Analyze a LEGO MindStorms EV3 Model – COR3

This LEGO MindStorms model is a training model. The original specification is shown at There are other interesting models and lessons on that website (, so strongly recommend and feel free to explore.

In this post, I will analyze the structure of different parts for this model and summarize its features, its pros and cons. When we built a LEGO model, we should keep an attitude of critical thinking (En… this is the motto of my graduation school). We will not only build it by following the specification, but also analyze this model so that we can utilize some of its design ideas on our self-designed models.

Chassis Design

The chassis of this model is super compact. The distance between the two big motors can only accommodate the medium motor. The color sensor and touch sensor are attached to the medium motor via the combination of multiple connectors. Therefore, although the model looks small, it is not easy to build the structure of medium motor.

External Beam Frame

One feature of this model is that there is an external beam frame which surrounds the body. This framework is typical for a vehicle designed to participate in either FLL (First LEGO League) or WRO (World Robot Olympiad Association) competition. One purpose is to support the wheels since this structure reduces the friction on the axis when wheels turn. The other is that it helps to guide the vehicle run alone the wall of the competition platform.

Medium Motor Structure

The medium motor structure is definitely the most complicated part of this model. In order to keep the whole model compact, this structure rarely uses beams, instead uses multiple connectors combined together to generate connection points in needed position and direction. The color sensor and touch sensor are directly attached to it.

Another feature for this structure is that there are two ways to connect to the front attachment. One is the both sides of the axis connector (red colors) shown in the below left diagram, the other is the stretching out axis shown in the below right diagram.

Front Attachment – Collector

The Collector attachment has two short axes which could connect to the red axis connector of the above medium motor structure. It is easy to amount or dismount it. When it is put down, the bottom frame is just sweeping off ground so that it can collect things and move them around.

Front Attachment – Dispenser

The second front attachment is a dispenser. It is mounted by using an axis connector to connect to the stretching out axis. When medium motor spins, the dispenser will sway left and right to throw things out.

Front Attachment – Snatcher

This attachment is kind of like a stick. It is the simplest front attachment of the three. Such a tool is useful when hooking things. Such kind of task is very common in both FLL and WRO.

Summary of the Feature

This model of LEGO EV3 has both pros and cons, as summarized in the following list.

So you could see that there is no perfect model. What you need to do is to just enjoy the creation process and have fun!

In the next post, I will introduce another model which tries to overcome the weakness of this model by making some minor changes on the structure. It also turns to the driving base design (The model included in the LEGO software) as reference. So Stay tuned!

6 thoughts on “Analyze a LEGO MindStorms EV3 Model – COR3

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  3. Pingback: Analyze a LEGO MindStorms EV3 Model – Discovery – Coding Courses Designed for Kids

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