Elisa G.
Hi, I'm Elisa, the mechanical engineer of the BOTtegai team, and in this section I’ll explain how to build your robot in the best way to compete in the FLL.
This section is divided into two parts: in the first one, I’ll talk about our robot, and in the second, I’ll help you use our ideas to build your own robot.
SHAPE
What you see here is Molly 3.5, the result of dozens of designs we've developed over the past three years.
One of the strengths of our robot is its shape, which allows it to align with any flat surface.
Thanks to the compact shape and small size of the front section, it's much easier to design attachments.
Additionally, the reduced size allows the robot to move more easily and efficiently around the playing field.
However, making it too small can reduce its structural integrity, so we recommend finding the right balance.
WHEELS
An important choice when designing your robot is the wheels.
Larger wheels provide higher movement speed, while smaller wheels offer greater precision during maneuvers.
All LEGO motors have a small amount of play, which inevitably leads to slight inaccuracies during movement. The larger the wheels, the greater the inaccuracy.
Choosing the right wheels means finding the best balance between speed and precision.
SENSORS
The second important choice to consider is the placement of the sensors.
In our model, we placed two color sensors at the front corners of the robot. This position maximizes the range in which the sensors can detect a line.
In some robot designs, the color sensor can also be used to recognize the attached tool and automatically start the corresponding program, ensuring maximum speed during maneuvers in the launch area.
GYRO SENSOR
A fundamental sensor used in FLL is the gyroscope, which is integrated into our Hub in Spike models. I recommend positioning the control unit directly above the wheel axis; this way, the gyroscope's oscillations will be minimized, reducing drift issues to a minimum.
PLATE
The last fundamental part concerns the design of the attachment platform. Its role is to ensure a firm anchoring of the attachments, preventing them from moving or deforming. At the same time, it should allow us to remove them easily and quickly. To ensure this, I recommend using a large number of axles facing downwards that fit into holes facing upwards.
To start building the robot, make sure you have a solid and compact structure for the four motors that allows you to effectively transmit power to the gears of your attachments.
On the side, you can find the internal configuration of our Molly 5.0.
MOTORS
STUDIO 2.0
Now it's time to start designing the robot. The first piece of advice I give you is to use Lego modeling software on a computer. We use Studio 2.0, but there are many others.
Creating the robot on a computer allows you to build and modify quickly. In a real model, you might have to disassemble the entire robot to modify some parts.
Additionally, with Studio, you can work even when you don't have access to your Lego collection, and it allows you to evaluate different solutions without the need to actually build them.
For example, Molly 2.1, Molly 2.4, and Molly 4.1 were never built, but they allowed us to learn a lot for subsequent models.
The method to achieve a successful robot is trial and error, so try to build as many models as possible and don't worry if you don't immediately reach the perfect model.
OVERBUILD
When building a robot, I recommend always adding a high number of structures. You will reach a point where all parts are connected, but don't stop there. Add as many connections as possible.
One disadvantage of designing a robot on a computer is that you can't know how solid the structures you've designed will be.
It would be a shame if, when you finally build your robot, it turns out to be unstable.
Start with the central structure that holds the motors together and ensure it is solid, then build the rest of the frame around it.
Finally, make sure there is enough space to connect the wires, and if possible, try to connect them as early as possible during the assembly phase.
