I thought for my first blog post I would add some details of the parts I’m using for the #ShrimpBot project. You can see videos of the shrimp bot here
Since I first came across the very low cost “Shrimping It” Arduino clone (HTTP://shrimping.it) I have been working on a project to create a low cost robot (ideally under £10). This has led to the development of the ShrimpBot. So far I have had this chassis working with a Shrimp, an Arduino and a Raspberry Pi.
The main component is the chassis, the template is available at HTTP://www.thingiverse.com/thing:36062. This site contains the latest laser cutter templates and assembly instructions.
I have made versions of this using 3mm perspex and 3.5mm plywood. While the perspex looks cooler the wooden version is cheaper, less likely to break and is easier to attach other items to. To keep costs down the wheels for the robot are cut out of the same material
There are lots of options available for robot motors, for the shrimpbot my priories where price and ease of use. For the current ShrimpBot design I have used a small motor and gearbox unit avaliable from Rapid in 1:200 and 1:120 geared ratios. You can also buy them from ebay but you need to be careful as the prices vary greatly. Last time I bought motors I got them from here
Using a motor and gearbox means that you don’t had to slow down the motors down using PWM and makes the robot easier to control, the disadvantage is you can’t speed up the robot either.
Assembly of the robot requires some double sided sticky tape (available from your local pound shop) and some superglue for the perspex version.
Once assembled you can control the robot chassis you will need to control it. It is possible to power the motors directly from an Arduino but as the outputs have limited power it will run slowly, it is inadvisable to connect the motors directly to a Raspberry Pi’s GPIO ports.
Ben Smith @ManchesterBudo http://smithyaks.wordpress.com/ has done some work on using transistors to control the motors.
If you want to turn the motors in both directions then you will need a motor controller. My current ShrimpBots use an L298 motor controller unit (about £3.50 on ebay)
The advantages of this unit are that it is easy to wire up and you can use a separate power supply for the motors.