Robust Dynamic Locomotion Through Feedforward-Preflex Interaction

2000 ◽  
Author(s):  
Jorge G. Cham ◽  
Sean A. Bailey ◽  
Mark R. Cutkosky
Keyword(s):  
Mechanical System ◽  
Elastic Properties ◽  
Sensory Feedback ◽  
Motor Pattern ◽  
Robotic Systems ◽  
Reflex Response ◽  
Rough Terrain ◽  
Uncertain Environments ◽  
Control Hypothesis ◽  
Running Robots

Abstract Unlike most legged robotic systems built to date, even simple animals have the ability to quickly and robustly traverse through rough terrain and over large obstacles and gaps. Recent evidence from insect physiology research indicates that arthropods achieve this fast robust locomotion largely without relying on sensory feedback or reflex response. Instead, locomotion is the result of the interaction between a basic feedforward motor pattern and the visco-elastic properties of the mechanical system, termed “preflexes.” In this paper, we consider the implications of this control hypothesis for the design of small running robots for uncertain environments. We present working prototypes that show how robust dynamic locomotion can be achieved without the use of sensory feedback. We then discuss modeling approaches for these kinds of systems and present results from simulations of representative models.

scholarly journals Self-Stabilising Quadrupedal Running by Mechanical Design

2009 ◽  
Vol 6 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Panagiotis Chatzakos ◽  
Evangelos Papadopoulos
Keyword(s):  
Mechanical System ◽  
Mechanical Design ◽  
Quadruped Robot ◽  
The Self ◽  
Rough Terrain ◽  
Stable Regime ◽  
Quadruped Robots ◽  
The Stability ◽  
Running Robots ◽  
Body Inertia

Dynamic stability allows running animals to maintain preferred speed during locomotion over rough terrain. It appears that rapid disturbance rejection is an emergent property of the mechanical system. In running robots, simple motor control seems to be effective in the negotiation of rough terrain when used in concert with a mechanical system that stabilises passively. Spring-like legs are a means for providing self-stabilising characteristics against external perturbations. In this paper, we show that a quadruped robot could be able to perform self-stable running behaviour in significantly broader ranges of forward speed and pitch rate with a suitable mechanical design, which is not limited to choosing legs spring stiffness only. The results presented here are derived by studying the stability of the passive dynamics of a quadruped robot running in the sagittal plane in a dimensionless context and might explain the success of simple, open loop running controllers on existing experimental quadruped robots. These can be summarised in (a) the self-stabilised behaviour of a quadruped robot for a particular gait is greatly related to the magnitude of its dimensionless body inertia, (b) the values of hip separation, normalised to rest leg length, and leg relative stiffness of a quadruped robot affect the stability of its motion and should be in inverse proportion to its dimensionless body inertia, and (c) the self-stable regime of quadruped running robots is enlarged at relatively high forward speeds. We anticipate the proposed guidelines to assist in the design of new, and modifications of existing, quadruped robots. As an example, specific design changes for the Scout II quadruped robot that might improve its performance are proposed.

scholarly journals Passive, Reflex Response Units for Reactive Soft Robotic Systems

2020 ◽  
Vol 5 (3) ◽  
pp. 4014-4020
Author(s):  
Alix J. Partridge ◽  
Andrew T. Conn
Keyword(s):  
Robotic Systems ◽  
Reflex Response

The central nervous origin of the swimming motor pattern in embryos of Xenopus laevis

1982 ◽  
Vol 99 (1) ◽  
pp. 185-196 ◽  
Author(s):  
J. A. Kahn ◽  
A. Roberts
Keyword(s):  
Motor Activity ◽  
Similar Pattern ◽  
Sensory Feedback ◽  
Motor Nerve ◽  
Motor Pattern ◽  
Cycle Period ◽  
Phase Lag ◽  
Nerve Activity ◽  
Rhythmic Motor ◽  
Swimming Pattern

Rhythmic motor nerve activity was recorded in stage 37/38 Xenopus embryos paralysed with curare. The activity was similar to the swimming motor pattern in the following ways: cycle period (40–125 ms), alternation of activity on either side of a segment, rostro-caudal phase lag. Episodes of rhythmic motor activity could be evoked by stimuli that evoke swimming and inhibited by stimuli that normally inhibit swimming. On this basis we conclude that the swimming motor pattern is generated by a central nervous mechanism and is not dependent on sensory feedback. In addition to the swimming pattern, another pattern of motor activity (‘synchrony’) was sometimes recorded in curarized embryos. In this, the rhythmic bursts on either side of a segment occurred in synchrony, and the rhythm period (20–50 ms) was half that in swimming. This was probably not an artifact of curarization as there were indications of a similar pattern in uncurarized embryos. Its function remains unclear.

scholarly journals State-dependent sensorimotor gating in a rhythmic motor system

2017 ◽  
Vol 118 (5) ◽  
pp. 2806-2818 ◽  
Author(s):  
Rachel S. White ◽  
Robert M. Spencer ◽  
Michael P. Nusbaum ◽  
Dawn M. Blitz
Keyword(s):  
Motor Activity ◽  
Motor System ◽  
Sensory Feedback ◽  
Activity Patterns ◽  
Motor Pattern ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Gastric Mill ◽  
Sensory Regulation ◽  
Motor Circuits

Sensory feedback influences motor circuits and/or their projection neuron inputs to adjust ongoing motor activity, but its efficacy varies. Currently, less is known about regulation of sensory feedback onto projection neurons that control downstream motor circuits than about sensory regulation of the motor circuit neurons themselves. In this study, we tested whether sensory feedback onto projection neurons is sensitive only to activation of a motor system, or also to the modulatory state underlying that activation, using the crab Cancer borealis stomatogastric nervous system. We examined how proprioceptor neurons (gastropyloric receptors, GPRs) influence the gastric mill (chewing) circuit neurons and the projection neurons (MCN1, CPN2) that drive the gastric mill rhythm. During gastric mill rhythms triggered by the mechanosensory ventral cardiac neurons (VCNs), GPR was shown previously to influence gastric mill circuit neurons, but its excitation of MCN1/CPN2 was absent. In this study, we tested whether GPR effects on MCN1/CPN2 are also absent during gastric mill rhythms triggered by the peptidergic postoesophageal commissure (POC) neurons. The VCN and POC pathways both trigger lasting MCN1/CPN2 activation, but their distinct influence on circuit feedback to these neurons produces different gastric mill motor patterns. We show that GPR excites MCN1 and CPN2 during the POC-gastric mill rhythm, altering their firing rates and activity patterns. This action changes both phases of the POC-gastric mill rhythm, whereas GPR only alters one phase of the VCN-gastric mill rhythm. Thus sensory feedback to projection neurons can be gated as a function of the modulatory state of an active motor system, not simply switched on/off with the onset of motor activity. NEW & NOTEWORTHY Sensory feedback influences motor systems (i.e., motor circuits and their projection neuron inputs). However, whether regulation of sensory feedback to these projection neurons is consistent across different versions of the same motor pattern driven by the same motor system was not known. We found that gating of sensory feedback to projection neurons is determined by the modulatory state of the motor system, and not simply by whether the system is active or inactive.

Analytic and Experimental Study of the Load Distribution on Spline Joints Length Considering the Contact Rigidity of the Bearing Surfaces

2012 ◽  
Vol 162 ◽  
pp. 74-83 ◽  
Author(s):  
Dan Mărgineanu ◽  
E. Mărgineanu ◽  
E.S. Zăbavă ◽  
A. M. Fârtă
Keyword(s):  
Experimental Study ◽  
Mechanical System ◽  
Elastic Properties ◽  
Load Distribution ◽  
Degrees Of Freedom ◽  
Surface Profile ◽  
Contact Rigidity ◽  
Contact Points ◽  
Actual Load ◽  
Contact Surfaces

The spline joints transmit torque from shafts to rotors by multiple contact surfaces. The joint's mechanical system is, therefore, undetermined, i.e. the number of contact points is much larger than the number of restricted degrees of freedom. Thus, the actual load distribution is greatly influenced by the joints elements elastic properties and their geometrical errors and surface profile. In this paper, an analytical and experimental study for the load distribution on the in joints length caused by the finite rigidity of the joints elements is presented.

scholarly journals Test analysis for implementation of mechanical and robotic systems in therapy applications

2020 ◽  
pp. 10-15
Author(s):  
Martha Isabel Aguilera-Hernández ◽  
José Luis Ortiz-Simón ◽  
Miguel Ramírez-Aguirre ◽  
Gustavo Emilio Rojo-Velázquez
Keyword(s):  
Mechanical System ◽  
Mechanical Systems ◽  
Robotic Systems ◽  
Test Analysis ◽  
Wheeled Robots

This article presents the results of tests performed on the mechanical system of wheeled robots, so they can be implemented as therapy instruments for people with different capacities (ASD). The results displayed show the robot's behavior following a trajectory and its dependence on operator handling. In this way, results can be extrapolated about the importance of design for the development of mechanical systems that can be reliable to be implemented as therapy tools.

scholarly journals Dynamics and stability of running on rough terrains

2019 ◽  
Vol 6 (3) ◽  
pp. 181729 ◽  
Author(s):  
Nihav Dhawale ◽  
Shreyas Mandre ◽  
Madhusudhan Venkadesan
Keyword(s):  
Sensory Feedback ◽  
Dimensionless Parameter ◽  
Sagittal Plane ◽  
Sensory Information ◽  
Open Loop ◽  
Rough Terrain ◽  
Two Dimensional ◽  
Flat Surfaces ◽  
And Control ◽  
Flat Ground

Stability of running on rough terrain depends on the propagation of perturbations due to the ground. We consider stability within the sagittal plane and model the dynamics of running as a two-dimensional body with alternating aerial and stance phases. Stance is modelled as a passive, impulsive collision followed by an active, impulsive push-off that compensates for collisional losses. Such a runner has infinitely many strategies to maintain periodic gaits on flat ground. However, these strategies differ in how perturbations due to terrain unevenness are propagated. Instabilities manifest as tumbling (orientational instability) or failing to maintain a steady speed (translational instability). We find that open-loop strategies that avoid sensory feedback are sufficient to maintain stability on step-like terrains with piecewise flat surfaces that randomly vary in height. However, these open-loop runners lose orientational stability on rough terrains whose slope also varies randomly. The orientational instability is significantly mitigated by minimizing the tangential collision, which typically requires sensory information and anticipatory strategies such as leg retraction. By analysing the propagation of perturbations, we derive a single dimensionless parameter that governs stability. This parameter provides guidelines for the design and control of both biological and robotic runners.

FORCED TORSIONAL VIBRATIONS IN THE PRESENCE OF RESISTANCE FORCES

2015 ◽  
Vol 8 (1) ◽  
pp. 9-11
Author(s):  
Беляев ◽  
Aleksandr Belyaev ◽  
Тришина ◽  
Tatyana Trishina
Keyword(s):  
Differential Equations ◽  
Mechanical System ◽  
Elastic Properties ◽  
Mechanical Systems ◽  
Torsional Vibrations ◽  
Rational Selection ◽  
Torsional Oscillations ◽  
Properties Of Materials ◽  
Resistance Forces ◽  
Selection Of

The work proposed differential equations describing the torsional oscillations of one- and two-mass mechanical systems taking into account the dissipative losses of various kinds and nature. The dependences for determining the equivalent rigidity of the elastic ties. Using the results of these studies can be realized rational selection of inertial and elastic properties of materials and components damper mechanical system

Potters Make Shorter Pots Under Conditions of Reduced Sensory Input

Perception ◽  
2018 ◽  
Vol 47 (8) ◽  
pp. 860-872
Author(s):  
Mounia Ziat ◽  
Min Park ◽  
Brian Kakas ◽  
David A. Rosenbaum
Keyword(s):  
Visual Feedback ◽  
Sensory Feedback ◽  
Sensory Input ◽  
Perception And Action ◽  
Behavioral Research ◽  
Control Hypothesis ◽  
Clay Pots ◽  
Do So

Although people have made clay pots for millennia, little behavioral research has explored how they do so. We were specifically interested in potters’ use of auditory, haptic, and visual feedback. We asked what would happen if one or two of these sources of feedback were removed and potters tried to create pots of a given height, stopping when they thought they had reached that height. We asked students in a pottery class to build simple clay vessels either when they had full sensory feedback (in the control condition for all participants) or when they had reduced input from one modality (in Experiment 1) or two modalities (in Experiment 2). Participants were asked to stop building the vessels when they thought the vessels were 5 in. high. We found that participants produced shorter vessels when one or more forms of sensory feedback was reduced. The degree of shortening did not depend on the type or number of reduced sensory channels. The results are consistent with a control hypothesis where potters must have learned how to use sensory feedback from the modalities to help them control their ceramic creations. The results help highlight the importance of the intimate connections between perception and action.

Continuous mobility of mobile robots with a special ability for overcoming driving failure on rough terrain

Robotica ◽  
2016 ◽  
Vol 35 (10) ◽  
pp. 2076-2096
Author(s):  
He Xu ◽  
X. Z. Gao ◽  
Yan Xu ◽  
Kaifeng Wang ◽  
Hongpeng Yu ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Driving Force ◽  
Failure Modes ◽  
Sliding Mode ◽  
Rough Terrain ◽  
Force Analysis ◽  
Uncertain Environments ◽  
Wheeled Mobile Robots ◽  
Robot Configuration

SUMMARYFor wheeled mobile robots moving in rough terrains or uncertain environments, driving failure will be encountered when trafficability failure occurs. Continuous mobility of mobile robots with special ability for overcoming driving failure on rough terrain has rarely been considered. This study was conducted using a four-wheel-steering and four-wheel-driving mobile robot equipped with a binocular visual system. First, quasi-static force analysis is carried out to understand the effects of different driving-failure modes on the mobile robot while moving on rough terrain. Secondly, to make the best of the rest of the driving force, robot configuration transformation is employed to select the optimal configuration that can overcome the driving failure. Thirdly, sliding mode control based on back-stepping is adopted to enable the robot achieve continuous trajectory tracking with visual feedback. Finally, the efficacy of the presented approach is verified by simulations and experiments.

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