Servo - September 2007

Dear SERVO:

I read Pete Miles’ reply in the July SERVO about the problems of using infrared beacons in the house and wanting to offer another approach.

I use RobotBASIC to develop a complete house navigation simulation using “infrared beacons.” It works perfectly, mainly because I used a very different approach. (Note: If you are not familiar with RobotBASIC, please see my article in the June issue).

The assumption in the simulation was that I had 10 or so beacons (each with a unique ID code) that could be turned on by remote control (Blue Tooth, for example).

The program used a computer

science data structure called a graph that essentially provided a “map” of the house. When the robot was requested from any given room, the program checked the map and turned on the beacons one at a time, in the proper order, allowing the robot to move (using the shortest path) from where it was to where it wanted to go.

The simulation involved a complex floor plan and demonstrated how simple navigation can be if only some manufacturer would provide a beacon detector, and several beacons (that perhaps look like smoke detectors) each with their own ID code that could be set with DIP switches. Since beacons could be placed throughout the house (probably primarily over doorways) they do not need to be extremely powerful ... typically, they would only need to be detectable from 15-20 feet. In the rare cases where that was not enough, two beacons could be used to get through a room or a hallway.

The point is, I believe infrared beacons can provide an extremely easy-to-use, economical way for hobbyists to navagate a complex environment. My simulation would even go around objects found to be blocking the path and then resume movement toward the beacon.

Of course, most microcontroller-based

robots would not have the memory or math ability to deal with the graph data but the new version of RobotBASIC ( 2.0) provides a built-in protocol that allows all the standard simulation commands to control a real robot over a wireless link. This means even small robots now have the ability to be controlled by a complete, powerful language giving new life to the goal of AI in small machines.

Hmmm ... looks like I rambled some, but I am very proud of the capablities of RobotBASIC and I think it opens many doors to more intelligent control that have been overlooked because of previous limitations imposed by the required use of simple microcontrollers.

John Blankenship

benefit from aspects of both commercial and academic approaches. Before beginning your next robotics project, consider how you’d approach design and development from a commercial and then academic perspective. Certainly, you want to learn something from everything you do, but if you’re looking at making your innovation applicable to a larger audience, then you have to consider the business issues in component selection, design, potential sales volume, and follow-on products.

When considering component selection, it helps to imagine that you’re building, say, 5,000 robots. Suddenly, a few cents for a component or the cost of an added square centimeter of pc board or aluminum chassis makes a big difference in overall cost. Sensors and other components that are just good enough for your application may not be pushing the technology envelope, but customers won’t care if the robots work as advertised. Conversely, a new microprocessor might be more expensive to install initially, but incorporating it in your design will give you a chance to learn about the device, and may provide a growth path for add-ons. The bottom line is that, with a combined approach, your robotics innovations can be both technologically and financially sound. SV

Dear SERVO:

This correction refers to Tom Carroll’s article on robotic arms. The following statements are incorrect: “the advantage of using R/C servos is the positional feedback;” “potentiometric feedback, as in R/C servos allow the controlling computer to know where each joint is positioned.”

There are no feedback mechanisms built into any standard servo today, with the exception of the AX- 12+ and a few specialized servos used in Biped type-robots.