How to build SUV Box Robot for LEGO Competitions

There are a few main challenges with box robots and in the following tutorial we would like to resolve them. Read on and let's see how we could do this. 

  • #971
  • 19 Aug 2018
  • 0:09

Motors should be in the right direction

What we learned based on your feedback is that it is difficult for students to use a robot where the motors are not in the right direction. When this happens students have to enter minus seconds or degrees of rotation for the robot to move forward. This was the case with Box Robot 2. Entering "-2" to move 2 seconds forward is just not very natural. It makes you think and pay more attention to details. But it is not natural. 

For the SUV robot we've placed the motors in the right direction. As a conclusion try to always place the motors in the right direction.   

Balance between accuracy of Light/Color sensors and high of the robot

This SUV Box robot has a large clearance. It could move through high obstacles which makes it a very good fit for Into Orbit FIRST LEGO League competition. But there is a balance here. When the robot is this high the sensors are further away from the field. Errors might occur. So be carefully.  

NEVER use the USB programming port

The LEGO Mindstorms EV3 Brick is really great. But it has two major flows.

1. It uses Mini-B

2. It is used by students :D 

When students use the brick they constantly plug and unplug the USB cable and they will eventually brake it. And it will happen in a few months. And we talk from experience here. We've seen a lot of bricks that are broken in this way.

And then you have to upgrade the software. But since the USB port is broken, you can not.

The solution is simple:

Do not use the USB programming port. Always program the robot through Bluetooth. Use the USB programming port only for Firmware upgrade.

For this particular robot we've even constructed it in a way to discourage you from using the port.  

 

SUV Competition Box Robot from LEGO Mindstorms EV3

The Sports Utility Vehicle box robot is the new marvelous box robot that we've created. It is designed for teams that would like to learn how to build balanced, stable and working robot chassis following our box principle. It is smaller and easier to build than box robot 1 and it is more simple than box robot 2. 

The main advantages of this robot compared to previous box robots are 

 - motors in the right direction, so when rotating the motor forward, the robot moves forward.

 - it is much easier to attach attachments. There are 4 different gears on which you could attach attachments. 

 - it has a large clearance - which means that it could move over obstacles.

Of course, it has a Gyro and two Color Sensors.  Not only that, but we have all the cables shown in the construction.

Attachments:

 - [How NOT To] Build An Active Attachment For SUV Box Robot

 - Simple Pinless Attachment for the SUV Box Robot

 - SUV Front Active Attachment for Box Robot

 - Attachments Frame for SUV Box Robot

[How NOT To] Build An Active Attachment For SUV Box Robot

In this attachment two knob wheels "(32072 ) Technic Gear 4 Knob" engage at 90 degrees angle. One of the knob wheels is a part of the robot and the other is a part of a pinless active attachment. This attachment is an example of how not to build an active attachment. These are some of the reasons why:

  1. When you use only "(32072 ) Technic Gear 4 Knob" the attachment will start to jump when it is loaded in some directions. This happens according to the forces in the knobs. That leads us to the next reason why you should not to build attachments in this way.
  2. You have to remove the attachment "jumping". This makes the attachment bigger, harder to attach and time consuming to design and build.

Build the attachment and experiment. See for yourself how it "jumps" up and down when the knob wheels are rotating and you hold the lever by hand. 

Simple Pinless Attachment for the SUV Box Robot

This is a simple pinless active attachment for the SUV Box Robot.

In this attachment we use "(32498) Technic Gear 36 Tooth Double Bevel". There are four pins added to the wheel and it it this pins that engage with the "(32072 ) Technic Gear 4 Knob". The more important thing is that the knob wheel and the gear wheel are parallel to each other.

While the motor rotates the attachment has 4 points of contact (instead of one or two when two Knob Wheels are in contact) with the robot knob wheel. There are no forces that drive the attachment to jump and lose engagement with the robot.

SUV Front Active Attachment for Box Robot

This attachment uses a connector ("(98585) Technic Connector Circular With 2 Pin Holes and 3 Axle Holes") with 4 pins to connect with a knob wheel ("(32072 ) Technic Gear 4 Knob") of the robot. Because both elements are parallel one to another there is no jumping effect.

The attachment uses two pins, but it is easy to attach and detach because it uses "(6558) Technic Pin Long with Friction and Slot". When you attach or detach the attachment the slots are keeping the pins strong on to the attachment.

Also an attachment connected to the robot in this way, can be move to the rigth knob wheel or to the left knob wheel.

Attachments Frame for SUV Box Robot

This is a frame for the SUV Box Robot. Tis frame is an adapter between the robot and the attachments. You can add-in several attachments on it and mount them on the robot simultaneously with one movement.

The frame has two locks that make the attachments stick to the robot. Also the front Knobs must not be used for very powerful activities due to jumpings, unless the frame with attachments become heavy enough to prevent any jumping of the frame.