Dynamic Simulation of Autonomous Boats for Cooperative Skimming and Cleanup

2013 ◽  
Author(s):  
Soonkyum Kim ◽  
Subhrajit Bhattacharya ◽  
Vijay Kumar
Keyword(s):  
Dynamic Simulation ◽  
Complementarity Constraints ◽  
Multiple Objects ◽  
Drag Forces ◽  
Revolute Joints ◽  
Control Schemes ◽  
Efficient Control ◽  
Towed Cable ◽  
A Chain ◽  
Linear Complementarity Constraints

We consider the use of autonomous boats for oil skimming and clean up of surface debris by operating two boats with a boom cooperatively. A boom, or a cable as considered in this paper, attached to two robots at each end can be used to efficiently manipulate multiple objects on the surface of the water. In our previous work, Bhattacharya, et al. (ICRA 2011), we showed the feasibility of this concept with an experimental testbed using two autonomous boats and a towed cable. This work showed that an accurate dynamic simulation of the system is indispensable in analysis and development of efficient control schemes. For the purpose of manipulating objects in such a way, not only do we need to model the drag forces, but we also need to model the interaction between the cable and the objects. In this paper we model the boom or the cable as a chain with a discrete number of rigid links connected by passive revolute joints and model the interaction of the cable with the water (drag) as well as the contacts with objects on the surfaces. We derive the equations governing the cable and object dynamics and model the contact interactions as linear complementarity constraints. The boats are driven by simple controllers that only require knowledge of positions and velocities at the both ends of the cable. Several examples are used to illustrate the performance of the numerical simulation.

Research on Dynamic Simulation of AUV Launching a Towed Navigation Buoyage

2013 ◽  
Vol 433-435 ◽  
pp. 1170-1174
Author(s):  
Guang Pan ◽  
Zhi Dong Yang ◽  
Xiao Xu Du
Keyword(s):  
Angular Momentum ◽  
Boundary Conditions ◽  
Dynamic Simulation ◽  
Numerical Scheme ◽  
Mathematic Model ◽  
Dynamic Equations ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Towed Cable ◽  
Undersea Vehicle

A mathematic model was established to simulate the process of AUV (autonomous undersea vehicle) launching a towed buoyage. Based on the lumped mass method and moment theorem and angular momentum theorem, dynamic equations of the cable and the buoyage were developed, respectively. Then the boundary conditions and the numerical scheme to deal with the cable with non-fixed length were presented. Moreover, the process of AUV launching a towed cable was simulated. By using the model, the results show the trajectory of buoyage and shape of towed cable can be well predicted.

Design and Analysis of Reduced Degree of Freedom Modular Snake Robot

2017 ◽  
Author(s):  
Peter Racioppo ◽  
Wael Saab ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Three Dimensional ◽  
Cross Sectional ◽  
Design Synthesis ◽  
Snake Robot ◽  
Routing Schemes ◽  
Revolute Joints ◽  
Modular Units ◽  
A Chain ◽  
The Moment ◽  
And Control

This paper presents the design and analysis of an underactuated, cable driven mechanism for use in a modular robotic snake. The proposed mechanism is composed of a chain of rigid links that rotate on parallel revolute joints and are actuated by antagonistic cable pairs and a multi-radius pulley. This design aims to minimize the cross sectional area of cable actuated robotic snakes and eliminate undesirable nonlinearities in cable displacements. A distinctive feature of this underactuated mechanism is that it allows planar serpentine locomotion to be accomplished with only two modular units, improving the snake’s ability to conform to desired curvature profiles and minimizing the control complexity involved in snake locomotion. First, the detailed mechanism and cable routing scheme are presented, after which the kinematics and dynamics of the system are derived and a comparative analysis of cable routing schemes is performed, to assist with design synthesis and control. The moment of inertia of the mechanism is modeled, for future use in the implementation of three-dimensional modes of snake motion. Finally, a planar locomotion strategy for snake robots is devised, demonstrated in simulation, and compared with previous studies.

Synthesizing Mechanical Chains for Morphing Between Spatial Curves

2019 ◽  
Author(s):  
Yucheng Li ◽  
Andrew P. Murray ◽  
David H. Myszka
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
Revolute Joints ◽  
Morphometric Analyses ◽  
Helical Segment ◽  
Varying Length ◽  
A Chain ◽  
Curvature And Torsion ◽  
Synthesis Methodology ◽  
Spatial Curves

Abstract This work investigates the kinematic synthesis methodology for designing a chain of three-dimensional bodies to match a set of arbitrary spatial curves. The bodies synthesized can be one of three types: a rigid segment, a helical segment with constant curvature and torsion but varying length, and a growth segment that maintains its geometry but may be scaled to become larger or smaller. To realize mechanical chains, only rigid and helical segments are used. After designing the segments, they may be aligned with the original spatial curves with their ends connected via an optimization. For two curves, these connections may be made with revolute joints to obtain high accuracy. For three or more curves, spherical joint connections allow for the best accuracy. To compare curves as is useful in morphometry, all three segment types may be employed. In this case, an accurate description of the changes between curves is important, and optimizing to connect the segments is not needed. The procedure for redefining the curves in a way that the techniques in this paper may be applied, as well as the methodologies for synthesizing the three segment types are presented. Examples include a continuum robot problem and the morphometric analyses of chochlear curves and the lambdoidal suture. This work extends the established planar techniques for synthesizing mechanisms and addressing morphometric issues that are motivated with curves in two-dimensions.

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