Mechanical Obstacle Avoidance System

[Sariel]

A simple proof-of-concept here. A single motor is driving all wheels via a differential. When the wheels are stopped, the differential redirects the motor to turn them instead of drive them, until the wheels can move again. Basically the differential acts as a load-balancer to find the direction of least resistance for the wheels. Might come useful if somebody's planning to build a LEGO Roomba or something ;)

 

[JintaiZ]

Awesome build!

[Good old Lego builder]

Very nice build! Great thinking!

[Ivorrr]

Looks like the first trials of people making autonomous vacuums. 

This is actually brilliant and interesting.

[1963maniac]

Sariel, Will you be posting building instructions?

[Horologist]

Similar concept to this:

http://www.isogawastudio.co.jp/legostudio/modelgallery_model/b064.html

Instead of using a differential to sense torque, that design has the drive wheels pivoting freely with the drive axle passing through the pivot. Thusly, the motor can either drive the wheels or turn the entire wheel casing, depending on which has the least resistance. Granted, your design is more stable while moving in a straight line.

Edited September 7, 2020 by Horologist

[msk6003]

5 hours ago, Horologist said:

Similar concept to this:

http://www.isogawastudio.co.jp/legostudio/modelgallery_model/b064.html

Instead of using a differential to sense torque, that design has the drive wheels pivoting freely with the drive axle passing through the pivot. Thusly, the motor can either drive the wheels or turn the entire wheel casing, depending on which has the least resistance. Granted, your design is more stable while moving in a straight line.

Actually, this system is widely used for toy cars. 

[Sariel]

10 hours ago, 1963maniac said:

Sariel, Will you be posting building instructions?

Photos and explanations should be sufficient to build it, I believe. All the mechanics are exposed. I'll be posting these to my website later today.

[MAB]

Interesting design. What happens if it goes down a corridor not much wider than itself, then glances on a wall? Does it come out again, or does it get stuck trying many directions that all lead to collisions?

[Sariel]

Much like vodka, if it can go in, it can go out too.

[Horologist]

2 hours ago, MAB said:

Interesting design. What happens if it goes down a corridor not much wider than itself, then glances on a wall? Does it come out again, or does it get stuck trying many directions that all lead to collisions?

Presumably its wheels would turn in place until they were facing back out of the corridor and the car would drive out.

[MAB]

6 minutes ago, Horologist said:

Presumably its wheels would turn in place until they were facing back out of the corridor and the car would drive out.

I wondered as they do not rotate by 180 degrees on the first attempt, so I wonder what would happen in a narrow corridor or even a corridor that narrows as you go along it. At about 37 seconds it looks like it is about to happen, then the video cuts.

[Sariel]

The wheels rotate as long as the resistance on drive output is greater than the resistance on the steering output. So yes, they can rotate 180 degrees or even more if necessary.

[aeh5040]

I became rather obsessed with this concept about 10 years ago, and came up with several approaches (sorry for low quality videos!):

 

Edited September 9, 2020 by aeh5040

[SNIPE]

23 minutes ago, aeh5040 said:

 

 

I have an unfinished project that uses a simular idea to this, except its a model inspired by hypno disc from the british tv show 'robot wars' and it uses a ring of 87745 clamped in place and driven by rubber tires on the inside of the ring. The wheels are taller than the body so that it can flip and still drive around.

Edited September 9, 2020 by SNIPE