In the Robotics Software Engineering program at URJC, we've recently welcomed four iRobot® Create® 3 robots —an event that's certainly cause for celebration!—. Although the base alone comes along with lots of features, we were determined to unlock their full potential within the ROS 2 ecosystem. To achieve this, we equipped each robot with state-of-the-art sensoring and computing capabilities, including:
This alone sounds exciting enough but… How is this being attached to the base? The platform is fairly new and we had few options… So we decided to tackle the problem ourselves. And here we are! We had some requirements to meet in our design:
That being said, let's get started with the assembly process!
The chassis is the main part where the rest of parts will be attached to. At the same time, is the only part that is physically attached to the payload bay of the robot.
14 of this heated inserts should be installed in the top part of the chassis. They are all mandatory, since the rest of the parts of the assembly will be bolted to this inserts. On the other hand, the remaining 13 heated inserts (Along with the bolts and washers) could not be mandatory. Just a few of them, as long as they are symetrically placed, will do the job. However, we decided to install them all following the picture below:
The reason why we added so manny mounting holes is because if we are lucky enough, some of this holes can be used if we decide to use the whole platform in any other robot! Also, we seek for rigidity. Furthermore, we did not feel comfortable putting weight in the iRobot® Create® 3 cargo plate, so we tried to redirect that weight to the four pegs included in the bottom side of the plate.
The lidar structure has two main parts, the legs and the scaffold. The scaffold is bolted to the legs, and the legs to the chassis.
There is another part, named “Lidar_Bracket_RPLidar_S2.3mf” which is specially designed to fit the Slamtec RPLidar S2. This part is supposed to be redesigned if the lidar sensor is swapped eventually.
DIN7991 (10mm) is used, along with 4 heated inserts, to secure the scaffold to the legs. This heated inserts should be installed in the intended holes from the scaffold. 4 DIN7991 (6mm) are used, along with remaining 4 heated inserts, to bolt the lidar bracket to the lidar scaffold. This heated inserts should be installed in the intended holes from the lidar bracket. Remaining 4 DIN7991 (6mm) are used for secure the lidar sensor to the lidar bracket. Lastly, DIN912 along with DIN125 are used to bolt the four legs to the chassis.
The camera structure has only one part common, which are the legs.
There is another part, named “Camera_Bracket_OAK-D_Pro.3mf” which is specially designed to fit the Luxonis OAK-D Pro. This part is supposed to be redesigned if the camera is swapped eventually. There is also another model named “Camera_Spacer_OAK-D_Pro.3mf”, used for align the camera with the axis of rotation.
DIN7991 is used to attach the camera chassis to the bracket, using the spacers. DIN933 along with DIN985 are used to secure the camera bracket to the legs. Lastly, DIN912 and DIN125 are used to secure the legs to the chassis.
There is only one part, named “PC_Bracket_Jetson.3mf”, which is specially designed to fit NVIDIA Jetson AGX Xavier. This model is special in the regard that the jetson chassis should be partially disassembled because longer bolts should be used.
The four DIN7991 bolts are used as replacement for the original bolts securing the Jetson assembly. In the picture below, you will see in green the section where the original bolt was placed. The heatsink (Purple in the section) is threaded at its top. The printed part (light yellow/cream) sits below the whole assembly, and its clamped together with the rest of parts using said bolts:
The remaining bolts and washers are used to attach the printed part to the chassis.
Why that weird shapes?
Aesthetics! Does it not look cool? :D (From the bottom view of the cargo plate, you are supposed to see a turtle with a weird robo-head… But now I am not sure if I have achieved that!)
How do I install heated inserts?
I always use this guide as a reference.
Where can I found this heated inserts?
They became popular enough to be found in common online marketplaces. I have ordered mine from here.
The author marked this model as their own original creation.