Introduction: ROSbot - Autonomous Robot With LiDAR and Husarion CORE2 Controller

ROSbot is an open source, mobile robot platform containing:

  • Digital camera
  • Laser scanner 360° RPLiDAR A2
  • Solid aluminum cover
  • Wi-Fi antenna
  • Orientation sensor (MPU-9250)
  • 2x left & 2x right DC motors with quadrature encoder
  • Husarion CORE2-ROS (with ASUS Tinker Board inside)

It's pretty large project but even if you can't do everything, you can choose which features you want to implement. The project has been created by Husarion team: https://husarion.com/
The assembled version or the CORE2-ROS controller is now available at: https://www.crowdsupply.com/husarion/core2

In case of any question please ask in comments :)

Step 1: Prepare (order?) the Aluminium Chassis

The chassis is laser-cutted from the 2mm thick aluminium plate. We designed it in CAD software and outsourced to a laser-cutting workshop. They have also offered painting, so we've eventually made two versions. The attached drawings are suitable to be the source files for laser-cutting company but don't forget about units - all dimensions are in milimeters.

Attachments

Step 2: Assemble the Chassis With M3x6 Screws and Nuts

Step 3: Then Attach the Motors With Encoders and Screw Them Using M3x6 Screws

We used motors similar to these "34:1 Metal Gearmotor 25Dx52L mm LP 6V" from Pololu: https://www.pololu.com/product/1584 but the general requirements are:

- RPM between 80...200 @6V

- voltage from 6V to 12V

- stall current max. ~2A

- the same dimensions (diameter, length and mounting holes) as Pololu 25Dx52L motors

Caution: longer screws can damage or block the motors

Step 4: Assemble the Two Other Motors to the Right Plate

Step 5: Attach the Right Plate to the Bottom Cover With M3x6 Screws

Step 6: Attach the Battery Pack for 3x 18650 Li-Ion Batteries and Insert the Batteries

ROSbot is supplied from 3 pieces of 18650 Li-Ion cells. I recommend using batteries with protection circuit and charging them with dedicated charger. Please avoid very cheap batteries and chargers - the damage of Li-Ion batteries can be dangerous. It's about your safety. The power source is important and needs to be reliable. All you need is to use good batteries and charger with protection and then don't worry about that :)

P.S. In the newer version of ROSbot we updated this and we used a battery pack with an additional connector for balancer. In that way we can charge batteries through a 4-wire cable, without opening the robot. I will describe that later.

Step 7: Screw the Standoffs for Sensors and Install the Sensors

The more external standoff is 8mm long and the one that is closer to the center is 10mm long, because there is only one layer of metal.

Step 8: Screw the Standoffs and Install Husarion CORE2-ROS Controller

Use four female-female, threaded standoffs, M3x50 size (metric 3mm thread, 50mm long). Use M3x6 screws to assemble with bottom cover and to install the Husarion CORE2-ROS controller.

Step 9: Install a Camera and LiDAR

We used the USB camera that we've had in the drawer :) and the RPLIDAR A2 360 degrees Laser Scanner. Screw them using M3x6 screws and nuts (for the camera only).

Step 10: Attach the Wheels Using Hex Couplers

We used the "wheels for robot toys" with brass couplers that are compatible with 4mm diameter, D-shaped motor shafts. The wheels have the 85mm diameter.

Step 11: Prepare the Cables

You need some cables:

4x cable that connects Sharp sensor with CORE2-ROS (see the next step)

1x cable that connects MPU-9250 sensor with CORE2-ROS (see two steps further)

1x cable for battery pack <-> CORE2 connection (with switch) - it's simple :)

1x generic USB extension cord for a Wi-Fi card (it needs to be installed outside the metal box)

The motors, LiDAR and camera have their own cables.

The connections diagram is shown on the attached photo.

Step 12: Prepare the Cables for Sharp Sensors

We used Sharp GP2Y0A41SK0F sensors.

See the photos and make 4 cables. Pinout is also included on the photo.

Step 13: Prepare the Cable for MPU-9250 Module

Pinout is attached and cable similar to the previous one. This time you don't need the IDC connector.

Step 14: Assembling Hardware Is Finished

This is how it looked in our case :)

Step 15: Using the ROSbot

The ROSbot can be used in two ways:

- as a remote controlled platform, programmed from cloud, without using ROS (Robot Operating System) and in that case please follow the guide from here: https://husarion.com/core2/tutorials/howtostart/ru...

- as a platform for learning ROS - in that case please take a look at these tutorials: https://husarion.com/core2/tutorials/ros-tutorials..

Step 16: The Final Effect

This is a short demo how the ROSbot can be used at the workshop or for personal purposes:

Have fun!