Upgrading Rover: Kabuto

Rover: Kabuto new frame

Remember when I said that I will upgrade the chasis of my rovers? I’ve finally did it!

20160228_221816

It is still half done, but I would like to share the journey that I made so far.

A few years ago when Bence and me started to dive into robotics, we came up with an idea for the frame of our rover based robots. We’ve made a prototype from cardboard to see if it would fit our needs. After measuring the dimensions, we’ve felt that’s what were looking for. I have asked a friend of mine to make the frame by using aluminum. The result looked like this:

aluminium frame
aluminium frame

This is one of the three that has been made. Unfortunately the project has paused here, for a few years nothing really happened to it. That time I didn’t really have any mechanics skills and my friends who had didn’t have time to work on it.

We also had a plan that instead of painting it in the regular way, we should do anodizing. It is better than the other one, but it also needs skills to do it.

For the new frame I had a few requirements:

  1. It should have better look than the older.
  2. The weight should be taken off from the motors.
  3. More place will be for sensors.

Better look & more space

For these points all I needed to do, to use what I’ve already had. The aluminium frame is already looking better than the polycarbonate base prototype case ( see the Rover: Kabuto page) for my project. As an improvement later it will be black, because that would look more cooler.

No pressure on the motors

What I needed to figure out is how to take off the weight from the actuators. I have started to read books, done research on the internet. As an outcome I had few cloudy prototype in my mind. I knew that I needed to involve bearings and axis to make this work. What I didn’t know that how the bearing will be attached and how will be the motors connected to the axis. I have ended up on the https://www.servocity.com/ site where I got a few ideas.

My final idea was that I will use quad pillow blocks . The motors will be inside of the aluminum, connected to the axis by a shaft coupler. The quad pillow block will hold the axis and allow it to rotate. On the other side of the axis will be hex mounting hub, that will connect the axis and the wheels.

Drill, screw and check

That was the first half of the work, the next was to do some drilling. I have never done previously drilling that needed precision, so I have read a few articles and watched youtube videos. I have come to a few conclusion, I need a workspace for drilling (I didn’t like the idea to do it in the flat) I have to make blueprints and I need more tools for doing the whole work. The workspace and tool problem was solved by the makerspace that I have found nearby. For the blue prints I did some measuring and prototyping then I’ve printed them it out.

Drilling in progress with template.
Drilling in progress with template.

NOTE: The first printing was not okay, there was an option set to fit to page, it was smaller compared to the original size. I have come to this realization by measuring the printed material. Lesson learned, measure all the time and check if the value is okay.

When the drilling was finished and I screwed the frame, bearings, motors together it looked like this:

New frame base screwed together.
New frame base screwed together.

Next step that I will attach the sensors on the top, I will add an ps3 eye usbcam and an asus xtion .
Sensors: Asus xtion and PS3Eye usbcam.
Sensors: Asus xtion and PS3Eye usbcam.

The first milestone of the project is that it will be able to make maps indoor. I will use ROS for that purpose and publish my project to the github.

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