742 research outputs found
Review article: locomotion systems for ground mobile robots in unstructured environments
Abstract. The world market of mobile robotics is expected to increase substantially in the next 20 yr, surpassing the market of industrial robotics in terms of units and sales. Important fields of application are homeland security, surveillance, demining, reconnaissance in dangerous situations, and agriculture. The design of the locomotion systems of mobile robots for unstructured environments is generally complex, particularly when they are required to move on uneven or soft terrains, or to climb obstacles. This paper sets out to analyse the state-of-the-art of locomotion mechanisms for ground mobile robots, focussing on solutions for unstructured environments, in order to help designers to select the optimal solution for specific operating requirements. The three main categories of locomotion systems (wheeled - W, tracked - T and legged - L) and the four hybrid categories that can be derived by combining these main locomotion systems are discussed with reference to maximum speed, obstacle-crossing capability, step/stair climbing capability, slope climbing capability, walking capability on soft terrains, walking capability on uneven terrains, energy efficiency, mechanical complexity, control complexity and technology readiness. The current and future trends of mobile robotics are also outlined
Design of a self-leveling cam mechanism for a stair climbing wheelchair
This paper presents a new version of Wheelchair.q, a wheelchair with stair climbing ability. The wheelchair is able to climb single obstacles or staircases thanks to a hybrid wheel-leg locomotion unit with a triple-wheels cluster architecture. The new concept presented in this work represents an improvement respect to previous versions. Through a different arrangement of functional elements, the wheelchair performances in terms of stability and regularity during movement on stair have been increased. In particular, attention has been paid to ensure a regular and comfortable motion for the user during stair climbing operation. For this reason, a cam mechanism has been introduced and designed with the aim to compensate the oscillation generated on the wheelchair frame by the locomotion unit rotation. A design methodology for the cam profile is presented. Moreover, a parametric analysis on the cam profile and on the mechanism dimensions has been conducted with the aim to find a cam profile with suitable dimensions and performances in terms of pressure angle and radius of curvature
Performance Analysis of Low-Cost Tracking System for Mobile Robots
This paper proposes a reliable and straightforward approach to mobile robots (or moving objects in general) indoor tracking, in order to perform a preliminary study on their dynamics. The main features of this approach are its minimal and low-cost setup and a user-friendly interpretation of the data generated by the ArUco library. By using a commonly available camera, such as a smartphone one or a webcam, and at least one marker for each object that has to be tracked, it is possible to estimate the pose of these markers, with respect to a reference conveniently placed in the environment, in order to produce results that are easily interpretable by a user. This paper presents a simple extension to the ArUco library to generate such user-friendly data, and it provides a performance analysis of this application with static and moving objects, using a smartphone camera to highlight the most notable feature of this solution, but also its limitations
Static balancing of planar articulated robots
Static balancing for a manipulator’s weight is
necessary in terms of energy saving and performance
improvement. This paper proposes a method to design
balancing devices for articulated robots in industry, based
on robotic dynamics. Full design details for the balancing
system using springs are presented from two aspects: One
is the optimization for the position of the balancing system;
the other is the design of the spring parameters. As
examples, two feasible balancing devices are proposed,
based on different robotic structures: The first solution
consists of linkages and springs; the other consists of
pulleys, cross mechanisms and (hydro-) pneumatic
springs. Then the two solutions are compared. Pneumatic,
hydro-pneumatic and mechanical springs are discussed
and their parameters are decided according to the
requirements of torque compensation. Numerical results
show that with the proper design using the methodology
presented in this paper, an articulated robot can be
statically balanced perfectly in all configurations. This
paper therefore provides a design method of the balancing
system for other similar structures
A comparison between two pneumatic suspension architectures
The aim of this work is to assess and compare the mathematical models of two pneumatic suspension architectures and show how they can converge, after appropriate simplifications, to a general linear form. After making this model dimensionless, it will be used to study, with a transmissibility analysis, the behaviour of a mono-suspension (quarter-car model). Finally, an example of a design process will be shown to highlight the strengths and weaknesses of both architectures and to provide the reader with a practical design too
Float-ram: a new human powered press for earth blocks
The Float-Ram is a novel kind of human-powered press for raw earth blocks. It is able to provide
very high performance, while maintaining a limited cost, due to some technical characteristics like:
•the adoption of a floating mould, which provides a bi-directional pressing action in simple way;
•Optimized kinematic structure, based on a cam-roller transmission system;
•General mechanical simplicity, since the node of all kinematic pairs is constituted by a single shaft.
Therefore the Float-Ram can be considered as an important media for the diffusion of high-quality raw earth
building in developing Countries
Evolution of Wheelchair.q, a Stair-climbing Wheelchair
This paper presents a solution for a
stair-climbing wheelchair that can climb single steps or
entire staircases. This device was designed in order to
ensure greater autonomy for people with reduced mobility .
The main component of the wheelchair structure is a
three-wheel locomotion unit that allows obstacle climbing
thanks to an epicycloidal transmission. The other
characteristic element is an idle track that behaves like a
second foothold giving static stability during
stair-climbing.
Another important feature concerned with this design is a
reconfiguration mechanism that makes the wheelchair
suitable both for stair-climbing and for moving on flat
ground. This feature allows performances and overall
dimensions comparable to traditional electric wheelchairs.
The choice and design of the mechanisms for the
reconfiguration phase are the main topics discussed in this
article and represent the principal innovations of this
wheelchair compared to earlier versions
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