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Stair-Climbing Robot with Self Leveling Platform
May 2022 - Jul 2022
Introduction
This project was part of a fun science competition organized by the local Science Museum, challenging participants to design and build a machine capable of carrying ping-pong balls while moving along a set of stairs. The goal was to create a robot that could reliably navigate uneven stair steps without losing stability or dropping its cargo, combining creativity, engineering, and robotics in a hands-on STEM experience.
Design / Process & Development
The robot was designed with a six-wheeled chassis controlled by the Mindstorms EV3 system. Central to the design is the rocker-bogie suspension mechanism, which allows the robot to traverse irregular stair surfaces while maintaining continuous contact between all wheels and the steps. Each side features two rocker arms connected to bogies holding the front / rear wheels, enabling independent articulation and stability without relying on springs. To secure the ping-pong balls during movement, the robot includes a self-leveling platform with two axes of movement, ensuring the container remains balanced. A steel ball suspended from the platform acts as a counterweight, lowering the center of gravity to further enhance stability and prevent tipping during stair ascent.
Rocker-bogie mechanism for 6 wheels
3D-printed self-leveling platform with 2 axes of movement
Specifications
Dimensions: 870mm (L) x 460mm (W) x 490mm (H)
Wheel diameter: 200mm (x 6)
Controller: Mindstorms EV3 controller
Power: Mindstorms EV3 large motors (x 4)
Programming: Mindstorms EV3
Results / Impact
The robot effectively climbed multiple flights of stairs using the rocker-bogie mechanism to maintain stability and wheel contact on uneven surfaces. The self-leveling platform generally held the container of ping-pong balls securely, but when the robot moved quickly with jerky motions, some balls occasionally fell off. This highlighted the challenge of maintaining cargo stability under dynamic conditions, emphasizing the importance of refining the design for more robust handling. Overall, the project demonstrated solid mechanical design and robotics control principles, while underscoring real-world challenges in balancing speed and stability.
Skills and Competencies Highlighted
This project developed critical skills in mechanical engineering, robotics control, and problem-solving. The design process emphasized creativity in utilizing the rocker-bogie suspension for stability, applied physics concepts like center of gravity and balance, and required precision fabrication (especially 3D-printing) and assembly.
Reflection and Future Directions
While the robot successfully navigated stairs and maintained balance through innovative mechanical design, the loss of ping-pong balls during rapid or jerky movements revealed a limitation in cargo security. To address this, future improvements could include redesigning the container with better containment features such as raised edges or cushioning, as well as smoothing out the robot’s motion through enhanced control algorithms to reduce sudden jerks. Additionally, exploring active stabilization methods or shock absorption systems could further protect the cargo. These refinements would enhance the robot’s practicality and reliability for carrying fragile or loose objects over challenging terrain.
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