4 votes
Accepted

Detection of linear acceleration vs rotational velocity/acceleration

The IMU itself cannot distinguish between "true" linear acceleration and "fictitious" (Coriolis) linear acceleration induced by rotation of the IMU coordinate frame with respect to ...
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2 votes

High derivative gain in PD control

Chuck's answer is spot on. Anyway, if you want to derive the reason mathematically, you can start off from the most common form of a PD controller where we employ a setpoint-weighting for the ...
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2 votes

How do I tune the cascaded PID controller in my flight controller?

In general, a cascade controller is nothing more than two independent controllers in series. With independent I mean that they do not intend to control the same value (= measurment, plant output). I.e....
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1 vote

What can cause yaw rotation on a multirotor when yaw control is disabled?

A disturbance yaw rate of $-0.1, \text{deg/s}$ seems way low. Are sure that in steady-state there won't be any cause external to your copter (very low airflow?) justifying it? Imbalance between the ...
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1 vote

High derivative gain in PD control

Real signals have noise. Because noise happens on a per-sample basis, you wind up with a derivative that is constantly fluctuating. A derivative gain acts on this fluctuation and feeds it to the motor,...
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  • 14.6k
1 vote

Tuning a cascaded attitude and attitude rate PID controller

You can operate the quadcopter with a poorly tuned attitude rate PID, log relevant quantities, build a model from the data, and finally use the model to tune the PID iteratively. Suppose that such an ...
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1 vote

BLDC Outrunner Direction Change?

Brushless (BLDC) motors are not inherently directional. They can be either clockwise or counter-clockwise, it only needs to be set in the software, or by swapping two of the motor wires on the ...
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  • 141
1 vote
Accepted

How should i select motor and blades for my Hexacopter?

Motor and blades must be selected on the basis of amount of thrust required. Estimation of thrust of a motor depends on battery voltage, prop size and motor choice. Changing one of these will change ...
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  • 164
1 vote
Accepted

How to attach flysky receiver to racerstar all in one esc and flight controller?

Let me assist you and point you in the correct directions: the manual for your Racestar FC and ESC is here (it is in picture form): https://www.racerstar.com/racerstar-starf4s-30a-blheli_s-dshot-4-in-...
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1 vote
Accepted

Helium Balloon Altitude and Velocity Control System

Two thoughts occurred to me when reading your question: Although I haven't analyzed your specific problem, I wonder if it is beneficial to have two full PID loops. In motion control applications, it ...
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  • 201
1 vote

What parts of the flight system could you remove if you only care about flying up/down?

Being honest, If I wanted to achieve this, I would get myself an open source quad-copter, and adjust the control system to apply some "Input Constraints". Basically allowing the built in stabilization ...
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1 vote

How many independent control inputs does a hexarotor have?

When assuming that the axles of all the rotors are oriented parallel to each other then the thrust will also only be along the same direction as these axles, so this only adds one degree of freedom. ...
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  • 921
1 vote

Compatibility of my quadcopter build

1) you 4in1 ESC as 3 outputs per motor and 1 input per motor... Your description of the brushless motor seems very confused. Brushless motor are commanded with 3 phases, theirs switching patterns ...
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  • 1,327
1 vote

Could a hot air balloon be powered from the ground like a drone?

The other option would be a laser. The baloon could reach migher altitudes without the corresponding increase in wire weight. Of course, it would need some means of holding position. Which it might ...
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  • 111
1 vote

Receiver is getting really hot

Either the voltage supply to the receiver is too high, or something's not right about what you're trying to drive it with. Compare the voltage supply to the receiver to the rated voltage of the ...
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  • 1,881
1 vote

How do I tune the cascaded PID controller in my flight controller?

I have since tuned the system just by using trial and error. The rate constants are much lower than their maximal values at which oscillation started. It helped to just measure which loop caused ...
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