scholarly journals Adapting Highly-Dynamic Compliant Movements to Changing Environments: A Benchmark Comparison of Reflex- vs. CPG-Based Control Strategies

2021 ◽  
Vol 15 ◽  
Author(s):  
Annika Schmidt ◽  
Benedikt Feldotto ◽  
Thomas Gumpert ◽  
Daniel Seidel ◽  
Alin Albu-Schäffer ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Control Strategies ◽  
Central Pattern Generators ◽  
Search Space ◽  
Future Research ◽  
Comprehensive Comparison ◽  
The Central Nervous System ◽  
Pattern Generators ◽  
Low Dimensional ◽  
Key Aspects

To control highly-dynamic compliant motions such as running or hopping, vertebrates rely on reflexes and Central Pattern Generators (CPGs) as core strategies. However, decoding how much each strategy contributes to the control and how they are adjusted under different conditions is still a major challenge. To help solve this question, the present paper provides a comprehensive comparison of reflexes, CPGs and a commonly used combination of the two applied to a biomimetic robot. It leverages recent findings indicating that in mammals both control principles act within a low-dimensional control submanifold. This substantially reduces the search space of parameters and enables the quantifiable comparison of the different control strategies. The chosen metrics are motion stability and energy efficiency, both key aspects for the evolution of the central nervous system. We find that neither for stability nor energy efficiency it is favorable to apply the state-of-the-art approach of a continuously feedback-adapted CPG. In both aspects, a pure reflex is more effective, but the pure CPG allows easy signal alteration when needed. Additionally, the hardware experiments clearly show that the shape of a control signal has a strong influence on energy efficiency, while previous research usually only focused on frequency alignment. Both findings suggest that currently used methods to combine the advantages of reflexes and CPGs can be improved. In future research, possible combinations of the control strategies should be reconsidered, specifically including the modulation of the control signal's shape. For this endeavor, the presented setup provides a valuable benchmark framework to enable the quantitative comparison of different bioinspired control principles.

scholarly journals Factors Affecting Cadence Choice During Submaximal Cycling and Cadence Influence on Performance

2009 ◽  
Vol 4 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Ernst A. Hansen ◽  
Gerald Smith
Keyword(s):  
Power Output ◽  
Current Knowledge ◽  
Central Pattern Generators ◽  
Moderate Intensity ◽  
Future Research ◽  
Factors Affecting ◽  
Number Of Factors ◽  
Road Gradient ◽  
Pattern Generators ◽  
Primary Basis

Cadence choice during cycling has been of considerable interest among cyclists, coaches, and researchers for nearly 100 years. The present review examines and summarizes the current knowledge of factors affecting the freely chosen cadence during submaximal cycling and of the influence of cadence choice on performance. In addition, suggestions for future research are given along with scientifically based, practical recommendations for those involved in cycling. Within the past 10 years, a number of papers have been published that have brought novel insight into the subject. For example, under the influence of spinal central pattern generators, a robust innate voluntary motor rhythm has been suggested as the primary basis for freely chosen cadence in cycling. This might clarify the cadence paradox in which the freely chosen cadence during low-to-moderate submaximal cycling is considerably higher and thereby less economical than the energetically optimal cadence. A number of factors, including age, power output, and road gradient, have been shown to affect the choice of cadence to some extent. During high-intensity cycling, close to the maximal aerobic power output, cyclists choose an energetically economical cadence that is also favorable for performance. In contrast, the choice of a relatively high cadence during cycling at low-to-moderate intensity is uneconomical and could compromise performance during prolonged cycling.

scholarly journals Adaptive and Energy-Efficient Optimal Control in CPGs Through Tegotae-Based Feedback

2021 ◽  
Vol 8 ◽  
Author(s):  
Riccardo Zamboni ◽  
Dai Owaki ◽  
Mitsuhiro Hayashibe
Keyword(s):  
Energy Efficiency ◽  
Force Feedback ◽  
Central Pattern Generators ◽  
The State ◽  
Proprioceptive Information ◽  
Robotic Control ◽  
Periodic Patterns ◽  
Biologically Inspired ◽  
Optimal Energy ◽  
Pattern Generators

To obtain biologically inspired robotic control, the architecture of central pattern generators (CPGs) has been extensively adopted to generate periodic patterns for locomotor control. This is attributed to the interesting properties of nonlinear oscillators. Although sensory feedback in CPGs is not necessary for the generation of patterns, it plays a central role in guaranteeing adaptivity to environmental conditions. Nonetheless, its inclusion significantly modifies the dynamics of the CPG architecture, which often leads to bifurcations. For instance, the force feedback can be exploited to derive information regarding the state of the system. In particular, the Tegotae approach can be adopted by coupling proprioceptive information with the state of the oscillation itself in the CPG model. This paper discusses this policy with respect to other types of feedback; it provides higher adaptivity and an optimal energy efficiency for reflex-like actuation. We believe this is the first attempt to analyse the optimal energy efficiency along with the adaptivity of the Tegotae approach.

scholarly journals Neuromodulation of central pattern generators and its role in the functional recovery of central pattern generator activity

2019 ◽  
Vol 122 (1) ◽  
pp. 300-315 ◽  
Author(s):  
Jorge Golowasch
Keyword(s):  
Nervous System ◽  
Central Pattern Generators ◽  
Normal Function ◽  
Model Systems ◽  
Future Research ◽  
Vertebrate Model ◽  
Pattern Generators ◽  
Parameter Values ◽  
Generator Activity

Neuromodulators play an important role in how the nervous system organizes activity that results in behavior. Disruption of the normal patterns of neuromodulatory release or production is known to be related to the onset of severe pathologies such as Parkinson’s disease, Rett syndrome, Alzheimer’s disease, and affective disorders. Some of these pathologies involve neuronal structures that are called central pattern generators (CPGs), which are involved in the production of rhythmic activities throughout the nervous system. Here I discuss the interplay between CPGs and neuromodulatory activity, with particular emphasis on the potential role of neuromodulators in the recovery of disrupted neuronal activity. I refer to invertebrate and vertebrate model systems and some of the lessons we have learned from research on these systems and propose a few avenues for future research. I make one suggestion that may guide future research in the field: neuromodulators restrict the parameter landscape in which CPG components operate, and the removal of neuromodulators may enable a perturbed CPG in finding a new set of parameter values that can allow it to regain normal function.

Impulses of activation but not motor modules are preserved in the locomotion of subacute stroke patients

2011 ◽  
Vol 106 (1) ◽  
pp. 202-210 ◽  
Author(s):  
Leonardo Gizzi ◽  
Jørgen Feldbæk Nielsen ◽  
Francesco Felici ◽  
Yuri P. Ivanenko ◽  
Dario Farina
Keyword(s):  
Healthy Subjects ◽  
Muscle Activation ◽  
Central Pattern Generators ◽  
Dependent Manner ◽  
Healthy Controls ◽  
Stroke Patients ◽  
Unaffected Side ◽  
Subacute Stroke ◽  
The Central Nervous System ◽  
Pattern Generators

It has been hypothesized that the coordinated activation of muscles is controlled by the central nervous system by means of a small alphabet of control signals (also referred to as activation signals) and motor modules (synergies). We analyzed the locomotion of 10 patients recently affected by stroke (maximum of 20 wk) and compared it with that of healthy controls. The aim was to assess whether the walking of subacute stroke patients is based on the same motor modules and/or activation signals as healthy subjects. The activity of muscles of the lower and upper limb and the trunk was measured and used for extracting motor modules. Four modules were sufficient to explain the majority of variance in muscle activation in both controls and patients. Modules from the affected side of stroke patients were different from those of healthy controls and from the unaffected side of stroke patients. However, the activation signals were similar between groups and between the affected and unaffected side of stroke patients, and were characterized by impulses at specific time instants within the gait cycle, underlying an impulsive controller of gait. In conclusion, motor modules observed in healthy subjects during locomotion are different from those used by subacute stroke patients, despite similar impulsive activation signals. We suggest that this pattern is consistent with a neuronal network in which the timing of activity generated by central pattern generators is directed to the motoneurons via a premotor network that distributes the activity in a task-dependent manner determined by sensory and descending control information.

scholarly journals Towards an Understanding of Control of Complex Rhythmical “Wavelike” Coordination in Humans

2020 ◽  
Vol 10 (4) ◽  
pp. 215
Author(s):  
Ross Howard Sanders ◽  
Daniel J. Levitin
Keyword(s):  
Neural Control ◽  
Central Pattern Generators ◽  
Future Research ◽  
Front Crawl ◽  
Screening Criteria ◽  
Pattern Generators ◽  
Complex Relationships ◽  
Cns Control

How does the human neurophysiological system self-organize to achieve optimal phase relationships among joints and limbs, such as in the composite rhythms of butterfly and front crawl swimming, drumming, or dancing? We conducted a systematic review of literature relating to central nervous system (CNS) control of phase among joint/limbs in continuous rhythmic activities. SCOPUS and Web of Science were searched using keywords “Phase AND Rhythm AND Coordination”. This yielded 1039 matches from which 23 papers were extracted for inclusion based on screening criteria. The empirical evidence arising from in-vivo, fictive, in-vitro, and modelling of neural control in humans, other species, and robots indicates that the control of movement is facilitated and simplified by innervating muscle synergies by way of spinal central pattern generators (CPGs). These typically behave like oscillators enabling stable repetition across cycles of movements. This approach provides a foundation to guide the design of empirical research in human swimming and other limb independent activities. For example, future research could be conducted to explore whether the Saltiel two-layer CPG model to explain locomotion in cats might also explain the complex relationships among the cyclical motions in human swimming.

scholarly journals Energy Retrofit in European Building Portfolios: A Review of Five Key Aspects

2020 ◽  
Vol 12 (18) ◽  
pp. 7465 ◽  
Author(s):  
Aurora Greta Ruggeri ◽  
Laura Gabrielli ◽  
Massimiliano Scarpa
Keyword(s):  
Energy Efficiency ◽  
Optimal Allocation ◽  
Future Research ◽  
Design Decision ◽  
Energy Retrofit ◽  
Risk Valuation ◽  
Energy Modelling ◽  
New Methodologies ◽  
Joint Consideration ◽  
Key Aspects

The research about energy efficiency in buildings has exponentially increased during the last few years. Nevertheless, both research and practice still cannot rely on complete methodologies tailored for building portfolios as a whole, because the attention has always been drawn to individual premises. Yet, energy efficiency analyses need to go beyond the single building perspective and incorporate strategic district approaches to optimize the retrofit investment. For this purpose, several aspects should be considered simultaneously, and new methodologies should also be promoted. Therefore, this paper aims to discuss energy retrofit campaigns in building portfolios, drawing an exhaustive and updated review about the challenge of jumping from the single-building perspective to a stock-based analysis. This research discusses the publications available on the topic from five key aspects that are all essential steps in achieving a complete and reliable study of energy efficiency at a portfolio level. They are energy modelling and assessment, energy retrofit design, decision-making criteria assessment, optimal allocation of (financial) resources and risk valuation. This review, therefore, advocates for joint consideration of the problem as a basis on which to structure further disciplinary developments. Research gaps are highlighted, and new directions for future research are suggested.

scholarly journals Towards an Understanding of Control of Complex Rhythmical ‘Wavelike’ Coordination in Humans

2020 ◽  
Author(s):  
Ross Howard Sanders ◽  
Daniel J. Levitin
Keyword(s):  
Neural Control ◽  
Central Pattern Generators ◽  
Future Research ◽  
Front Crawl ◽  
Screening Criteria ◽  
Pattern Generators ◽  
Complex Relationships ◽  
Cns Control

How does the human neurophysiological system self-organize to achieve optimal phase relationships among joints and limbs, such as in the composite rhythms of butterfly and front crawl swimming, drumming, or dancing? We conducted a systematic review of literature relating to CNS control of phase among joint/limbs in continuous rhythmic activities. SCOPUS and Web of Science were searched using keywords ‘Phase AND Rhythm AND Coordination’. This yielded 998 matches from which 23 papers were extracted for inclusion based on screening criteria. The empirical evidence arising from in-vivo, fictive, in-vitro, and modelling of neural control in humans, other species, and robots indicates that the control of movement is facilitated and simplified by innervating muscle synergies by way of spinal central pattern generators (CPGs). These typically behave like oscillators enabling stable repetition across cycles of movements. This approach provides a foundation to guide the design of empirical research in human swimming and other limb independent activities. For example, future research could be conducted to explore whether the two-layer CPG model proposed by Saltiel et al [1] to explain locomotion in cats might also explain the complex relationships among the cyclical motions in human swimming.

Are central pattern generators understandable?

1980 ◽  
Vol 3 (4) ◽  
pp. 535-540 ◽  
Author(s):  
Allen I. Selverston
Keyword(s):  
Ad Hoc ◽  
Central Pattern Generators ◽  
Poor Quality ◽  
Specific Model ◽  
Connectivity Matrix ◽  
Sufficient Information ◽  
The Central Nervous System ◽  
Pattern Generators ◽  
Rhythmic Behaviors ◽  
Reductionist Approach

AbstractMost rhythmic behaviors are produced by a specialized ensemble of neurons found in the central nervous system. These central pattern generators (CPGs) have become a cornerstone of neuronal circuit analysis. Studying simple invertebrate nervous systems may reveal the interactions of the neurons involved in the production of rhythmic motor output. There has recently been progress in this area, but due to certain intrinsic features of CPGs it is unlikely that present techniques will ever yield a complete understanding of any but the simplest of them. The chief impediment seems to be our inability to identify and characterize the total interneuronal pool making up a CPG. In addition, our general analytic strategy relies on a descriptive, reductionist approach, with no analytical constructs beyond phenomenological modeling. Detailed descriptive data are usually not of sufficient depth for specific model testing, giving rise instead to ad hoc explanations of mechanisms which usually turn out to be incorrect. Because they make too many assumptions, modeling studies have not added much to our understanding of CPCs; this is due not so much to inadequate simulations as to the poor quality and incomplete nature of the data provided by experimentalists.A basic strategy that would provide sufficient information for neural modeling would include: (1) identifying and characterizing each element in the CPG network; (2) specifying the synaptic connectivity between the elements; and (3) analyzing nonlinear synaptic properties and interactions by means of the connectivity matrix. Limitations based on our present technical capabilities are also discussed.

Effect of Central Pattern Generators Depended Different Walking Strategies on Gait Ability of Patients after Stroke

2017 ◽  
Vol 27 (2) ◽  
pp. 40
Author(s):  
Hua WU ◽  
Zaihua RU ◽  
Congying XU ◽  
Xudong GU ◽  
Jianming FU
Keyword(s):  
Central Pattern Generators ◽  
Pattern Generators
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