12
votes
How do the PID parameters (Kp, Ki, and Kd) affect the heading of a differential driving robot when they are increased individually?
Proportional term: this controls how quickly to turn the steering when the heading is not at the set value.
A low P will lead to sluggish steering, reacting only slowly to set
heading changes. It may ...
- 1,041
11
votes
Accepted
Quadcopter PID Algorithm
The glaring issue I see at the moment is that you are forcing polarity on the I and D terms. In general, you are using a lot of sign checks, sign assignments, and conditional programming.
None of that ...
- 16k
10
votes
Accepted
How can we use the accelerometer for altitude estimation?
The barometer carried on the pixhawk has an altitude resolution of 10 cm. If that isn't enough, you could write a kalman filter that uses the accelerometer data in the prediction step and the ...
- 1,853
9
votes
Accepted
Multiple control loops with overlapping effects
Typically with a multiple input, multiple output (MIMO) system, a control engineer uses a state feedback controller. This style of controller leverages a state-space model of the system and generally ...
- 16k
9
votes
Accepted
How to tune the PID parameters using Fuzzy Logic?
The paper Controlling of Quadrotor UAV Using a Fuzzy System for Tuning the PID Gains in Hovering Mode by E. Abbasi, M. J. Mahjoob explains how to tune PID gains with fuzzy logic. You can find many ...
- 1,104
7
votes
Do I need to use separate function in PID algorithm to make the bot go LEFT or RIGHT?
No, but you do need to calculate the P/I/D terms correctly. You have:
I = I + previous_I;
followed by:
previous_I = I;
...
- 16k
7
votes
Accepted
PID control: zero out integral on error sign change?
Generally, in a well-tuned PID, most of the job is done by the P term, which is responsible for driving PV to SP. Then, D and I serve as corrections: the D term regulates the profile as of how we ...
- 3,995
6
votes
PID with position and velocity goal?
In the case of MIMO systems (Multi-Input, Multi-Ouput), my warm suggestion is to go with State Space Control, which will give you enough freedom to move the closed-loop poles and thus achieve your ...
- 3,995
6
votes
Accepted
PID controller that targets a set rotation and a set velocity at that rotation?
Find here a similar question.
A well-tuned position PID is most of the time capable of accomplishing the task of reaching a target with zero velocity. The central point here is that you shall provide ...
- 3,995
5
votes
Accepted
Length and Width of a Line Following Robot
Actually, the caster wheel has ideally no effect on the kinematics of the vehicle. In reality there will be some resistance from the caster wheel that does impact the vehicle motion, but we can still ...
- 1,377
5
votes
Accepted
What's wrong in controlling Roll+Roll rate in a quad-copter instead of using 2 separate loops for each?
That only works when the desire roll angle is 0. What happens if you are trying to turn and have a desired roll angle of 1deg? Even changing your sum to match the angle error, $w_1 (\theta - \theta_d) ...
- 2,794
5
votes
Accepted
Meaning of a negative step response with quaternion
Welcome to Robotics, PaoloH! This is a fantastic question for Robotics - It has some Matlab/Simulink, some control theory, some spatial (quaternion) representations, etc. Robotics is the place to come ...
- 16k
5
votes
Which controller (PI or PD) is generally more robust to noisy sensor measurements and why?
Proportional control amplifies equally across all frequencies.
Integral action amplifies low frequencies more, and high frequencies less (in fact, its gain at DC is infinite, and at infinite frequency ...
- 1,891
4
votes
Comparing LQR and PID controllers for inverted pendulum problem
You are correct in claiming that both PID and LQR can be applied to the linearized form of the cart-pole problem. If you have a look at the answers to the related question Ugo linked to in the ...
4
votes
Accepted
PID Control: Integral error does not converge to zero
I don't think this is related to integral windup at all.
I noticed that the I-error does not converge to zero
That's a good thing, because it means your integral term is not useless.
The integral ...
- 1,425
4
votes
Accepted
Quadrocopter PID
Technically, you can do it either way, but consider the following scenario: You are flying with a heavy load, and there is a wind gust. Each rotor is operating at almost 100% capacity due to the heavy ...
- 16k
4
votes
Fixed Wing UAV: Do inherently unstable systems desire to be stable for all cases when a closed loop control is implemented on them?
Not all fixed wing aircraft are inherently instable. That feature greatly depends on the center pressure and gravity center designed position. Passenger aircrafts are quite stable, and fight planes ...
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4
votes
PID with position and velocity goal?
If in fact you need the robot to be at the same speed as the tracked object at the time it arrives with it, you might need to employ more sophisticated methods. However, a controller that is the ...
- 41
4
votes
PID with position and velocity goal?
In many cases, a single traditional PID controller is adequate to track an object and match both position and velocity of the object.
With the error term of the PID in terms of position, the integral ...
- 4,525
4
votes
Balance Bot PID tuning
Just a hint from my extensive experience from self balancing robots:
The most important aspect of a self balancing robot, is the actuator acceleration (torque) control.
(...) the motors start ...
- 71
4
votes
Accepted
PID Controller Output Mapping for Motor Speed Control
Convert your PWM units to belt velocity units, or vice-versa. The quick and dirty way of doing this is to multiply your P, I, and D terms by $16,393 \over 0.5$. The PWM-to-belt velocity mapping won'...
- 4,386
4
votes
What is the best adaptive controller for robotic arms?
The given strategies can be divided into two groups: model-based and model-free control. The AMPC and MARC suggestions are model-based the other are model-free. Theoretically, a pid controller can be ...
- 794
4
votes
Accepted
Inverted pendulum controller
Without going into the details of the underlying equations of motion, I could argue that the D part is needed to damp out the oscillations of the pole while reaching for the (unstable) equilibrium ...
- 3,995
4
votes
PID Control: Is adding a delay before the next loop a good idea?
Don't disengage your controller.
The purpose of a controller is not only to steer your system to the desired setpoint according to a predetermined dynamical response but also to counteract potential ...
- 3,995
4
votes
Inner current controller benefits
What would be the benefits of implementing this full nested control architecture for the control compared to my current implementation
Textbooks are always a great source of information!
Reference: &...
- 3,995
4
votes
Impact of using PID Output as a Change (Delta) vs Absolute
All PID controllers are relative in the sense that they act on a reference error, which is the difference between the reference signal and the sensed signal. Assuming the integral error starts at the ...
- 16k
4
votes
Does PID controller work on every actuator
does the PID controller work on every actuator?
The short answer to this is yes.
PID controllers are used to stabilise a plant/system. They are heavily used in ...
4
votes
How to control a 4 wheel mechanum wheel robot with PID?
Let's consider first the task you are wanting to accomplish: following some sort of Cartesian space trajectory. So, you are wanting to make sure your robot is only moving in the x-direction. However, ...
- 884
3
votes
PID tuning for 6 dof robotic arm
I think the vibrations of the mechanical structure are due to the mechanical structures natural frequency. The dynamixel servos you mentioned are quite performant and have a acceleration and ...
- 6,652
3
votes
How Should I tie My quadcopter to some thing, to adjust pid on one axis
Since you're trying to adjust the stability, you should make sure that your method of restraint isn't restricting the motion along that axis.
So, the preferred way to restrain a quadcopter is by ...
- 11k
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