A re-design of BFR-MR1

I realised that the design of my robot didn’t meet one of my initial goals for the project. Although a sturdy and reliable design, most of the components were still on show and the design didn’t make it easy to add a cover to enclose the electronics. I redesigned and made a new base plate for the robot. The brackets that fix the servos for the drive wheels to the base were moved from the top of the base plate to the bottom. This freed up some space on the top of the base plate and gave the robot a much bigger ground clearance. The Raspberry Pi, Arduino and batteries were then fixed to the top of the base plate. I could then fabricate an enclosure to cover everything. I made separate sides, top and front and back to the enclosure out of aluminium sheet. The head pan servo was mounted in to the top of the enclosure, reusing the pan/tilt camera mount from the previous robot design. I had to fabricate some spacers for the rear castors and the IR sensor bar to space everything off the base plate correctly. I also treated myself to a small TFT screen (Adafruit 2.2″ TFT) that is mounted into the top of the enclosure. Combined with a home-made array of tactile switches this means I can start/stop the robot or switch between modes without connecting to the robot with another computer. The front and back of the enclosure had to be removable to access connectors and batteries for charging. A coat of paint and the robot was ready to go.

New design of BFR-MR1

New design of BFR-MR1

 

BFR-MR1 TFT screen and switch array

BFR-MR1 TFT screen and switch array

 

Modified IR sensor bar attached to front of robot

Modified IR sensor bar attached to front of robot

This design keeps a lot of the electronics tucked away whilst still allowing access to the necessary connectors with the ends of the enclosure removed. I like this design but I would still like to replace the aluminium enclosure with a custom carbon fibre one. I have ordered some foam to carve into shape which can then be used to make a mould to create the carbon fibre piece. This will hopefully happen quite soon and I promise a blog entry outlining the process if it is a success!

Meanwhile I have been developing some software for the robot. The TFT screen is attached to the raspberry pi, as are the tactile switches. A bit of time was spent working out how to use the SPI interface through python to send pixel data to the screen. I found this series of tutorials online that were very helpful http://w8bh.net/pi/TFT1.pdf. I can now write text to the screen and I have interfaced the buttons so that I can cycle through options on the screen and select what I would like the robot to do, or display sensor data.

I have been thinking about what I would like the robot to do and a lot of it revolves around vision so that is going to be the focus of future work. Identifying targets to reach and obstacle avoidance to allow the robot to get to its goals are my main aims for the future.

 

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