So I had been thinking of a simple design for a while now, based on a stink beetle but also a bit like a pentagon, so Stink Bot was born. In my usual style it's made from 3mm compressed particle board, or chipboard (MDF) and this time I experimented with some metal brackets that I got at Bunnings. I used an Arduino Pro Mini and based the sketch on the Tubby Bot because it works so well. I didn't use a switch this time, instead I used a two pin plug on the busbar to interrupt the earth or 0Volt line.
I decided to try the metal brackets so I cut them in half, marked the position of the holes and drilled as required, they are much stronger than the MDF ones I used last time and easier to make if the truth be known, for me that is.
Once the holes were drilled I assembled the brackets on the motors and marked the holes for the chassis, I also marked each bracket to match the mounting position on the motors and motor position on chassis so all the holes would match up on final assembly, makes it much easier later on.
I used a caster on the rear in the middle, it makes it so easy to steer the robot with the operation of motors, the layout I use is very stable as well, it will climb over small obstacles with ease, especially with the torque of these motors. It even moves very well over carpet.
The motors mounted flush to the lower chassis which is what I wanted and I had to make provision for the wheels in the lower chassis and I like the look of the finished setup. As you will see later I had a huge amount of space to play with which opens up the robot for so many extras that could be mounted in it as well.
I mounted the ultrasonic sensor on the top chassis and under cover to protect it from being hit if the bot runs into an obstacle, which it doesn't but you never know. The dowel size means that it goes either side of it as well so it worked out nicely for me. As always I recommend you mix and match your designs as well, give it some life.
The room is huge as I mentioned before so you could add so much to it. As I said I used the Arduino Pro Mini so it's very small, in fact it's held in via a cable tie or two only, the battery holder is held in place with hook and loop tape, dots actually made and sold by Velcro, yes it is called hook and loop tape, Velcro is a brand name. I know that some of you won't like the wheels coming through the chassis like this but I like it a lot so I will use this setup again. The metal brackets are so easy to modify.
The sketch I used is a very simple one, it's the one that I used in the Tubby Bot and it works so well so I used it again. Have a look at Tubby Bot for the sketch.
I didn't want to use a switch, cost factor, so I set up a two pin and plug setup to isolate the power on the busbar as I mentioned, the busbar makes it very easy to supply the robot with power, it even makes it easy to have two different power supplies, one for the motor and one for the Arduino. Made up on protoboard (PCB) you can configure it in as many ways as you need, switching included. Once again I will point out the use of rechargeable batteries, 4 X 1.2Volts is 4.8Volts (5.27V fully charged) and 4 X 1.5Volts is 6Volts which is not at all good for the Arduino but great for the motors, hence setting up two power supplies to get the motors to go a bit faster and speed up the robot.
He has turned out better than I thought, the motors were so easy to modify for continuous operation, large size helped so much and gave a large area inside the robot to hide the two voltage divider resistors that take the place of the trim pot. The metal gears were easy to remove the limit pin from the output shaft gear, good pliers and gentle twist and out it came, both times. The trim pots were held in by plastic clips that bent out of the way easily, didn't break so it can all be returned to normal operation later on if required, and yes I kept ALL the components that I removed so I can fix them later. Anyway, simple and quick build that I am very pleased with, especially the motors.
The build was great fun as always and I hope it inspires you to build a robot or two of your own, Cheers, TJ.
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