Engineering Design Robot Development, Stage 1
I am a 3rd year Engineering with management student at Trinity College Dublin. As part of my Engineering Design module, I am going to build a simple robot and program it to do basic tasks such as avoid obstacles. Then, at a later stage, I will make alterations to the robot to enable it to perform more complex tasks.
The robot is the ELEGOO Tumbller Self-Balancing Robot Car and can be purchased on Amazon for €70. It operates using an Arduino Nano circuit board.
As with many engineering projects, it is very helpful to develop a comprehensive set of design drawings before beginning the assembly process. The development of 3D CAD drawings are not required to assemble the robot as a detailed set of assembly instructions are provided, however these drawings will become useful at a later stage when I begin making alterations to the robot. Below is a rendered drawing of the first draft CAD drawing, created using SolidWorks. This is only a rough draft as at the time of creating this drawing I did not have the physical robot available to me and so I was unable to take measurements of the various components.
As can be seen from the image above, much of the components are quite basic and in need of further detail, which will be added when I have access to the physical robot. However, on the ELEGOO website I was able to find the model of the ultrasonic distance sensor and the type of Arduino board used, an Arduino Nano in this case. These devices are widely available and so detailed CAD drawings are readily accessible online. Below are images of the respective CAD drawings of each of the devices.
Each of these devices, as well as two other chips, are connected to an expansion board. As this is quite a complex board, I developed a very basic first draft, simply consisting of a board with notches on which to attach the Arduino and sensor. At a later stage I will develop this further.
Furthermore, the wheel rims are a relatively simple feature of the robot and so it was quite easy to develop a reasonably accurate drawing, as shown below.
In addition, the ELEGOO website provides 3D drawings of the supporting plates (the blue plate and the clear plates). These drawings are provided in .stl file format which was easily imported into SolidWorks. The Recognise Features function was used to convert the files into useful drawings, from which much of the measurements were based for this first model.
The motors are very basic prototypes, intended only for completion of the model. When I know their make and model, I will create accurate drawings.
Materials and colours have been added to the various parts as accurately as possible, they can easily be changed when the robot is delivered. The columns are copper, the front plate and the two top platforms are clear PVC, while the lower platform is aluminium, as specified on the ELEGOO website. In addition the tyres are rubber.
The next stages of developing this model are as follows:
I want to determine the specifications of the motors in order to develop a highly accurate motor model.
Develop the expansion board, to include the two remaining chips and all the features of the board itself.
Refine the dimensions. This step can only be completed when the robot arrives as I have used all available dimensions already in making this model. However, as some dimensions are still unknown, I will have to make the remaining measurements myself.
Update: 06/03/2021
I am still awaiting delivery of the robot, however, I have spent some time updating the CAD drawings. I managed to get pictures of the motor model used and was able to develop more detailed drawing of them as a result.
More significantly, I have created the two remaining chips and added complexity to the circuit board. The chips used are the TB6612FNG Module and the GY-521 Module (using MPU6050 chip).
Furthermore, I have added all the necessary screws using the Solidworks toolbox library. The screws used are all M3 of lengths ranging from 4mm to 6mm.
Update 15/03/2021
I have made the final update to the CAD drawing by adding the tyre thread. I was hoping to leave this until the robot arrived as, judging from the pictures, it is not a standard or simple thread design. However, as the robot still hasn't arrived, I finished the thread just so I can now sign off on this phase of the project and move on. The thread design and a final render are shown below.
Next I’m going to do a little bit of redesign work. This current design requires the use of the robots self balancing feature. However, to navigate through an obstacle course and do other tasks it will be easier to simply add a third wheel or balancing mechanism to add stability and reliability.
