For the last several posts, I have been writing about how hobby servos work and demonstrating the operation of devices made for controlling servos, such as RC receivers and serial servo controllers. That should have given you a good idea of the kinds of control signals we must create if we are to control servos with our own hardware. Today, I am moving on to the subject of controlling servos ourselves, and I will begin with a simple hardware approach. Continued…

Only5 is designed to be a general-purpose, high-performance robot. It uses many Pololu parts including the Pololu 5" Robot Chassis RRC04A and the Baby Orangutan robot controller. For more information see the project page.

Here is a short video showing its impressive speed:

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Groovin’ Grover is a marionette manipulated by four hobby servos and a Pololu Maestro servo controller. You can control each of Grover’s limbs independently and make him walk, wave, and – most entertainingly – make him dance. Groovin’ Grover is easy to assemble and wire up. This Instructable explains how to build your own Groovin’ Grover.

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Last time, I gave a basic introduction to the simple pulse interface for sending commands to servos. In this post, I want to explore some of the details and ramifications of the servo interface in a bit more depth. I’ll be using the Mini Maestro 12-channel servo controller, which offers a lot of servo control flexibility, and a current probe with my oscilloscope to illustrate servos’ responses. Continued…

This excellent guide from C.I.r.E. (Club de Informática, robótica y Electrónica) shows in detail how to build a fast (> 2 m/s) line-following robot from scratch, and it makes use of a number of Pololu products.

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This project by Kazuhiro Ouchi (in Japanese) shows a 3pi robot with an ARM mbed controlled by Bluetooth keyboard.

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So far, I have been talking about servos largely from the perspective of their typical use. While I hope I have provided a decent foundation about their intended use and some idea of what is inside a servo, these are things you could learn from hobby stores and taking apart a few servos. Today, I want to move on to a discussion of the electrical characteristics of servos, with the control interface as the primary topic. From the servo manufacturers’ perspective, the control signal can be an internal detail, so discussing it means we are moving on to a realm that is less officially documented. I will try to keep things general and back up my claims a bit where practical, but some details might not apply to all servos. Continued…

We found this robot pictured on the Adafruit forums driving through some snow. It was made with a TReX, a 4WD Wild Thumper, and a Boarduino.

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Now that the cat’s out of the bag about RC servos having motors inside (it was a very transparent bag), it’s appropriate to emphasize that servos are not “servo motors” and that “servo” is not short for “servomotor”. Servo is short for “servomechanism”, whereas servo motors are motors intended to be used in servos. It’s important to understand the distinction because we should care about names and communicating well; making the distinction between the terms will also help emphasize why servos are so special. Continued…

A customer recently wrote: “I think you really need to add comments from users under each product (like sparkfun does). Makes it easy to review good/bad about a project and ask a question not in docs.” I rejected the idea when some of our developers pushed for comments on our web site a few years ago, and upon reconsideration, I am still firm in my opposition. Continued…