![]() If nothing else happened, the total angular momentum of the drone would now be +1. Suppose I decrease the angular velocity of rotor 1 such that now it has an angular momentum of -1 instead of -2. Let's say you want to rotate the drone to the right. I'll assign each rotor a value of +2, +2, -2, -2, which adds up to zero (I left off the units). Just to make things easier to understand, I will say the red counterclockwise rotors have a positive angular momentum and the green clockwise rotors have a negative angular momentum. If there is no torque on the system (the system here being the drone), then the total angular momentum must remain constant (zero in this case). Yes, it gets rather complicated, but all you need to know is that the angular momentum depends on how fast the rotors spin. What is the moment of inertia? It is similar to the mass, except it deals with rotation. Angular momentum is a lot like linear momentum, and you calculate it by multiplying the angular velocity by the moment of inertia. With the two sets of rotors rotating in opposite directions, the total angular momentum is zero. In this configuration, the red rotors are rotating counterclockwise and the green ones are rotating clockwise. How do you accomplish this by changing the power to the four rotors? Before answering, I will draw a diagram of the rotors (viewed from above) labeled 1 through 4. Let's say you have a hovering drone pointed north and you want to rotate it to face east. So, you will still need for the thrusters to be greater than for just a hover.ĭescending requires doing the exact opposite: Simply decrease the rotor thrust (speed) so the net force is downward. After that, you could decrease the thrust a little bit-but there are now three forces on the drone: weight, thrust, and air drag. So what about moving up, which pilots call climbing? Just increase the thrust (speed) of the four rotors so that there is a non-zero upward force that is greater than the weight. To hover, the net thrust of the four rotors pushing the drone up must be equal to the gravitational force pulling it down. Now, a drone can do three things in the vertical plane: hover, climb, or descend. The faster the rotors spin, the greater the lift, and vice-versa. This is the basic idea behind lift, which comes down to controlling the upward and downward force. Of course, all forces come in pairs, which means that as the rotor pushes down on the air, the air pushes up on the rotor. ![]() You can think of a rotor as a fan, because they work pretty much the same. See our full treatment for a possible answer to the question Wired left open for its readers.)ĭrones use rotors for propulsion and control. (Wired also did a great article on multicopter thrust and power relationions. ![]() We have decided to transcribe a portion of the article here in case the link were to break in the future. For ease of explanation and source material we will transcribe an article from Wired here. Let's look at the dynamics of a quadcopter. Quadcopters (all multicopters really) require precise speed control to multiple motors in order to achieve stability. The chances of a person with little coding ability developing a cutting-edge flight control system are quite low. With the advent of microprocessors capable of assisting flights has come drones even at the toy level with a price point of even around $20 or less. this is a great example of an area where there is absolutely no need to try to re-invent the wheel. Now, unless you are very strong in coding. He needs electronic help (which is really a human condensing hours of thought process into a machine capable of recplicating those thoughts at a higher speed the next time around). While quadcopters are so easy to build due to their lack of moving parts, this ease comes with a price.įortunately, the price is largely being paid with great value for the money if you will.Ī quadcopter has six degrees of freedom (3 translational and 3 rotational) but only 4 inputs, the 4 motor speeds.įrankly, a human is not capable of controlling a quadcopter in real time by himself. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |