Positioning motors on BigDaddy Competition Robot - Second try (Part 7) Pro Preview

This second way of positioning the LEGO Mindstorms EV3 motors on the robot leaves more space for the Mindstorms brick and for attaching a third motor. We are experimenting and showing the advantages and disadvantages of this particular construction.

  • #77
  • 22 Mar 2015
  • 6:28

Why a second way?

In the BigDaddy series of video tutorials on LEGO Mindstorms robotics constructions we are trying to show the whole process of engineering and re-engineering. We are coming up with a design and we are re-designing when needed. 

The first positioning of the motors made us use a Cardan Shaft with Cardan Joins to transfer power at a large angle. The great disadvantage is that we loose power for every cardan join we add. 

The Robot Construction and the motors placed at an angel

Again the 'front', 'rear' and 'central' frame of the BigDaddy competition robot are ready. Most of the time you should consider placing the motors along or perpendicularly to the central frame. But in this particular video tutorial we are positioning the motors at an angel. Constructing LEGO robots where different moduls are at an angle always seem challenging. Use the building instructions to learn and improve your toolbox of solutions on this topic.

Other episodes from the series:

Constructing BigDaddy Competition Robot (Part 1 - Front)

Constructing BigDaddy Competition Robot (Part 2 - Front)

Constructing BigDaddy Competition Robot (Part 3 - Front to Rear)

BigDaddy Competition Robot (Part 4 - Complex Transfer of Power in a Triangle)

BigDaddy Competition Robot (Part 5 - Power to Rear Wheels)

Positioning motors on BigDaddy Competition Robot (Part 6)


- In this lesson, we will continue with improving the BigDaddy construction and last time we finished with adding a Cardan shaft that transfers power from a motor to the front of the robot where we add an attachment. The problem with the Cardan shaft is that in such a situation where you have a large degree the whole shaft is very fragile and you have large power loss. In this video, we are going to remove it and search for other ways to position the motors. Again, we are starting from the base construction and I'll try to position the motors in another way. In the previous video, they were positioned like this. There are actually like this and now let's try to position them like this so one of the motor is for the rear wheels, one of the motor is the medium motor for the front wheels and one of the motors for attachments. Let's first place the medium motors. It's quite straightforward we have two black pins and we have an axle over here that's turning the front of the robot and we just add the medium motor and that's it. Now we will transfer power to the medium motor from the brick. We can control the front tires and we can turn. The next step is to add the motor for the rear part of the robot. We will need an axle. Let's add one here and the motor should be something like this. As you can see, we have many options to position the motor and we've chosen to use a simple beam. Now if we add the beam like this you can see that it's on another level so it's one hole above this frame and I will add one more beam here to have additional holes and we are done. Now the beam is not very stable but we add the motor and we do use the fact that these two holes or the brick are on the same line as the center of the motor where we place the axle.

Here it is one of the motors. It's not very stable and that's why I would like to attach the beam on one more place not only on one place but on the second and for this I'll weight this part right over here on the framework.

As a result, we have an additional part and this part is right here and we can attach the beam to this part and we have a much more stable construction.

Just lock it and now one of the motors is already here. The next thing is that we must have the second motor and for the second motor I will try to position it like this and in this way we have the first motor for the rear part of the wheel, the medium motor for the front part and the third motor probably for attachments. Again, we use the same principal. How do we position the motor on the frame? Something that we should do is that I must free this hole right here and I'll want one more blue pin so that I could attach the motor to this blue pin.

Here it is I have the blue pin and now I could place the motor and in order to find a way to place it we add some additional beams.

Again, the motor is attached only on one part and for this we want a second beam and the second beam over here and here we are. As a result, we have a construction with three motors one for the rear part, one for the front part and one for attachment. We can add an axle on this motor but as you can see it's quite difficult now to transfer some power from this motor to an attachment that's placed at the front of the robot. It's possible but you must have a quite complex system of gears or so some other solutions and it won't be competition ready. So again, we will continue searching for other solutions and how do we place the brick and the three motors on this construction.