Common Wheel Encoders • Magnetic Pickup – used in most ABS • Hall Effect • Optical
Systematic Errors • Unequal wheel diameters. • Average of actual wheel diameters differs from nominal wheel diameter. • Actual wheelbase differs from nominal wheelbase. • Misalignment of wheels. • Finite encoder resolution. • Finite encoder sampling rate.
Non-Systematic Errors • Travel over uneven terrain • Travel over unexpected objects • Wheel-slippage • Change in tire shape over time
References http://email@example.com/library/abs1.htm “All About ABS”; Carley, Larry; CarleySofware, 2000 http://www-personal.engin.umich.edu/~johannb/index.html Personal web page for Johann Borenstein of Univ of Michigan – many links to papers on odometry including the UMBmark standard.