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Questions tagged [sensors]

A sensor (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument.

23
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9answers
12k views

Absolute positioning without GPS

Using an IMU a robot can estimate its current position relative to its starting position, but this incurs error over time. GPS is especially useful for providing position information not biased by ...
38
votes
4answers
21k views

What is the difference between Kinect for Windows and Kinect for XBox?

As I see there is a huge price gap between the two \$223 vs \$99 (at amazon). My intention is to use one of those from Ubuntu linux to perform depth sensing, navigation etc. and naturally I prefer ...
15
votes
6answers
28k views

What is the cheapest / easiest way of detecting a person?

I'd like to know if anyone has had success detecting a warm-bodied mammal (ie. Human) using standard off the shelf, inexpensive sensors? Ideally, I'd like to use an inexpensive sensor or ...
8
votes
4answers
1k views

Why do 3-axis accelerometers seemingly have a left-handed coordinate system?

Careful inspection of page 35 (figure 58) of the ADXL345 datasheet shows that under gravitational loading only, the chip uses a left-handed coordinate system. My own experiments with this chip ...
24
votes
2answers
22k views

How to fuse linear and angular data from sensors

My team and I are setting up an outdoor robot that has encoders, a commercial-grade IMU, and GPS sensor. The robot has a basic tank drive, so the encoders sufficiently supply ticks from the left and ...
6
votes
3answers
3k views

What main factors/features explain the high price of most industrial computer vision hardware?

I am a student who is currently working on a computer science project that will require soon computer vision and more specifically stereoscopy (for close depth detection). I am now looking for a great ...
8
votes
1answer
824 views

Multiple position estimates fusion

I have a system in which I have two separate subsystems for estimating robot positions. First subsystem is composed of 3 cameras which are used for detecting markers the robot is carrying and which ...
6
votes
4answers
734 views

How to localise a underwater robot?

I am building an autonomous underwater robot. It will be used in swimming pools. It should be capable of running in any normal sized pool, not just the pool in which I test. So I cannot rely on a ...
1
vote
2answers
747 views

Finding the position of a servo

I am building a collision avoidance system for my robot. As a part of this system I am using a pan and tilt kit (http://www.robotshop.com/en/lynxmotion-pan-and-tilt-kit-aluminium2.html) My aim is ...
1
vote
3answers
3k views

Detecting the presence of a person in a room

I am working on my first hobby project and I'm not very familiar with sensors yet. I am trying to build a system which detects the presence of a person in a small room with a single entrance/exit door....
6
votes
2answers
6k views

Questions regarding 3D scanning and camera choice [closed]

A few days ago, I just shared my concerns about the price of computer vision hardware on this same exact forum (see What main factors/features explain the high price of most industrial computer vision ...
5
votes
2answers
1k views

Accelerometer calibration - how to get cross-axis sensitivities

I've already asked a related question (accelerometer bias removal) here on robotics and got a bit better results on corrected accelerometer output. To get even better results I found the calibration ...
4
votes
3answers
29k views

How to estimate yaw angle from tri-axis accelerometer and gyroscope

I would like to estimate the yaw angle from accelerometer and gyroscope data. For roll and pitch estimate I've used the following trigonometric equations: ...
3
votes
2answers
257 views

Can high voltage power lines provide a super highway for drones?

Is there a way to convert the EM field that surrounds high voltage power lines for direct usable electricity for air or ground drones for continuous flight or travel? Added: Yes could the EM field be ...
7
votes
1answer
3k views

Angle Random Walk vs. Rate Noise Density (MPU6050)

I’ve made a datalog from a MPU6050 (IMU: gyroscope and accelerometer) at 500Hz sample rate. Now I want to calculate the characteristics from the gyro to evaluate the sensor. For the gyro I’ve found ...
5
votes
1answer
5k views

How do ultrasonic range finders detect objects at an angle?

As far as I can tell, an ultrasonic rangefinder works by reflecting inaudible soundwaves off of objects and timing their return. But if the object has a flat surface and is angled with respect to the ...
3
votes
3answers
4k views

Stream Real-time Video with Environmental Data Overlaid

I want to embed environmental data collected from sensors into a live video stream from a camera. Has anyone done this or know how I would go about doing something like this? Is there a library ...
8
votes
4answers
372 views

What kind of sensor do i need for knowing that something is placed at a position?

I have a small device that's picking up small rocks from a pile and moving them to another place. Its a kind of crude way of trying to push the whole pile onto a bigger gear and hoping one of them are ...
6
votes
3answers
10k views

Stereo camera Vs Kinect

Any one can advice me on the ideal perception sensors for pick and place application using a robotic manipulator with ROS support. I have generally looked at things like Kinect and stereo cameras (...
5
votes
0answers
348 views

How does one implement a third order complementary filter for estimating altitude using data from an accelerometer and a barometer?

I am working with the CJMCU build of cleanflight on a small drone. As of now, the algorithm for altitude hold uses a first order complementary filter to combine data from the barometer and the ...
3
votes
1answer
79 views

What different sensing approaches are used in the current batch of indoor 3D cameras?

I'm aware of the PrimeSense camera powering the Kinect. Are more advanced sensor types available now in the < $500 range? For example, has there been any sort of game-changer in structured light ...
2
votes
5answers
821 views

Shield IMU from magnetic interferences

I experienced some drifting when coming near to magnetic fields with my IMU, so I wondered if it is possible to completely shield the IMU from external influences. Would this be theoretically possible ...
0
votes
2answers
62 views

Matrix is singular error in GraphSLAM

I have gone through The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. I implemented the code for GraphSLAM. The fundamental formula of GraphSLAM is $$\mu = \Omega^...
11
votes
3answers
6k views

How can I detect the edge of a table?

I'm new to robot making and just got my first arduino to play around. I want to make a robot that will wander on a table, and it will last longer I think if I could make it avoid falling from the ...
4
votes
2answers
426 views

What is an effective distribution of grayscale sensors on robot

I'm working on a robotics project, and I am using grayscale sensors to automatically follow a black line: turning 90 degrees, going round in a circle, and passing through gaps in the lines etc. I was ...
3
votes
1answer
359 views

What approaches should I consider to create rotating a turret

First a bit of background, I am planning to make a highly maneuverable airship controlled by four thrust vectored propellers. I don't want to rely on a rudder and forward momentum for turns but ...
2
votes
2answers
388 views

How to implement a distance proximity sensor with wider range

More in the line of robotics observing their environment, I'm trying to implement a proximity sensor that can sense objects in front of it to a least up to $-30^ \circ \space$ to $\space+30^ \circ $ ...
2
votes
2answers
933 views

Can I make an automatically-parking robot car with IR sensor?

It would be easy to understand if you imagine a robotic vacuum cleaner. (For some models) It goes back to a specific place automatically to recharge. Like this, I want to make a robot which ...
1
vote
2answers
2k views

Is it possible for a robot to navigate through predefined coordinates?

I am a total newbie in robotics so please bare with me. I have a school project where my team has to design a robot that is capable of picking up 3 golf balls in different sizes at predefined ...
0
votes
0answers
47 views

Actual dimension of Omega in Graph Slam

I have a doubt about GraphSlam Algorithm introduce in this paper. I add a picture to express my doubts (from page 411, 9th in paper): As per my knowledge $\Omega$ is the information matrix. So in ...