Power consumption analysis of different hexapod robot gaits.

The paper is focused on the power consumption analysis of different gaits of our constructed hexapod robot controlled by different Central Pattern Generator (CPG) models. There are a lot of gait patterns in the literature constructed either by different CPG models or using a series of oscillations with adjustable phase lag. The mentioned models, as well as those proposed in our previous paper are used and compared from the viewpoint of energy demand. In general, power consumption of the constructed hexapod robot is experimentally analyzed based on the current consumption in the applied servo motors, which drive the robot limbs. For this purpose the suitable drivers allowing a simple measurement of electric energy consumption of servo motors are used. The obtained experimental results show different energy demand for different robot gaits. Because power consumption is one of the main operational restrictions imposed on autonomous walking robots, we show that the performed energy efficiency analysis and the choice of the appropriate robot gaits depending on the actual situation can reduce the energy costs

Incorporating Passive Compliance for Reduced Motor Loading During Legged Walking

For purposes of travelling on all-terrains surfaces that are both uneven and discontinuous, legged robots have upper-hand over wheeled and tracked vehicles. The robot used in this thesis is a simulated hexapod with 3 degrees of freedom per leg. The main aim is to reduce the energy consumption of the system during walking by attaching a passive linear spring to each leg which will aid the motors and reduce the torque required while walking. Firstly, the ideal stiffness and location or the coordinates for mounting the spring is found out using gradient based algorithm called `Simultaneous Perturbation and Stochastic Approximation Algorithm\u27 (SPSA) on a flat terrain using data from a single walking step. Motor load is approximated by computing the torque impulse, which is the summation of the absolute value of the torque output for each joint during walking. Once the ideal spring and mount is found, the motor loading of the robot with the spring attached is observed and compared on three different terrains with the original loading without the spring. The analysis is made on a single middle leg of the robot, which is known to support the highest load when the alternating tripod gait is used. The obtained spring and mounting locations are applied to other legs to compute the overall energy savings of the system. Through this work, the torque impulse was decreased by 14 % on uneven terrain

Evidence for Composite Cost Functions in Arm Movement Planning: An Inverse Optimal Control Approach

An important issue in motor control is understanding the basic principles underlying the accomplishment of natural movements. According to optimal control theory, the problem can be stated in these terms: what cost function do we optimize to coordinate the many more degrees of freedom than necessary to fulfill a specific motor goal? This question has not received a final answer yet, since what is optimized partly depends on the requirements of the task. Many cost functions were proposed in the past, and most of them were found to be in agreement with experimental data. Therefore, the actual principles on which the brain relies to achieve a certain motor behavior are still unclear. Existing results might suggest that movements are not the results of the minimization of single but rather of composite cost functions. In order to better clarify this last point, we consider an innovative experimental paradigm characterized by arm reaching with target redundancy. Within this framework, we make use of an inverse optimal control technique to automatically infer the (combination of) optimality criteria that best fit the experimental data. Results show that the subjects exhibited a consistent behavior during each experimental condition, even though the target point was not prescribed in advance. Inverse and direct optimal control together reveal that the average arm trajectories were best replicated when optimizing the combination of two cost functions, nominally a mix between the absolute work of torques and the integrated squared joint acceleration. Our results thus support the cost combination hypothesis and demonstrate that the recorded movements were closely linked to the combination of two complementary functions related to mechanical energy expenditure and joint-level smoothness

Comportamento complexo da atividade individual de insetos em ambientes delimitados

Orientadora : Prof. Dr. Marcio Roberto PieCoorientador : Prof. Dr. Ricardo Luiz VianaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ciências Biológicas (Entomologia). Defesa: Curitiba, 30/06/2016Inclui referências : f.37-42;55-58;70-72;92-101Área de concentração : EntomologiaResumo: Como podemos mensurar a complexidade do comportamento animal? Nesta tese utilizo análises de recorrência (i.e. Plots de recorrência e RQA - Recurrence quantification analysis), descrição de comportamentos de movimento, incluindo o uso de modelagem matemática, para a compreensão do comportamento complexo de atividade individual de insetos em ambiente delimitados. Embora o estudo de insetos como sistemas complexos, em especial insetos com algum nível de organização social (colônias, agregações), seja promissor, a influência do comportamento individual na emergência de padrões auto organizados é pouco estudada. Estruturei a tese em três capítulos distintos. O primeiro capítulo desta tese é sobre o uso de análises de recorrência no estudo comportamental da atividade de insetos, sua aplicação e significância na interpretação de sinais estocásticos e determinísticos no comportamento animal. Comparei o padrão de atividade de três espécies de formigas, assim como de uma espécie solitária/gregária (Tenebrio molitor) para explorar a influência de níveis diferentes de complexidade social. Esta foi a primeira aplicação de análises de recorrência no estudo do comportamento de atividade, e uma das primeiras aplicações do método para fenômenos biológicos. Nossos resultados demonstram o potencial de análises de recorrência na análise de padrões de comportamento complexo. O segundo capítulo introduz a pouco conhecida espécie de vespa Perreyia flavipes, onde descrevemos pela primeira vez na literatura sobre o seu comportamento. Perreyia flavipes apresenta comportamentos interessantes em um intervalo curto de vida (36 hrs), tal como tanatose e cuidado maternal primitivo. Atos comportamentais são descritos e comparados entre os sexos, e suas possíveis funções são discutidos. O terceiro capítulo enfoca no comportamento das larvas de Perreyia flavipes, que apresentam comportamento gregário, se movimentando em grupos e de modo aparentemente coordenado. Neste capítulo abordo a influência de espaços delimitados no comportamento individual de P. flavipes através de dados experimentais e modelagem matemática. Espero que o presente estudo auxilie nos avanços dentro da área de mensuramento de testes empíricos de sistemas complexos em contextos biológicos. Palavras-chave: Sistemas complexos, tracking de movimento, comportamento de insetos, dinâmica de movimentosAbstract: How could we measure the complexity of animal behavior? In this thesis I use recurrence analysis (i.e. recurrence plots and RQA - Recurrence quantification analysis), motion behavior description, including mathematical modelling to understand the complex behavior of individual activity of insects in boundaries spaces. Although the study of insects as complex systems, specially, insects with some degree of social organization (e.g. eusocial colonies, aggregations) is promising, the influence of individual behavior in the emergence of self-organized patterns is not well studied. I structured the thesis in three distinct chapters. The first chapter of this thesis is about the use of analysis of recurrences in the behavioral study of insect activity, its application and significance in the interpretation of stochastic and deterministic signals in animal behavior. I compared the activity patterns of three ant species, as well as a solitary/gregarious species (Flour beetle), to explore varying levels of social complexity. This was the first application of recurrence analysis to the study of animal activity, and one of the first applications to biological phenomena. In particular, our results underscore the potential of recurrence analyses in the analysis of complex behavioral patterns. The second chapter introduces the not well studied species of sawfly Perreyia flavipes, where we describe for the first time in the literature its behavior. Perreyia flavipes presents interesting behaviors in a short life span (36 hours), such as thanatosis and primitive maternal care. Individual behavioral acts are described and compared among sexes, and their potential functions are discussed. The third chapter focuses on the behavior of Perreyia flavipes larvae, which have gregarious behavior, moving in groups and apparently coordinated mode. In this chapter, I study the influence of boundaries spaces in the movement behavior of individual larvae by experimental data and statistical modelling. I hope that the present study helps in the advances in the area of behavioral measurement of empirical experiments of complex systems. Keywords: Complex systems, movement tracking, behavior of insects, movement dynamics

Feasibility of novel gait training with robotic assistance : dynamic entrainment to mechanical perturbation to the ankle

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 149-156).Rehabilitation of human motor function is an issue of the utmost significance, and the demand for the effective rehabilitation service is even growing with the graying of the population. Robotic technology has provided promising ways to assist recovery of the motor function of upper extremities. In contrast, current robotic therapy for lower extremities has shown inferior efficacy. In this thesis, the source of the limited efficacy of current robotic walking therapy is addressed. Essential mechanical components for robustly stable walking are identified as energy dissipation and proper compensation. Based on these essential components, design criteria of effective robotic walking therapy are suggested as foot-ground interaction and ankle actuation. A novel strategy of robot aided walking therapy reflecting the design criteria is proposed; dynamically entraining human gait with periodic ankle torque from a robot. Experiments with normal subjects and neurologically impaired subjects support the feasibility of the proposed rehabilitation strategy. The gait period of subjects entrain to the periodic mechanical perturbation with a measurable basin of entrainment, and the entrainment always accompanies phase-locking so that the mechanical perturbation assists propulsion. These observations are affected neither by auditory feedback nor by a distractor task for normal subjects, and consistently observed in impaired subjects. A highly simplified one degree of freedom walking model without supra-spinal control or an intrinsic self-sustaining neural oscillator (a rhythmic pattern generator) encapsulated the essence of these observations. This suggests that several prominent limit-cycle features of human walking may stem from peripheral mechanics mediated by simple afferent feedback without significant involvement of supra-spinal control or central pattern generator. The competence of the highly simplified model supports that the proposed entrainment therapy may be effective for a wide range of neurological impairments.by Jooeun Ahn.Ph.D

Engineering Dynamics and Life Sciences

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

Dynamical systems : mechatronics and life sciences

Proceedings of the 13th Conference „Dynamical Systems - Theory and Applications" summarize 164 and the Springer Proceedings summarize 60 best papers of university teachers and students, researchers and engineers from whole the world. The papers were chosen by the International Scientific Committee from 315 papers submitted to the conference. The reader thus obtains an overview of the recent developments of dynamical systems and can study the most progressive tendencies in this field of science