Electrical Power Sources for Mobile Robots

Electrical power is the most common source of energy in mobile robotics. Electrical power systems are cheap, practical, easy to implement and can be used in any environment – even indoors, as no pollution takes place locally. However electricity is used up at some time, at this point shortcomings of these systems come into play, long recharging times or bulkiness for large capacity systems to name just a few. A way to constantly regenerate power, or at least to slow down depletion of energy resources is needed. In the following we will take a look at elements which could be used to build electrical power sources for robots.

 

Rechargeable Batteries

Lead-Acid (Pb-Acid) Battery

The rechargeable battery, or secondary cell, that can be recharged by reversing the chemical reaction has been invented in 1859 by french physicist Gaston Plante. Plante’s cell was the lead-acid battery, used on a massive scale nowadays. The lead-acid battery has three or six cells, with a voltage of 2V per cell, connected in series and it is used in a wide range of vehicles, from automobiles or bikes to airplanes. Its great advantage is that it can provide strong current to start an engine even though its capacity is limited.

Lead-acid battery inner structure

Lead-acid battery cells

The electrolyte is a diluted sulphuric acid solution, the negative electrode is made of lead and the positive electrode is made of lead dioxide. During use the negative electrode is separated into electrons and positive lead ions. The electrons pass through the external electrical circuit while the positive ions combine with sulfate ions in the electrolyte and form lead sulfate. When electrons reenter the cell at the positive electrode another chemical reaction takes place, the lead dioxide combines with hydrogen ions in the electrolyte to form water, releasing lead ions into the electrolyte to form again lead sulfate. Continue reading (…)

How to Build a Simple Differential Wheeled Mobile Robot System

If you’re passionate about Robotics and have always wanted to build your own mobile robot, this might be a good starting point. From physically building the robot platform, to setting up, programming and hardware or software fine tuning, while not necessarily difficult everything needs to be taken into account. In this article you can find out how to make a simple robot with two independently motorized wheels and basic sensors to avoid obstacles or follow certain targets, as well as learn about general rules that need to be followed when putting together such a project, regardless of the platform employed or the technical build solution.

Building blocks of a mobile robot

A mobile robot can be regarded essentially as an ensemble of five main parts and subsystems, as discussed below.

Simple wheeled mobile robot platform

A wheeled mobile robot platform

The Platform

This would be the main part of a robot’s body, its chassis, designed to carry all of the other components, transmission mechanisms, electronics and so on. It needs to be sufficiently large and provide adequate fixtures to accommodate all necessary parts as well as sturdy enough to cope with the weight of the parts as well as with additional loads which can appear in dynamic conditions such as vibrations, shocks or chassis torsion (e.g. when traveling over rough terrain), actuators torque, supplementary weight to be picked up and so on.
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I Find a lot of Inspiration in Robotic Design Concepts

Imagination is never-ending, concepts surfacing in the robotics field reveal interesting ideas which can be an inspiration source for future projects.

From idea to final product the road is often full of obstacles, but everything starts with an idea and eventually ends as a product on the shelves of stores. The images presented in this article include robotic concepts drawn in shapes that seem to disregard any rule. From abstract concepts to uncommon characteristics, these examples of robotic design concepts are meant to inspire and to give impetus to future projects.

We’re awaiting comments and concepts based on your ideas.

01. ParcelRobot

02. Beetle

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Robotic Hands with the Nearest Approach to the Human Hand

Is there life without hands? Yes, certainly, but it would look very different if we didn’t have hands. A hand is the main tool used in manipulation of objects with various sizes and different weights. Each finger has its own role to make a functional hand, it can move independently, can feel and can adopt a position to accomplish different tasks. Human structure is the largest and the best source of inspiration for researchers and engineers in robotics, as they are trying to create an universal robotic hand to be used for most tasks, a hand that could not look or work differently than the human hand.

To build the perfect robotic hand researchers and engineers need to replace bones, tendons, muscles and nerves with metal, plastic and electricity. In addition to all these things, engineers should build a mechanism with the same dimensions, proportions and senses. If replication of the hand is almost complete, there is still a long way for researchers and engineers to solve the interaction between brain and hand for a robot.

In this article I made a list with best created anthropomorphic hands to date.

DART

DART (Dexterous Anthropomorphic Robotic Typing) is a project that took shape at Virginia Tech, a robotic hand that imitates almost entirely the performance, shape and form of a human hand. Perhaps it is hard to imagine a robot in front of a computer, but if the robot would have a DART hand it would certainly type on a computer keyboard like a human – 20 words per minute. A human can type with both hands an average of 3 words per minute, while one DART hand can type 20 wpm plus the use of keys like delete or backspace.

Hand muscles were replaced with 16 servo motors for fingers and another three motors for wrist motion. Tendons were replaced with wires and are located in the forearm. Continue reading (…)

Useful Tools for Drawing Electrical Circuits

Before implementing a circuit, a graphical representation brings benefit but also disadvantages for developers. As a positive aspect, graphical representation of electronic circuits creates an overview of the components used and how they are connected. Such representation is also a great way to draw attention on details that require changes which would increase the cost of production and the time required to create a physical circuit prototype.

The negative side, circuit sensitivity can influence the outcome of the work, for example external noise cannot be fully known or taken into account when creating wiring schematics and this can lead to errors or results not fully predictable in the physical implementation of the circuit however there are several software tools that do offer pretty accurate simulation features. In this article you can find an overview of CAD software tools designed for creating and modifying electrical schematics, circuit diagrams as well as designing production-ready PCB modules.

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How the PR2 Robotic Platform Works

I have an idea for a complex robot and I don’t have one around me as a platform. What can I do? I have two options: to lose precious time to build one or buy a platform and try to change it. This is a dilemma which may lose its meaning since PR2 exists.

PR2 is a robotic platform especially designed to test and integrate various applications and technologies. It can be used in educational purposes, research, innovation or at home if you are willing to spend a sum around 309.000 EUR ($400.000).

Willow Garage have developed this platform ready to be modified in terms of software and hardware. The modular system allows for developers to use different grippers, forearms or whole arms. Sensors can be added, changed or removed also.

In terms of software, the platform uses open source projects like ROS, Open CV or Point Cloud Library. ROS is an open source project made by Willow Garage where any enthusiast is free to add new features or modify existing functionality. Open CV gets along very well with ROS and is used for real time computer vision. Point Cloud Library includes a large number of libraries used for mapping and object recognition.These three software platforms control the movement of robot, allow visualization and recognition of objects from the environment and also allow adding new functionality, teaching the robot to do various tasks. Continue reading (…)

A Guide Through the World of Electronic Circuitry Symbols

Any robot relies on electronics to control its parts, relay data, and basically define and handle its function. Electronic modules are practically electrical circuits of varying complexity, interacting with each other at certain levels. Electrical circuits are based on diagrams, which are graphical representations that specify physical components required for the circuit to perform certain functions. Electrical symbols are used as abstract representations of physical electronic components that are used in the circuit, and each such representation should be simple in order to be recognized in any circumstances with no ambiguity. These circuit diagrams are not only useful in prototyping circuits, they can also be a great help in understanding and detecting errors that may occur in the circuit operation.

Printed circuit board (PCB) and probe

Printed circuit board (PCB) and probe

In time graphic representations of the physical components were standardized, each of these symbols having a certain logic behind its design. This compendium does not aim at exhaustively covering every possible component and representation, it should rather provide a pretty good coverage of the most common electronic components employed in robotic electronic circuitry, and maybe familiarize the reader with electrical schematic symbols and their purpose. Below you can find electrical symbols for common components, logic gate symbols as well as brief explanations of each element. This article is under continuous development.

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