Category: QuadCopter

A Quadcopter study looked like a fun challenge. It’s a busy area of interest, so there are papers and materials to use as a guide.

In the process, I’ll (re)visiting optimal control, estimation, classical and state-space design techniques, system linearization methods, and what-not. This is a good problem due to the many degrees-of-freedom and multiple inputs

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QuadCopter DC Motor(BLDC) + Propeller + Gearbox Dynamics

QuadCopter DC Motor(BLDC) + Propeller + Gearbox Dynamics

I decided to start on the, “inner loops”. By this I mean the control loops for each propeller drive system. A Brushless DC Motor (BLDC) is standard for hobby-sized quadrotors, so let’s assume the motor type. I haven’t sized anything yet: propellers or motors, but I can get the dynamic model figured out and put …

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Timeout: QuadCopter Project…Why?

Timeout: QuadCopter Project…Why?

I didn’t do a very good job getting this, “QuadCopter” project kicked-off. I’ll probably interchange the term with, “quad-rotor” frequently. First, what is a “quad-rotor”? Well you probably know it’s a thing with four rotors. We buy it as a, “drone” and we fly it with a remote control or via a phone app acting …

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Quadrotor Propeller Speed Control: Commanding 4 props to stabilize the platform

Quadrotor Propeller Speed Control: Commanding 4 props to stabilize the platform

In a recent post I shared a mathematical model for the combination brushless DC motor (BLDC), gearbox, and propeller model. A small quadrotor motor might not have a gearbox. It might have the propeller mounted directly to the shaft of a small hobby motor. A gearbox helps, “match” the motor to the, “load”: the propeller. …

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Revisit the Motor+Gearbox+Propeller Model

Revisit the Motor+Gearbox+Propeller Model

  It was fun to just mess with the motor-propeller differential equation and linearization in my earlier post. However, when I got into looking-up some rough parameter estimates and performing dimensional analysis (seeing if the units worked-out right for me in the equations) I ran into some problems. I realized I was not only needing …

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Propeller Blade, “Lift”

Propeller Blade, “Lift”

In  the last post I was able to clarify the load torque of the propeller applied through the gearbox to the motor shaft. I haven’t yet covered the main point of the propeller: LIFT! A propeller blade is just a spinning wing at each cross-sectional location. The propeller force described in the NASA diagram in an …

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Quadcoptor Platform Equations of Motion: Dynamic Model

Quadcoptor Platform Equations of Motion: Dynamic Model

It’s been over one month since I last posted. Back then I took a journey into fluid mechanics to offer a glimpse into how propellers work. I was motivated to do this as I was previously working-out the electric motor and propeller dynamics when I started to recall my mechanics studies. It’s a good time …

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Quadrotor Dynamic Model: Propeller Gyroscopic Effect.

Quadrotor Dynamic Model: Propeller Gyroscopic Effect.

I copied the equations below from the last post, where we see we matched our Bouabdallah paper‘s equations for rotational motion. We know some propeller input is going to be a part of the applied torque. There is going to be a set of equations for linear motion too, but let’s clarify what is going on …

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Finalizing Equations Of Motion: Thrust Inputs from Propellers

Finalizing Equations Of Motion: Thrust Inputs from Propellers

This post explains how we determine propeller thrust and drag factors for our quadcopter project. The last couple posts have been working-out the sum-of-torques on our quad-copter. The first, “unforced” model considers the gyroscopic effect of the total air-frame. That was the first, “equations of motion” post a few weeks ago. Next we looked at …

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Quadrotor: Simplifications for, “Classical” Controller Design

Quadrotor: Simplifications for, “Classical” Controller Design

The last few posts covered each of three dynamic details separately: Gyroscopic effect of the rigid body (the entire quadcopter). Gyroscopic effect of the spinning propellers. Propeller thrust and drag effects. We’re going to use all of this information as we look at controlling the flight of a quadcopter, but first we’re going to make …

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Quadrotor Roll & Pitch Axis Lead Compensation (PID)

Quadrotor Roll & Pitch Axis Lead Compensation (PID)

In the last post I simplified the model to arrive at a transfer function representing the roll and pitch axes independently for our ‘+’ shaped quadrotor. The following video explains how we stabilize this inherently unstable system. The PDF that follows is produced from the Maple document I review in the video. This, “lead-compensator” design …

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