Autonomous Rolling Robot

Mechatronic Project

Mechanical design of the rolling robot

The rolling stones proposed the first extra-terrestrial concert on Mars for their upcoming album tour, ‘Exile on Mars Street’. To achieve this, IDESA will be sending two autonomous robots to Mars: ‘Rolling and Stones’. Both robots will communicate and working closely together, at which ‘Rolling’ will be responsible for locating and navigating to suitable building materials. ‘Stones’ will then be deployed for resources collection and printing the foundations of the stage which the band will perform on. The objective of the project is to propose a system design, prototyping and testing.

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Design Brief
The IDESA will be deploying two autonomous robots to Mars: ‘Rolling and Stones’ for the Rolling Stones upcoming album tour, ‘Exile on Mars Street’. Rolling will be responsible for navigating suitable location and building resources. Stones will then deploy for construction of the arena where the band will be performed on. The rolling robot is expected to be able to locomote in the sphere for advanced terrain mapping and the secondary robot, Stones, should incorporate a printer function for construction of the arena.

My Contributions
Projects in collaboration with 3 members of the team of different roles to design a prototype for the proposed project. I was assigned to proposed mechanical design solution for the robots in the system. Responsible for designing the mechanical components for the projects, communicating and executing prototype testing with the software and electronics team to ensure a functioning, finished prototype and fulfilling the project requirements.

Mechanical design

Prototyping

Autodesk Inventor

Product design and development

The Design Process

Click to reveal details about the process

01

Initial Brainstorming

Generate a large number of ideas quickly in a collaborative and non-judgemental environment. All team members are encouraged to contribute to the brainstorming session by generating their own unique concepts or building upon the ideas of others.

02

Concept development

This stage involves evaluating and refining the ideas that were generated during the brainstorming session. This is where the team selects the most promising ideas and begins to develop them into design concepts.

03

Prototype development

Develop a detailed plans and specifications for the chosen solution, and fabricate it.
This stage includes proposing a final prototype design, CAD and hands-on prototype development and fabrication.

04

Testing and evaluation

Evaluation of the design solution and identify any issues or areas for improvement.
This stage includes evaluation on the performance of the system and making improvements and design iterations.tr
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Concept Development
One of the key considerations during the early stages of the concept generation were mobility and steering ability. 3 concepts were generated, wherein the first 2 concept regard a pendulum powered system, which were driven by constant change in centre of mass for motion.

The system consists of the centre motor which allow the robot to move forward/backward, and 2 discrete motors driving 2 individual pendulums that allow right/left movements.

Concept suggested a wheel-pendulum hybrid system. Forward/Backward motion are generated by the wheels located at side, while the pendulum facilitate steering by tilting left/right.

Concept C implements the use of omni-wheels. This type of system enable travel in any direction, without the need for rotating and translate. This feature allows more efficient travel route which is highly applicable to the proposed event. As compared to 2 wheels system, the 3-wheel configuration provides an additional support point for additional stability.

Design overview
The system is consisted of 2 service robots,' Rolling and Stones'. The rolling robot, Rolling, must be capable of locomote in an enclosed sphere and the secondary robot stones, should incorporate a printer function for construction of the arena.

Omni-wheels configuration
Both robots employed a similar omni-wheels configuration, which enable the device to travel in any direction. This allows more efficient travel route which is highly applicable to the proposed event. As compared to 2 wheels system, the 3-wheel configuration also provides an additional support point for additional stability.

Implementations for simplifying design iterations
The design was heavily influenced by the battery configuration and PCB design due to its size and weight distribution. As different configurations were tested and inputted from the electronic lead, which resulted in several design iterations. Omni-direction framework with adjustable motor position and modular battery casing were implemented to simplify the iteration process.

Design Iteration
A slot at the front of the base plate accommodates the insertion of the battery housing module. Cut-outs on the base plate enable the position of the motors to be altered by relocating forward and backwards. The angle at which the motors are configured can be adjusted by swapping the modified motor brackets. This enables the accommodation of different battery configuration with minimum redesign to the system.

1st iteration of battery pack module assembly

Secondary robot design ' Stone' .

Secondary robot design ' Stone '
To simplify the design and development process, the secondary robot, Stone, which were not restricted by the rolling design constraint, was utilised as the test bed and verification for the omni-direction system as the rolling robot was being developed.

About the final design
The final design of the device boasts a unique and efficient two-battery configuration. It comprises of one large battery and one small battery, with the small battery pack positioned at the rear of the device to act as a counterweight, thereby improving the device's stability. Additionally, the large battery pack housing features a dedicated platform to securely hold the electronics.

Final iteration of battery pack module assembly

Order of assembly

Final Prototype
At the outset of the project, key requirements were established and the system has fulfilled them. The rolling robot was successfully able to move within the sphere and the electronics were accommodated. However, during testing, certain issues were discovered that will need to be addressed in future work. For example, the form factor needs to be reduced. This can be achieved by dividing the electronics, such as the circuit board, into smaller components that can be placed in appropriate locations. This will result in more efficient use of space compared to using a single circuit board. Despite efforts to limit the surface of contact, there was significant motion resistance between the components and the surface of the sphere. To overcome this issue, it is recommended to use caster wheels around the disc plate to improve mobility efficiency.

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Cable Management
To avoid the motor getting tangled up in the cables, they are directed from the area behind the motor support component towards the disc plate above for connection to the circuit board. A top cover will also be installed to prevent the cables and electronics from interfering with the motion of the sphere and to allow for the placement of the Aruco code.
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Hao Ran Guan