[HELP] I'm trying to motorise the mars perseverance rover

[Ilovespace]

Hy, I'm a engineering science student ( still in high school, my country is a bit weird you specialise at the 2nd year ) and I wish to motorise the mars rovers perseverance set from this year but really don't know how to do it, so I'm asking for help. If you have any idea I'm in.

Thank you for reading me ^^.

[Bluehose]

I guess you can't with lego motors, they are too big. Use small lego compatible motors.

[aeh5040]

Start by deciding which functions you want to motorize, perhaps?

[Ilovespace]

1 hour ago, aeh5040 said:

Start by deciding which functions you want to motorize, perhaps?

Ho well, the wheels of course. And maybe the mechanical arm later. If I succeed to do the wheels first.

[Davidz90]

For wheels, there is really no reasonable way to motorize them other than having small motors directly in wheel hubs, unless you want to sacrifice steering.

[Timewhatistime]

6 hours ago, Davidz90 said:

For wheels, there is really no reasonable way to motorize them other than having small motors directly in wheel hubs, unless you want to sacrifice steering.

I hope that this will not be a surprising advice for an engineering student.

[Seasider]

No way to motorise it unfortunately due to where the body sits relatively to the wheels

Edited November 19, 2023 by Seasider

[Maaboo the Witch]

2 hours ago, Timewhatistime said:

I hope that this will not be a surprising advice for an engineering student.

Ooh BURN!

[gyenesvi]

Okay, let's give the guy some actual constructive advice as well..

You have picked a hard challenge, but I think something could be done, depending on how much money you throw at it :) What kind of electronics do you have, and how much experience with motorization? Furthermore, what would you like to use it for? Just to drive around on flat surface, or do you want to take it to some uneven surface as well? I guess you have the model itself, and tried to push it around. I have heard that it does not really roll well on uneven surface, because the legs are kind of wobbly. I am guessing that driving on uneven surface will require powering the steered wheels as well, while for driving on even surface, it may be enough to power the middle wheels.

One thing is for sure, if it can be done, it will require motors to be mounted straight to the wheels, on the legs. You could take two (or three) approaches. 

1. Official Lego solution: Mindstorms / Spike motors (Powered Up electronics). The best chance is to use the small and/or medium angular motors, but they can be hard to find (only in the (discontinued) Mindstorms and Spike Essentials set officially). You could mount these even to the steered wheels (the end of the legs would be the motors themselves). Or you could use the medium version and mount it to the middle wheels.

The steering is probably not that hard, you need to put a motor somewhere in the body to just drive the existing mechanism. You could use either Powered Up technic linear motors, or these angular motors (medium or big one).

Besides the availability and the price, another the problematic point of this system is that you will need a battery hub with enough ports to control all the motors you will have. The biggest hub is the Mindstorms/Spike hub with 6 ports. If you only use two drive motors on the middle wheels, and one motor for the steering, you could have three more left for other functions. If you power the 4 steered wheels, and steering, you will only have 1 port left for other stuff. But the large hub will require more space inside the body, which will be tight I guess.. Anyway, I think this could be a fairly simple construction to start, albeit kind of an expensive one.

2. Use Power Functions system with Cada micromotors.

https://decadastore.com/products/micro-motor-jv5043

These could be attached to the legs, and will require some gearing to power the wheels themselves, some thing like below, but using the micro motor instead of the bigger one on the image.

They could even be used for the steering I guess, after gearing them down. You will also need a battery hub, which could be smaller in this case; with Power Functions receivers, you could power many functions, and multiple motors from the same port. Power Functions electronics is out of production by Lego, but you can find many good enough alternatives on Aliexpress, quite cheap ones. Also, the Green Gecko workshop seems like a good alternative. They have Power Functions receivers that work with radio instead of infrared, which is much more reliable.

https://www.greengeckoworkshop.com

I think I would go with this second option, buy maybe 6-10 of the micro motors ($15 each), 2-3 receivers and a small rechargeable battery hub, stack 4-6 micro motors on the same port for drive..

One interesting thing is the dual steering system in the model. I think when you select in-place steering, the left and right wheels will have to spin in opposite directions. So maybe you will have to put the left-right motors to separate ports and control them independently, which should be fairly easy, just a matter of connecting the cables.

(3) Geekservos

These are small, cheap and powerful RC servos that have a lego compatible form factor, that come in continuous rotation and 270 degree variants, but they require completely custom electronics. I guess not the simplest to start with..

Hope this all helps.

Edited November 19, 2023 by gyenesvi

[aeh5040]

20 hours ago, Ilovespace said:

Ho well, the wheels of course. And maybe the mechanical arm later. If I succeed to do the wheels first.

Despite what some have said, this is all very much possible.

I would actually suggest starting with the arm mechanism. That should be much much easier - there is plenty of space for motors, and they can be static. The experience of doing that will help prepare you for the harder challenge of the wheels.

The wheels are harder because of the articulation. The simplest option is hub-mounted motors on the two middle wheels.

[Ilovespace]

3 hours ago, gyenesvi said:

Okay, let's give the guy some actual constructive advice as well..

You have picked a hard challenge, but I think something could be done, depending on how much money you throw at it :) What kind of electronics do you have, and how much experience with motorization? Furthermore, what would you like to use it for? Just to drive around on flat surface, or do you want to take it to some uneven surface as well? I guess you have the model itself, and tried to push it around. I have heard that it does not really roll well on uneven surface, because the legs are kind of wobbly. I am guessing that driving on uneven surface will require powering the steered wheels as well, while for driving on even surface, it may be enough to power the middle wheels.

One thing is for sure, if it can be done, it will require motors to be mounted straight to the wheels, on the legs. You could take two (or three) approaches. 

1. Official Lego solution: Mindstorms / Spike motors (Powered Up electronics). The best chance is to use the small and/or medium angular motors, but they can be hard to find (only in the (discontinued) Mindstorms and Spike Essentials set officially). You could mount these even to the steered wheels (the end of the legs would be the motors themselves). Or you could use the medium version and mount it to the middle wheels.

The steering is probably not that hard, you need to put a motor somewhere in the body to just drive the existing mechanism. You could use either Powered Up technic linear motors, or these angular motors (medium or big one).

Besides the availability and the price, another the problematic point of this system is that you will need a battery hub with enough ports to control all the motors you will have. The biggest hub is the Mindstorms/Spike hub with 6 ports. If you only use two drive motors on the middle wheels, and one motor for the steering, you could have three more left for other functions. If you power the 4 steered wheels, and steering, you will only have 1 port left for other stuff. But the large hub will require more space inside the body, which will be tight I guess.. Anyway, I think this could be a fairly simple construction to start, albeit kind of an expensive one.

2. Use Power Functions system with Cada micromotors.

https://decadastore.com/products/micro-motor-jv5043

These could be attached to the legs, and will require some gearing to power the wheels themselves, some thing like below, but using the micro motor instead of the bigger one on the image.

They could even be used for the steering I guess, after gearing them down. You will also need a battery hub, which could be smaller in this case; with Power Functions receivers, you could power many functions, and multiple motors from the same port. Power Functions electronics is out of production by Lego, but you can find many good enough alternatives on Aliexpress, quite cheap ones. Also, the Green Gecko workshop seems like a good alternative. They have Power Functions receivers that work with radio instead of infrared, which is much more reliable.

https://www.greengeckoworkshop.com

I think I would go with this second option, buy maybe 6-10 of the micro motors ($15 each), 2-3 receivers and a small rechargeable battery hub, stack 4-6 micro motors on the same port for drive..

One interesting thing is the dual steering system in the model. I think when you select in-place steering, the left and right wheels will have to spin in opposite directions. So maybe you will have to put the left-right motors to separate ports and control them independently, which should be fairly easy, just a matter of connecting the cables.

(3) Geekservos

These are small, cheap and powerful RC servos that have a lego compatible form factor, that come in continuous rotation and 270 degree variants, but they require completely custom electronics. I guess not the simplest to start with..

Hope this all helps.

Okay well that's a lot, thank you very much it is a great help, I actually didn't even know that lego discontinued the small and medium angular motor, hopefully I think I have already some. 

I'm going to need some reflexion time to think wich way I'm going to do this ( and also because I'm going to ask my ingenieury classmate and teacher about this). Actually I can't really decide I think, since I don't have the set right now ( will have it the 29 normally), but I have heard to about the suspension problem (not sure if this is English correct ).

Anyway I talk to much. You have been of an incredible help, thank you really really much o(^o^)o.

1 hour ago, aeh5040 said:

Despite what some have said, this is all very much possible.

I would actually suggest starting with the arm mechanism. That should be much much easier - there is plenty of space for motors, and they can be static. The experience of doing that will help prepare you for the harder challenge of the wheels.

The wheels are harder because of the articulation. The simplest option is hub-mounted motors on the two middle wheels.

I'm doing the arm at the end. I really really want to make it more "accurate ". And also because I think I can take it as my final project for my engineering class (which if the teacher is OK, would be freaking amazing). But thanks for the ideas. 

[Maaboo the Witch]

24 minutes ago, Ilovespace said:

o(^o^)o.

Sooooo adorable! I'm using this. 

[Seasider]

Once you start physically building the project please do post some photos here of your progress I’m sure lots of us will be interested in how you get on.

another potential route is to mount the drive motors inside the main body and then have axles running down each “leg” with 90deg gears to then drive the wheels. I’ve not built this but the one issue I can see it it’ll do funny things as the suspension moves.

you’ve set yourself quite an interesting and potentially complex engineering problem .. good luck

 

[Diamabolo]

I saw this attempt... https://www.instagram.com/p/Cz37DEMsgkZ/?igshid=NzBmMjdhZWRiYQ==

[shroomzofdoom]

In it's current state, the wheel stability would be difficult to say the least. If you push it with your hand and turn it at the same time you'll see what I mean. You're probably going to have to consider scaling up the size of the legs to support these elements being motorized.

Nothing in Lego (or engineering) is impossible...it just often takes just time, parts, and dedication!

[wissamms]

Otherwise you can go big :)

[shroomzofdoom]

Some similar examples (not Curiosity):
https://www.wired.com/2012/08/curiosity-rover-made-with-lego-mindstorms/ 

https://pybricks.com/projects/sets/mindstorms-robot-inventor/fan-inventions/exploration-rover/

 

[Carsten Svendsen]

Maybe it would be enough to power the middle wheels on such a small model. I'm thinking you could maybe just use gears and chains to go from the wheel to the chassis. I don't know what's inside the body, but it seems like it's just hollow space.

[Bluehose]

30 minutes ago, Carsten Svendsen said:

Maybe it would be enough to power the middle wheels on such a small model. I'm thinking you could maybe just use gears and chains to go from the wheel to the chassis. I don't know what's inside the body, but it seems like it's just hollow space.

Sir, that is a good idea.

But then we need to make this choice : no off-road performance.

[Jeroen vW]

How about a small N20 motor? They are geared down, so larger torque, slower speed.

File is here:

https://www.thingiverse.com/thing:3968044

Greets

Jeroen

 

Edited November 22, 2023 by Jeroen vW