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Questions tagged [feedback-loop]

38 questions
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mass calculation from transfer function or bodeplot

I have a double mass rotary model. The two masses are connected by an axis which together acts as a spring damper system of the fourth order. The system is actuated by a motor and the angle of rotation is measured by rotary encoders at each end of…
Somanna Thapanda
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Why can't proportional gain alone, reduce the error to zero?

I was told that the proportional gain alone cannot the drive the error signal to zero in a feedback loop. Why is that? If there is a tiny error, there will be a tiny or larger (depending on the number of proportional gain) correction, so why won't…
ergon
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Is active noise cancellation useful in vehicles?

The cabin noise of vehicles is a large concern in the luxury market. Why haven't any automakers used the same techniques as are employed in active noise cancelling headphones. In these devices a microphone is used as an in-loop sensor to suppress…
Chris Mueller
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Can a PID controller have a simple on/off output?

The crux of a PID controller is:- output = Kp * error + Ki * integral + Kd * derivative So typically there is proportionality and a continuously varying (analogue) output. In the case of a simple process like a domestic gas boiler, the boiler is…
Paul Uszak
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What is the effect of changing the angle of a helicopter flybar?

A helicopter flybar is a kind of gyroscopic stabilizer which acts in feedback to the pitch of the blades. The effect, in words, is that as the helicopter starts to pitch or roll in a particular direction more lift is applied on that side, keeping…
Chris Mueller
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Finding stability of open loop system connected to closed loop system

I have a simple cruise control closed-loop system with negative feedback and have no problem using the Nyquist stability criterion to find its stability. However, I have another function that describes the fuel consumption of the throttle in the…
user15540
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Given drive rotation angle, controlling torque, how do I maintain movement speed with varied load?

I'm working on design of a 3D movement drive (for 3D printers/CNC mills etc) using DC motors and helical drive. A DC motor drives the leadscrew actuator which supports the working elements (head, table or head bridge). The current of the motor…
SF.
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Is lead filter same as PD combined with a low pass filter?

I am curious to know the difference between a lead compensator (lead filter) and a PD controller with a low pass filter. From the theory I can see that the transfer function of both these controllers are same. By choosing appropriate gains and…
Somanna Thapanda
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How to improve a PID control loop by adding feedforward?

Assume you have a system model that is controlled by a PID controller (feedback). You want to add feedforward to improve the characteristics of the controlled system. How can you design the transfer function of the feedforward? (Cf. this image) On…
Karlo
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Stability of a closed-loop with disturbance in output. Characteristic equation alone or substitution

A general block diagram of a feedback controlled process with a disturbance in the output is: If we assume that the following blocks are equal to 1, and therefore we remove them: $$ K_m = G_v = G_m = 1$$ We have the following expression in…
Daniel V.
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How to convert a DC motor into a servo motor using a rotary encoder and a microcontroller?

Operating/ Rated Voltage: 24V No load Speed: 350 rpm No load Current: 150mA (max) Max efficiency: 1.4 Kg-cm/300 rpm/ 14.2W/ 0.87A Max power: 4.5 Kg-cm/180 rpm/28.2W/1.4A Stall Current: 2.9 A (max) Stall/ max Torque: 8 Kg-cm Gear Ratio: 1:34 1496…
Samm Flynn
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Closed loop response of a discrete system

I have trasfer functions of a plant and a controller in laplace domain. I checked for the closed loop response by applying a step response. The system is found to be stable. I checked the response of the system for the same step reference in…
Somanna Thapanda
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Can an electric motor act as a load for the electric generator rotated by that motor?

I have an experimental generator and an off-the-shelf motor that I intend to arrange like in Fig. 1. The problem is that if I connect the required load to the output of the generator the power drawn from the DC source is too big and the electricity…
Robert Werner
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Feedback loop and zero - error in steady state

I need help with this exercise. I 've tried many times with pen and paper but I'm stuck. I don't want a full answer but some feedback . Here is my progess: $$\frac{dx}{dt} = Ax(t) + Bu(t) \Rightarrow sX(S) = AX(S) + BU(S) \Rightarrow \\\Rightarrow…
tonythestark
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How can I get final value of $V_{out}$ at $t=∞$ in RC circuit?

I can obtain the transfer function in this RC circuit. $$ \frac{V_{out}}{V_{in}} = \frac{1}{(RCs+1)} $$ When $V_{in}$ is set to $10V$, how can I get final value of $V_{out}$ at $t=∞$? I tried to use the final value theorem but I can't get the…
hihello
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