Can the Nvidia Drive AGX Xavier be used without the use of external microcontrollers?

Hi,

For my 4th year capstone project we are transitioning our SAE Racing vehicle into a fully autonomous system. To do this, we need a powerful computer that can control the whole system seamlessly which is why we want to go with Nvidia AGX Drive.

My team and I have been struggling to understand how we can control the steering motor, drive motor and braking system. Do we need separate microcontrollers to control each device or can we assign specific CPUs of the AGX Drive to be the controllers themselves?

I am new to this so please bare with me! From my understanding, you can use simple arduino in order to send signals to the motor controller which is already build in the brushless motor. The question is, can we bypass arduino and connect the motors directly to the agx drive?

Thank you for your help,

AY

Hi aslam.yehia,

You could follow up below topic, that should be helpful for your project:
https://devtalk.nvidia.com/default/topic/1042073/jetson-agx-xavier/getting-started-with-autonomous-driving-using-jetson-xavier/

Thanks

The Xavier is likely to be good enough for making decisions about racing on its own (gas/brake/steer/gear.)

Once you have those decisions, you need to physically actuate the steering, gas, brake, and gearbox. You need something that can do this – servo motors, solenoids, or similar (depending on the specifics of your physical interface.)

Those actuators typically come with some form of communications interface – UART, RS-485, CAN, Ethernet, or something like that – if they are “servo actuators.” If this is the case, you need to output the right commands using the right communications protocol from the Xavier to your actuator. This should generally be straightforward, although for certain protocols that aren’t supported directly by the Xavier, you may need some kind of intermediary electronics.

Sometimes, those actuators are just “raw” motors (DC motors, or solenoids, or stepper motors,) which need a “driver” to actually switch the high-power driving current on/off. Those controllers are typically boxes with big MOSFETs and some other circuitry in them. The Xavier does not have the capability to do this switching itself. Those drivers, in turn, will need to be driven by some kind of input signal. For simple stepper motor drivers, you typically provide “step and direction” inputs. The Xavier could probably provide those signals over the I/O interface port (the “raspberry pi compatible” pins.) However, some motor drivers (H-bridges) will need PWM signals to modulate power delivery, and the Xavier does not have a simple API to generate suitable PWM signals for an H-bridge. If you need to generate those yourself, you should probably use a microcontroller to do so. (I’d recommend the Teensy microcontroller board series, connected over USB, but you can do whatever you want, including PIC over I2C, Arduino over serial, or whatever.)

Finally, you may also need to interface with various kinds of sensors. Some sensors (linear actuator potentiometers, for example,) are analog, and the Xavier does not have a good instrumentation-type analog input. (The audio inputs are DC de-coupled, which is bad in this case.) Some sensors are digital signals of high data rates, using no specific protocol, for example wheel encoder sensors. The Xavier does not have a simple package for tying counters to encoder inputs to figure out how far they have spun, although it may be possible to dive into the ARM peripheral reference manuals and configure a timer/counter to do this for you, once the technical reference manual is available. Typically, you’ll be better off using a microcontroller for those kinds of sensors.
Other kinds of sensors (such as IMUs, and various magnetic position sensors) will interface with I2C or SPI or UART, and thus you can talk to them straight from the Xavier, as it has those busses available.

So, the answer depends entirely on what your physical setup is, and how “smart” your controllers or actuators are on their own.

I would look into using a Vesc (https://www.enertionboards.com/electric-skateboard-parts/FOCBOX-programmable-brushless-motor-controller/) This is controllable via USB (ttyACM). MIT Racecar has a driver for Vesc 4.12 (Vesc has progressed to Vesc 6). Note that the focbox Vesc is called Vesc-X and needs the focbox tool to flash (not bldc). I havent used this myself but Jetson hacks has some info on controlling servo and BLDC motors with Vesc. The only other option may be to use Teensy (another MC) which would be a pain.

CAN bus is also an option. I also have the Xavier and need to control a servo motor and I am going to use the Vesc route to check if it works.

The VESC is nowhere near powerful enough to use for a full-scale racing vehicle. (Although I myself use one for my 1/8 scale RC rover)

For more information about Formula SAE, see: https://en.wikipedia.org/wiki/Formula_SAE

My son is working on his project where his rover is using multiple controllers (teensy including, and teensy is not a pain at all!) on CANBus. Unfortunatly, VESC while have CANBus interface, doesn’t support UAVCAN protocol. My son is currently working on enhancement to VESC firmware to support UAVCAN.

-albertr