Development of Small Robot with Inline Archimedean Screw Mechanism that Can Move Through Wetlands

This paper deals with manipulator systems comprising a long-reach manipulator (LRM) with a short-reach dextrous manipulator (SRM) attached to its end. The former, due to its size, is assumed to have significant structural flexibility, while the latter is modeled as a rigid robot. The particular problem addressed is that of active damping, or vibration suppression, of the LRM by using SRM specifically for that purpose Such a scenario is envisioned for operations where the large manipulator is used to deploy the small robot and it is necessary to damp out vibrations in LRM prior to operating SRM. The proposed solution to the problem uses the reaction force from SRM to LRM as a control variable which allows to effectively decouple the controller design problems for the two manipulators. A two-stage controller is presented that involves first, determining the trajectory of the short manipulator required to achieve a desired damping wrench to the supporting flexible arm and subsequently, brings the small manipulator to rest. Performance of the active damping algorithm developed is illustrated with a six-degree-of-freedom rigid manipulator on a flexible mast. Comparison to an independent derivative joint controller is included. The paper also discusses how the proposed methodology can be extended to address other issues related to operation of long-reach manipulator systems.

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Survey of SLAM in Low-Resourced Hardware

IJAIT (International Journal of Applied Information Technology) ◽

10.25124/ijait.v3i01.1307 ◽

2019 ◽

Vol 3 (01) ◽

pp. 1

Author(s):

Ismail Ismail

Keyword(s):

Power Supply ◽

Current Work ◽

Design Solution ◽

Main Question ◽

Computational Power ◽

Low Resource ◽

Survey Paper ◽

Limited Power ◽

Small Robot ◽

Robot Platform

Many of researches in SLAM are targeting desktops or laptop computers. Mounted in a robot platform such as Pioneer, these high computational power hardware do all the processing in SLAM. Still others, SLAM algorithms exploit GPU power to provide deep details in map reconstruction. Yet, it is desirable to deploy SLAM in a small robot without advantages from high computational power hardware. Single board computer with limited power supply and low computational power is frequently the main board available in a small robot. Therefore, it is important to consider the design solution of SLAM that targets such a system. With this in mind, current work presents a survey paper of SLAM in low-resource hardware. The main question to be answered with this current work is "How researchers deal with hardware limitation when implementing SLAM?" Classification based on a method to tackle the problem is presented as the conclusion of this paper.

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Tribological Design Challenges of a Space Grade Lead Screw Mechanism

10.2514/6.2022-0034 ◽

2022 ◽

Author(s):

Christopher Worsdale

Keyword(s):

Lead Screw ◽

Screw Mechanism ◽

Design Challenges

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Dynamic Modeling of the Double-Nut Planetary Roller Screw Mechanism Considering Elastic Deformations

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4050613 ◽

2021 ◽

Author(s):

Xiaojun Fu ◽

Geng Liu ◽

Xin Li ◽

Ma Shangjun ◽

Qiao Guan

Keyword(s):

External Force ◽

Load Distribution ◽

Equations Of Motion ◽

Great Influence ◽

Compressive Force ◽

Mass System ◽

Elastic Deformations ◽

Roller Screw ◽

Screw Mechanism ◽

Nonlinear Equations Of Motion

Abstract With the rising application of double-nut Planetary Roller Screw Mechanism (PRSM) into industry, increasing comprehensive studies are required to identify the interactions among motion, forces and deformations of the mechanism. A dynamic model of the double-nut PRSM with considering elastic deformations is proposed in this paper. As preloads, inertial forces and elastic deformations have a great influence on the load distribution among threads, the double-nut PRSM is discretized into a spring-mass system. An adjacency matrix is introduced, which relates the elastic displacements of nodes and the deformations of elements in the spring-mass system. Then, the compressive force acting on the spacer is derived and the equations of load distribution are given. Considering both the equilibrium of forces and the compatibility of deformations, nonlinear equations of motion for the double-nut PRSM are developed. The effectiveness of the proposed model is verified by comparing dynamic characteristics and the load distribution among threads with those from the previously published models. Then, the dynamic analysis of a double-nut PRSM is carried out, when the rotational speed of the screw and the external force acting on the nut #2 are changed periodically. The results show that if the external force is increased, the preload of the nut #1 is decreased and that of the nut #2 is increased. Although the nominal radii of rollers are the same, the maximum contact force acting on the roller #2 is much larger than that of the roller #1.

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