| Electronics > Projects, Designs, and Technical Stuff |
| Question about PID controller for Quadcopter |
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| ammjy:
Hello. Thanks you for your time. Now, I'm studying one quadcopter simulation model that I found on Github. that name of simulation is "QuadSim Master" and link is as follows. (https://github.com/dch33/Quad-Sim) (Already I have sent question mail to publisher, but, it is already 5 years ago project so, I don't think that I can receive answer mail.) and I have few question about it. 1st attached screenshot show us that PID controller block of Quadcopter. as you see, P and I controller connected with Phi command. but, D controller connected with Angular Velocity P. I don't understand why only D controller not connected with Euler Angles Phi. another, Theta and Psi controller also same. each D controller of Thea and Psi also connected with Q and R. I want know reason or clue. 2nd attached screenshot show us that state-space model of BLDC motor. but, as you see, A = -1 / (Time Constant of Motor) B = 1 C = 1 / (Time Constant of Motor) D = 0 Initial conditions = Initial RPM * (Time Constant of Motor) //Time Constant of Motor is quadModel.T //Initial RPM is IC.w1 I can't make any clue that why developer of this simulation made state-space model of Motor with this form. If anyone know about it, could you give me some clue or advise for these two questions ? please, let me know. |
| ammjy:
Answer about second question : Simple RC BLDC motor can be simplified as a first-order low-pass filter and It can be expressed as w = 1 / (Ts + 1) * wss where, wss - desired steady-state speed; T - Time Constant if we express first-order low-pass filter transfer function "w" with state-space model. it looks same with A = -1 / (Time Constant of Motor) B = 1 C = 1 / (Time Constant of Motor) D = 0 namely, 1 / (Ts + 1) is same with A = -1 / (Time Constant of Motor) B = 1 C = 1 / (Time Constant of Motor) D = 0 |
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