Servo - August 2015

70 SERVO 08.2015 t’s a great time to be a roboticist. With so many microcontroller board options like Arduino, Raspberry Pi, and SparkFun RedBoard, it’s never been easier to find a brain for your robot. However, a brain without a good driving base is like Batman without Robin, or Frodo Baggins without Samwise Gamgee. The folks at Actobotics have the perfect solution for those looking for a driving base that is easy to build, ripe for expansion, and super affordable: the Runt Rovers.

Will the Runt Rovers be able to save the day for roboticists stymied by the lack of a good driving base for their microcontroller boards? With the help of two of the Runt Rovers — the simple two-wheeled Sprout and the more sophisticated six-wheeled Bogie — we were sure to find out.

Everyone Loves an Origin Story

The Runt Rovers are an offshoot of the Actobotics building system and are available through ServoCity. We had our first exposure to Actobotics last time when we worked with the system in conjunction with the Force servo arm. The precision machined aluminum and distinctive hole pattern gives the parts a stylish polish and a cool factor that usually seems to evade plastic parts. The hole pattern makes integrating servos into your designs so much easier.

With other kits, the small unusually spaced holes on servo horns would rarely match up with larger structural parts. The hole pattern on Actobotics parts are the perfect fit for just about any servo attachment you could imagine, but Actobotics is perfect for so much more than servos. The system also features great parts like mounting brackets, hub mounts, gears, and sprockets for use with motors, too.

After having such a positive first experience, we had high hopes for the Runt Rovers. One difference between the Runt Rovers and a lot of the other Actobotics parts is immediately apparent. While they still sport some of the familiar hole patterns, the structural parts for the Runt Rovers are all plastic. This is not at all meant as a knock against the kits. In fact, the thrifty construction is one of their greatest virtues. The Runt Rovers are a lot gentler on your wallet than slobbery Hooch to the pristine interior of Turner’s car. The six different Runt Rovers range in price from the bargain rate of about $16 for the simplest Runt, to the still very bargain price of about $70 for the most sophisticated Rover.

The six Runt Rovers are a veritable Justice League of efficient robot design. The simplest kit is appropriately named the Peewee. The smallest Runt (and we mean that — the website shows a Coke™ can towering over it for scale) has two wheels and two motors, and a simple rectangular frame. The frame includes the distinctive hole pattern in the center of the top body plate for expansion with other Actobotics parts.

The next Runt is the Sprout, which is one of the ones that we got our hands on. The Sprout is also a two-wheeler, but with a slightly larger frame and a few more mounting points. One of the great things about the ServoCity website is that on each page dedicated to the Runt Rovers, the entire kit is shown laid out with the parts identified so you know exactly what you’ll be getting.

The pages also feature tons of pictures with the Runts in action, and some cool design suggestions with some soda cans for scale. Just in case you can’t tell from the pictures of the complete bot, if there’s one more set of mounting holes on the bottom plate, the laid out parts give you your answer.

The third Runt is Junior, which includes four wheels, four motors, and a slightly bigger frame. The fourth Runt is the Whippersnapper, which is also a four-wheeler. The Whippersnapper has a taller profile than Junior — the main body is big enough to house a standard servo sitting upright. The fifth Runt is the boxy Half-Pint.

If the Runt Rovers were the Fantastic Four, Half-Pint would be The Thing. The hefty bot provides enclosed storage for all of your electronics, and numerous surfaces