please help..what is the suitable sensor for my project?

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please help..what is the suitable sensor for my project?

Postby useful84 » Tue Dec 29, 2009 1:09 pm

i want to build a mobile robot that able to detect the change of the angle wherever it moving in the sloping ground. it will automatically change the speed of the motor when it is on a slope. when it is in the flat terrain, it will switch back to the normal speed condition. But when it moving up in the sloping upward terrain and moving down in the sloping downward terrain, it will increase and decrease the speed respectively.can i use LISY300AL Single-Axis Gyro for my robot?if not,what is the recommended sensor that can be used?
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Re: please help..what is the suitable sensor for my project?

Postby waiweng83 » Tue Dec 29, 2009 1:28 pm

The gyro alone only can detect the angular velocity (turning rate), but not the tilt angle of your robot. In order to get the tilt angle for 1 axis, you will need a single axis gyro and a 2-axis accelerometer. Alternatively, you can also use the 5-degree IMU sensor which consists of a 2-axis gyro and a 3-axis accelerometer.

After that, you will also need to fuse the reading from gyro and accelerometer by implementing the complimentary filter or kalman filter in your software. Try to google for "kalman filter" or "complementary filter" and you will get a lot of references.
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Re: please help..what is the suitable sensor for my project?

Postby useful84 » Tue Dec 29, 2009 2:17 pm

so i cannot use this LISY300AL Single-Axis Gyro for my robot?but actually my robot does not use to determine the specific angle but i just want it to detect whenever it is moving on the sloping ground..that's all..
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Re: please help..what is the suitable sensor for my project?

Postby waiweng83 » Tue Dec 29, 2009 5:40 pm

so i cannot use this LISY300AL Single-Axis Gyro for my robot?


The gyro alone only can detect the angular velocity (turning rate), but not the tilt angle of your robot. In order to get the tilt angle for 1 axis, you will need a single axis gyro and a 2-axis accelerometer.


you can still use the LISY300AL single axis gyro, but you need to add another 2-axis accelerometer.

but actually my robot does not use to determine the specific angle but i just want it to detect whenever it is moving on the sloping ground..that's all..


How to know whether you are on slope without knowing the tilt angle?
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Re: please help..what is the suitable sensor for my project?

Postby robosang » Tue Dec 29, 2009 5:59 pm

you actually need to know the angle inorder to control your motor to move in certain speed, cannot simply provide a speed if you detect your robot is falling to 1 side, it will become worst. This what we call control....
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Re: please help..what is the suitable sensor for my project?

Postby useful84 » Tue Dec 29, 2009 11:27 pm

ok i got it..thanks a lot
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Re: please help..what is the suitable sensor for my project?

Postby useful84 » Wed Dec 30, 2009 2:00 pm

is there any cheaper sensor that i can use for my project?since i have to use LISY300AL single axis gyro with 2-axis accelerometer,it will be quite expensive..can u please suggest the cheaper sensor?
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Re: please help..what is the suitable sensor for my project?

Postby sich » Fri Jan 01, 2010 6:25 pm

That's the minimum requirement for a robot to move up n down slope. I assume that you're building a robot with more than 2 wheels. If you want cheap and inaccurate sensor, mercury switch can be considered. However this is not encouraged as I think it's impractical for the real world environment. And...this will never work if you're building a 2 wheels balancing robot like Segway.

Here's the example:
http://en.wikipedia.org/wiki/Mercury_switch
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Re: please help..what is the suitable sensor for my project?

Postby aurora » Sat Jan 02, 2010 11:11 am

When you say increase the speed when moving uphill, and decrease speed when going downhill, in other word, you are trying to design a robot that can compensate the speed for the uphill downhill? With same power loading, normally robot will struggle during uphill (hence the speed also slow down), and faster during downhill. So, by increase/decrease the speed, you compensate for this phenomena?

If that is true, you don't need an accelerometer/gyro, you need a shaft decorder that can detect the speed of your wheel. Connect the shaft encorder to your microcontroller, and when the speed drop/increase, just make change accordingly.
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