I don't know if it is affecting. I am planning to buy one but before that i want to learn if it is suitable for my project.
I should give some details. Robot has two wheels and shaped as circle. Radius of the surface of robot is about 60mm. I have an electormagnet and it can grab a specimen i have to take from some place and put it another location. Specimen is shaped as circle and radius of specimen is 10mm. It is stell and weigh about 50gr=0.1pounds. Also electomagnet is going to be placed 100mm away from the robot.
I thought instead of a gripper, it would be better to use an electromagnet. It is more practical. However i doubt that this electromagnet and dc motors may affect the magnetic field so the magnetometer gives me the wrong direction. As i learnt, the magnetic field value of the world is about 0.6Gauss. But it doesn't mean anything for me :D.
I think if i place the magnetometer enough away from the electromagnet, its effect on the magnetic field around the magnetometer becomes much lower because of the inverse square law. But i don't know anything about calculating magnetic field of an electromagnet and value of magnetic field around a point in the space. So i don't know how far should i place the magnetometer.
With rotay encoder, i know how much each whell turns, with this information i can calculate the difference and calculate how much does the system turns with the knowledge of the distance between wheels :D I don't know if it is a lopng shot because of the accumulation errors or whell slipping or other reasons. But i have no choice to calculate the angle data without these two option.
By the way platform which robot works on is a rectangle and size of the rectangle is 1meterX1meter