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# Tag Info

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 ...
• 4,445
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 ...
• 4,005

• 904
Accepted

### 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 ...
Accepted

### 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 ...
• 941

### 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 ...
• 1,853

### 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 ...
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 ...
• 25.3k
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 ...
• 1,577
1 vote

### What frequency does my quadcopter output-sense-calculate-output update loop need to stay stable?

Your question can only be answered specifically if we have the model parameters of your system. The most principled approach to answering your question would be to represent the highly nonlinear ...
• 926
1 vote
Accepted

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 ...
• 4,005
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, ...
• 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 ...
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 ...
• 111
1 vote

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 ...
• 1,411
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 ...
• 562
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 ...
• 531
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 ...
• 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 ...
• 336

Only top scored, non community-wiki answers of a minimum length are eligible