I've made a bunch of changes to Mirobot recently that solve all of the issues that I've collected from the people using it over the last year.

It's a complete redesign of the chassis which solves quite a few of the issues in one shot

• No more pegs needed to hold it together. These used to pop out and get lost and were also quite difficult for kids to get in right. Now as you put in each piece it holds the previous one in place until it's all held together by the PCB
• I moved the chassis base up so it now also holds the steppers in place and means you don't need to use extra stepper mounts. It also means the sides go on much easier now
• Because the base has moved up, all of the wiring is now neatly tucked underneath which makes it a lot less intimidating for the less technically able
• No big and fragile antenna - yay! This was the bit that broke the most often.

Here's a quick video showing what it takes to assemble it now:

Electronically, the major change has been switching out the WiFi module for one based on the Hackaday favourite ESP8266 (I'm using the ESP-01 because it has easily plugged in pins). Aside from meaning that the external antenna is no longer needed, it should solve a lot of the reliability problems because I can build the firmware myself. The initial code for this is up on GitHub and it includes both an on-board web server for serving out the local javascript app and a WebSocket server for real-time control. I've also added the ability to re-flash the Arduino over HTTP which means firmware upgrades will be a lot easier this time and can be done from the browser.

Another electronics change has been to move the PCB to the front of the board which means that the collision switches can now be integrated and don't need wires. I'm going to keep the line following on a separate PCB but it will clip straight on instead of needing more wires this time. The battery pack has been separated again and sits at the back for better weight distribution. This also makes it easier to change the batteries.