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Brandon helped me solve an interesting problem during my PhD. I was building a sun-tracking sensor for a solar-powered lunar rover, and I needed to calculate the vector from the robot to the sun.

Brandon showed me how to use skyfield to solve the problem for a robot on Earth, and then he went back and forth via email to show me how to solve the problem on the moon.

In the end, we used skyfield to generate lookup tables for the places and times that we cared about, and it worked out great!


Surprisingly you can solve massive TSPs using heuristics. The solutions are not guaranteed to be optimal, but they can get very close to optimal without a crazy amount of computing power.

The Concorde TSP solver can apparently solve instances with 85.6k cities to optimality. Pretty amazing!


Ride share companies are surviving so it’s clear that some good enough solutions do exist.

There’s a difference between the algorithms ride shares have to use and the heuristic based solution for 85.6k cities.

The graph for ride shares is constantly changing as passengers request rides from random starting points to random destinations.

This version of TSP is much harder to solve.


Sorry but how is ride share problem a TSP problem? Rides are assigned one at a time and I do not think they would take into account future rides while doing the assignment optimization.


Not my industry, but imagining that they accept rides within a 48 hour windows from now. You’d quickly get something somewhat similar to a TSP. But given that you have lots of additional constraints (people tend to have a clear idea when they want to get from A to B) compared to the classical TSP, it might actually be easier to solve. As those constraints limit the paths you must evaluate.


True. I got derailed because the person I replied to and the replies to my comment used to TSP formulation to discuss this.

You’re right that the problem space is simply matching available drivers to riders.


Are any subtopics particularly interesting to you?

Mechatronics, Computer Vision, Control Theory, State Estimation, Path Planning, etc?


Second that.

Similar questions get posted pretty often in engineering subreddits and it's difficult to answer as robotics is so multi-disciplinary.

Very few people in this world are skilled enough in embedded programming, PCB design (motor control and sensors), materials and structures, dynamics and kinematics, controls and machine design (CAD, selecting manufacturing processes, selecting various COTS mechanical parts like actuators and bearings) to be a one-man-robot making orchestra.

Advice to OP: pick a specialization to start with, and focus on learning that while using pre-made parts for the rest. For example, buy a ready-made robotic arm and write path planning and controls software to operate it. Or build your own CNC router/pick-and-place/3D printer/pen plotter but use off the shelf/open-source electronics and firmware.

Once that's done, pick another specialty and move on to that if it interests you.


Picking up this idea, someone should write a robotics version of "Build Your Own Metal Working Shop From Scrap"[0]. It's a seven volume series where basically you start with rocks, make a series of tools, and end up with a metal shop.

https://www.goodreads.com/en/book/show/19811050


Even better if the parts for your robot(s) are machined using the DIY metal-shop tools! It's DIY all the way down...

All joking aside, I've always longed for a complete set of those Gingery books in print format. I have ebooks of most of them, but I'd love to have a bound set. And even more, I'd love to have time (and space) to actually take a stab at building the Gingery metal shop. Seems like it would be real blast (no pun intended).


Good advice.

Can you recommend the names of any off-the-shelf robotic arms or tools that can be modified or hacked?

Any good standard starting points for controller software?


I recently researched "cheap" (not really but not super extra expensive) robot arms.

(Disclaimer: I haven't bought any of them, so can't say anything about the quality.)

UFactory Lite $3900 https://www.ufactory.cc/product-page/ufactory-lite-6-kit

Dorna 2 $4200 https://dorna.ai/product/dorna-2/

ReBeL cobot €5000 https://www.igus.si/product/20962?artNr=REBEL-6DOF-01

Interbotix https://www.trossenrobotics.com/robotic-arms/ros-research-ar...

DOBOT $2700 https://www.trossenrobotics.com/dobot-mg400-industrial-deskt...

Wlkata Mirobot $2000 https://www.wlkata.com/products/professional-kit-of-wlkata-m...


The Niryo arm is a high quality kit with good software support package if not updated as often as it could be

https://www.niryo.com


There's plenty of toy arms for programming on every electronics site, including amazon. They're basically just a series of exposed hobby servos mounted together in a plastic skeleton. The motors are pretty much standard. You can even buy them with or without an control board.

Buy an Arduino Mega or something. That way you'll have way more pins that you'll need, and shouldn't hit up against the memory limits. Arduinos have a huge community, and the free IDE has all libraries and everything you need. I bought one and an MP3 shield from AdaFruit last year and successfully made a GNK droid. complete with flashing lights and multiple modes of tranquil gonks.


Check out PBRT, an academy award winning book about a rendering codebase!

https://pbrt.org/


I think it is a reference to “Cracking the Coding Interview”, a book that teaches you how to pass FAANG interviews.


Yup, a bit tongue in cheek. CTCI is a nice book, but it inspired a whole industry dedicated to landing a job at Meta.


Find a project you want to build and stop at nothing until it works. Repeat. Caveat: pick things that are just beyond your current level of knowledge.


I’m a PhD student with ~5years ROS experience. What is your programming experience level? Why do you want to learn ROS?


The Kershaw Leek pocket knife. Flips open one-handed and makes a satisfying “snick”. I’ve used mine daily for 5 years.

https://www.amazon.com/dp/B0009VC9YK/ref=cm_sw_r_cp_api_glt_...


Kershaw Skyline for me, been my favorite go to knife forever.

Even lost it for a couple of years in the yard until the chickens dug it up one day and I just cleaned it up and it was as good as new.


Have had the exact same Kershaw knife for about the same period of time. It’s my go-to for opening boxes and things around the house. It’s a great product.


I've the similar Kershaw 'Tactical' Blur for 12 years; they are great knives.


Personally, I hate anything that clutters my home directory. Have they added an option to relocate ~/snap?


Could it be that the examples of “good” architecture were selected over centuries by the communities that chose to preserve them, while the “bad” examples were chosen by pretentious hacks who don’t have to live and work near these buildings?

I love the author’s point, but I wonder if there are better examples of modern architecture that just aren’t being celebrated by the in-crowd.

Reminds me of Howard Roark.


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