5

A kinect mounted on your robot is enough for mapping and localization. There are a few different packages that will work: rgbdslam can create a 3d map using a kinect You can use depthimage_to_laserscan to take in a depth image from the kinect and output a laser scan message which you can then use with gmapping for mapping, and the nav stack to navigate your ...


4

You said, "on some occasions the sensor will read values consistently (at maybe 20 vals per second)". 20 values per second is 20Hz. This means that you are polling every 50ms. In the datasheet linked in the other response, it says, "we suggest to use over 60ms measurement cycle, in order to prevent trigger signal to the echo signal" In the operation ...


3

If you are interested in learning ROS but do not have sophisticated hardware available, you can use the Gazebo simulator to simulate a robot and use ROS with that. Keep in mind that ROS is not the only way to write software for robots, and also not necessarily the best way.


3

I'm pretty sure that a very basic IR proximity sensor would do the trick. Glass is opaque to all but visible light. IR (as well as UV) will not penetrate the glass and you ought to be getting reliable distance measurements to the glass's surface.


3

Honestly, I don't think you should use the cameras just because you have them. The ultrasonic sensor is a way simpler and more effective solution. There are ways to tell depth with one camera, but they are far from effective in most cases. If you want to try it, I would say play around it when you don't have a deadline if you're interested in the learning ...


3

Your question is multiple questions inside of one. As answered in comments, your question should probably be limited to the sensor and/or technology for longer range detection of large (moving?) objects. The use of an arduino is mostly irrelevant. As per comment by @Ian, ultrasonic sensors will probably not be useful at 50 meters, I think due to physics of ...


3

Sensors with two elements have separate transducers acting as the transmitter and the receiver. A sensor with a single element uses the same transducer as a transceiver to create the sound pulse and to listen for the echo. These sensors need time to switch from one mode to the other (Tx or Rx). This means that the minimum sensing distance is likely to be ...


2

The accuracy of fiducial markers (i.e. glyphs) depends on your camera's resolution, noise ratio, focus, and field of view. Essentially, you will need to ensure that there are enough pixels in the recorded image to represent the real-world precision that you want. To make this easier, it would help if the glyphs are as large as possible and the camera is ...


2

A single transducer sensor has to both send out the sound and then sense the return sound. It takes time for the vibration to stop after making the sound and that is time it can't sense a return. So close distances can't be sensed by a single transducer sensor.


2

Well.. It was a power issue! I'm using one of the arduino replicas and the 5v pins is only outputting 4.5v instead of 5. The problem was solved by providing an external power source. I don't find it cool to power robots externally but this is the only way in my case.


2

It'll involve a bit of reading, but Johann Borenstein's papers include several 1980s-90s publications about ultrasonics (plus loads of other interesting stuff). Some pure ultrasonic systems, some mixed with other navigation techniques. One interesting effect I read about was reflections. If the "beam" hits a wall at an oblique angle, then instead of ...


2

From my experience, don't use them for obstacle detection on high speed robots. Your'e just as good as without using them.


2

Unless you need very good resolution or a very tight detection pattern, I would go with an ultrasonic sensor. They can be very cheap and easily meet your detection range specs, for the very low end look at something like the HC-SR04, and for more serious applications Maxbotix offers a wide range of sensors.


2

There are two issues in the question: noise (interference) among the three sensors how to handle the motion with relation to the sensor readings The noise between sensors is most probably a hardware issue (cabling or EMI) or it might be related to the sensors being close to each other. Without more info about the current implementation, this is all I can ...


2

Sonar, as used in robotics means having an ultrasonic emitter and and ultrasonic receiver. There are also some sonar with a single emitter/receiver. However, they all use ultrasonic sound ways in order to sense the distance to an object. Well, actually they really sense the time between the emission of the ultrasonic wave and the reception of it, which is ...


1

Yes, there are IR sensors as well, which provide ranges up to 3-4 meters Pololu Range Finder. Also, we can find Laser range finders that measure up to 30m distance. But these Laser range finders are expensive in compared to ultrasonic sensors and mostly used for mapping purposes.


1

Cheap ultrasonic sensors will give you a signal when the first echo (from the closest object) is received. Hence, you'll get a reading of 'X' for object B, and probably nothing for the object A, no matter if it's moving or not. Which makes sense, because if you keep moving in the current direction, object B is the one you should be most concerned about.


1

Because you have not specified any particular Infrared nor ultrasonic device only generic responses possible. Infrared range finder devices which triangulate normally project a small focused light on the target. The receiver likely is only looking for the refection in a defined area. So interference from reflection of other infrared signals should be ...


1

Robots usually locate themselves on a field using sensors. None of the sensors are perfect as they each have their own limitations; hence, the more sensors the better. Here are some sensor options: Motor Encoders on the wheels to track the distance and turns IMU/Gyro to track acceleration and calculate speed and position Magnetometer to correct bearings ...


1

Checking for three is a subset of checking for many; so, I am going to consider the more general solution. I will discuss the three point solution at the end. First, convert the polar coordinates to Cartesian Coordinates. First, to make things simple, use your robot as the reference frame (make it the center of the universe). That means, for each target ...


1

My solution disadvantages/limitations are: Needs computation/processing power Robots should move slowly Robots scan environment quickly as possible as you can Here are the steps: Create a radar like system with a servo and two ultrasonic distance sensor or use 360 deg. servo and a ultrasonic. (http://www.instructables.com/id/Arduino-HC-SR04-Ultrasonic-...


1

ROS generally requires a full x86 or x64 computer, such as an Intel NUC. This can then communicate to things like arduino, but the brains of the computer is in the NUC. As such, ROS is intended for large projects, and may be unsuitable for a hobby project. If this is to be your first adventures into robotics, stick with arduino for now. When you want to ...


1

You said it yourself: you're using an echo-based ultrasonic sensor. Imagine this: you are a sensor looking at a piece of fiber optic cable. From far enough away, you see the cable as an object. You can determine how far away it is because you are looking at it. The cable gets closer and you continue looking at the object until, at some point, it becomes ...


1

I think the code is just fine. You must however test the code by placing ultrasonic sensor at fixed distance from the wall and testing the distance. Also, it seems you are using SR04 ultrasonic sensor which has a beam angle of 15 degrees and accuracy of 3mm. This might result beam being reflected from water column container. As mentioned in the datasheet ...


1

Ultrasonic sensors work by emitting a set of pulses and reading the return signal (here is a better overview), this causes problems when you have more than one as they cannot distinguish between their own sensor and the other. I would suggest putting a 500ms delay after each reading to avoid as much interference as possible while you keep the same read rate.


1

According to the datasheet the sensors automatically sends and receives the pulses, you would need to independently control the speakers and microphones I am not aware of any ultrasonic sensors that give you that fine control, you would need to purchase separate ultrasonic transmitters and receivers, and construct the appropriate filtering and amplification ...


1

Having an overhead camera (like a single low cost webcam if needed). Ultrasonics is meant to be directional while cameras are not meant to be. The downward facing camera placed at a height and horizontally centered over the area can detect robot and obstacles in Cartesian coordinates and that information can be transferred to the moving robot using Bluetooth ...


1

I think that the strange behaviour that you are experiencing comes from lost echoes. The HC-SR04 is at it's best performance with obstacles of 0.5 square meters (you can check this in the data sheet). With smaller obstacles some of the echoes at random wont be detected. The sensor waits for echoes to return up to about 182 mS no matter how fast you trigger ...


1

If you are going to be operating on strictly flat surfaces, single camera optical flow can be used, although it's not an optimal solution. By knowing the camera intrinsics and extrinsics, you can predict expected optical flow for features that lay on the ground, and any grouping of flow vectors that violate that potentially indicate obstacles that rise above ...


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