V5 inertia sensor v.s internal motor encoder

Hello, does anyone know what will allow us a better/more accurate VRC autonomous. Should we use the encoders or buy an inertia sensor?

It kinda depends on your programming skill level and what you’re trying to do with your programming. Having a gyro always helps, but the best solution would probably be a combination of the two.

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Although, using the intertial sensor does not require advanced programming. There is a sample program included in the latest version of VEXCode that is very straightforward. The inertial sensor would provide more accurate and consistent turns over the use of encoders.


It really depends, the interial sensor also has a built in accelerometer, which can measure acceleration. If you’re using that to calculate distance it would not be accurate.

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In my experience, the internal motor encoders are pretty bad. Because the internal encoder only measures the rotation of the little white gear inside the motor, slop from the gear cartridges can make it inaccurate. On top of that, internal encoders are prone to wheel slippage and any slop your system has outside the motor. The best option, if you were to use encoders, would be those free-spinning encoder tracking wheels that are tensioned to the floor.

We haven’t gotten to experimenting on the inertial sensor (still waiting on the pros release), but know that it can drift over time, though hopefully not as badly as the old gyro. Also, the accelerometer can be used to calculate x y and z position based on its starting position (aka where it was calibrated). Basically, it’s like three dimensional odometry without the need for any math or special tracking wheels.

tl;dr i’d invest in inertial sensor, although if you have space on your robot to use tracking wheels it will be the most robust solution as it isn’t subject to drift over time.

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V5 inertia sensor is used for controlling any change in motion of a robot. It is also used for navigation. On the other hand, the internal motor encoder provides closed-loop feedback signals by tracking the speed of the motor. Please check our Facebook page for more information and recent updates.

Thanks for the help we will definitely try the tracking wheels, but if we encounter issues we will consider the inertia sensor.

Theory is different than practice. You are right in theory, but wrong in practice. The inertial sensor is not perfectly accurate; when you double integrate its measurements over time, your position estimate will suffer immensely from every small inaccuracy in the original measurement, producing a position estimate that is utter garbage. I strongly recommend encoders, preferably unpowered encoder wheels.


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