Intro: Robot Mechanical Beetle. V1
This is a little robot that I made after coming across some micro worm motors. I have no idea what the motors are actually supposed to be used for, but they are ideal for small robots. The beetle can move about at some speed and can also avoid obstacles using his feelers. I've tested him over flat, stony and inclined surfaces and he performes brilliantly.
If the clip doesn't work - try this one
This is my first version and I'm sure I'll be improving the design in my next efforts. Overall though I really like the way this little fella moves about. He's got a gangly, jumping type of gait and moves about with some speed. I also added a couple of "feelers" so when he runs into something, only one side moves and he turns.
Also I have been experimenting a lot with the shape of his legs. I wanted to get the most out of movements without the legs hitting each other. After a little hit and miss I came up with a pretty good gait. I have tried him outside, across rough surfaces and he works just as well! I was really surprised at how well he managed to get over stones and sticks that were in his way.
You can probably see from the pictures below that I also had to put a wheel on the back so he wouldn't flip over. This was an afterthought though as I didn't think I would need it.
check out the video below to see the beetle in action.
Step 1: Things to Gather
1. Small worm motors (4) - eBay
2. 9 v battery holder - eBay
3. Copper wire (size 3mm)
4. Momentary switches (2) - eBay The ones I used were small but the lever failed after awhile. The ones I have suggested here would be much hardier
5. 9 v battery
7. Paperclips large (2)
8. Strong, double sided tape. The kind that you use to attach metal stripping to a car. You can find this at a hardware store.
9. small on/off switch - eBay
10. Rubber ends from a coat hanger. These are the type that have 2 clips to hand pants on. You could also use some heat shrink
1. Wire cutters
3. Small file
4. Soldering iron
Step 2: Design and Attaching the Motors Together
The first thing you need to do is to lay everything out andwork out how the bug will look. As you can see from my original design, I have had to change quite a lot in order for this little beetle to work. Initially, I wanted to use 3v button batteries but found that there wasn’t enough power. If you got some battery holders that held 2 of these each (bringing the voltage to 12v), you could definitely use them. It would make the beetle a lot smaller and lighter.
1. On the back of the motors, there are a couple of plastic pins which need to be filed off. This will ensure that the motors sit flush.
2. Add some strong, double sided tape to one of the motors. Make sure that you don’t cover the little black screw as this connects to the wheel that spins.
3. Carefully stick 2 motors together as shown below. Do this twice
Step 3: Wiring the Motors Together
This is probably the most fiddly part. The motors are very small and the soldering lugs are tiny. The key thing in this step is to take your time and make sure that your connections are good. I have also included a drawing to help you understand how the wiring should be done. Essentially, what you want to do is to wire up 2 of the motors so they are joined and run off one set of wires.
1. Add solder to all of the solder lugs on the motors.
2. Cut 4 small pieces of wire and tin each of the ends.
3. Solder to the lugs as per the drawing. Remember, you are wiring the motors so 2 of them run from one set of wires.
4. Lastly, as per the drawing, solder on another 4 longer pieces of wire. These will be the leads that will connect to the battery and lever switches. Give the motors a test and see if all 4 spin. They should all spin in the same direction.
Step 4: Modify the Battery Holder
You will need to modify the battery holder slightly. This is to ensure that the wiring from theterminals are out of the way from the legs.
1. There should be a hole already drilled about half way down to one side. Drill another exactly opposite.
2. Next, with a pair of needle nosed pliers, pull the wire from the hole it is currently in. You might need to turn the battery connectors to be able to do this. They turn quite easily.
3. Push the wires through the 2 holes that you have made
4. One the back of the holder, add some double sided tape as shown in the image below.
5. You can also drill a couple of holes in the 2 sides if you want as these will be used later
Step 5: Making the Feelers and Wiring
The wiring is quite simple and I have added a schematic to hopefully help you If you do need more info on how to wire the feelers up, then check out this link.
1. Glue the 2 momentary switches together. You can see in the images below that I have used some micro ones. I would suggest that you find something a little hardier as these eventually broke at the lever.
2. Next form the fellers out of some large paperclips. You just have to un-bend each corner to form the shape below. Solder onto the switch levers.
3. Add some solder to the solder points and connect the 2 middle pins together. You will also need to attach a wire to one of the legs.
4. Next, wire the 2 end pins together and attach another wire to one of the pins as shown below.
5. Lastly, add some superglue to the side of the switch and glue to the top of the battery holder.
Step 6: Attaching the Wires Together
When putting your beetle together, you want to find the best way to keep all of the wires closely together. It will stop any of the wires from catching on the spinning legs and getting pulled out. It also makes the beetle more compact and neater.
1. First thing is to attach a couple of the motor wires to the inner lugs on the switches. These don’t have anything attached as yet. You can see in the images below that there are 2 white wires coming out through a couple of holes in the battery holder. If you haven't already, you will need to drill the missing holes.
2. The 2 wires should come from the 2 motors that are at the front of the beetle.
3. Solder the wires onto the inner soldering lugs on the switches. Make sure though that they are crossed over! So the wire from the left motor should be soldered onto the right switch and vice versa for the other one.
4. The 2 extra wires that you added to the switches need to be threaded through the same holes as the battery wires (see the last image). The wire attached to the middle pin is to be soldered to the negative wire and the wire attached to the outside pin should be soldered to the positive wire.
5. The other 2 motor wires (you can see them in the last image) will be attached to the switch along with the positive battery wire.
The schematic below comes from this website. It is a good guide on how the wiring should go but you will see that it is slightly different. In the drawing, the bottom motor wires are connected to a separate wire that has been added to the battery holder. I have attached this to the negative battery wire.
Step 7: Adding the Legs and Switch
1. Attach the switch to the back of the battery holder with some super glue.
2. Solder on the back motor wires to the switch as well as the negative wire.
3. Test and make sure that the motors are running the correct way!
4. Next, form the shape of the legs. You will want the front legs to have narrower shoulders as shown in the images below. If you don’t do this then the legs will just keep on hitting each other!
5. To enable the legs to have some grip I used some little rubber stoppers that I found on the end of some coat hangers. You know the ones which have a couple of clips at each end and are used to hang pants. You could also add some heat shrink as as an alternative. Bend the feet up sand push on the little rubber caps.
6. Before you super glue the legs nto the holes in the motors, make sure you roughen up the ends with a file. If you don’t, then the glue will have nothing to grab onto and the legs will fall out eventually.
Step 8: Adding the Tail
When I had finished my little beetle I couldn't wait to turn him on and watch him scatter across the table. To my horror though, I found that my beetle kept flipping over and wouldn't stay on his feet! I tried changing the angle on his legs, making them shorter or longer but it didn't have much effect. This is because the centre of balance was off kilter and was throwing the beetle off balance. To remedy this I added a little wheel as a tail. You could leave the wheel out though if you wanted to and just add the piece of copper. The main thing here is to ensure that there is something behind the beetle which will stop it turning over.
1. Bend a piece of small copper tubing (or whatever wire you have which will suit) into a triangle shape. If you have access to a tape player, there is a little wheel in the tape section which you can use. I recently pulled one apart and had the wheel spare.
2. Flatten the section which is to be attached to the battery and bend it so the ens of the copper it touching the ground. Super glue into place
Test and if the beetle doesn't flip - your away!
Step 9: You Did It!
So - now I hope you've made your own little beetle robot. There a heap of different modifications that you can make with this robot. The most surprising thing that I found out about building the beetle, is his amazing ability to go over rugged terrain! I have used him on my driveway which is covered in medium sized rocks and the beetle goes over these with ease. I have used him in the garden and it's amazing how he can navigate through and over most obstacles.
If he does come across a wall, his feelers kick into action and make him turn. This is done by stopping one side of the beetle moving whist the other continues to turn the beetle away from the obstacle.
So what would I do differently next time...
- Use more robust lever switches. The ones I used eventually failed and the levers fell off!
- Make the tail section a little shorter. Actually the tail that I made worked well, I would have liked though to have experimented more with the length and angle.
- Try and get the centre of balance right. this way I wouldn't need to add a tail!
- Used some more compact batteries. I initially was going to use some 3v button batteries but found that they didn't have enough power. Still think that it can be done - just need to find the right battery holders.
- Make him so if he does flip he can still move. Having the beetle move up-side-down as well would be a great feature and would ensure that he could get out of all types of trouble.