First thoughts on an automatic container yard, and a container grab mechanism
As a part of my train layout, I have been thinking about a fully automated container yard – of course controlled by the LEGO® EV3 Mindstorm. My idea: A train comes in, the gantry lifts the container of the wagon, identifies the container, and place it on an empty spot in the container yard.
It sound simple – but it’s really not. The challenges are:
- XYZ: The gantry must be able to move parallel and perpendicular to the track (X & Y) to move to the right location, and up/down (Z), to place/pickup container from the yard or a wagon.
- Precise: The mechanism needs to be very precise, else there will be a need for adding many sensors for aligning etc. With millimeter precision, it has to place the container at an exact location, stored this location in a database, and be able to return to that location for picking up – only relying on the XYZ coordinates of the container location.
- Identifying containers: My initial idea is to identify containers using a color-“barcode”. More about this in another post.
- Grabbing container: The gantry needs a mechanism to grab a container, with 100% reliability, and without allowing the container to rotate. If the container rotates, it will be nearly impossible to operate without adding active aligning.
I started out by investigating on the grab mechanism. First attempt was to use the linear actuator, and pivoting fingers, like in the LEGO® set 42006. However, this design was a bit too wobbly, and the grab mechanism tended to rotate a bit, due to the axle rotation into the actuator.
The “test container” has a 1×1 Studded Technic Brick in each corner, where the grab mechanism can lock in:
Instead of using the actuator, I tried to go for a design, where hooks in each corner pivots very closely to the container. Additionally, I added some passive guides, to align the grab mechanism into place.
I am very happy with the result! It is much sturdier and very reliable! (I haven’t tested it a 100 times yet though…). See the the video below.
the Brick Dane 