Dynamic Analysis and Modeling of Jansen Mechanism

AbstractTheo Jansen mechanism is gaining wide spread popularity among legged robotics researchers due to its scalable design, energy efficiency, low payload to machine load ratio, bio-inspired locomotion, deterministic foot trajectory among others. In this paper, we present dynamic analysis of a four legged Theo Jansen link mechanism using projection method that results in constraint force and equivalent Lagrange's equation of motion necessary for any meaningful extension and/or optimization of this niche mechanism. Numerical simulations using MaTX is presented in conjunction with the dynamic analysis. This research sets a theoretical basis for future investigation into Theo Jansen mechanism

Rolling Locomotion Control of a Biologically Inspired Quadruped Robot Based on Energy Compensation

We have developed a biologically inspired reconfigurable quadruped robot which can perform walking and rolling locomotion and transform between walking and rolling by reconfiguring its legs. This paper presents an approach to control rolling locomotion with the biologically inspired quadruped robot. For controlling rolling locomotion, a controller which can compensate robot’s energy loss during rolling locomotion is designed based on a dynamic model of the quadruped robot. The dynamic model describes planar rolling locomotion based on an assumption that the quadruped robot does not fall down while rolling and the influences of collision and contact with the ground, and it is applied for computing the mechanical energy and a plant in a numerical simulation. The numerical simulation of rolling locomotion on the flat ground verifies the effectiveness of the proposed controller. The simulation results show that the quadruped robot can perform periodic rolling locomotion with the proposed energy-based controller. In conclusion, it is shown that the proposed control approach is effective in achieving the periodic rolling locomotion on the flat ground

Human responses to the Younger Dryas in Japan

The effect of the Younger Dryas cold reversal on the survival of Late Glacial hunter-gatherers in the Japanese Archipelago is evaluated, through a synthetic compilation of 14C dates obtained from excavated Late Glacial and initial Holocene sites (332 14C dates from 88 sites). The estimated East Asian monsoon intensity and vegetation history based on the loess accumulations in varved sediments and pollen records in and around the Japanese Archipelago suggest an abrupt change to cool and dry climate at the onset of Younger Dryas, coupled with the Dansgaard–Oeschger Cycles as recorded in Greenland. The chronometric placement of sites based on an assessment of 14C dates show that the site numbers decrease from the Bølling–Allerød to Younger Dryas and increase from the Younger Dryas to Preboreal. However, human population dynamics inferred from a site distribution analysis was little changed from the previous Bølling–Allerød and to the following Preboreal. Moreover, hunter-gatherers consistently employed ceramic pottery technology since its emergence prior to the onset of Younger Dryas, while the quantity of ceramic vessels that were undermined during the Younger Dryas dramatically increased at the onset of the Holocene, implying that a substantial change in hunter-gatherer socioeconomy occurred after the end of Younger Dryas

Generalized Singularity Analysis of Snake-Like Robot

The purpose of this paper is to elucidate a generalized singularity analysis of a snake-like robot. The generalized analysis is denoted as analysis of singularity of a model which defines all designable parameters such as the link length and/or the position of the passive wheel as arbitrary variables. The denotation is a key point for a novelty of this study. This paper addresses the above new model denotation, while previous studies have defined the designable parameters as unique one. This difference makes the singularity analysis difficult substantively. To overcome this issue, an analysis method using redundancy of the snake-like robot is proposed. The proposed method contributes to simplify singularity analysis concerned with the designable parameters. The singular configurations of both the model including side-slipping and the one with non side-slipping are analyzed. As the results of the analysis, we show two contributions. The first contribution is that a singular configuration depends on designable parameters such as link length as well as state values such as relative angles. The second contribution is that the singular configuration is characterized by the axials of the passive wheels of all non side-slipping link. This paper proves that the singular configuration is identified as following two conditions even if the designable parameters are chosen as different variables and the model includes side-slipping link. One is that the axials of passive wheels of all non side-slipping links intersect at a common point. Another one is that axials of passive wheels of all non side-slipping links are parallel

Energy-based control for a biologically inspired hexapod robot with rolling locomotion

This paper presents an approach to control rolling locomotion on the level ground with a biologically inspired hexapod robot. For controlling rolling locomotion, a controller which can compensate energy loss with rolling locomotion of the hexapod robot is designed based on its dynamic model. The dynamic model describes the rolling locomotion which is limited to planar one by an assumption that the hexapod robot does not fall down while rolling and influences due to collision and contact with the ground, and it is applied for computing the mechanical energy of the hexapod robot and a plant for a numerical simulation. The numerical simulation of the rolling locomotion on the level ground verifies the effectiveness of the proposed controller. The simulation results show that the hexapod robot can perform the rolling locomotion with the proposed controller. In conclusion, it is shown that the proposed control approach is effective in achieving the rolling locomotion on the level ground

Analysis of safe manual control by using Furuta pendulum

This paper focuses on the interaction of manual and automatic control in a demanding task where the process is unstable and has actuator limitation. The problem is inspired by control of high performance aircrafts but which is similar to controlling the arm of a Furuta pendulum while maintaining the stability of the pendulum. The task is to control the position of the pendulum arm manually while maintaining the pendulum in the upright position. The analysis of regions for safe maneuvers is important to realize the desired control system