Novel Differential Servo Drive for Autonomous Robot Tracking and Maneuver I

This senior design project aims to design, manufacture and assemble an omnidirectional differential swerve drive featuring four individual swerve modules to be integrated into a scoring system to complete the tasks set by the collegiate VEX Push Back competition. The drivetrain must have full translational, rotational, and sideways movement by controlling the torque and steering of each wheel which is highly beneficial for the precise path following and fast directional changes the robot encounters in competition. The team evaluated multiple drivetrain designs including traditional tank, H-drive, and coaxial swerve drive against criteria such as mass, manufacturability, cost, and reliability. The design process utilized SolidWorks for part creation and assembly modeling to optimize the module's footprint and reduce mass. Engineering analysis of torque-speed curves for the VEX V5 Smart Motors was conducted to ensure the selected 6:1 gear cartridges and gear ratios could meet the target performance goals. The implemented solution is an integrated differential swerve module featuring a unique dual-purpose gear system where two motors cooperatively control both wheel orientation (steering) and wheel speed (driving). Key subsystems include: Differential Steering Mechanism: Consists of two inner spur gears and two outer spur gears. Driving System: Utilizes a 24-tooth driving bevel gear meshed with a 48-tooth, 2.75-inch diameter bevel gear on the wheel. Wheel-to-Ground Contact System: Employs a 2.75-inch diameter wheel surrounded by rollers to allow for pivoting with minimal friction. The system is also modular, meaning each module can be assembled, serviced, or replaced without affecting the rest of the drivetrain. Each module is primarily constructed from PETG and PETG-Carbon Fiber (PETG-CF). Preliminary testing of 3D-printed prototypes has validated that the PETG-CF gears mesh properly and run smoothly under motor power. Calculations indicate the motor's peak torque, combined with the gear reduction, provides sufficient driving force and a theoretical maximum speed of approximately 81.05 inches per second. The current design successfully fits within the required 15 cubic inch area. While developed for the VEXU competition, this modular differential drive has potential applications in defense and automotive industries where compact, highly maneuverable robotic platforms are required. Some examples include recon rovers and search and rescue rovers.