My handmade motor driver. When the IBT-2 did not work.

Good afternoon! I want to share my experience of building my own 2dof platform, or rather a radical solution to the problem with motor drivers.

Attention:
I have a poor understanding of electronics and find it difficult to read documentation on various microchips, but this project gave me some knowledge in this area. I may not be accurate in some aspects and my view may be incorrect, but (spoiler alert) the thing works.

Background:
I got inspired to build my own car simulator. Cheaper and easier. I had no problem with the frame and mechanics, but I struggled with the electronic part for at least six months. The main problem came from where I didn't expect it - the notorious IBT-2 motor drivers (based on BTS7960) started failing to work. The first pair of these drivers worked for several months until one of them overstressed and burned out. I thought it would be a common problem, so I ordered six such drivers to have a spare. I wouldn't be writing this post if they all worked for at least a month. ALL 6 DRIVERS WENT INTO PROTECTION MODE! And I never understood the reason. The platform starts, the race starts, the platform works for about two minutes, and then the right motor stops working. This sequence of actions was repeated a hundred times with different drivers, with different operating modes. The right motor cuts off the driver regardless of the driver (the first working driver was foolishly lost...). I bought a couple more IBT-2 from another store, and the result remained the same. In the end: a bunch of broken drivers, a non-working installation, and a loss of interest in finding out the reasons for the problems...

It's cute, but it doesn't work...

But often in these experiments, the thought visited me - what if I build my own simple driver, so that I could fix it in case of a breakdown, and it worked properly? I went to the internet with this question...

My path:
My search was successful! Well, almost... I found out about the existence of a Chinese driver based on IRF3205 transistors with l6384 microchips (I can't leave links yet, sorry...). They work, but not very well. I decided to order them and waited for a month and a half while studying the theory of motor drivers. It's a complex science, but the principle is simple: two transistors conduct current in one direction, while two others conduct in the opposite direction, each pair controlled by a driver. Additionally, a logic microchip is needed to control the drivers, so that 4 control contacts can be transformed into two: direction of rotation and speed of rotation.

Why am I not using the Monster Shield? The motors are rated at 100W, 24V. The Monster Shield is not suitable. The main task was to find something that works with high voltage and won't burn out from high current.

What will be needed for the project? According to the documentation, the IRF3205 has a large voltage margin (55V) and a huge current margin (up to 110A at room temperature). This component suits me.


The L6384 motor driver was not available in local stores. I found a similar microchip, the IR2109. According to the specifications, it operates at 10-20V and responds quickly, so it should work. To make things easier for installation, replacement, and experimentation with analogs, the microchip has a DIP package.

The logic microchip I have is an HD74LS02, also in a DIP package for the same reasons. It operates on 5 volts and has four NOR logic groups. However, I made a mistake as this microchip produces an inverted signal. This means that if we apply full speed to the motor, it will stop, and if it should stop, it will spin at maximum speed. One must be careful when applying maximum PWM to the transistor since it could burn out.

Power supply is a complicated part. There is a 24V supply for the transistors, 12V for charging the transistors with the driver, and 5V for the logic. I took two 400W 24V power supplies for each motor. Despite the motors having 100W, the seller recommended choosing a power supply three times more powerful, so I chose one four times more powerful. I used a module based on the LM2596 to convert one of the power supplies to 12V for the drivers.

The Arduino UNO is the brain of the entire project. It is better to power it with separate 9-12V power, and a suitable firmware (I use SMC3). There was a problem with this firmware since I could not figure out where to connect the three control contacts for the motor with only two contacts available. The solution was simple: use the MODE1 in the firmware and connect two wires for the speed in PWM and the direction to any EN pin. It was more difficult to invert the signal.

I decided to leave the microcontroller powered by USB, which may not be the best option. Installing a separate power supply for the Arduino seemed like a foolish idea. Be careful with this since it could burn the Arduino and the USB port of the computer or even the entire computer. I did not have this problem, but it is always at your own risk. They say that it is possible to make an optocoupler to prevent this.

Afterword:
Thank you, ChatGPT, for the translation. If you have any questions, feel free to ask. I will try to answer them.

Now let's talk a little about my platform.
I built the platform inspired by the one I tried at the exhibition. The motors are located at the bottom front and the levers are attached to the lower front of the chair. It has a simple base and four legs. I really like the compactness of this design, although it still takes up a considerable amount of space. It makes quite a loud noise when moving without a driver. With a driver, it dances less, but the settings work wonders (there are a couple of videos of dances). The frame was welded from steel, square tubes were convenient to use, but they were rusty, so they were sanded and painted to look nice and not rust (although it stands at home))). Here are some photos (if I can insert them)) ):

(I kind of learned)) )


I thought to tilt the steering wheel forward to make it easier to get behind the wheel, but there was a terrible backlash, so it was twisted tightly.




It remains to attach plywood panels to the platform so that the cat doesn't break anything with its paws and the driver doesn't accidentally pinch a foot. The plywood looks strange in this design, so I plan to cover it with black and red vinyl. This is the current state of the platform.