Mouse Droid based on Runt Rover Whippersnapper with Raspberry Pi

This is my first attempt a building a robot powered by a Raspberry Pi.

The base is a Runt Rover Whippersnapper by Actobotics. It was cheap and very easy to put together, and I wanted it to have 4 wheels. My idea was to basically build a Mouse Droid from Starwars, but I'm not interested in making it identical to the ones in the movies. I just want a small autonomous robot.

I was able to get the basic robot working with Python code I wrote myself by using:

• a 2000 mA Powerbank (used for charging cell phones) to power the Raspberry Pi wirelessly.
• a Edimax Wifi dongle to connect to the Pi... though I may try and convert to Bluetooth in the future.
• a L298 Dual H-Bridge motor controller to drive the motors.
• 4, AA 1.5V batteries to power the L298.

This works perfectly and I am very happy about it. I was even able to get the servor working on a testing board, I just haven't connected it yet. I plan to add the PING sensor in the future for collision avoidance.

April 25, 2016:

I am trying to fix the turning problem by replacing the L298 with an Adafruit DC Motor Pi Hat. I'm just learning about all this and I had a couple of messages posted on the Adafruit board but I think I figured it out. With the Pi Hat which I accidentally bought from Robotshop when I was trying to buy the 16 Channel PWM Hat, I will be able to control 4 motors but no servos. So I'll have to get the PWM Hat to control any other servos it looks like. The hats are stackable, but I'll also need to order a taller header bus/thingy/doey to stack them properly.

Of course, I have practicaly 0 soldering experience and I want to practice a few small items first before I try and solder a GPIO header onto a $30 controller board.

Alternatively I might be able to use the PWM at with the L298, but I think the Motor Hat plus the PWM servo hat will make a better solution.

Please let me know if I'm completely screwing up here and if you have any better ideas please tell me!

Videos:

The built in video tool seems to not like my embed codes.

Rover moving back and forth: https://youtu.be/EtUPPmMu4y4

Rover failing to turn properly: https://youtu.be/CWzI2EXhmxQ