Sensory feedback plays a significant role in generating walking gait and in gait transition in salamanders: a simulation study

Quadruped animals achieve agile and highly adaptive locomotion owing to the coordination between their legs and other body parts, such as the trunk, head, and tail, that is, body–limb coordination. This study aims to understand the sensorimotor control underlying body–limb coordination. To this end, we adopted sprawling locomotion in vertebrate animals as a model behavior. This is a quadruped walking gait with lateral body bending used by many amphibians and lizards. Our previous simulation study demonstrated that cross-coupled sensory feedback between the legs and trunk helps to rapidly establish body–limb coordination and improve locomotion performance. This paper presented an experimental validation of the cross-coupled sensory feedback control using a newly developed quadruped robot. The results show similar tendencies to the simulation study. Sensory feedback provides rapid convergence to stable gait, robustness against leg failure, and morphological changes. Our study suggests that sensory feedback potentially plays an essential role in body–limb coordination and provides a robust, sensory-driven control principle for quadruped robots.

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EFFECT OF CHLORINATION ON PHOTOLUMINESCENCE PROPERTIES OF POROUS SILICON

International Journal of Nanoscience ◽

10.1142/s0219581x07004249 ◽

2007 ◽

Vol 06 (01) ◽

pp. 17-22

Author(s):

B. NATARAJAN ◽

V. RAMAKRISHNAN ◽

V. VASU ◽

S. RAMAMURTHY

Keyword(s):

Porous Silicon ◽

Analytical Solution ◽

Significant Role ◽

Simulation Study ◽

Surface Passivation ◽

Photoluminescence Properties ◽

Emission Efficiency ◽

Capacitance Method ◽

P Type ◽

Effect Of Surface

The surface passivation of porous silicon plays a significant role in emission efficiency of the material. Photoluminescence (PL) studies were carried out for p-type porous silicon and chlorinated porous silicon to understand the effect of surface passivation on porous silicon. Visible photoluminescence was observed at 625 nm for both porous silicon and chlorinated porous silicon. The whole sample exhibits a PL band at red region and intensity decreased in chlorinated porous silicon. This paper presents an analytical solution that covers contributions from the components of silicon tetra chloride interface, silicon backbone, and voids using a serial–parallel capacitance method. Simulation study indicates that there is a good correlation between theory and observed PL.

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Robust Control of Semi-passive Biped Dynamic Locomotion based on a Discrete Control Lyapunov Function

Robotica ◽

10.1017/s0263574719001504 ◽

2019 ◽

Vol 38 (8) ◽

pp. 1345-1358

Author(s):

Chengju Liu ◽

Jing Yang ◽

Kang An ◽

Ming Liu ◽

Qijun Chen

Keyword(s):

Robust Control ◽

Lyapunov Function ◽

Control Method ◽

External Disturbance ◽

Discrete Control ◽

Gait Transition ◽

Control Lyapunov Function ◽

Walking Gait ◽

Foot Strike ◽

Passive Model

SUMMARYThis paper focuses on robust control of a simplest passive model, which is established on a DCLF (discrete control Lyapunov function) -based control system, and presents gait transition method based on the study of purely passive walker. Firstly, the DCLF is introduced to stabilize walking process between steps exponentially by modulating the length of next step. Next, the swing leg trajectory from mid-stance position to foot-strike can be planned. Then the control law is calculated to resist external disturbance. Besides, an impulse is added just before foot-strike to realize a periodic walking pattern on flat or uphill ground. With walking terrain varying, the robot can transit to an adaptive walking gait in a few steps. With different push or pull disturbances acting on hip joint and the robot gait transiting on a continuously slope-changing downhill, the effectiveness of the presented DCLF-based method is verified using simulation experiments. The ability to walk on a changing environment is also presented by simulation results. The insights of this paper can help to develop a robust control method and adaptive walking of dynamic passive locomotion robots.

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Realization of 485 Level Inverter Using Tri-State Architecture for Renewable Energy Systems

Energies ◽

10.3390/en13246627 ◽

2020 ◽

Vol 13 (24) ◽

pp. 6627

Author(s):

Vijayaraja Loganathan ◽

Ganesh Kumar Srinivasan ◽

Marco Rivera

Keyword(s):

Renewable Energy ◽

Significant Role ◽

Direct Current ◽

Simulation Study ◽

Output Voltage ◽

Single Phase ◽

Energy Systems ◽

Experimental Setup ◽

Renewable Energy Systems ◽

The Cost

In this paper, a ‘k’-state inverter producing a higher number of voltage levels was designed, and we studied the inverter’s working. Further, a tri-state inverter was derived from the ‘k’-state inverter, which could build a maximum number of output voltage levels with the requirement of fewer components, thereby reducing the cost and size. A single Tri-state architecture generates three direct current (D.C.) voltage levels; therefore, cascading five tri-state architectures can generate 242 levels of DC voltages. Further, the inversion is done via the H bridge, which leads to 485 levels of the output voltage. Algorithms to design the amplitude of voltage sources and the generation of pulses are discussed in this paper. The proposed tri-state inverter takes a significant role in advancing renewable energy systems in utilizing inverter technology. A simulation study validated the operation of the proposed inverter. Moreover, an experimental setup was built for a single-phase 485-level inverter, and the structure’s performance was verified through the experimental results.

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