A Gap Metric Approach for Controller Certification of a Hydraulically-Actuated Legged Robot

Author(s):  
Jose Luiz Montandon Neto ◽  
Thiago Boaventura
Author(s):  
Emanuele Guglielmino ◽  
Ferdinando Cannella ◽  
Claudio Semini ◽  
Darwin G. Caldwell ◽  
Nestor Eduardo Nava Rodri´guez ◽  
...  

This paper presents a study on the impact of the vibration on a hydraulically-actuated legged robot designed for outdoor operations. The choice of using hydraulic actuation in lieu of electric actuation as is common in robotics has been driven by the need to cope with heavy loads and respond swiftly to external inputs and disturbances. However in such machines hydraulically-induced vibration (fluid borne noise and structure borne noise) is a major issue. Volumetric pumpmotor assembly is a primary cause of vibration. These are transmitted to the robotic structure, which has been designed as light as possible to minimise the robot’s total weight and power consumption and make it more agile. Initially a multi-body analysis of the robot was carried out to select an appropriate vibration isolation system. Subsequently a numerical and experimental modal analysis was carried out on the structure. The latter was carried with modal hammer tests and pump running tests. This has allowed identifying the main modes of vibration of the structure. The pros and cons of this approach are described and areas of improvements identified.


2013 ◽  
Vol 133 (3) ◽  
pp. 663-671
Author(s):  
Hiroshi Hirata ◽  
Yorinao Mizushima ◽  
Shigeto Ouchi ◽  
Nariyuki Kodani

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3679
Author(s):  
Dingkui Tian ◽  
Junyao Gao ◽  
Xuanyang Shi ◽  
Yizhou Lu ◽  
Chuzhao Liu

The highly dynamic legged jumping motion is a challenging research topic because of the lack of established control schemes that handle over-constrained control objectives well in the stance phase, which are coupled and affect each other, and control robot’s posture in the flight phase, in which the robot is underactuated owing to the foot leaving the ground. This paper introduces an approach of realizing the cyclic vertical jumping motion of a planar simplified legged robot that formulates the jump problem within a quadratic-programming (QP)-based framework. Unlike prior works, which have added different weights in front of control tasks to express the relative hierarchy of tasks, in our framework, the hierarchical quadratic programming (HQP) control strategy is used to guarantee the strict prioritization of the center of mass (CoM) in the stance phase while split dynamic equations are incorporated into the unified quadratic-programming framework to restrict the robot’s posture to be near a desired constant value in the flight phase. The controller is tested in two simulation environments with and without the flight phase controller, the results validate the flight phase controller, with the HQP controller having a maximum error of the CoM in the x direction and y direction of 0.47 and 0.82 cm and thus enabling the strict prioritization of the CoM.


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