[TC26] CRAB ROV

[n8walker]

Hello everybody,

I am finished with my entry but I did not have time yet to post any WIP content. Nevertheless I took some pictures during building, so I can show you my design process now:

The CRAB - ROV - Camouflage Robot for Arctic Biotopes - Remote Operated Vehicle

The idea was to build a sideways walking robot with an appearance like a crab. The leg kinematic is based on the Klann linkage:

https://en.wikipedia.org/wiki/Klann_linkage

This kinematic is actually used in some underwater walking robots right now, so I thought it to be reasonable to use it in some arctic vehicle.  At first I created a test vehicle with 8 legs:

Crab robot WIP 2 by n8walker23, auf Flickr

Crab robot WIP 1 by n8walker23, auf Flickr

This proof of concept went fine, the legs can easily move, rotate and lift the vehicle. The gearing down of the drive motors is not even necessary. The next task was to shrink that mechanism, as a smaller vehicle would be even more efficient at moving as fast as possible without straining the linkage or overloading the motors. A kinematic for the claws had to be designed as well. My layout would be: one motor for back four legs, one motor for front four legs, and one motor for each claw. So this was the next stage:

Crab robot WIP 3 by n8walker23, auf Flickr

Crab robot WIP 4 by n8walker23, auf Flickr

The motion of the sensors (the eyes) is coupled to the motion of the claws and it has some simple bodywork. The eye motion can cover an area of roughly 45 degrees. This design was followed by the next optimization loop:

Crab robot WIP 5 by n8walker23, auf Flickr

Crab robot WIP 6 by n8walker23, auf Flickr

I am quite happy with the bodywork at this stage. The rear propellers are driven simultaneous with the rear legs and the front legs are connected to a two-cylinder fake engine. The weight of the robot was 787g. Roughly 350g of that are the electronic parts. Now it was time to streamline the construction, decrease part count and weight and improve building quality. At the next iterations the robot would be modular. This made it much easier to apply little modifications, as it is not necessary any more to disassemble everything all the time to get access to critical regions. Also, I replaced the fake engine by  a fan, as i found a combustion engine not really fitting to the concept.

Crab robot WIP 7 by n8walker23, auf Flickr

Crab robot WIP 8 by n8walker23, auf Flickr

Crab robot WIP 9 by n8walker23, auf Flickr

Crab robot WIP 10 by n8walker23, auf Flickr

This is the final stage of the robot. Weight is reduced to 738g. Now I need to do some programming to have a nice remote control and to get good pictures and maybe a video as well.

Regarding the colour scheme, I tried some variants, but some choices are already set by the colours of the mindstorms parts:

Crab robot WIP 11 by n8walker23, auf Flickr

I think (e) is looking the cleanest, so this scheme is applied right now. Most fitting to the contest would be (d) i guess, with mostly white and yellow. But I think it is a good idea to use the turquoise of the mindstorms box somewhere else in the model so the box does not stand out too much. This leads to a solution like (b), but I think, that is too colorful. What are your thoughts on that?

 

Edited December 29, 2023 by n8walker

[Seasider]

Well the competition says using one of 2 colour schemes. So as you’ve gone white for your main colour you should use red and yellow accent colours. Your yellow legs fit with how yellow was used before. 

[n8walker]

Alright, I will give it a try, I can still swap back to the current scheme once the contest pictures are taken. Thank you for the input. 

[Plumbum]

My two cents:

I very much like the general idea and your implementation is fantastic - however personally I would not have guessed immediately that this entry was specifically designed for a contest aimed at designing an arctic vehicle. 

Thinking out loud w.r.t. potential approaches to make this more easily recognizable as an arctic vehicle I can think of 3 potential solutions listed below in descending order of assessed usefulness - again, those are just my two cents 

1. Large and small accessories to the model itself like skis, power generators, sledges etc.: I feel like this option is most suitable, given the time-constraint. Three potential accessories that immediately come to mind are
   1. A sledge on skis/other tracked vehicle to transport the CRAB-ROV to its operation area - imo just building a simple sledge with a unloading mechanism (e.g. crane or simple ramp) would be totally sufficient - no need to go overboard with super-sophisticated vehicles pulling this sledge 
   2. Some sort of mobile control-station (e.g. with a nice radar-dish) /Minifigure in winter-attire holding a remote-control
   3. An brick-built arctic landscape, e.g. some untouched arctic plans with some rocks scattered around or a iceberg near the robot
2. Vehicle type and specific equipment like tracked undercarriage, snow plow etc: A (underwater) robot is probably very universally usable and thus offers relatively little option space for distinctive (arctic) features - the only thing that comes to my mind are heating-packs to protect the sensitive electronic components from the cold and lots of lights to help see the robot in the dark arctic winter
3. Colour-scheme: I personally tend to connotate orange livery more strongly with the research/arctic exploration-theme. However, in light of the given green colour of the mindstorms box, this colour-combination probably wouldn´t work very well

I´m very much looking forward to your finalized entry, best of luck in the competition 

[n8walker]

Thank you for your detailed feedback, I will see, what I can implement in the given time. 

Building a ROV was my plan immediately, because I guessed, most people would choose a manned vehicle and I wanted a different approach. 

The crab design came to my mind quickly as well, and I like the cute look of the robot. Also it is built in original scale, so it is a rather small robot. The mission plan of this ROV would be to be deployed in the vicinity of local wildlife, let's say a seal. Due to its crablike appearance it wouldn't disturb the animal and could observe it and follow it around. Even if the seal decides to dive into a ice hole, the ROV can follow it. So I have to think about, what equipment to give to the robot without disturbing the disguise. Also the robot is quite fast and shaky, so I will probably lose all equipment while moving . But I think, a control station with a nice radar dish and probably some solar panels to improve the robots signal connection and recharge it during the mission time would be a nice addition. 

For the photoshoot there is a little bit of arctic landscape planned. I have a white blanket which looks a lot like snow and the robot leaves funny looking tracks on that blanket. 

Colour change according to seasiders recommendation is planned. Sadly I don't own orange technic parts, so that colour is no option. 

Best Regards 

Edited December 31, 2023 by n8walker

[n8walker]

Soo,I did some updates, colour scheme is now white with yellow and red accents. I added a robust red transporting bracket to lift the robot. You could even grab it with a hook and a winch. As well a little cargo space is added at the rear. Inside of that is a fluid containing drum, which is connected to the medical equipment at the crab scissors. This could be used to either collect blood samples from local wildlife or give some vaccination. A little base station for the ROV was built, too. It gives the robot the opportunity to recharge with solar power and improves the robots signal connection with a big satellite dish. This base station has a transport bracket as well, to lift it up. 

Crab robot WIP 12

Crab robot WIP 13

Crab robot WIP 14

Crab robot WIP 15

[Plumbum]

I love the additions you made, it looks absolutely splendid - great job 

Especially the attention to detail is fantastic - the inclusion of the medical equipment and the transporting really add to my impression of a well-rounded and thought-trough robot - and imo allowing you to tell a very nice, cohesive story with this model. Also I very much dig the design of the solar-panels 

[n8walker]

Thank you very much!

[Thirdwigg]

I like the color changes that you made here. It looks much more in theme now.

[n8walker]

Hello everybody, attached you can see further pictures of the modules and assembly