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Need help with a following robot

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Hi I need to help my brother with this robot he gots to build for school.
He brought it to the last minute and now we have 5 days before the robot is due.

He wants to have an IR sensor that follows you when you flip a switch.
the motors we are using is 12vdc geared motors at 1.5 amps.
We are using a PIC 16F84A microcontroller and we are using a dual h-bridge Ic which is the L298.

We want it to follow the person
Any suggestions?
 
i dont know if this would work or not but you could use a proximity detector like the sharp GP2DXX. then program the PIC so that when the distance between you and the robot increases above a predefined value move the robot in the forward direction.

usually proximity detectors sense their distance from a stationary object. but a human would be a moving object. so you might have to use a different approach.

another way of doing this is that you carry a low range transmitter in your pocket that is constantly transmitting at a specific frequency. mount a reciever on the bot and monitor the power level of the recieved signal. and the moment the power level drops below a certain level, move the robot in the forward direction.
 
one of the possibilitys is using 2 sonars angeled to the persons back. then it mesures the distance and moves towards it. and when one sences the distance far more longer, than the ortherones(one "bean" misses the berson) then the robot turns to the person again... i dont know if you could do it, but in theory it works...
 
that could also be tried.

the biggest problem that im seeing in making such a thing work is that there is a gap between the legs of a human. and when one walks amount of the gap changes. for a proximity sensor, be it based on IR or sonars, work by measuring their distance from a constant surface area. but this could be solved by actually making such a sensor and then doing lots and lots of calibration.

good luck
 
i thought that those sonars should be amed at the persons back. so no caps betwean the legs. But if this is too much then the person in front could also wear a cape ;) . but yes this is all about experimenting...
 
I would think it would be too easy to loose the person/object it is following with IR or sonar. If someone walked between you and the robot, it would be lost and might follow the other person. Saw a video once of a robot that followed a red ball using a camera. It lost the red ball and started following a little kid in a red shirt. haha
I think the transmitter would work the best because it would use trial and error to find the signal. Move forward. Is signal stronger? No, turn left. Move forward. Is signal stronger? Yes, keep moving. etc...
 
yes but if the signal is weaker and the robot think ok now i turn left BUT the person turned right then trhe robot will go loony and then start spinning around... it then also needds two recievers, but this RF starts to depend on humidity and find and other factors so it's not so good... the producers also say in dataheets not to use those transmitters\recievers on such ocasions cause the result is not accurate.
 
A whiled back ago RoboticInfo helped me out on this, he said for this type of project it would be best to go with a Cmu cam which was a great idea and simple but expensive and he said that IR and ultrasonic would be more difficult. I really don't care if someone walks in front of me it is just to follow.
 
I suggest using a camera <<< this is the best way to track a person but it is away so advanced >> Just use a camera, webcam, connected to the laptop. and work on the code.

Using sonar sensor is possible, but alittle bit tricky...since sonar can take sonar pictures of the object. Most sonars detect with a range of 23 degress...you can use their pictures to detect the object. <<Also this is a lot of work>>

Infra-Red proximity sensor can work also but you have to use at least 8 sensors. The idea is simple, put all these sensors in a way that covers the entire robot. Corners, back, front, left and right. once the object gets detected in one sensor it will move to the direction of that sensor. however, the only problem with the IR sensor is its range.
 
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Actually you are wrong the IR sensors go over 59'' and that is enough to track a person. Also you do not need to use 8 sensors where did you get that from. All you need is 3 no more.

All he said he wanted it todo was follow?

A cmu cam would be the easiest but it is the most expensive
but is simple and does what he wants.
 
Roboticsinfo,

Ok, let me explain these things again. It is better to use 8 IR sensor to cover the entire robot. The reason is that the robot will move to any direction the sensor detects this, and the object must be inside the range. The reason for using 8 sensors is BECAUSE Infra Red is a light, photon, and it follows the optics. In other words, they detect a single point where the photon gets hit and it gets bounced back to the IR receiver. So, you have multiple points but to cover the corners u must use another points for that. <<That's why I suggest 8>>

The range of the most IR sensors cannot exceed 59" . This is the maximum. Where did u get the information? over 59"? Unless you invented your own IR sensor this will be possible. The most popular IR sensor is Sharp GDs series https://www.acroname.com/robotics/parts/sharp_guide.pdf

The sonar is better because the wave gets scattered from the source so it provides 23 degrees of sonar vision. Yes, you can take sonar pictures using this information.


The CMUCam is the easiest if and only if the person wears one single color that is unique to the environment. Otherwise, you will need to use your own code and reprogram the CMUCam microprocessor. Simply, to detect a person without color detection, you have to use two different techniques in computer vision; Template comparison, where you have a close shape to that person and you compare it to the picture, and Edge detection ,where you differentiate the edges of that person. << That’s why I said it is away so advanced, you need at least to use a lot of algorithms and you must have a solid knowledge in computer programming>> Also, I want to add one more thing about color tracking of the Cmucam alone is useless because not all the objects around looks exactly in the same color. There is always color intensity around us. To solve this, you must use a halogen flash light , like the one in your camera. All the colors will look exactly the same.
 
Make four transmitters and receivers. Each run on a different frequency. Have them all produce different codes. Why 4? 1 for each direction. If you only have 1 transmitter and receiver, then you will only turn motors on in one direction!!! which means it cannot follow you around in circles :idea:

Then with the receivers, add a VU meter to it so you can detect the output digitally. Now you can use your microcontroller to decode each code. and, to determine which transmitter is the weakest, drive the signal through some logic gates. very weak signals do not work well with logic gates.

now wear a belt, and place one transmitter in front of you, behind you, and on your sides. Turn all transmitters on, and you should be ok.

I don't know if this works 100%, but it is worth a try.
 
MrMikey83 said:
the transmitter would work the best because it would use trial and error to find the signal. Move forward. Is signal stronger? No, turn left. Move forward. Is signal stronger? Yes, keep moving. etc...

THis guy has a better idea. Take his advice.
 
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nalrawahi said:
Roboticsinfo,

Ok, let me explain these things again. It is better to use 8 IR sensor to cover the entire robot. The reason is that the robot will move to any direction the sensor detects this, and the object must be inside the range. The reason for using 8 sensors is BECAUSE Infra Red is a light, photon, and it follows the optics. In other words, they detect a single point where the photon gets hit and it gets bounced back to the IR receiver. So, you have multiple points but to cover the corners u must use another points for that. <<That's why I suggest 8>>

The range of the most IR sensors cannot exceed 59" . This is the maximum. Where did u get the information? over 59"? Unless you invented your own IR sensor this will be possible. The most popular IR sensor is Sharp GDs series https://www.acroname.com/robotics/parts/sharp_guide.pdf

The sonar is better because the wave gets scattered from the source so it provides 23 degrees of sonar vision. Yes, you can take sonar pictures using this information.


The CMUCam is the easiest if and only if the person wears one single color that is unique to the environment. Otherwise, you will need to use your own code and reprogram the CMUCam microprocessor. Simply, to detect a person without color detection, you have to use two different techniques in computer vision; Template comparison, where you have a close shape to that person and you compare it to the picture, and Edge detection ,where you differentiate the edges of that person. << That’s why I said it is away so advanced, you need at least to use a lot of algorithms and you must have a solid knowledge in computer programming>> Also, I want to add one more thing about color tracking of the Cmucam alone is useless because not all the objects around looks exactly in the same color. There is always color intensity around us. To solve this, you must use a halogen flash light , like the one in your camera. All the colors will look exactly the same.

Now I believe that you know about robotics, but anyway you don't have to use 8 sensors because the person wants it to follow them, not avoid obstacles and 3 would be able to get the center and the right and the left.
How ever programming would be a bit difficult but who doesn't love the challenge. You are right about the cmu cam because you do need a bright color for the robot to follow a nice red T-shirt would do.

Anyway the reason you think that the IR. can only go 59''
is because you must only now of the popular sharp sensor, it goes higher buddy and I will give you the link when I find it on my favorites or (AKA)
Bookmark.
 
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