4-Wheel Pivot Drive
From DEW Robotics
4-Wheel Independent Pivot-Wheel Drive describes a 4wd drive-train in which each of the (4) wheels are independently driven and may be independently pivoted for steering purposes. The design offers the potential for excellent drive-train performance and a solution to conventional (tank) drive-train design constraints. The design also brings some clear design and control challenges.
This arrangement provides the possibility to operate in several Drive/Control different modes:
- Crab mode – pivots all wheels together and at common speed to steer the robot in any direction on the 2-d playing surface (true 2-d drive). The mode does not control chassis orientation.
- Snake mode – pivots front and rear wheels in opposite directions to guide the robot through a turn
- X-bias – drive direction aligned with the long-axis of the robot
- Y-bias – drive direction aligned with the short-axis of the robot
- Automobile mode – pivots front wheels only to guide robot through a turn
- X-bias
- Y-bias
- Tank mode – Does not use pivots to steer (but can use pivots to change drive orientation ala Twitch). Steering accomplished by differential L & R drive speeds.
- X-bias
- Y-bias
Overview
A detailed Mathematical Analysis of the Pivot-Wheel System is available in pdf format.Team 1640 2009 Summer Program