Thrust is always in the same direction relative to the drone airframe, it’s along the Z axis of the minidrone. We’ll start by focusing on the thrust command. So we’ll keep the motor mixing algorithm and build a feedback control system with it in the loop as well.Īlright, let’s get rid of the human operator and think about how we can accomplish the same thing autonomously. But it turns out, thinking in terms of roll, pitch, yaw, and thrust is also beneficial when we’re developing an autonomous control system. This is the controller configuration that a lot of operators use when manually flying their quadcopters. Now our remote control toggles are aligned with the intuitive roll, pitch, yaw, and thrust rather than mind bending motor speeds. When we command thrust, for example, this single thrust command gets split evenly to all four motors, the yaw command is distributed positive to two motors and negative to the other two, and so on. While possible, thinking in terms of motor speed seems really hard, and we want to make our job easier, so instead we can use the motor mixing algorithm we created in the last video and command thrust, roll, pitch, and yaw directly. In this way, you, as the feedback controller, could get the drone to hover by expertly changing the commands to these four motors. And to pitch the vehicle, you would increase one of the front/back pairs and decrease the other. Then to roll the vehicle, you would increase one of the left/right pairs, and decrease the other. Yaw requires that two opposing motors increase speed and the other two decrease speed so that yawing left, for example, would require this kind of toggle motion. If you want to increase thrust, you’d speed up all four motors by moving the two toggles in this direction. This puts you in the feedback path because you could see where the drone is, and then react to its position and attitude by moving the four toggles in very specific ways. The left toggle would control the two front motors and the right toggle would control the two rear motors. That is, we have a remote control with toggles that directly control all four motor speeds. Well, to start, let’s assume that rather than do it autonomously, we want to command the minidrone manually. So the question becomes, how do we command these four motors autonomously so that happens? The output that we want is to have the the minidrone hover at a fixed altitude. It takes fourmotor speeds as inputs, which then spin the propellers, generating forces and torques that affect its output state. In the control system we’re developing, the plant is the minidrone itself. I’m Brian, and welcome to a MATLAB Tech Talk. That means, we’re going to figure out which states we need to feedback, how many controllers we need to build and how those controllers interact with each other. In this video, we’re going to use that knowledge to design a control system architecture for hovering a quadcopter. We also covered the four sensors that we have at our disposal to estimate the system states. In the last video, I showed that we can manipulate the four motors of a quadcopter to maneuver it in 3D space by getting it to roll, pitch, yaw and change its thrust.
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