effectiveness. To this end, the following models will be used in this study: the Lagrangian Discrete Random Walk (DRW) model to trace the motion of BCPs, the dynamic mesh method to simulate the visitor movement, and the Reynolds Averaged Navier-Stokes (RANS) model to solve the airflow. The validation results of the numerical method are in full agreement with the available experimental data in the literature. The findings of the present study indicate that the visitor's movement has remarkable effect on the basic airflow, and the... 

The staggered quantum walk is a type of discrete-time quantum-walk model without a coin which can be generated on a graph using particular partitions of the graph nodes. We design Hamiltonians for potential realization of the staggered dynamics on a two-dimensional lattice composed of superconducting microwave resonators connected with tunable couplings. The naive generalization of the one-dimensional staggered dynamics generates two uncoupled one-dimensional quantum walks; thus more complex partitions need to be employed. However, by analyzing the coherence of the dynamics, we show that the quantumness of the evolution corresponding to two independent one-dimensional quantum walks can be... 

To get a deep understanding of a diffusion process and realizing the most efficient methods for investigating a real network, has always been of great interest and utility to us. In this work, we aim to study and compare our mobility in a network using a normal random walk and a long-range navigation strategy such as Lévy Walk. We study the Global Mean First Traverse Distance (GMFTD) and the entropy rate for this long-range navigation process and later, compare with a normal walk strategy. For this study, GMFTD is utilized instead of Global Mean First Passage Time (GMFPT). The reason for such a choice is the fact that for more accurate and precise results, we need to also take into account...