Discussion: How Would You Roadtest the MagAlpha Angle Sensor Kit

I didn't realize the sensor could be mountable to different motors. Exploring the installation options in a RoadTest has some merit. That heavy lifting Randall mentions in his write-up is critical for the sensor to work effectively. 

Having read a bit more on it, the sensor is very interesting and designed for new and existing applications. The sensor can be read digitally (SPI interface), or it offers a normal rotary encoder output, for (say) retrofitting where an optical encoder would go, or for places where an optical encoder is more impractical (e.g. greasy/dirty machine environments), as well as a PWM output.
I think this RoadTest lends itself really well for project/application-based testing, i.e. building and working with it and seeing if it suits particular applications or not.

I think it would be interesting for those who like working with FPGAs or microcontrollers, to create all sorts of software/HDL applications for it. This reminds me of the Measurement HAT RoadTest, where Jan and I had quite a lot of fun discovering how to use the device and creating apps.

It doesn't need a lot of FPGA or microcontroller experience to get going with the sensor, since there are many resources for connecting existing encoders to FPGAs/processors, (e.g. plenty of online tutorials on encoders with Arduino) but of course if the user has experience with that then it helps.

For those that do not like working with FPGAs or microcontrollers, there is the possibility to try to retrofit wherever a rotary encoder is currently used, or alternatively to explore using the PWM output.

For the example applications I could think of (some are listed below), not all require the servo motor, but the motor is already a ready-made example application, excellent for seeing the sensor in operation (the sensor acts as the feedback to manage the motor position and speed basically).

The diagram here shows how servos work, however the 'Rotary Encoder' in the diagram is actually the magnetic sensor, and the 'Servo Amplifier' is actually a brushless DC driver.  The Programmable Controller in the diagram could be replaced by a PC connected via USB. This is a very simplified diagram, modern servo systems are a lot more advanced.

Some example applications:

(1) Servo motor testing
With the supplied kit, you could use it to see how much torque you can apply to a servo motor, before its position is affected, and you could see how quickly the servo motor recovers back to its original position if you knock it, by seeing how quickly the PWM recovers, or by recording the rotary encoder value repeatedly (e.g. using a microcontroller and storage) and then plotting the values. This is all great for CNC and robotics applications. The supplied servo is already effectively one axis for (say) a robot arm, and the sensor is already within the control loop, but there's nothing stopping a user from attaching the encoder output in parallel to their own microcontroller, e.g. Arduino or whatever one is comfortable with.

(2) Position sensing digital read-outs (DRO) for milling or lathe machines
These are environments that are not nice for optical encoders, and direct linear measurement is expensive if done properly. It could be possible to build a far cheaper DRO connected to the dial on such machines, i.e. an indirect measurement. It beats having to manually count the rotation angle and number of turns. For this, the sensor board would be extracted from the end of the servo motor.

(3) Distance measurement
I think a really granular (sub-millimeter) measurement wheel is possible, again by extracting the board from the servo motor.

(4) Practicality of using magnetic sensors investigation
From the sounds of it, it could greatly reduce costs to use a magnetic sensor, since there's no need for any fancy coupling that would be required for an optical encoder shaft. However, I don't know if this is the case, so it would be interesting if someone tried it - i.e. attach a magnet to a shaft themselves, and see how accurately the magnetic sensor needs to be positioned and if the results change significantly if there is misalignment. This would be really useful info, including magnet recommendations.

I have some products currently in design stage that a sensor like this could be very helpful with.  NDAs prevent me from divulging them openly. Please PM me so we can discuss in private. 

Hey Randall, I have a few products in design phase currently that a sensor like this would be very helpful with. Current NDA agreements prevent public disclosure at this time but if you will pm me I would love to discuss this sensor further.

You could make a very accurate telescope pointing system with this encoder.

Hi Michael. I sent you a PM.

Randall

I am a hobbyist in the electronics field and have been trying to get into being a roadtester and even though I've already applied to quite a few of them I haven't been picked for one. So, I wanted to ask an honest question. What does a new person (on e14 and to Roadtests) with knowledge and electronic skills to solder on SMD components (from package sizes 1206, 0805, 0603, SOT23, LL34, sop8, all the way to the tiny 0402 as well as other little and big components/chips) need to do to be able to be picked for the available roadtesting projects? I mean I know that there are minimum requirements and that's not what I mean, I mean what will it take for someone like me, who isn't an electrical engineer and that wants to learn and help others to learn as well, to get picked for a roadtest? 

Hi A.J. - I can't speak officially for the Road Test selection committee, and I dont know what and how many Road tests you've applied for, but I can share my experience. When I first got going with Road Tests, the ones I applied to & got selected for were learning courses and beginners experimenters kits like MicroBit, small build learning kits, Arduino & Raspberry Pi. A Road Test or two with these builds a reputation for bigger and more complex road tests later. The Road tests lately seem to have been fairly specialized content, and some have small quantities of expensive instrumentation.  A bit ago there was some Road Test for Raspberry Pi Pico that are a good starter Road Test. You can also participate in Project 14 and the Design Challenges, which also help to build reputation and build confidence to the E14 staff that you will deliver your promised results on Road Tests. Road Test report-out has been an issue to the E14 staff in the past. Hang in there, dont get discouraged, and also look around other contests and challenges to participate with. 

Hi Anthony,

I won't dwell on the non-tech aspects, because there are some requirements which are not related to engineering, for instance reliability is something probably high on the list, because there's a handshake agreement/promise to do the review, because the manufacturers won't offer more review items for the program if reviewers are not reliable, and Randall and the rest of the element14 staff are best placed to comment on that, and how newcomers can demonstrate their reliability, but I can help from a technical perspective.

From the technical perspective, it varies from one device to another, and you get the option to propose how you'll RoadTest/Review the item, which doesn't need soldering, coding, etc., if you don't want to initially. In fact many reviews items do not require soldering or coding or any onerous level of knowledge. Sometimes, by just reading up on the item you've been tasked to RoadTest, that is sufficient for you to become an expert on it, because others do not have the time to study it in depth, and they rely on you to write up your findings in simple language so they can quickly get up to speed on a product. If you can achieve that in a review, then from my perspective (others may feel different) I feel it's already a great review before even any soldering iron is switched on : ) For me I dislike reviews that launch into a complex discussion of the product without any overview or simple explanation of what it's all about, because I don't have the time to research everything, I (and I'm sure others) rely on people who write blogs/reviews etc., to do the distillation and write-up of the information, that so I can learn from them.

Here's an example of a review that could be improved a lot (from my perspective, others may disagree): Infineon BLDC Shield   (I don't like to share a negative example, but if it helps others write a good review then some good has come out of it!).

The reason is, he launches into the review, titled Infineon BLDC Shield, without even stating what BLDC means. Even if you'd studied engineering at a university for 4+ years, you would likely come out of it without knowing what BLDC means. Secondly, he wasted time creating videos that were pointless, they do not even show a BLDC motor (technically they do, but they are not being controlled as such from the equipment he is RoadTesting. The code he wrote doesn't seem all that interesting either. Instead, it would have been nice to learn about what the performance of the board he was reviewing was (e.g. how much voltage and current can it support for driving motors), and an explanation of BLDC as mentioned, and what it is used for. No code or videos would be needed for that. Of course, good code or good videos are great too. And thirdly, he didn't stand by his review because someone asked him a question in the comments of the review, and he didn't answer, so to me that's unreliability. On the other hand, maybe he didn't realize someone asked him a question, because the site does have some notification issues.

Anyway, back to this particular RoadTest for the MPS magnetic sensor, it is for a device that doesn't need soldering, and can be used as-is. However, some reviewers might get their soldering iron out and connect to a microcontroller like Arduino or Pi Pico perhaps, because a lot of boards/devices use standard connections/interfaces, and you'll soon start to recognize those, even if you've not studied engineering.
At a board-level, and between boards, often the popular interfaces are called I2C and SPI. By looking at the datasheet of the device, it will indicate which one, and in this case, the MPS sensor board offers SPI, however it's not essential to use that interface if you're not currently unfamiliar with it. For those that do want to do a bit of coding, the support information is actually really good - the manufacturer (MPS) has gone to the extent of writing a complete guide. 

Most electronics nowadays involves some programming, and something like Pi Pico, or Arduino, are great for helping pick up some knowledge in that area. Another option is to install Python on your PC, and try some exercises on that. Eventially, you'll get to a stage where you will feel comfortable connecting electronics to such devices, and controlling them through software.

For a newcomer, I reckon these RoadTests listed below would have been good opportunities, these were in the recent past 6 months or so, but eventually other similar ones may appear. None of these required any programming, or circuit construction:

Fundamentals with Multicomp Multimeter + Accessories
METCAL GT120-HP-T6 Soldering Station
AIM-TTI Bench Power Supply
Fundamentals with Multicomp: Show Us How To Solder

This current MPS magnetic sensor RoadTest might suit a newcomer, or you could hold out for one you feel more confident about. Plenty of RoadTest reviews are about the hardware or software, and not necessarily connected to anything else. As mentioned sometimes it's just great for someone to investigate use-cases, provide helpful information and explain in their review why a product may be of interest. That was the case with the Fundamentals with Multicomp: Show Us How To Solder RoadTest, where at a high level all the reviewers needed to do was switch on the device, let it heat up and try to solder a couple of parts, it didn't even need to be a functioning circuit. For my review (I was one of the reviewers for that one), I didn't completely solder a functioning circuit either, since I felt it wasn't core to the review, and (for me) it felt more important to show some solder joints instead of the rest of the circuit.

So, in summary, there are lots of RoadTests where the technical knowledge isn't onerous, because the reviewer becomes the expert through just trying the product out and reading up on it, and in part things like the reviewer's reliability and a desire to stick with it are extremely important too. Also, everyone is friendly here and would help if you got stuck.

There is some great advice from successful road testers already but here are a few points from my perspective:

It took me many tries and many years to learn how to consistently write winning proposals, but all you need to do is make each one a bit better than the last one and eventually you will start winning. You can look at the road test blogs that were published for road tests where you did not win to see what your proposal would need to convince someone that you could produce a better road test that the one that was published. It could be that you could write a more entertaining road test, but to convince the evaluators, you need to demonstrate it by including a link to something entertaining that you published. It could be that you have a passion to learn about this technology and to prove it you need to explain this or link to something that demonstrates your passion. (you obviously have passion for road testing - make sure it comes across). If you don't have a well know track record of completing road tests, you need to demonstrate you will finish the job by pointing to some example of your dedication. If your proposal demonstrates perseverance, passion, a reasonably comprehensive test plan (that shows you have researched the technology), and maybe throw in a little entertainment potential you are well on your way to success.

In case it helps, I wrote a blog explaining my thought processes during a successful proposal I wrote:

/products/roadtest/b/blog/posts/the-story-of-a-power-proposal-of-the-supply-variety

At the end of it there is a link to what the judges were looking for.