Welcome to the Pololu Blog, where we provide updates about what we and our customers are doing and thinking about. This blog used to be Pololu president Jan Malášek’s Engage Your Brain blog; you can view just those posts here.
So far, I have discussed a very simple circuit and a very simple microcontroller approach to generate the control pulses needed to control hobby servos. For some applications, those methods are sufficient, but we often want either to control many servos or to do something in addition to controlling servos, and that is when the limitations of the simple approaches and the demands of the servo interface become more apparent. In this post, I will move on to some more sophisticated techniques to generate servo control pulses. Continued…
Our High-Power Motor Drivers are used to drive the motors in this homemade Segway-like personal transport by Hans Michael Steiner.
Waiter Robot can make a “Robot Bar” for your next exhibition, show, private event, or sales promotion. They use Pololu 3pi Robots to deliver food and drinks in an remarkable way. Update: The original site for this project is no longer accessible, so we have removed the link.
This video shows a heavily-modified 3pi that uses distance sensors and encoders along with a flood-fill algorithm to find the shortest path through a walled Micromouse maze. The robot is described in more detail in this forum post.
Today, I want to discuss the microcontroller equivalent of the simple servo control circuit I presented last time. As I mentioned then, the circuit is about as simple as it can be, yet it requires eight components to arrive at a sub-optimal servo control waveform. Some of its deficiencies, such as the slow rise time of the pulses, can be addressed by slightly more advanced circuits that might implement an astable multivibrator using an integrated circuit such as the famous 555 timer. In terms of part count, the 555-based servo controller might be a bit better than the two-transistor approach, but the 555 has many transistors inside it. As long as we are comfortable categorizing a component with many transistors inside it as a single part, we might as well skip the 555 and go straight to a low pin-count microcontroller, which has thousands of transistors inside it and which will allow us to make a far superior, single-component servo controller. Continued…
This small hexapod using the Micro Maestro is controlled remotely using a Bluetooth module. Very detailed build information is available in this blog post.
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…