A group of people and I are making a Solo8 v2 robot. Our lab power supplies are not powerful enough. In the github I see you have specified a 20A and 30A power supply, how do you cable and configure these to power the robot? I’ve read that you limit your motors to 15A, how do the power supplies handle this?
Alternatively, we could use batteries. I see you have linked to a 68g, 11V, 850mAh battery, is the thought to put two or three of these in series to power the robot, what is your set up here?
We also need an Emergency Stop button, preferably one with two NC channels so we can cut VCC from both power supplies, this is then also required to withstand 24V 30A per channel. What is your set up here, I am having difficulties finding a button rated for this.
Hi,
you can use smaller power supplies for most behaviors like walking or running.
I would recommend to start with a smaller power supply until you run into limitations.
Please note that the 15A max current is on the low voltage side of the motor driver boards.
On the 24V supply line the total current for the robots is only a couple of amps depending on the executed behavior.
We use the 30A power supplies for jumping - mostly because all the degrees of freedom demand a very high current at the same moment. The power supplies are not dynamic enough to supply those short peak currents and the voltage drops. If the voltage drops below 8V the motor driver cards will reset and produce the high frequency sound that you can hear in some of our videos. For the 1m jumps we had to supply the front and hind motor driver cards separately with two external power supplies.
We are starting to look into onboard batteries - but we haven’t done any testing yet.
To use the batteries we’ll need a power management board - @thomas.flayols is working on the design. The onboard batteries should help with providing the short peak currents. We are planning to use two lipo batteries in series (one in the front and one in the back of the robot).
I have some questions regarding the wiring of the emergency stop button.
The ribbon wire has 4 supply plugs (2x GND and 2x VCC) for the power supply side.
Do you use two parallel power supplies? One for each pair of VCC/GND.
If so, do you have some sort of protection circuit ensuring that the two power supplies are electrically separated?
Furthermore, we have bought the same e-stop button mentioned in the previous post. It has as you stated - two normally closed switches.
Could you, if possible, provide the wiring diagram for your ribbon cable. We do not have a protection circuit at this time we are therefore reluctant to connect the two VCC’s and the two GND’s together in each respective switch inside the e-stop. Or do you just connect the VCC from each power supply and not the GND’s.
Yes - for dynamic behaviors like jumping we use two power supplies to prevent the supply voltage from dropping below 8V.
We don’t have any special circuit. Electrically the robot is split into two parts - one power supply for the front legs and one power supply for the hind legs. We connect all the ground wires inside of the estop. The Master Board is connected to the power of the hind micro driver boards.
You’re right - the power supplies shouldn’t be connected in parallel.
There is a wiring diagram below - it’s simplified - we route all the wires out of one side of the e-stop.
We use this cable gland for the estop and this clamp to connect the ground wires.
