Changes between Initial Version and Version 1 of WAM/AccuracyRepeatability


Ignore:
Timestamp:
May 13, 2011, 2:00:42 PM (10 years ago)
Author:
edison
Comment:

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  • WAM/AccuracyRepeatability

    v1 v1  
     1= WAM Accuracy and Repeatability Study =
     2
     3== Repeatability Test ==
     4
     5{{{
     6#!div class="center" align="center"
     7[[Image(htdocs:wam/accuracy/wam_moving_towards.jpg)]]
     8
     9'''Figure 1: WAM arm moving towards dial indicator'''
     10}}}
     11
     12{{{
     13#!div class="center" align="center"
     14[[Image(htdocs:wam/accuracy/wam_touching.jpg)]]
     15
     16'''Figure 2: WAM arm touching dial indicator'''
     17}}}
     18
     19{{{
     20#!div class="center" align="center"
     21[[Image(htdocs:wam/accuracy/encoder_scale.jpg)]]
     22
     23'''Figure 3: Motor encoder scale'''
     24}}}
     25
     26Encoder resolution: 40,000 counts/rev
     27Motor resolution: 0.009 deg/count
     28Joint 1 transmission ratio: 30:1
     29Ideal joint resolution: .0003 deg/count
     30Approximate moment arm: 1 m
     31Ideal repeatability: 0.005 mm
     32
     33=== Repeatability Data ===
     34
     35{{{
     36#!div class="center" align="center"
     37[[Image(htdocs:wam/accuracy/repeatability_data.png)]]
     38}}}
     39
     40== Accuracy Test ==
     41
     42{{{
     43#!div class="center" align="center"
     44[[Image(htdocs:wam/accuracy/single_link_pen.jpg)]]
     45
     46'''Figure 4: WAM - single link'''
     47}}}
     48
     49{{{
     50#!div class="center" align="center"
     51[[Image(htdocs:wam/accuracy/single_link_closeup.jpg)]]
     52
     53'''Figure 5: Closeup of single link WAM'''
     54}}}
     55
     56{{{
     57#!div class="center" align="center"
     58[[Image(htdocs:wam/accuracy/dual_link.jpg)]]
     59
     60'''Figure 6: WAM - dual link'''
     61}}}
     62
     63=== Notes regarding accuracy data: ===
     64It is important to note that the repeatability data is a better measure for calibrated accuracy than is uncalibrated accuracy.  Uncalibrated accuracy was measured as shown in the figures to the right. A pen attached to the outer link was used to plot points on paper taped to the floor and the WAM base was secured to the floor.
     65
     66Potential sources of measurement error include:
     67 * the floor was assumed to be flat
     68 * physical measurement error with rulers & T-squares
     69 * physical measurement of WAM origin difficult to measure accurately
     70
     71Sources of system error (calibration error) include:
     72 * transmission ratio errors
     73 * tolerance stack-up of parts
     74 * tool location measurement (tip of pen)
     75
     76=== Accuracy Data ===
     77
     78{{{
     79#!div class="center" align="center"
     80[[Image(htdocs:wam/accuracy/accuracy_vs_reach.png)]]
     81}}}
     82
     83{{{
     84#!div class="center" align="center"
     85[[Image(htdocs:wam/accuracy/graphs.png)]]
     86}}}
     87