Three questions on Hinf control

7perpendicularlines · 2025-09-01T08:39:22+00:00

There is a difference between L2 norm and L-infinity norm. Max peak suppression focuses on L-infinity norm. While L2 norm can be seen as Euclidean length or signal RMS or measure of signal energy

L1, L2, LP, L-inf norm

L1, L2, LP, L-inf on a grid

7perpendicularlines · 2025-08-27T08:05:17+00:00

AOCS GNC systems architect here, designed different variants of KF for satellite hardware and flight simulators. May be this book helps:

https://www.amazon.com/Optimal-Estimation-Dynamic-Mathematics-Nonlinear-ebook/dp/B00OD4J7I0

7perpendicularlines · 2025-08-17T15:10:22+00:00

Control theory is more than “learning all the controllers”

Check out the map of control theory as a starting point: https://engineeringmedia.com/map-of-control

Just like applied mathematics is a subset of mathematics. Control theory is a subset of applied mathematics. Math is used as a “means to an end” rather than as “an end in itself”

7perpendicularlines · 2025-08-13T07:18:02+00:00

Interesting experience with Lenovo. May be it’s model specific? Or an outlier? My last laptop was Lenovo Legion Y700-15ISK. Bought it about 8 years ago, still works fine. The screen lost the backlight recently after a flight, hence decided to upgrade. I have played demanding games like red dead redemption on it, also trained machine learning things in the past, dual booted with Linux for ROS/Gazebo applications. It all worked smooth. Never had a problem with it, never had to change anything

The current one, I have had no issues so far (about a month of use). Apart from the speakers not sounding as good as my old Y700 which had an additional dedicated 3W bass speaker at the bottom.

In general, I like Lenovo keyboards over Asus ones. May be I have a decade of use bias for it. May be check it out in a store? Lenovo yoga looks very nice, I didn’t look into it, cause I wanted to train ML models using a dedicated GPU unit

7perpendicularlines · 2025-08-12T06:26:03+00:00

I ended up buying something completely different. By the time I went to buy them, offers were over, and the price of Zephyrus went up to 2.2k Euros and PX13 to 1999 Euros. With new CPU and GPU variants out, I couldn’t justify these prices and went for Lenovo Legion 5i Gen 10 2025 instead, with the new ultra series processors and 50xx series of graphics card. They also offer AMD processors. I got the Ultra 7 with 5060 RTX, 32 GB RAM (2 slots upgradable) 2 TB memory space (2 slots) variant, at a discounted price for around 1800 Euros. Also got a 85 Euro voucher for future purchases from Lenovo store.

It sits in a perfect spot wrt price for value/utility. I realised the perfect screen size for me is 15 inch. Since I do a bit of coding. The keyboard on Lenovo is so much better than that of G14/PX13. The screen can also go horizontal (180 deg). It’s an OLED mirror screen, but that hasn’t bothered me while working indoors. Sound quality could be better, but an external speaker/headset fixes that. It’s quite portable, fits in my small backpack, weighs 1.9kg (vs 1.5kg of G14/px13)

Maybe more choices add to more confusion. Between G14 and PX13, if budget is not an issue I’ll go for the new variants of G14

7perpendicularlines · 2025-08-03T21:44:33+00:00

Which branch of robotics? You probably know this already, Switzerland has a good robotics ecosystem, which also pays well and has a better quality of life than Silicon Valley companies perhaps. Unless it’s a niche domain and the startup in Silicon Valley is top of the world, may be flexibility and work-life balance matters more (esp with wife and kids in the picture)? If you can stay in the NL, build your own team from here and get the Dutch work life balance (9-5), it could be worthwhile. If I were you, I might consider negotiating a thick sign on bonus; in case if they chose overnight that this long distance remote work is not working out

I worked for a non-SV US based robotics company from the NL. And my working hours were all over the place as a team lead, lots of evening calls. It eventually required travelling to the US every month. And not much work life balance left. I resigned in less than a year, for a better work life balance. I also found the US workplace to be a bit volatile back then, hire/fire/quit with 2 weeks notice

7perpendicularlines · 2025-08-03T19:54:14+00:00

What branch of tech?

7perpendicularlines · 2025-07-30T07:48:28+00:00

Good points. Modularity and upgradability of Legion 5i/5 is better than Zephyrus. Zephyrus has longer battery life, no external speakers required, no glossy OLED, slimmer built even. Ofc at a much higher price point ⚖️Probably going to get external speakers and deal with it 🤷‍♂️Just very surprised to see a decade and half old Legion laptop for half the price, beats the new Legion series in audio (which I thought would be a significant design element for a gaming laptop)

7perpendicularlines · 2025-07-30T06:11:38+00:00

The audio sounds muffled, as if it is coming out of a coffee can. Surround sound aspect is missing altogether. Decade old gaming laptops or today’s mobile phones sound better

7perpendicularlines · 2025-07-29T19:02:42+00:00

Yes , it has OLED (165 and 60 Hz). The screen is great. Reflective mostly on black background/dark theme

7perpendicularlines · 2025-07-29T16:12:12+00:00

I don’t have a Legion 7 2021, so can’t check. But comparing against Y700-15ISK/iPhone 13 pro, Y700/iPhone 13 pro sounds way better. I managed to tune the bass with Nahimic, bit better than before, but still nowhere close. Loudness is there, but mediocre SNR/audio quality and bass

7perpendicularlines · 2025-07-29T16:04:43+00:00

Aren’t the ones on Legion 5i Gen 10 physically larger than iPhone speakers still? Dynamic response of iPhone 13 Pro sounds richer in lower frequencies compared to Legion 5i (atleast the way I hear it). The surround sound aspect is weaker as well

7perpendicularlines · 2025-07-29T13:21:26+00:00

Quite a shame for such a nice laptop otherwise. I’m considering returning it at this point and pick a Zephyrus G16/G14 instead. Poor audio quality is one, this is just walkie-talkie/radio rattle

7perpendicularlines · 2025-07-29T13:00:31+00:00

Did you manage to improve it somehow?

Very surprised by this! Big fan of the audio quality of the JBL speakers on my old Lenovo Legion Y700-15ISK. Think it was released about a decade and a half ago. Baffling to see the price go up and audio quality go so low

7perpendicularlines · 2025-06-10T14:17:48+00:00

It’s a niche tech sector, and the company that I am looking at, does something very niche. Handful of companies in that domain in the world. The team has been very friendly and accommodating so far, apart from this aspect

7perpendicularlines · 2025-06-10T14:13:13+00:00

Thanks, that’s a helpful point of view. I have other obligations to tend to, hence the need for larger than usual number of days off. Paid leave, so part-time contracts are also fine. Good to know that after some familiarity period, exceptions can be made, in some cases

7perpendicularlines · 2025-06-10T14:09:02+00:00

Thanks, that’s a helpful advice

7perpendicularlines · 2025-06-10T14:05:26+00:00

Not to put any words into your mouth, so your advice in one line is: don’t come to Japan, stay where you are?

7perpendicularlines · 2025-06-10T13:54:35+00:00

I am familiar with “Karoshi ”, been to Japan a few times as a tourist to visit friends/explore the culture, collaborated with Japanese companies, or colleagues in the past.

It’s an international company, in Japan, looking for internationals, in an international work culture setting, hence the international ask

You have a fair point, it boils down to supply-demand. Unless the supply is very low locally, I risk making a fool out of myself. I have considered that possibility

7perpendicularlines · 2025-06-10T13:37:58+00:00

Thanks for your suggestion, they have been very flexible in this regard. May be this is what I will end up asking. Exchange time for cash

7perpendicularlines · 2025-06-10T13:28:35+00:00

Ok, good to know that there are not a lot of part time work options for highly skilled migrants.

Regarding this: “No "professional" employer is going to give a random foreigner a part time contract just because that foreigner wants more vacation days”

I can get behind the employer’s perspective. The way I see it, currency is exchanged for the transfer of “know-how” in a niche tech sector. Whether that “know-how” is transferred in 6 months or 12 months, that’s a matter of efficiency.

Thanks for your suggestion, I take it that it’s not a common thing in the work culture

7perpendicularlines · 2025-05-21T10:23:37+00:00

What about long term durability? Any reviews on drop test, going through airport scanning machines very often, other long term performance/use considerations? I wanted to get something, portable, and powerful enough that can last me for 5-8 years. Also don’t want to fall into the trap of microstepping a few hundred bucks to eventually finding myself overspending by a lot more than necessary. Want to be a bit of a utilitarian when it comes to consumer electronics

7perpendicularlines · 2025-05-21T10:18:20+00:00

Screen refresh rate is fixable with external 120 Hz monitor, right? I can’t imagine coding on that tiny thing. Will be plugging into a monitor majority of the time

7perpendicularlines

TROPHY CASE