Experimental-Numerical Comparison of Contact Nonlinear Dynamics Through Multi-level Linear Mode Shapes

Bonisoli, Elvio; Lisitano, Domenico; Conigliaro, C.

doi:10.1007/978-3-030-12391-8_38

Cited by 2 publications

(1 citation statement)

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“…The human-like locomotion of the Robot is simulated imposing alternately the traction longitudinal force to Rollo's feet, i.e., a time dependent input forces f according to the robot steps. The first order ordinary differential equation Equation (A2) is efficiently solved using the superimposition principle in modal coordinates [42,57], i.e., solving 2n uncoupled equations in modal coordinates η and then applying direct modal transformation y = ψη to obtain the system evolution if the physical coordinates x. However, the locomotion simulation is a non-classically damped problem, because of the localized dampers presence at the wheel floor contact.…”

Section: Discussionmentioning

confidence: 99%

Dynamic Balance of the Head in a Flexible Legged Robot for Efficient Biped Locomotion

et al. 2021

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In the biped robotics domain, head oscillations may be extremely harmful, especially if the robot is teleoperated, since vibrations strongly reduce the operator’s spatial awareness. In particular, undesired head oscillations occur in under-actuated robots, where springs and passive mechanisms are used to achieve a human-like motion. This paper proposes an approach to reduce the vibrations of a biped robot’s head; the proposed solution does not affect the dynamic locomotion properties, on which specific control logic could have been already tuned. The approach is tested on Rollo, a flexible-biped-wheeled robot, whose head vibrates throughout the robot locomotion. The two requirements, i.e., head vibration reduction and unchanged Rollo locomotion properties, are traduced in constraints to the robot possible modifications. Based on a 1D finite element model of the robot, tuned on experimental modal analysis, the undesired vibration causes are detected, and a solution for their reduction is proposed. Rollo’s head vibration amplitude is attenuated using a tuned vibration absorber, which achieves impressive performance in the robot. An archetype of the proposed vibration absorber is tailored designed on Rollo, without invasive changes to the robot structure. The proposed approach solves a significant problem in the biped robotic research community. The approach used to reduce the Rollo head oscillations may be utilized in other biped robot machines with or without flexible legs.

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Section: Discussionmentioning

confidence: 99%