Model Definition
As a car-following model, the IDM describes the dynamics of the positions and velocities of single vehicles. For vehicle, denotes its position at time, and its velocity. Furthermore, gives the length of the vehicle. To simplify notation, we define the net distance, where refers to the vehicle directly in front of vehicle, and the velocity difference, or approaching rate, . For a simplified version of the model, the dynamics of vehicle are then described by the following two ordinary differential equations:
, and are model parameters which have the following meaning:
- desired velocity : the velocity the vehicle would drive at in free traffic
- minimum spacing : a minimum net distance that is kept even at a complete stand-still in a traffic jam
- desired time headway : the desired time headway to the vehicle in front
- acceleration
- comfortable braking deceleration
The exponent is usually set to 4.
Read more about this topic: Intelligent Driver Model
Famous quotes containing the words model and/or definition:
“For an artist to marry his model is as fatal as for a gourmet to marry his cook: the one gets no sittings, and the other gets no dinners.”
—Oscar Wilde (1854–1900)
“Mothers often are too easily intimidated by their children’s negative reactions...When the child cries or is unhappy, the mother reads this as meaning that she is a failure. This is why it is so important for a mother to know...that the process of growing up involves by definition things that her child is not going to like. Her job is not to create a bed of roses, but to help him learn how to pick his way through the thorns.”
—Elaine Heffner (20th century)