Safety

Turning the robot on and off

The two main electrical safety mechanisms are the included 15A breaker on the 24V input and the so called button box. The former serves the purpose of opening the circuit if excessive current is flowing through the 24V line. This prevents further damage should a short circuit occur or a defective part draws too much current. It is very important to keep in mind that the fuse will not cut the supply at 15A and can maintain a sustained current upwards of 20A if the load is continuous, thus it should not be viewed as a current limiting safety device. Regardless of the current control capabilities it can be used reliably as the robot’s main switch for 24V.

Open

Once power is supplied to the 24V line and the breaker switch is active the robot is on, that is, the main control board (FPGA) and network switch are powered and once they boot they can be accessed through the local network. Commands can be sent but no body parts will respond if the motors are turned off. To turn on 24V power to the motors the respective red buttons on the box can be activated and they will light on accordingly indicating power is being sent. The buttons for 5V and 12V don’t carry any power, but signal the DC/DC converters on the core board to turn on. If the 5V (6V) servos are to be used for a long period of time, please turn the 12V line on to activate the cooling fan as well regardless of if the hands are in use to activate the cooling fan for the regulators (it runs on 12V).

Current limits

In the image below you can see the recommended current limits to be applied if the supply is able to generate much greater currents. They are also indicative of the recommended power that the power supply for the robot needs to provide.

Open

In the next picture the idle current draw is shown for the 24V and 5V lines when the robot is first turned on and no body parts or servos are active. This can be used for reference when first turning the robot on as a sanity check. For example if current values differ greatly from the ones displayed here, it could mean that either there is something wrong (drawing excessive current) or that there are some other robot systems or parts already active before initialization.

Reverse polarity

Please take care not to connect the supply cables incorrectly and always double check before turning the power on. Both (5V and 24V) power lines have NO dedicated reverse polarity protection. For the 5V line the protection is only the one the manufacturers of the respective devices (RPi, Jetson, projector, …) built in the products, so it should also not be expected to be very robust.