How to deploy a motor driver and MCU onto larger sized robot without a PCB?

Question

The robots I built previously were all similar to the 4WD Kit from amazon. With these kits it's easy to use an H-Bridge breakout similar to this and using a perfboar to solder to the connections to the MCU or Rpi3.

My current project is an RC snow plow bot, which is a bit bigger. I am using this 43A motor driver, and this scooter motor I got from a scrapped mobility scooter; and rear steering using a servo.

I plan to use the ESP32 MCU along with that BTS7960 driver. There will also be an Nvidia TX2 with ROS2 installed that will interface with the ESP32 over UART.

Obviously I cannot use breadboard jumpers for this, so what's a good solid way to do this, without having to create a PCB.

Are the perfboard / permaproto the best options? Does not seem so to me since the motor driver is so large, but I admit I am inexperienced in this area.

What are other options without using a printed PCB?

Answer 1

One way to go is to invest in a good crimper a good size kit of electric terminals and utilize busbars to make your connection points.

The reason I mention the crimper is that you have to avoid using stripped wires as much as possible as they tend to fray and drop strands everywhere, which can be dangerous.

Instead, crimp eyelets when the wires need to merge on busbars or crimp pins that will allow you to plug straight into the motor controller PCB.

While you are at it, make sure to buy and use wire hold points - small plastic clips that allow you to use a ziptie and secure bundles of wires as they go back and forth.

For the smaller wires, such as UART connections (by the way, TTL UART traveling more than a few inches in an electrically noisy robot will give you trouble), you can use inline connectors and splices as needed.

Answer 2

You've pretty much covered it.

The first thing I will say is that you could use a breadboard and jumpers, as long as the breadboard is in some type of enclosure to keep things from getting knocked off of it. The old fashioned solid core jumpers that lay flat against the board are better for this sort of use, because they're harder to accidentally tear off.

The next step up from that, in my opinion is as you said a protoboard. These are labor intensive to build but more compact and less amateur looking than a breadboard. Although I've build a lot of these myself, my current approach is to go straight from breadboard to PCB. The reason for this is that any design that's suitable for a protoard can be designed on a pcb in only an hour or 2, and ordering pcbs is fast and cheap. The only time I use protoboards these days is if I need a pcb in the next day or 2.

The size of the motor doesn't really matter as far as your control board is concerned. The motor drivers should be connected using large gauge wires to the motors, and then to your control board with smaller wires. Your control board won't be rigidly attached to the motor drivers, so their presence doesn't really change the equation.