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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 ...
9 votes
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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 ...
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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 ...
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 ...
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7 votes

Plastic that's transparent to IR range sensors

FWIW, I once needed to create a plexiglass window/shell for a near-IR camera. Most CCD and CMOS sensors are sensitive in the near IR range (e.g. around 850nm), which is where @user3095849 suggested ...
7 votes
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How to localise a underwater robot?

Localization under water was always a problem in ocean robotics as electromagnetic signals do not propagate very well in water. I think your best localization sensor in that case would be the good old ...
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6 votes

Plastic that's transparent to IR range sensors

First you need to know the wavelength of the sensor. According to the sharp sensors datasheet for GP2Y0A21YK, the cover should efficiently transmit light throughout the wavelength range of the LED(λ = ...
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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 ...
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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 ...
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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 ...
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5 votes
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Does an electronic compass work underwater

A compass will work just fine under water, I am an avid scuba diver and a compass is a standard piece of kit for navigating.
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5 votes
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Questions regarding 3D scanning and camera choice

My favorite is the Learning OpenCV book. It has a fantastic stereo / 3D section that introduces concepts from the ground up. If you're at a university, you might be able to find the digital version ...
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5 votes
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Cheap and efficient 3D sensor?

Honestly it depends what you want, I will cover some options from cheapest to most expensive Ultrasonic sensor on a servo 5-50$ depending on the model. It can be fairly accurate with around 1cm ...
  • 1,909
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 ...
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4 votes

Absolute positioning without GPS

I know this is an old question but I will just add a bit to the currently existing answers. First, this is a very complex problem that everyone is trying to tackle, including google with their Tango ...
4 votes
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Stereo camera Vs Kinect

The Kinect is certainly a popular choice these days for robotics. However, time-of-flight, structured light, and stereo cameras all have their own strengths and weaknesses. These two threads have a ...
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4 votes

How to localise a underwater robot?

If it's actually underwater, how about a webcam looking at the tile pattern on the floor? (Could be considered "cheating" as it will obviously fail in a natural lake, for example.) You can find a ...
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4 votes

How to localise a underwater robot?

One of the prime sensors for global localisation on land is GPS. This is not an option underwater because electromagnetic waves get absorbed quickly. There are however alternatives, which provide ...
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4 votes
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Sensors' field of view in car driving

How fast are you driving the car and are you allowing slip during turning? From this powerpoint, the turning radius is given by: $$ R = \frac{L}{\delta} $$ where $R$ is the turning radius, $L$ is ...
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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 ...
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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 ...
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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 ...
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4 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 ...
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 ...
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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 ...
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4 votes
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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 ...
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4 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 - ...
4 votes
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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 ...
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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 ...
3 votes

Simple yet effective angular position sensor to be used in robotic hand

Another popular rotary sensor is the ratiometric Hall effect sensor. Use a device like the A1324. It's a 3-pin device which gives an analog voltage proportional to the magnetic field strength. For a ...
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