Dynamic simulation of insect walking

Ekeberg, Örjan; Blümel, Marcus; Büschges, Ansgar

doi:10.1016/j.asd.2004.05.002

Cited by 135 publications

(156 citation statements)

References 34 publications

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“…The nervous system must exert its effects through the existing dynamics [5,23], and here we have discovered that this neuromechanical coupling can reveal unexpected control functions even at the level of individual muscles. During slow locomotion, simulations of neural feedback acting through a set of coordination rules have had success in capturing locomotion in quasi-static regimes, including walking, gap crossing and foothold searching [8,10,47,49,50]. For posture control tasks, the linear control potentials of the ventral femoral extensor (figure 3a) support the simple transfer functions in these models.…”

Section: Discussionmentioning

confidence: 99%

A single muscle's multifunctional control potential of body dynamics for postural control and running

Sponberg

Spence

Mullens

et al. 2011

Phil. Trans. R. Soc. B

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A neuromechanical approach to control requires understanding how mechanics alters the potential of neural feedback to control body dynamics. Here, we rewrite activation of individual motor units of a behaving animal to mimic the effects of neural feedback without concomitant changes in other muscles. We target a putative control muscle in the cockroach, Blaberus discoidalis (L.), and simultaneously capture limb and body dynamics through high-speed videography and a microaccelerometer backpack. We test four neuromechanical control hypotheses. We supported the hypothesis that mechanics linearly translates neural feedback into accelerations and rotations during static postural control. However, during running, the same neural feedback produced a nonlinear acceleration control potential restricted to the vertical plane. Using this, we reject the hypothesis from previous work that this muscle acts primarily to absorb energy from the body. The conversion of the control potential is paralleled by nonlinear changes in limb kinematics, supporting the hypothesis that significant mechanical feedback filters the graded neural feedback for running control. Finally, we insert the same neural feedback signal but at different phases in the dynamics. In this context, mechanical feedback enables turning by changing the timing and direction of the accelerations produced by the graded neural feedback.

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Section: Discussionmentioning

confidence: 99%

A single muscle's multifunctional control potential of body dynamics for postural control and running

Sponberg

Spence

Mullens

et al. 2011

Phil. Trans. R. Soc. B

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show abstract

“…While these models replicate basic joint kinematics [38], some control aspects may have to be revised to account for the joint torques in free walking. One aspect concerns the timing of step phase transitions.…”

Section: (C) Implications Of Joint Torques For Models Of Walking Controlmentioning

confidence: 99%

“…In current control models, joint torques are generated assuming distinct states of antagonistic neural activity [8,38]. These states of activity are thought to reflect joint kinematics, in that for example leg retraction and extension are generated by retraction and extension torques.…”

Section: (C) Implications Of Joint Torques For Models Of Walking Controlmentioning

confidence: 99%

Joint torques in a freely walking insect reveal distinct functions of leg joints in propulsion and posture control

2016

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Determining the mechanical output of limb joints is critical for understanding the control of complex motor behaviours such as walking. In the case of insect walking, the neural infrastructure for single-joint control is well described. However, a detailed description of the motor output in form of time-varying joint torques is lacking. Here, we determine joint torques in the stick insect to identify leg joint function in the control of body height and propulsion. Torques were determined by measuring whole-body kinematics and ground reaction forces in freely walking animals. We demonstrate that despite strong differences in morphology and posture, stick insects show a functional division of joints similar to other insect model systems. Propulsion was generated by strong depression torques about the coxatrochanter joint, not by retraction or flexion/extension torques. Torques about the respective thorax-coxa and femur-tibia joints were often directed opposite to fore-aft forces and joint movements. This suggests a posturedependent mechanism that counteracts collapse of the leg under body load and directs the resultant force vector such that strong depression torques can control both body height and propulsion. Our findings parallel propulsive mechanisms described in other walking, jumping and flying insects, and challenge current control models of insect walking.

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“…2) lie decades of careful empirical study on invertebrate walking [17] that have yielded algorithmic prescriptions less familiar to optimal control theory, but readily studied using the tools of dynamical systems theory [11,48] and demonstrably capable of coordinating complex multi-limbed locomotion in physical [13] models operating in the quasi-static regime. Yet recent experiments have identified [10] and simulation studies confirmed the important role of feedforward pattern generators in the walking behavior of this animal model [21]. In contrast, early models of rhythmic vertebrate behavior suggested the prominence of a strongly centralized feedforward CPG signal [34], whereas recent studies [35] have revealed a more nuanced balance between feedforward and feedback influences.…”

Section: Neuromechanical Control Architectures (Nca)mentioning

confidence: 94%