Representing State and Motion

So, we’re back in our car.py file, and let’s see how we can actually modify this car object and add a color variable. Inside our class code, we can see that there’s a default color for our car. Red represented by the character r. So, how do you think we might customize this? Well, just … Read more

So here I’ll show you how to interact with a car object that can keep track of its own state. First, you’ll see some import statements and some code that we’ll go through in detail soon. But before we dive into the code that makes up an object, we’ll learn how to interact with it. … Read more

You’ve been working with a predict state function that takes in a current state and some change in time, dt. And it outputs a new state estimate based on a constant velocity motion model. It turns out a constant velocity model is actually a good simple model to use, especially if changes in time are … Read more

The one unifying theme in this lesson is representing and predicting state. But there are two threads that we’ll use to explore this idea. On the programming side, we’ll use something called object-oriented programming as a way to represent state in code. We’ll use variables to represent state values and we’ll create functions to change … Read more

Now you’ve seen two examples of car motion models. In the first example we assumed our car was moving at a constant velocity. But in the second example we said that the car was slowing down with a constant acceleration. And after three seconds had elapsed we ended up with different estimates for our car’s … Read more

Now, what if I gave you a more complex motion example? And I told you that our car starts at the same point at the zero meter mark, and it’s moving 50 meters per second forward, but it’s also slowing down at a rate of 20 meters per second squared. That means that every second … Read more

Let’s take a closer look at the last example. The initial state of the car is at the zero meter position and it’s moving forward at a velocity of 50 meters per second. Let’s assume that our car keeps moving forward at a constant rate. Every second it moves 50 meters, so after three seconds … Read more

When you localize a car you’re interested in only the car’s position and its movement. This is often called the State of the car. The state of any system is a set of values that we care about. In the cases you’ve been working with, the state of the car includes the car’s current position, … Read more

Great job getting this far. Now you’ve seen that we can transform the state of a car using matrix multiplication. This kind of linear algebra can be used to update multiple state variables in just one line of code and this becomes really useful when you’re working with big data sets and variables that represent … Read more

Let’s look at how vectors are used in the math behind self-driving cars. The way we have been representing state is as a list of values which just has a length, a length of two values, in this case. But, a state vector is a column of values whose dimensions are 1 in with an … Read more

So far you’ve seen that, the state of a car contains multiple values which we’ve been putting into a Python list. But these values are typically contained in one data type, a state vector. A vector is similar to a list in Python in that it contains multiple values but they are mathematically very different. … Read more

All self-driving cars go through the same series of steps to safely navigate through the world. You’ve been working on the first step, localization. Before cars can safely navigate, they first use sensors and other collected data to best estimate where they are in the world. In this lesson, we’ll be talking about representing and … Read more