Clicking on the 'Acceleration Calculator' button at the right of the input section on the main screen brings up a new window showing the time and distance the robot will take to achielve top speed, as well as the speeds expected within an arena of any given size. The default arena size is 8 feet square, so no change is requires for this analysis. The 'Help' button in this window provides explanations of all the output fields.
The 'Distance to Top Speed' output is of interest. A robot is typically designed to reach top speed in roughly half the width of the arena, but the proposed drivetrain leaps to its top speed of 2.8 MPH in less than one foot! Combined with the low motor current draw noted above this indicates that the 50:1 gear reduction loads the motor too lightly to achieve best performance from the robot.
Returning to the main calculator screen, clicking on the 'Gear Ratio Tips' button brings up the Optimum Gearing for Combat Robots page that explains the steps used by the Torque Calculator to select the proper gear reduction for a robot. Scroll down to the 'Adjusting gearing for special conditions' tab and follow the instructions to try the different gear ratios available for the Polulo motors and different wheel sizes to optimize the robot's performance for an arena of any given size.
In our example, replacing the motor selection with the Pololu Micro HP 30:1 gearmotors improves the performance of the robot:
- The the maximum amp draw per motor rises to an acceptable 0.45 amps.
- Pressing the 'Recalc' button on the Acceleration Calculator updates the window and now shows the robot now accelerating to 4.4 MPH in a comfortable 3.5 feet. That's a considerable gain in performance over the 50:1 motors.
Now that you know what to look for you can evaluate other drivetrain options for your robot.