[TC21] Pimp my 8852

[howitzer]

I wanted to enter this contest but I couldn't really think of any original concept which would feel like remotely doable (with my skills anyway) so I thought that the original transforming robot set would make for a fine enough entry, if made with today's building style and perhaps pimped out with additional functions so that's what I set out to build.

As you know, the original thing has basically one function, that is transforming between the robot form and the vehicle form, and in addition it has a HOG steering. Replicating this transformation is of course the main goal here (with variable length wheelbase and lifting/lowering the cabin-head-thing) but the scope of this contest enables additional features too. So my aim is to do the following:

- RI hub for power and functions control

- Transformation (2x hard-coupled L-motors)

- Drive (XL-motor) and steer (angular L-motor)

- Colour sensor to detect when the transformation is at either extreme to act as a limit stopper

And if I have time I will add:

- Distance sensor (to detect possible collisions and stop the driving)

- Ability to stop the transformation at any intermediate position, combined with the colour detector to take it to either end and stop at correct point

- Remote control with PU remote (so that there's no need for smartphone)

- The original had a sort of arms, which I might want to also replicate in some fashion

- Some sort of face/lighting system using the hub's 5x5 segment display

Here's my progress so far:

The hub will be positioned at the top and I intend to have two linear actuators to perform the lifting action, driven by the same geartrain which extends the wheelbase. I'm not yet sure about the rear dual axles, but at the moment those feel like a good idea. XL-motor not positioned yet in the photo, the other three motors are in place, and the lifting assembly for the hub is just a mockup, I will at least have to raise it 1 stud in order to fit the cable connectors on the other side of the hub. Sensors are also absent at the moment, but the colour sensor will be hidden inside and the distance sensor to the very front (as far as the cable length allows).

[GerritvdG]

Cool to see another 8852. Now we have a PU and a PF version… good luck!

I’m still puzzling to get all the power functions into my small 8852.

[howitzer]

24 minutes ago, GerritvdG said:

Cool to see another 8852. Now we have a PU and a PF version… good luck!

I’m still puzzling to get all the power functions into my small 8852.

I wanted to make it larger, in order to fit all the functions I want without too cramped chassis. It's going to make an interesting comparison between these two! Good luck to you too!

[BB8]

An interesting project. I'm wondering how you implement - Distance sensor. In the future, I want to make an automatic parking system out of sensors, but so far there are no sensors for this (

[howitzer]

4 hours ago, BB8 said:

An interesting project. I'm wondering how you implement - Distance sensor. In the future, I want to make an automatic parking system out of sensors, but so far there are no sensors for this (

I'm planning for a simple collision detector, nothing too fancy (can't even do that much with just a single sensor anyway...)

[howitzer]

So, I did a disassembly and reassembly of the rear section and got about this far with the project:

Then I realized that the XL motor in the rear has too short cable to reach the hub when at extreme position, so I'll have to design the whole chassis again. I think I'll attempt to fit the motors side-by-side in the middle, so that drive motor is in the center and transformation motors in the sides.

[howitzer]

I didn't have much time to build during the holidays, until I got common cold and had to cancel all new year's eve plans. So I've been doing some more building in the last couple of days. Mostly I've been working on the geometry of the thing, trying to find places for linear actuators and their transmission so the thing is still very much kludged together with what parts I had laying around, with no regards for aesthetics or even structural soundness in some places.

Anyway, here's my current progress, though it's not finished even in the sense of all the mechanical parts, as it appears that the current upgearing needed for the linear actuators to travel far enough, isn't big enough. So lots of work still ahead, and I haven't even started the programming yet, save for some very simple motor testing. Here's a photo of the current configuration:

[howitzer]

Ok, so I wasn't at all happy with what I had built. Too complicated drivetrain, too many badly reinforced places in the chassis and so on, it probably wouldn't have worked. So I set out to completely rethink the mechanisms, and after a couple of days of trial and error I have come up with this:

Now, the problem here is that the XL linear actuators have too short of a travel. Otherwise the thing works really well, but they hit the maximum travel at maybe halfway of what I want. I'm currently pondering if there's any way to make it travel farther (some kind of lever mechanism) but I fear I'll run out of time as the contest closes soon and there's so much to do still...

[1gor]

Are gear racks from Arocs better (longer travel than XL linear actuators)?

[howitzer]

17 hours ago, 1gor said:

Are gear racks from Arocs better (longer travel than XL linear actuators)?

Yes, but only slightly. They also don't have the efficient screw-driven actuation, which needs lot of reduction and causes efficiency losses through the drivetrain. I think I'll have to connect the linear actuators to somewhere else, in order to get the desired effect, but that also complicates the drivetrain so we'll see if it works out or not...