A new Red Brick 70A ESC (including BEC) was received and checkout performed to select a SImonK module to load.
COMP_PWM is an option on SimonK ESC firmware for sensorless brushless DC motors (Kirby 2011),
This article looks at the current waveforms resulting from that implementation, and is an expansion of (Duffy 2014).
I ‘needed’ to explore modern controller technology for slot cars.
It is a very long time since I played with slot cars, more the technology (rewinding motors) than the racing, but as a 13 year old, I did a share of that too.
There is a risk of damage when flashing ESCs. It accrues from the fact that ESCs have a three-legged H bridge and if a high and low FET are turned on simultaneously, damaging currents may flow. In fact, this can be an issue if the FETs are on together for just microseconds on each PWM cycle. Loading the wrong hex module is a recipe for disaster, it may turn on FETs in an unexpected way.
So, for safety, the ESC should be powered from a current limited power supply during flashing and initial motor testing.
In a process of continuing development, this article describes a variation on the inexpensive current limiter for flashing and initial testing of ESCs – Mk I.
I had some Skywalker 40A with BLHeli v11 spare from the tricopter project, so I have put them on the APM X450 quad for a trial.
The BLHeli beacon is really annoying, so I turned it off. Otherwise it is a pretty basic Multi BLHeli configuration.
The ESCs were throttle calibrated using APM’s all at once procedure… but it didn’t work as expected, the motors remained stopped when armed. A lot of fiddling around to find some parameter changes did not work until power was cycled. Set MOT_SPIN_ARMED=200, THR_MIN=220.
Initial tests in stable, alt hold and loiter modes have been good.
I ‘needed’ to experience a tricopter, and I chose a Hobbyking X900 frame kit.
The 1245SF props arrived and replacement HK922 servo, both were fitted.
The tricopter is very hard to fly with 1245SF despite lots of time tuning pitch and roll, and level PID parameters. It appears that the propellers are just too much and that control loop stability is hard to achieve at lower motor speed.
So, the 1145 propellers were refitted and fine tuning of the saved PID parameters commenced.
The replacement servo works fine, stable stand alone with and without load, and mechanically smooth through its entire range (no sign of any stiff spots in the gears as in the previous one).
The project is coming to an end, the tail mechanism is an obvious vulnerability in this implementation though it seems to work quite well… more in the final report.