The XRP is an open-robotics platform designed to help you learn engineering, robotics, and software development. As an educator, I wanted to assess the ease of use of this platform for someone with limited prior experience. Although my FTC robotics team builds and codes great robots, I have a basic understanding of Tinkercad, and my programming knowledge is limited. I'm also 63 years old. This is my journey.

Supplies

Purchase the following supplies (links in supporting file):

You will also need access to a computer and a 3D printer.

Step 1: Copy the Chassis and Cut Off the Caster Section.

Using Tinkercad, make a copy of the standard XRP chassis. Cut off the caster wheel section of the chassis using a box shape.

Step 2: Cut Out Space for the Larger Wheels

Step 3: Download This Model As an STL File

Tinkercad has to re-render each shape in a large modified model. I like to save my model as a solid shape periodically to avoid corrupting my model.

Step 4: Upload File to a New Design - Name It Mecanum Drive

Step 5: Cut Out the Middle Section

Step 6: Cut Off the Rear

Since I want the final robot to fit in an 8-inch sizing cube, I have to cut down the rear end of the chassis. The dimensions are in the photos.

Step 7: Download This Model and Create a New Design Called Half Chassis

This will save your progress thus far as a single shape.

Step 8: Cut Off the Front

Cut off the XRP channel on the front, leaving at least 1mm cross support.

Step 9: Create a Solid Box With These Dimensions

Step 10: Align and Group With the Rear of the Chassis

Step 11: Create a Cut Out With These Dimensions, Align to Rear, and Group

Step 12: Add Supports to Motor Mount Ends

Step 13: Download This Model and Create a New Design Called Final Chassis

This saves the half-chassis as a solid shape.

Step 14: Copy the Model, Paste It Next to Original

Step 15: Mirror the Half Chassis

Step 16: Align the Chassis Halves and Group

Step 17: Add 4mm High Box to Middle and Group

Step 18: Copy the Power Box File

Make a copy of the board and power box

Step 19: Paste the Powerbox Onto the Workplane of the Final Chassis

Step 20: Cut Out Box From Middle

Step 21: Add Power Box to Middle and Group

Step 22: Download Stl and Create a New File Called Mecanum Final

At this point, the CAD file is quite complex and should be saved as a solid shape one last time.

Step 23: Make Final Cuts for Wires

Step 24: Remove XRP Logo From Robot

Add two 1 mm high boxes to cover the logo.

Step 25: Print the Chassis.

The Chassis is now ready to print. Be sure to add supports and print at 20% infill or greater. The frame must be sturdy so that all 4 wheels stay aligned. This will be a 12-hour or more print.

Step 26: Assemble the Robot.

Screw the wheels onto the motors. Pay attention to the way the treads face. Attach the motor cables to the motors. Slide the motors into the chassis. Feed the motor cables up through the holes in the frame. Add batteries to the battery box and slide it into the power box. Flip the bot over and slide the XRP board gently into the power box slots. Carefully attach all motor cables. If you want to add the servo attachment, print it and superglue it to the front crosspiece.

Step 27: Code the Robot

Okay, this is where my journey got really hard! There are several great online tutorials for the XRP robot, such as the Experimental Robotics Platform and the Digikey article on the Mecanum drive. Unfortunately for me, the last computer language I was proficient in was BASIC, but my brain executed a (Delete*.*) many years ago. I needed help, but was having a hard time figuring out the math and logic. I turned to ChatGPT for help. This was an amazing AI teacher. When I got stuck, it slowed down and explained everything to me like I am 63 (I am)! I highly recommend you work with ChatGPT or a real programmer to learn the ins and outs of this program. Download these files to your computer. Go to the XRP code editor and upload these files to your XRP module. They need to be saved into specific subfolders to make sure the bot can find them. The pictures show where to save each file.

Step 28: Drive the Robot Using Pestolink

Open the pestolink_mecanum.py file in the XRPCode editor. Change the robot name in line 27 to your name. Save it to your XRP.

You are now ready to drive!

Attach a USB joystick to your computer. To make this work, you need to connect your robot to your computer using a USB cable, not Bluetooth. Start at the XRP code editor and open the Pestolink_mecanum.py file. Hit run. Make sure the robot's power button is on. Unplug the USB cable from the robot.

Go to the PestoLink site. Connect your robot. Drive your robot!

Step 29: Add Bling!

I didn't like that the robot processor and all the wires were exposed, so I created a cover to keep them all hidden. This cover must be affixed with tape or Velcro because you will need access to the board to program or turn it on.

Step 30: Conclusions

So. It turns out that I can do this! You can, too. I hope this instructable brings you robot happiness. Happy Birthday, Instructables! Here's to 20 more! You can find my CAD files here: XRP mecanum chassis

Introduction: An XRP Mecanum Wheel Robot