To collect appropriate data from a motor and guarantee high performance, IQ goes through an extensive testing procedure with each of their UAV products. We’ll use the Vertiq 8108 as an example for this overview.
Depending on the size of the motor and how much thrust it can produce, it can be run on one of our two force/torque (F/T) sensors. We then use a National Instruments data acquisition system (DAQ) on each stand to collect data. For the Vertiq 8108, we use the ATI Automation Mini85 F/T sensor with an NI USB-6341 DAQ. The Vertiq 8108 gets mounted to the test stand using two nylon plates. One plate interfaces with the mounting holes on the F/T sensor, the other interfaces with the motor. The sensor is highly sensitive to temperature changes, so we use thick non-metal mounts to make sure thermal drift doesn’t produce inaccurate readings.
Once the motor has been flashed with firmware and calibrated, we begin tuning and testing in voltage control mode over UART. During the tuning process we check lead time and tune cross inductance, then we do a voltage sweep to confirm that the motor has good settings. We start with a no-load test procedure, where we spin the motor with no load at different commanded voltages. In this test, the motor self-reports its KV. If this KV value is consistent with what we specified to the manufacturer (like 150KV for the Vertiq 8108), then we proceed to the next step. If the KV value is not consistent with our expectations, we iterate on the tuning process.
The next step is our derate test, where we spin the motor with a propeller at full throttle in order to make the motor derate. By doing this we figure out the continuous limits for speed/torque. Once the motor derates we evaluate it to see where it settles.
We then do an efficiency sweep or thrust test, where we spin the motor with a propeller through its entire operating range. We sample at 0V at the beginning and end of the test to ensure that the F/T sensor’s readings are consistent throughout the run. For each voltage we command, we ramp to that voltage over the course of 5 seconds, let the motor settle for 2 seconds, and then sample for 5 seconds. This generates speed, torque, and thrust values at various levels of input power with a given propeller. This data allows UAV makers to see if the product could be incorporated into their vehicle. You can find the results of the Vertiq 8108 thrust testing here.
When testing each module, we like to do a head-to-head comparison with a competitive product. For the Vertiq 8108, we tested against the U8 Lite with Flame 60A HV ESC and the Alpha 60A LV ESC. We performed the efficiency sweep on both motors to compare the performance under equivalent conditions (same test stand and props). This comparison data is available upon request.
February 18, 2022