[ScorpiusWireless]

Problem:

So we are getting closer. 
The project involves dozens of sun set lots of firmware to enable one piece of hardware to be used for over a dozen products. 

One of the sub sets is brushless motor control. The MPD is the first decoder to include a 12C 4 pin port.
In fact reaction on social media was that great we are just adding a second 12C port. In short this allows a wired connection to various gadgets from screens to sound products etc. One key use will be a brushless controller set up in the car. 

This is for wireless only. There are already dozens of ESCs being made for analogue slot cars. However none for digital. And certainly none for wireless digital. 

So what’s the problem?
Digital requires constant voltage on rails. That’s not a problem on a 6 lane commercial or club track. Scorpius designed a simple $2 plug that turns an analogue lane into a digital lane with constant voltage available.
When a fellow competitor deslots and ends up in your lane it’s referred to as a rider. This often results in the car deslotting again with possible damage to the car.
Some of the analogue brushless community frowned upon my digital brushless wireless proposal. I thank them for their insight.

So what to do?

How the heck can I resolve this issue? (This is for certain situations only and not home use).

Enter the Scorpius Wireless Analogue Module.

   

How it works:
The MPD decoder and the WAM
are both placed on the same channel. Both will now receive simultaneous data from the Scorpius Wireless controller.

A firmware upgrade to the WAM will see power delivered to track reduced to zero when throttle is zero. As soon as you touch the trigger even 1mm track the WAM will return track power to full. 

This is a rare event but must be addressed.

So there we have a solution using an existing product so the only development cost is a firmware upgrade.
Why do I want to use the MPD for analogue racing? Mainly the convenience of wireless, a maintenance free controller and state of the art throttle and brake adjustments which ultimately lead to quicker lap times.
It’s all about the control.

Brushless is just one of projects happening but we still have many things to complete before starting the brushless motor aspect however.

We have other things to complete first but we can get around to this when the brushless addict is addressed.

[Scot Reeves]

[Scot Reeves]

Good choice on the Texas Instruments ,  they do seen popular, now   .

[ScorpiusWireless]

Well a lot of things took priority over the brushless aspect of this project. In fact we haven’t even started it except to say we added an additional data port in case required.

Ok so the age old problem of slot car ESCs running jerky when using pwm controllers. Motor outputs on all digital chips on the market all use pwm for motor power.
Seems most ESCs are designed for PWM. But the slot car industry seems to use ones that are not designed for PWM. Why? I don’t know except to say RC runs off batteries which are analogue not PWM. Could it be these designs are just copies of older designs?
Now let’s talk about noise. It’s known that lower frequency motors are noisier. Higher frequencies can cause excess heat.
Some motors don’t take kindly to certain frequencies too. I remember upgrading Scalextric cars to NSR motors back in the early days of Scorpius development. Worked fine on SSD systems. On the Ninco digital system motors would get so good the motor melted the chassis and the engine fell out, an important observation.
With the Scorpius proposal we can bypass the chip and run track power direct to the ESC to avoid PWM. But what if your power supply is PWM? Most are. Will that be an issue? Probably. I’m sure that most power supplies are PWM. 
So that leads us back to PWM. As mentioned earlier 95% of the ESCs on the market are PWM. The RC industry doesn’t suffer from jerky motors and cars stalling. It comes back to filtering. But it also “sympathetic” frequencies also play a major role as discovered with the chassis melting of not sympathetic.

So what to do? Configuration and customisation is the answer. It’s why we selected the Texas BLDC as it is configurable as a starting point. But that’s another load of work. Seeing the Scorpius chip already has configurable brakes and throttle mapping via controller, do we need it? Answer is yes because in my opinion the frequency needs to be configurable also. But do we need a configurable ESC? Answer is probably no because we can also do that in the Scorpius car chip. I can’t really think of any other aspects that need configuration. If anyone thinks of one please tell us.
So if a configureable ESC is not strictly required it means we can use most ESCs designed for RC. 
I’m fairly confident we can get a smooth running brushless set up just by adding a frequency config program and a suitable ESC. 
If that doesn’t work I can vampire cleaner power off the car chip braid wire inputs and bypass the chip abc use the Texas offering. The power levels are then controlled just using logic from the MPDs data port. However that’s 6 wires all up instead of 3 and I’m fussy on my installs. The less wires the better. So I’d prefer the freq config method.

Also upping the frequency will help smooth the pwm, but that means a higher capacity driver and perhaps heat could need to be factored in.

So a lot of thinking, methods and ESCs to think about. At this stage the freq configuration method is preferable but that will require experimenting with various motors.

It will be interesting to see where this goes. We still have lots of other more important work to do so we may not get to this straight away. But it will happen. I look forward to that day.

[Kevan]

Let's go back to my earliest days racing RC cars, probably 1978.

Cars had a servo with a wound resistor and wiper arm from a Parma Slot car controller.  The transmitter operated the throttle servo which simulated a Slot car controller.

Then in the mid 80's we saw the first electronic speed controls which did away with the throttle servo/wiper/resistor and we called these ESC's for short.

Roll on 20 years and we saw the first LiPo's and brushless motors come on the market, early ones were what we called 'coggy' at low speeds, (what you called jerky).

Not long after, sensored brushless motors and ESC's were released, more expensive but much better as drive was very smooth as the ESC's 'knew' where the brushless rotor was whereas the unsensored brushless motors/ESC's didn't.

So to cut to the chase, I'd suggest Slot cars that use brushless motors are using unsensored motors and that's why they're 'coggy'.

...Slot car controllers still use the same basic setup as they did when I was racing RC cars 47 years ago (and much earlier than that in Slot cars) and that setup hasn't been replaced electronically like it was for us RC car guys, so these Slot car brushless 'ESC's' aren't ESC's, they're Ecoms.

...wireless could change all that though and maybe these can be called ESC's

[ScorpiusWireless]

Good information thanks. I’m pretty sure a few guys reporting cogging are using sensored. But I’ll double check. And no issues when using resistance controllers.
The issue seems to be square wave versus sine wave, or PWM controllers versus resistance controllers. After all 12V is 12V, but the waveform is the only difference I can see at this stage.

Filtering is also an important aspect. Perhaps these ESCs have poor or zero filtering.

The wireless controller aspect is not relevant I don’t think, the output of a digital car chip is PWM even if the power supply is not PWM. Most ESCs convert variable incoming voltage so that’s why digital golf will need to use the motor wires off their digital car chip to drive the ESC.
So I’d expect various issues.

[Kevan]

Good information thanks. I’m pretty sure a few guys reporting cogging are using sensored.

I doubt it, sensored brushless motors need two extra wires and a sensor board and not sure these exist in drone sized brushless motors yet.

[ScorpiusWireless]

Yes you are correct. It seems slot cars took ages to get digital, ages to get digital functionality, ages to get brushless and now another wait for sensored. Sigh.

[Kevan]

The tiny size of the motor might make it unfeasible.  Compared to an 1/8 scale RC car motor a drone brushless is smaller than some pinion gears I've seen 

[ScorpiusWireless]

I have no doubt too the quality of ESC firmware has improved over time.