Choosing the parts
Throughout this book, we have looked at the tradeoffs between different kinds of sensors, different chassis kits, controllers, and so on. These are tradeoffs on weight, complexity, availability (you don't want an irreplaceable part), and cost, covered in detail in Chapter 6, Building Robot Basics – Wheels, Power, and Wiring.
If a particular kit inspired the robot—for example, SpiderBot was inspired by a hexapod kit; yours could be a robot arm or caterpillar track kit—this will likely constrain the other part choices you need to make. I'd need to support 18 servo motors; however, I had a 16-motor controller available, so I elected to use two input/output (I/O) pins of the central controller for the remaining two servos. This added software complexity, though.
Another tradeoff was the main controller. I knew that I'd want SpiderBot to be Wi-Fi-enabled, but it wasn't going to be doing visual processing, so a small, cheap...