This is a buldozer, tank, robot, digger toy or a serious robot platform and maybe some other things. I mean it is a bit modular. I will try to expain the modularity step by step below :D
The electronics & code I've provided makes it run, remote controlled by pc via bluetooth link and yes it talks. It comes to life with the famous warcraft game voices.
First of all, about the base the platform;
1- Can house two reductor gear motors inside for it to be used as a powered robot.
2- Or instead of motors, the supplied extra axle parts can be printed and placed, making the mobile platform usable as a push operated toy.
On the platform, the builder can mount:
0- Nothing, just leave it emtpy or place a breadboard on top for electronics
1- A front bulldozer bucket ( can work manually or be connected to a rc servo)
2- A tank turret ( has a small space inside for placing simple electronics, battery, light etc )
3- An expansion part to obtain more interior space to store batteries, sensors and electronics. There are holes for sensors on the part and the turret still can be mounted on top of it.
4- Extension levels, they are like shelves and they can be used to place electronics, sensors, batteries, cameras, speakers, anything you like and you can use these as many as you can on top of each other.
5- Digger mechanism ( can work manually or be connected to a rc servo. The digger can also be used separate from the robot platform, the base has the necessary holes for screwing them together, see the video below)
0- Ordinary wheels with two versions
1- O ring wheels, can be used either one oring around each wheel or one for each side, stretched around two wheels like a tank track
2- Bicycle chain wheels; 7-8 speed bicycle chain cut to proper length can be used as a caterpillar track.
All three wheel types above have two versions which are
0.1- Free rotating version (For a push toy)
0.2- Gear motor version for powered use ( with narrower shaft and a set screw, see them up close at the video below)
Step 1: Chassis, Wheels and Its Accesories
The chassis is made up of 4 parts, there are two screw locations one sideways and the other lengthwise.
As said in the previous step, the chassis has space inside for two geared DC mini motors(see the last picture of this step) which can be purchased cheaply from many sources. It is 43mm long excluding the shaft and 16mm in diameter.
If it is going to be built as a pure mechanical toy, then the supplied extra axle parts can be built and used to fill places of the motors.
Most important thing about the chasis may be the mechanism at the center consisting of two conical shaped parts that enables the user to tighten the chain by lengthening and shortening the entire chasis by turning a single screw.
If you plan to build a push-toy version then you might just glue the parts together or use the longditudinal screw hole and a suitable screw&nut to tighten & fix parts together.
You can not use both of the screw locations in the chasis, you can either use one, or the other, as the screws will collide if used simultaneously.
You can download the STL files for chasis, wheels and other accesories from This Link.
Step 2: Digger
The digger part can be fixed to the chasis by using two small screws. It can also be built and used stand alone.
Two handles at the sides raise and lower the main arm and thumb lever raises and lovers the bucket arm & bucket. Those controls can also be connected to a RC servo unit and operated robotically. :D
Digger's STL files can be downloaded from This Addres
Step 3: Printing and Assembly
I've planned to make a motorized robot platform version and printed the bicycle sprocket type wheels (2 free rotating and 2 motor axle versions), tank turret and the front bucket with my UP printer. The assembly is straightforward, cleaning the parts after printing is a bit tricky as usual. After cleaning the assembly goes on like this;
1- Start with the mechanism at the middle of the chassis. Put them together like shown at the picture. Connect them with the screw and nut you selected before to fit the slot & hole in the mechanism.
2- Assemble the mechanism to the front and rear chassis parts.
3- Solder power wires to the motors and İnsert them to their places, taking the wires out of the chassis via cable holes.
3- If you want to build a wheeled version, omit the screw in step 1 and use the same screw along the chassis from front to back fixing all parts together.
4- Connect the two motors in parallel and connect a battery to them see if your robot actually moves. If the robot turns around then reverse the polarity of one of the motors.
Step 4: Making the Tank Palette From a Bicycle Chain
Before i find a suitable chain I used the robot without one for some time. It moves quite ok even though only one of the two wheels on both forward and rear normally drives.
Later I've took off this old chain from my bicycle, which has 2000+kms on it and quite worn out. But it can work as the palettes of my tank for a long long time :D
After cleaning the chain, measure the required length over the tank parts and then cut it with the bicycle chain tool.
Wrap the bicycle chain around the tank sprockets and fix it back again by using the bicycle chain tool. Tighten the chain by using the chain tension screw between the wheels.
Do the battery test of the previous step to see whether the alignment of everything is just fine and the robot moves well.
Step 5: Electronics & Code and Yes This Robot Talks :)
I've made a simple circuit on proteus, it has PIC 18F2525 controller because of its rom size, i needed a bigger rom size because i wanted this robot to talk. I've used warcraft voice samples which I've downloaded from the net.
The code uses the a kind of one-pin DAC algorithm to reproduce the converted sound samples by using a single digital output pin. Sound samples' data is embedded into the code. There is a simple RC filter to improve the cracking sound produced by the 1 pin digital output. A small amplifier can even enhance the output also amplifying it.
There are two H bridges for the DC motors, a temperature sensor and a serial link, for the bluetooth serial communication. The temperature sensor is for using the robot as a temperature robot, it will go to unexplored terrain :D and report back the temperature of its environment at our request. Sounds scientific.
There are three additional servos on the schematic, they are planned to control the buldozer bucket, the digger or anyhing else, a camera maybe. But not yet implemented at this version of the code. Also two bumper switches are seen, they are not implemented either. But it talks, obeys orders sent thru bluetooth, that will be enouth for testing the robot platform. You can easily adapt many other source codes you can find on the internet.
Step 6: Code - Electronics Development & Testing
I've made the circuit on a breadboard, also inserted the cables coming from the motors to the board. So it was unable to move for some time. After the code took shape and things started to talk and move, I've transferred the circuit to a smaller breadboard and installed a Li-Ion battery to make it move freely. I may make a permanent board to place inside the turret along with a smaller battery later.
Step 7: Remote Control Apps Used
I've used a free android app called "blue sticks control" for directing the robot by a cellphone and realterm serial terminal program to control it by pc. They both work well.
Bluestick control program sends numeric keypad data when the arrows are pressed so I've arranged my code to accept them. And you can simply use the numeric keypad on the pc, to control it thru realterm program.
Info about connecting to a serial bluetooth module etc are I guess present everywhere on the net. Not mentioning them again here.
serial commands and what the robot does in response is as follows.
w - plays we move
y - plays yes my lord
r - plays ready to serve my lord
numeric keypad 8 4 6 2 will make the robot run forward, left, right, back, will also tell its direction
any other character sent will cause the robot say "sorry" :)
Step 8: Field Testing & Missions :D
I've sent my probe on some special missions where no man had gone before :p.
No i've just placed it outside the terrace door and commanded it to wander outside occasionally requesting temperature data. I liked this and repeated similar mission all around my place all night long :D
well the robot passed my tests. It worked for me. Hope it works for you too.