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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.

38
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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 ...
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 ...
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 ...
16
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1answer
1k views

How does a six-axis force/torque sensor work?

I would really like a six-axis force/torque sensor for my robot, but I just can't afford one. I was thinking about making one of my own. I have experience using strain gauges, but I can't work out ...
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 ...
13
votes
2answers
311 views

How can I detect if a DC motor on a robot is starting to fail?

What characteristics can I look for which could be reliable early warning signs that a DC motor on my robot, say one used for the drive, could be failing? I'm looking for an answer that deals in terms ...
12
votes
2answers
447 views

What are methods for dealing with compass lag (rate dependent hysteresis)?

I've got a tread-driven robot, with low precision wheel encoders for tracking distance and an electronic compass for determining heading. The compass has significant (> 1 second) lag when the robot ...
12
votes
4answers
6k views

Do magnets affect IMU values?

Im in the process of making a robot which requires 12 3x10mm cylindric magnets for the construction. They are 30mm from the center of the robot where I plan to have the IMU. I was thinking about ...
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 ...
11
votes
1answer
2k views

How can the dynamic effects of motor current on a digital compass be characterized and compensated for?

Digital compasses (magnetometers) require a hard/soft iron calibration in order to be accurate. This compensates for the magnetic disturbances caused by nearby metal objects -- the robot's chassis. (...
10
votes
2answers
1k views

Sonar for obstacle avoidance: how many sensors and where to place them?

For avoiding obstacles during 2D robot navigation what is the best position/angle to place the sonar sensors? How many should there be? I would like to know if there is some theory or examples for ...
10
votes
2answers
175 views

How to model the noise in a range sensor's return?

Range sensors (for example sonar, infrared, and lidar) are notoriously noisy. How can I characterize the noise characteristics to include these in a probabilistic localization sensor model?
10
votes
3answers
153 views

Selecting an accelerometer for Deduced Reckoning

I have never used an accelerometer before, but I am aware that they come with I2C, SPI and analog outputs. If I choose to use an I2c or SPI, device, will I accumulate errors due to communication time? ...
9
votes
2answers
183 views

Robotics Location Following and Tracking?

I am building a robot that will follow a target as the target moves around. I would like some help with the setup for tracking the target. The most obvious solutions are Ultrasound or Infrared sensors,...
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 ...
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 ...
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 ...
8
votes
1answer
239 views

innovation step ekf localization?

Let's say we have a bunch of observations $z^{i}$ from sensor and we have a map in which we can get the predicted measurements $\hat{z}^{i}$ for landmarks. In EKF localization in correction step, ...
8
votes
2answers
602 views

How can I build a 10cm-200cm IR range sensor?

Everybody here is probably aware of the Sharp distance sensors (GP2Y0 series, e.g. GP2Y0A02YK0F). They use a diode to emit infrared light and measure the angle of the reflected light with a PSD (i.e. ...
7
votes
5answers
3k views

Polling or Timer interrupt?

We hope to build a simple line follower robot and we got a problem when we were discussing about PIC programming. We planed to write a endless loop, check the sensor panel reading and do the relevant ...
7
votes
7answers
5k views

What are some low cost alternatives for lidar? [closed]

It need not be as effective as lidar or it may have some disadvantages when compared with lidar. What are the probable alternatives? Edit: I'm intending to use it outdoors for navigation of ...
7
votes
2answers
5k views

How to get prevent twisting of cables

I am planning to create a motor turret described in this question. But to simplify the problem, I'm thinking of a wind turbine with a generator in the main head that can rotate freely through 360 ...
7
votes
4answers
3k views

Robot docking for self-recharging

I want to build a simple obstacle avoider robot, but this time I want it to be self-recharging so I am building a dock for this purpose, so I want it to be able to locate the dock and go for it when ...
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 ...
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 ...
6
votes
4answers
266 views

How to find out how far a motor has taken a vehicle?

I have a small motorized vehicle with gears as wheels running up and down a track made of gear racks. How can this robot know when it has run half the track? And what's the best method to keep it from ...
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 (...
6
votes
6answers
974 views

How to measure displacement, cheaply and without using an accelerometer?

Motion is known to be confined in a sphere with radius of about 0.5m, and resolution doesn't have to be very high (5cm is enough). The device will actually be incorporated in a toy designed for kids. ...
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 ...
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 ...
6
votes
1answer
659 views

Electronic noses for detecting dog urine

I have very limited experience with sensors or robotic components at all, and I hope you will excuse the lack of detail in this Question. I want to set up posts around my yard with electronic noses ...
6
votes
1answer
264 views

Using Armatures in Morse Robotic Simulator

I'm trying to add my own robot in Morse 1.1 (using Ubuntu 12.04). I am struggling to add an armature actuator and armature pose sensor to an existing robot. Can someone please explain how this can be ...
5
votes
6answers
339 views

Spatial tracking between two UAVs

I have two Unmanned Aerial Vehicles (planes) which work well. They can fly to various waypoints automatically using GPS. Now I would like them to fly together in formation. I would like them to fly ...
5
votes
3answers
442 views

Are there surface texture sensors for integration in circuits?

I have a project in mind for a robot which is able to recognize surfaces, and thought about including the following sensors: a temperature sensor a colour sensor, or a complex of electronic ...
5
votes
4answers
11k views

Stabilizing a quadcopter with optical flow

My quad copter can balance itself in the air using data collected from mpu6050. With the sonar sensor, it can hover at a specific height, but it moves on the horizontal plane in a random direction. ...
5
votes
2answers
126 views

How can I compare robot and human hands?

I want a comparison between human hands and robot hands, with respect to grasping and squeezing objects. How can I perform such a comparison, using sensors, as one would with a benchmarking database?...
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 ...
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 ...
5
votes
4answers
1k views

Does an electronic compass work underwater

I'm building a submersible ROV, so I need a way to navigate. So using a compass would help but this brings up the question, does an electronic compass work underwater? My thoughts are the water might ...
5
votes
4answers
145 views

Why linkage-based haptic devices are much more common than cable (tension)-based ones?

According not only to this link, but in my humble opinion to common sense as well, cable-based haptic devices have got lower inertia and are less complicated mechanically. I also believe that ...
5
votes
1answer
241 views

Transducer for underwater applications (passive sonar)

I'm kicking around the idea of building a small passive sonar for an autonomous submarine. I've looked through the net for parts and finding a good transducer for converting the sound underwater into ...
5
votes
1answer
1k views

Simple Sensor Fusion for pose estimation

I am currently working on a balancing robot project, which features fairly low-cost sensors such as an 9-Dof IMU with the measurement states $\textbf{x}_\text{IMU} = \left[a_x, a_y, a_z, g_x, g_y, ...
5
votes
1answer
700 views

Yaw angle calculation for drone PID from two distance sensors

I'm building a control system with a Parrot AR 2.0 drone where I have access to thrust controls for up/down (z), left/right (y), forward/backwards (x), turn left and turn right (yaw) through a Ruby ...
5
votes
1answer
267 views

Can ultrasonic and button sensors be run in a VEX analog port?

I'm running out of digital ports, and have no sensors that fit the definition 'analog'. Would it be possible to run a touch sensor, a quadrature encoder, or an ultrasonic sensor on an analog port? I'...
5
votes
1answer
10k views

Send Arduino sensor data to server with GPRS shield

I'm trying to send Arduino sensor data to a server using a GPRS shield (SIM900 shield from Geeetech). I have this particular set up because the data will be updated to a website and the device will be ...
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 ...
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: ...
4
votes
1answer
170 views

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

I'm designing a joint which will have to move with a velocity of ~60RPM and I have to come up with resolution requirement for the encoders within this joint. I notice however that this is easier said ...
4
votes
2answers
230 views

How to measure pull force on a (kite) rope?

I'm building a kite flying robot, in which I've already got some sensors built in. I now also want to measure the pulling force on the rope which is attached to the kite. So I thought of attaching a ...
4
votes
2answers
1k views

A sensor that can see glass/transparent objects and surfaces

I am currently thinking about making a robot that will autonomously drive around the place. The place I want this robot to drive in however contains quite a few glass walls. When mapping the area I ...