The figure below shows one link of a SCARA robot that is to

The figure below shows one link of a SCARA robot that is to be driven by a DC motor with position feedback from an incremental encoder. To eliminate error from gear backlash, the encoder will be coupled directly to the arm, as shown. Find the minimum resolution of the encoder to allow positioning of the axis for link 2 (point A on the sketch) to within +/- 0.10 mm. Assume you can read both the leading and trailing edges of the encoder signal

Solution

solution: here incremental encoder will operate at maximum frequency of F=180KHz and speed of 5000 rpm

hence maximum possible resolution is

R=F*60/N

R=60*180000/5000

R=2160 counts/sec

2) hence given incoder will give maximum count of 2160 per sec for total range and hence 1 count corresponds to displacement x or minimum input or resolution

2160 for .20 mm

1 for x mm

hence x=(.20*1/2160)=9.259*10^-5 mm

3) hence minimum resolution is .09259 micrometer, hence shaft alignment of .09259 micrometer will give single count on incremental encoder