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17 votes

Why do people use camera instead of laser sensor for robot navigation?

A 3D laser range finder or LIDAR such as the one on the Google Car is far more expensive than a camera. The other reason is that while in case of a LIDAR the distance of every pixel is available, the ...
Bence Kaulics's user avatar
9 votes
Accepted

How do I determine the required encoder resolution for a control system?

First I would question your math that got you to the 12b sensor. If you have a $dy$ of 1 mm over an arm that is $r = 1$ m long, then $\sin(\theta) = dy/r \rightarrow \theta = \mbox{asin}(dy/r)$. If ...
Chuck's user avatar
  • 16k
8 votes
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Why do 3-axis accelerometers seemingly have a left-handed coordinate system?

The answer is that 3-axis accelerometers don't have a left handed coordinate system just for the gravity. In static condition (i.e. if the accelerometer is not accelerating with respect to any ...
traversaro's user avatar
8 votes
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Instantaneous velocity calculation from accelerometer?

The only way to get a velocity from an accelerometer is to numerically integrate the output of the accelerometer. That is, $$ v = v_0 + a*dT \\ $$ where $dT$ is the elapsed time between ...
Chuck's user avatar
  • 16k
6 votes
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Stabilising an inverted pendulum

There are lots of ways to solve this problem, which falls into the category of Control Engineering. There are two standard approaches: Classical Control: The control command has to be proportional ...
Paul's user avatar
  • 1,268
6 votes
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How to measure pull force on a (kite) rope?

The component you highlighted is called a tensile load cell. You could buy one from a supplier, but it probably would be cheaper to buy a cheap digital hanging scale and taking the sensor out of it - ...
Pete Kirkham's user avatar
6 votes
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What is the difference between active and passive sensors?

Let's recall that sensors are used to measure a physical quantity. The distinction between passive and active sensor characterize the sensor ability to retrieve a measurement without or with inputing ...
N. Staub's user avatar
  • 1,402
6 votes
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PID and Kalman filters

There isn't really a relationship between them, unless you're asking how the dynamics feed each other when combined into a system. If that's the case, then I would suggest maybe starting with a ...
Chuck's user avatar
  • 16k
5 votes
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Measure weight of an object using a servo

This is going to depend on the style of motor in the servo and the style of gearbox. If the servo can't be back-driven when unpowered, then it's likely some form of a worm gear assembly that will ...
Chuck's user avatar
  • 16k
5 votes

Do multiple LIDAR systems in same area interfere?

Based on two different company's sensors for use in autonomous cars - yes they do interfere. And honestly, I am not sure what is going to happen when you have 30 cars in an intersection, the noise ...
user20737's user avatar
4 votes
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Balancing a plate with an IMU offset from the center

Basically it does not matter. But you have to be carefull if the plate is rotating fast, because the rotation of the plate around its center point, with the IMU placed out of center, will cause the ...
TobiasK's user avatar
  • 1,657
4 votes

How to have a 'Auto Go Home' feature, like the DJI Phantom 3, on a project built quadcopter?

I would go with one of two-ish methods to do this, but both methods require the craft to know its own position. You could do this with GPS, or an IMU, or any other means or combination of position ...
Chuck's user avatar
  • 16k
4 votes

Why do people use camera instead of laser sensor for robot navigation?

In addition to those points in Bence's answer, cameras can: Calculate many complex features that result in very robust matching between frames, and object recognition High angular resolution (typical ...
Gouda's user avatar
  • 892
4 votes

How can I compare robot and human hands?

The only benchmark I know in development is at NIST. Their Intelligent Systems Division project page should help. On that page they discuss the specific possible metrics of grasp cycle time, grasp ...
SteveO's user avatar
  • 4,386
4 votes
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How can I compare robot and human hands?

You should check out: The Yale-CMU-Berkeley (YCB) Object and Model set. It is designed for facilitating benchmarking in robotic manipulation. The set consists of objects of daily life with different ...
Ben's user avatar
  • 5,825
4 votes
Accepted

Is it better to use software or hardware for object sorting?

It really depends on the objects you are sorting, and the flexibility you're looking for as the system is maintained over the years. Using physical methods to sort is very reliable. Many times you ...
SteveO's user avatar
  • 4,386
4 votes
Accepted

Noisy magnetometer data

First, let's look at if your findings seem reasonable given the datasheet specifications for the sensor. For this, I'll assume that Wikipedia is generally correct and that the strength of Earth's ...
Chuck's user avatar
  • 16k
4 votes
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Detection of linear acceleration vs rotational velocity/acceleration

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 ...
Adam Williams's user avatar
3 votes

Small IR distance sensor that works on black surfaces

Ultrasonic sensors have a deadband of about 2-5 cm, so wouldn't be useful for close-range sensing. Also ultrasonics work best with hard, solid surfaces. Carpet, clothing, drapes, cushions, etc. will ...
jetdillo's user avatar
3 votes

Small IR distance sensor that works on black surfaces

A surface that appears black doesn't reflect much visible light (it's the absence of visible light reaching your eye that makes it look black), if the surface also doesn't reflect IR light very well, ...
jonvw's user avatar
  • 31
3 votes

What is the easiest and efficient way to detect human in close range distance and make the robot follow it?

Following a human can be relatively easy, but it depends on your requirements and your sensors on how easy this is. If you use ROS there are some available packages: people_tracker which uses a ...
agold's user avatar
  • 260
3 votes

Where should I put the angle sensor on my cart-pole robot?

The gyroscope placement shouldn't make any difference since the rotation rate will be the same everywhere (assuming your robot is rigid enough). The accelerometer will pick up the rigid body ...
Brian Lynch's user avatar
  • 1,377
3 votes

Accelerometer calibration - how to get cross-axis sensitivities

I realize this question is 2 years old, but I have direct recent experience with this. The way I did this is with 6 rotated cube positions with 1000 points at each position, so a total of 6000 ...
Sonicsmooth's user avatar
3 votes

Stabilising an inverted pendulum

The theory that describes what you are looking for is call Control Theory. Search for the Nonlinear Systems textbook by Hassan Khalil for an excellent overview of the material--the inverted pendulum ...
JSycamore's user avatar
  • 926
3 votes

Shield IMU from magnetic interferences

Nope. Magnetometers measure the magnetic field. The field it's measuring is going to be the sum of fields from a variety of sources. The field you're interested in is the earth's. But it is not ...
holmeski's user avatar
  • 1,853
3 votes

Why do people use camera instead of laser sensor for robot navigation?

navigation in urban environments Depending on the laser, there might be legal constraints on where you can use it. Running around town throwing laser rays around might require special permission/...
Bending Unit 22's user avatar
3 votes
Accepted

Do multiple LIDAR systems in same area interfere?

One could use lasers with slightly different wave length - just as different channels for Wi-Fi signal. Also there could be used some kind of wave modulation... but I don't think LIDARs use such ...
Szczepan's user avatar
  • 450
3 votes

Is there a sensor that can measure through an object?

I am not sure you will be able to find a cheap off the shelf sensor. But if you are an RF engineer and willing to implement something yourself, you might want to read: A Multifrequency Radar System ...
Ben's user avatar
  • 5,825
3 votes
Accepted

Reading Intention for exoskeletons motion estimation

You have many options: encoders at exo joints to provide absolute angles, IMU on limbs for estimating motions, force sensing shoe soles for force distribution, force sensors at joints, crutches ...
drerD's user avatar
  • 491
3 votes

Is it better to use software or hardware for object sorting?

You would have to do both. It's very very challenging to move an object without using hardware, and it's incredibly hard to see the colour of a brick with hardware. You'd have to break it down into ...
Josh's user avatar
  • 141

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