Mobile Robot Design for UPV Mobile Robotics Course
This robot was developed as part of the Mobile Robotics course at the Universitat Politècnica de València (UPV). Its design is inspired by the “Do Your Own Robot” framework and incorporates two key functionalities: omnidirectional movement using Swedish wheels and basic obstacle avoidance.
Components
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Arduino Uno microcontroller
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2× L298N H-bridge motor drivers
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HC-SR04 ultrasonic distance sensor
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Battery pack (6× 1.5V AA batteries in series)
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4× DC motors
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4× Swedish (Mecanum) wheels
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Mounting frame for electronic components
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Assorted cables and connectors
Design Overview
The robot employs Swedish wheels (also known as Mecanum wheels), which enable omnidirectional movement including forward/backward motion, lateral “strafing,” and in-place rotation. This enhanced mobility is achieved by individually controlling the speed and direction of each wheel via two L298N H-bridge motor drivers.
Power is supplied by six 1.5V batteries connected in series, providing sufficient current for motor operation. Obstacle avoidance is implemented using a basic algorithm based on input from a single front-mounted HC-SR04 ultrasonic sensor.
Performance and Limitations
One of the main challenges encountered is the inconsistent quality of the Swedish wheels. Some rollers are seized while others rotate freely, resulting in unpredictable and unreliable motion depending on wheel orientation. Moreover, Swedish wheels require a certain level of ground friction to function correctly, which further complicates movement control.
The obstacle detection is limited to frontal sensing. A future enhancement could involve adding additional ultrasonic sensors on the sides to improve environmental awareness and navigation capabilities.
Another area for improvement is power management. The robot’s behavior varies depending on the charge level of the batteries, affecting wheel performance. Implementing a dedicated power switch would facilitate easier testing and system resets.
Future Enhancements
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Replace or upgrade Swedish wheels for more reliable and precise motion
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Add additional ultrasonic sensors for side detection
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Integrate a power switch for easier control during testing
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Investigate and specify the exact DC motor model for documentation (no specific info from Aliexpress)
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Explore alternative or rechargeable power sources for more consistent operation
Rotation demonstration
The rotation of the robot works as intended.
Strafing Demonstration
As the video shows the strafing does not work, due to the aforementioned problems with the rollers. The movement is erratic and is more like an unstable rotation.
Obstacle avoidance
The obstacle avoidance works, although the movements could be more controlled and fluid.
Written by Mikkel Bølset Gisleberg