Hi from RaccoonLab, a team of enthusiasts in field robotics! We want to share our true-HITL UAVCAN-based simulator for PX4.
We believe a unified UAVCAN bus for drone onboard electronics will become a mainstream approach shortly. Our simulator is already based on UAVCAN (in opposition to UART-MAVLINK) and emulates exactly the same messages as real UAVCAN-sensors.
In this video, we will look at how to connect brushless motors to a Windows computer via USB. We are going to connect a network of Servosila brushless motor controllers to the computer. The other option is CANbus interface, but we will look at CANbus in a dedicated video. A regular USB cable is used. Note that the USB cable is not used to power the controller and its motor.
The first brushless motor controller in network appears to Windows as a Virtual COM port. Once connected via USB, it can be found in a general list of devices in the Window's "Settings" window. Up to 16 controllers can be connected this way via a single USB cable to the same control computer or a PLC. If one of the interconnected brushless motor controllers is connected to a computer via USB, then that particular controller becomes a USB-to-CANbus gateway for the rest of the network.
If your computer happens to have more that one serial port, you may wish to check a COM port's number assigned by Windows to the controller. Then, you pick this COM port in a drop down menu in the Servoscope software, and click Connect. If the COM port is not listed in the drop-down menu, click the Refresh button. If everything is good, the controller appears in a list of devices. Double-click to open up a control and configuration window.
Protocol AXI4 was developed for High-bandwidth and low latency applications. It is designed to allow communication between master and slave devices. Master is typically a DMA or CPU and slaves are DRAM controllers, or other specific protocol controllers: UART, SPI, and others. Sometimes one component can implement multiple instances of this protocol. Usually, a prefix is used to differentiate between multiple AXI4 interfaces.
For example, Ethernet MAC can integrate DMA and slave interface used to command MAC. MAC can accept commands on the slave interface that contain data about the location of the next ethernet packet and MAC can start fetching this packet using the separate master interface instance.
This article was motivated by common design mistakes AXI4 designers make when they are designing their Digital IP. (Looking at you Xilinx)
In this video tutorial, we will control a pair of brushless motors from a Raspberry PI computer. We will use one of the computer's USB ports to connect a network of brushless motor controllers. We will power the computer, the controllers, and the brushless motors using a single battery, similar to a autonomous vehicle design.
The first motor is an outrunner type, a kind of what you would use for a vehicle propulsion. The bigger motor comes with a quadrature encoder which means it can be used as a powerful servo.
I made a cable to power my set up. On one end, the cable has a socket for plugging the battery. The cable splits into a two parallel parts to power the controllers, and the Raspberry PI. The bottom part of the cable further splits to power a pair of brushless motor controllers.
By the way, the controllers need 7 to 60 Volts DC. I put proper connectors at the ends of the cable, so that I could just plug it into the controllers.
Servosila brushless motor controllers come in rectangular or circular form factors. The controllers have USB and CANbus ports for connecting to control computers such as Raspberry PI.
