A few months ago I asked my daughter Alisz what Lego creation I should build next and she suggested that I build a ladybird, so over the past few months that’s what I’ve been working on. It uses a crawler mechanism to move, has a shell that opens and wings that pop out. The shell and head are made of around 1800 plates (and a few bricks for good measure), and around 1000* Technic pieces to drive each of the mechanisms.
The crawler mechanism is inspired by the Motorized Micro AT-TE created by JK Brickworks, which has been highly modified and strengthened to handle the 3kg of Lego it needs to support, and is powered by two XL motors.
The shell and head are inspired by the Ladybird created by Arjen Vuurzoon, and have been scaled up and redesigned to predominantly use plates (especially in the head/eye area).
While I initially tried a hinge similar to the dual axis hinge used in the original design, they were unable to support the additional weight of the enlarged shell. This eventually led to me using a dual “type 2” turntable hinge mechanism driven by worm gears. Due to space constraints the forward/backwards tilt axis is only used as an adjustment, with the shell opening outwards from the body.
The wings fold over and out simultaneously, which made for some interesting challenges when developing the mechanism. The first iteration of the wings was very complex as it involved two separate mechanisms driven by a single motor that had to be precisely aligned in order to function properly. The second iteration of the wings are more compact and only rely on a single movement to drive the wings over and outwards simultaneously, resulting in less time spent aligning cogs. More information on the wings can be found in my folding wings post.
The head is secured by two axles that slide in once the top of the head has been opened. Inside the head are two SBricks that drive the motors using a custom profile optimised for tank style steering, given that steering is achieved in a similar manner to a tank (the only difference is that the ladybird doesn’t have tracks). Also housed inside the head are the motor and reduction gears that control the shell in/out movement.
The battery is housed underneath the wings and requires the shell to be open in order to be replaced. The head can be removed and a separate battery pack used to open the shell if the internal batteries are completely flat, or the shell can be removed from the body. Once the shell has been opened, the wings can be removed to reveal the battery pack which can then be changed over as required. A long lift arm is attached to the battery pack to make switching as easy as possible.
* – Very, very rough estimate