Servo - August 2016

Mechanical and Structural Prototyping

I have never made a secret of my fondness for the many robot parts and components available at ServoCity and their Actobotics line. Yes, I have used LEGO, VEX, and Tetrix Max for prototyping robots with kids in a school robot club, but the vast amount of hardware available from ServoCity (Figure 10) is one of the best ways to go for serious robot builders.

There is a similarity with the Tetrix Max and ServoCity’s beams, but the beams made by ServoCity are larger, more robust, and have a more usable hole pattern for attaching the many types of brackets, channels, motors, grippers, and so many other items that will assist a builder in prototyping. This applies to the first-time builder with some mechanical experience to the professional robotics engineer working in a NASA lab prototyping a Mars rover.

Parts Selection for More Complex Devices

Many electronic devices that we buy — whether a computer, modem, a Raspberry Pi, or similar — are many times little more than a case, a custom circuit board, and maybe a few off-the-shelf internal ‘things’ such as a hard drive, LCD display, and various industry standard connectors.

Yes, I am simplifying a complex piece of equipment, but I am doing that to emphasize the complexity of a robotic device.

Robots involve movement and movement requires motors. Mounting motors and designing motion-transferring mechanisms such as belts, shafts, chain drives, or similar requires many specialized parts that require CAD designing and machining, or 3-D printing. Many of these things cannot be purchased from suppliers for a final product.

Final Thoughts

The following words from Isaac Asimov’s short story in the iRobot series, Runaround, really says a lot about people’s understanding of what parts make up a robot. The story (written in 1942) is set on the planet Mercury in the far future of 2015. Two men were sent there to oversee a selenium mining project and a robot named Speedy had become lost on the very hot surface. The only robots that they could use to ‘ride’ out and find him were old 2005 models that had ancient technology. One of the men commented on how old they looked:

Donovan whistled. “Look at the size of them, will you? The chests must be 10 feet around.” “That’s because they’re supplied with the old McGuffy gears. I’ve been over the insides — crummiest set you’ve ever seen.”

Asimov had a PhD in biochemistry but had no education in mechanics and electronics, so, a set of gears named after someone seemed logical. One might think that it would be nice if our 10 year old robots (or even present day robots) had a particular company’s gear sets as a truck might have an Allison transmission. No, there will never be specific parts designated just for robots in my opinion. We will still build them with off-the-shelf parts from reliable suppliers, and machine and form the rest of the robot’s parts from tried and true design and testing.

Buy and build with good parts from reliable suppliers. Our machines need the best. SV

All Electronics Corp. ................................. 39

BotKits ........................................................ 39

EarthLCD .................................................... 39

ExpressPCB ................................................ 21

Actuonix Motion Devices ......................... 51

Front Panel Express ................................... 44

Hitec ....................................................... 2, 45

Maxbotix .................................................... 45

M.E. Labs ................................................... 22

Mikronauts ................................................. 65

NTE Parts Direct ........................................ 45

PanaVise ....................................................... 7

Pico Technology .......................................... 3 Pololu ..........................................Back Cover QKits .......................................................... 39 Robot Power ............................................... 7 Super Bright LEDs ..................................... 45 The Robot MarketPlace ............................ 23 Tormach ..................................................... 65