The motor controllers arrived, I can start playing...

The controllers from Aventech arrived on Wednesday. I can now start building and testing.
First thing, it to make sure the controllers works and cope with the power of the motors and also see if I can should use 12 volts or 24v.

For this test, I just used free wires to quickly connect everything. I am controlling the MD03 controllers with 0-2.5-5v signal. I am also using a small board I make few years ago to generate the 5volts required by the controllers.

It is not great, but good enough for testing.
The control is done via two linear variable resistor of 10k to provide the 0-5v signal.
2.5v is equal to stop, 0 is full backward, 5v is full forward.

Using 12v as power source did not give very good result. The power to the motors was not great and at full speed, the robot was not very fast.
After adding the second battery to work on 24v, the motors are more responsive and speed is much better. So I guess, I will have to use both batteries in 24v setup. The mini PC I am planning to us work with 12v input, so I will have to review this and find a solution.


So, the mechanic is working, the power controllers are doing the job too. Next step is to do a proper cabling job and change the control to I2C protocol from the computer and start playing with Visual Basic.

New motor controllers

Today, I ordered two motor controllers from Daventech (http://www.robot-electronics.co.uk/acatalog/Motor_Controllers.html). The MD03 model. I already have two PID motor controllers with encoder input and all the rest, but they can only deliver 3amps and my motors can drain much more.
So the idea is to using these MD03 drivers that can cope with 20amps current. They can be controlled via I2C protocol which I planning to use to connect all the robot elements. These drivers can also use PWD + sense signal, so later, I am planning to re-use my PID controllers to get accurate position and speed. I will cover this later I guess.
So now, I just need to wait for the delivery and start testing...

A wheelchair from ebay

Last week, I won an ebay auction for an electric wheelchair. Its a Twister Junior electric wheelchair in need of TLC. I got it for £62.

That will provide the motors, the gears, the wheels, the chassis and the batteries. The motor controllers are using a "DX BUS" protocole that nobody knows. I have other ideas to control the motors, so that's ok.
Motors are veryu quiet, but use a lot of power. my 3amps PID controllers from a previous project will not cope with that, so I need to find another way.
Also, the motors work on 24v. I would prefer to use 12v as power source. I will have to investigate and see if 12v make the motion fast enought. so far, I just took it in pieces and cleaned it.

The BIG idea !!

My big idea is to build a robot.
There are plenty of toys and gadgets that does exactly this, but I want to build mine and i want it to be like I want. Of course, I do not have the budget of NASA, so it will mostly be made of bits and scavenged parts. Here are some requirements and limitations I have:

- The robot must be able to go outside (garden) as I do not want it to sit in my house and take space for nothing (well, this could be my wife requirement:-) Also, I have a small kid and I do not want him to get his hand of finger stuck in a gear or something.
- This robot must be as cheap as possible
- This robot will not clean the floor or cut the grass, for this, I could buy one already done.
- I hope to make this robot clever At least, be able to navigate by itself and have some interaction.
- This robot should fit in my car, and thru doors (60cm wide max)
- The robot ill run ith VB code (I like coding in VB)

Ok, so now lest start building....

First post....

Hello and welcome to my blog. I am dedicating this blog to my new DIY project: building a robot. This is not the first tentative here, but I hope this time I will succeed and finish it ;-)
To keep me motivated, I am going to share my experience via this blog and hopefully get feedback from others who share the same interest.
So keep checking, this blog....