5 votes
Accepted

Why is it so hard to walk?

I'm not sure I agree that bipedal walking is so much harder that airplane control. It depends on how you look at it. Many robots can walk (bipedal walking) and many airplanes are difficult to control ...
hauptmech's user avatar
  • 4,425
5 votes
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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 ...
Ugo Pattacini's user avatar
5 votes

For what step disturbance value the system will become unstable?

The stability is a property of the linear systems themselves, hence there is no meaning in considering stability as regarded with the input disturbance $T_d$. To verify if the closed-loop system $C/...
Ugo Pattacini's user avatar
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 ...
Bending Unit 22's user avatar
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 ...
galtor's user avatar
  • 470
3 votes

Can we show converenge for a variant of inverse dynamics controller?

This would be too long for a comment, so I will add some work as an answer: The proof of $A(\mathbf{q})$ being invertible is not perfect. First, add some structure to the $K_p$ and $K_d$ matrices. ...
domo_arigato's user avatar
3 votes
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Can we show converenge for a variant of inverse dynamics controller?

This answer is inspired by Ryszard Szwarc's answer in: https://math.stackexchange.com/questions/4509062/how-to-show-that-the-matrix-0-i-m-1k-p-m-1k-d-has-eigenvalues. The dynamics of the system is in ...
QualsPassed's user avatar
3 votes

Helicopter Stabilization Algorithm

Stabilization of a helicopter and a quadrotor are similar tasks - have a reference signal, compare that to feedback, then act on the difference. A quad rotor has four motors, and the helicopter ...
Chuck's user avatar
  • 16.1k
3 votes

How to use quaternions to feed a PID quadcopter stabilization loop?

This paper, Full Quaternion Based Attitude Control for a Quadrotor by Emil Fresk and George Nikolakopoulos, demonstrates what you are trying to achieve. Abstract— The aim of this article is to ...
jgkim2020's user avatar
2 votes
Accepted

Quadcopter PID Control: Is it possible to stabilize a quadcopter considering only angle measurements?

It is possible to stabilize a quadcopter using only angle measurements in a single loop pid. However it is easier to stabilize a quadcopter using a cascaded PID controller. Yes you are tuning more ...
user123456098's user avatar
2 votes

Humanoid balancing

They are two main approachs for humanoid robot walking. Practically it depends on the physical capabilities of your robot and what you want to achieve. If your robot is able to sustain strong impact ...
Olivier Stasse's user avatar
2 votes
Accepted

Quadcopter PID Tuning for Altitude Hold/Position Hold along Z axis

Currently I am performing my research on that, and in my case I decided to tune all the PIDs. Angles of the quadrotor tend to zero, while altitude controller tend to the objective height. That's ...
galtor's user avatar
  • 470
2 votes
Accepted

Quadcopter PID: Controller is Saturating

I feel like I make the same comments every time you ask a question about your controller: How are you tuning the gains? I think your slack line is interfering with your results. Your quadcopter is ...
Chuck's user avatar
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2 votes
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PID Gains: Drop in control loop rate, need to retune?

All three constants should be able to stay the same assuming that you calculate the derivative and integral using the actual time step size. The only effect of a lower sampling rate should be a ...
fibonatic's user avatar
  • 941
2 votes

Using Quaternions to feed a quadcopter PID stabilizing controller to avoid Gimbal lock

you should not be seeing a singularity. For the standard roll, pitch, and yaw Euler angles, which are defined by a 3-2-1 rotation from level to the vehicle attitude, there is only a singularity at ...
holmeski's user avatar
  • 1,853
2 votes
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Fixed Wing UAV: Do inherently unstable systems desire to be stable for all cases when a closed loop control is implemented on them?

I'm going to ignore your section on aircraft and attempt to answer the (vague) question, Do inherently unstable systems desire to be stable for all cases when a closed loop control is implemented ...
Chuck's user avatar
  • 16.1k
1 vote

Can we apply LQR control in high dimension - like to a full robot?

Please only ask one question at a time and make sure it's answerable. We prefer practical, answerable questions, so questions which ask for a subjective recommendation on a method (for how to build ...
Tully's user avatar
  • 25k
1 vote
Accepted

Stabilising 3d cameras for mapping outdoors - mechanical or programmatic

That's a very tricky problem for vision-based SLAM systems. But if you are using the depth camera just for depth sensing and perception, I guess that might be ignorable under the condition that the ...
Chanoh Park's user avatar
  • 1,567
1 vote
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Cascaded PID controller implementation

Instead of using multi-core programming, you could employ multi-threading on the one hand, where basically you assign the two loops to two different concurrent tasks. The scheduling of the tasks is ...
Ugo Pattacini's user avatar
1 vote

How to keep a sensor pointed downward

Your LIDAR will need some active stabilization. Under gravity alone it will sway like a pendulum. You could start with a web search for "servo gimbal". Resulting hits show complete devices, ...
r-bryan's user avatar
  • 1,271
1 vote

For a quadcopter do i need to place the gyroscope sensor at the center of mass?

Most quadcopters position the flight controller/sensors at the center with the battery slightly above or below but still on the center. If you are planning on building a race quad that will not use ...
Syntactic Garbage's user avatar
1 vote

Inverted pendulum controller

I think the simple answer is that the cart-pole dynamics (linearized) are second-order (i.e. the moving parts have mass and thus inertia). In fact, it's also a non-minimum-phase system (has a zero in ...
Bill's user avatar
  • 111
1 vote

stable altitude quadcopter

Typically quadrotor have a nested control approach. That means one P(I)D loop controls the orientation (using IMU readings) and another one the position (using position sensors, e.g. ultrasound for ...
N. Staub's user avatar
  • 1,412
1 vote
Accepted

Comparison of Balance Bot design

The "Balance Bot" robot you describe is widely known as the "inverted pendulum on a cart". For static balancing (keeping the body upright), it is generally desired to have as much as possible time to ...
JJM Driessen's user avatar
1 vote

Why is it so hard to walk?

A bipedal robot is essentially unstable - a little knock will cause it to fall over. A commercial aircraft is essentially stable - a little gust of wind might move it off course, but it will keep ...
Pete Kirkham's user avatar
1 vote

Locking the yaw direction of a laser pointer

My guess would be it is going to be fine if you make sure that the stepper reacts fast enough. Hand motions are naturally jerk (and acceleration) limited, so your reaction will also be -- unless you ...
cube's user avatar
  • 729
1 vote
Accepted

Quadcopter: X-Y Velocity PID Controller

Your setup as is will certainly not work. Roll and Pitch do not map to X and Y one-to-one. You will need to use linear algebra to convert demanded XY (see this stack overflow question on how) into ...
FrisbeeGirl's user avatar
1 vote
Accepted

Quadcopter refuses to fly when the Yaw PID component is added

disclaimer: This is more of a longer comment than an answer. I'm not sure what the problem is. There is a lot going on here (thankfully a lot of information is provided, too) and my attention shifted ...
Bending Unit 22's user avatar
1 vote

PID Control: Integral error does not converge to zero

When I look at your graphs of position error and integral error, I don't see any unexpected behaviors for a system which is not quite tuned well enough. You are not showing integral windup nor ...
SteveO's user avatar
  • 4,386

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