# Tag Info

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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 an inertial frame. You must make that distinction in your choice of models. Your estimator will represent your robot's acceleration in some way in its state, ...

2

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 derivative part: $$u(t) = K \cdot \left( e(t) - T_d \cdot \dot{y}(t) \right).$$ The Laplace transform of a feasible $D$ term is thus:  D(s) = -\frac{sKT_d}{1+sT_d/N}...

2

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. One controls the rate and the other the position (or what ever is the case in your specific issue). Nevertheless, you still have only one output from both ...

1

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 RPMs provided by the motors (max current not reached) ❌ The open-loop response of different motors will certainly vary because of the variability of the building ...

1

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, resulting in the noise or jitter you observe.

1

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 physical phase output pads of the ESC. The only time a brushless motor will care about rotation is if they have different direction threads on the shaft where the ...

1

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 the amount of thrust generated. Motors must be purchased from the manufacturers providing thrust tables that shows how many grams of thrust will be generated ...

1

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-1-esc-aio-f4-osd-flight-controller-w-or-bec-current-sensor-p-195.html What you want to do is use the PPM out from the Flysky iA6B, connect it to the PPM in of ...

1

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 is common to have a position controller whose output feeds into a velocity controller, but typically one of these controllers will be PI (or PID) and the other ...

1

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 system to keep the drone stable and level, while only allowing me to modify the desired altitude. Depending on how advanced the system is, it should also be ...

1

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. The other three degrees of freedom come from the effective torques due to thrust imbalance in front-back (pitch) and left-right (roll), and imbalance in the ...

1

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 makes the motor turn. 1b)Concerning power you need to check what the PDB specification are for its 5V line, if the current supported is high enough you can power ...

1

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 need anyway - a blimp, for example, will need to be flown actively against a storm when tethered. Obviously, the baloon needs to be made of some material which ...

1

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 receiver. If the receiver specifies a voltage range (i.e. 3V - 5.5V), then the supply needs to be within that range. If the receiver doesn't specify a range, then ...

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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 oscillations when they happened.

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