[Joe Johnson]

I have heard a lot of folks say they are using "dead reckoning."

I am confused by the term.

It seems to me that some folks mean they output PWM values of PWM1 for T1 seconds, and then output a value of PWM2 for T2, etc. This entire process only requires a clock and uses no sensors whatever. (Note to the purist out there: PWMi is a vector of dim 16)

For others, they have rotational sensors on their wheels that they used to infer robot motion (distance and perhaps orientation). In this case, teams would vary their PWM output based on location. For example, PWM values PWM1 until X1, then PWM2 until X2, etc. (There are fancier control schemes with could plan paths, use proportion control, etc. but you get the idea).

Still others are using rotational velocity sensors (a.k.a. gyros a.k.a. yaw rate sensors) and inertial sensors (e.g. accelerometers) that they integrate (twice in the case of the inertial sensors) to get position. In this case, teams use the position information similarly to the way the rotational sensors are used.

In any case, I always wonder what a team means when they say they are using "dead reckoning" to control their robot.

Having seen them work so well in Ypsilanti, I am especially curious to learn what team Rush (#27) means by the term. It is hard for me to believe they could be as repeatable and effective as they were by using just time, but I admit I have been wrong once or twice in the past.

Joe J.