Difference between revisions of "RC15OmniWheel"

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(Created page with "As part of the [http://wiki.robojackets.org/mediawiki/RoboCupMechanical RoboCup 2015 Mechanical], the Omni Wheels allow the robots to move in any direction at anytime. =...")
 
 
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As part of the [http://wiki.robojackets.org/mediawiki/RoboCupMechanical RoboCup 2015 Mechanical], the Omni Wheels allow the robots to move in any direction at anytime.
+
This page is a sub-section of the [http://wiki.robojackets.org/w/RoboCupMechanical RoboCup 2015 Mechanical] page. Specifically, the Omni Wheels allow the robots to move in any direction at anytime.
  
 
== Background ==
 
== Background ==
Line 20: Line 20:
  
 
== Potential Design Variants ==
 
== Potential Design Variants ==
 +
 +
=== Body/Housing ===
  
 
#Injection molded design
 
#Injection molded design
Line 32: Line 34:
 
#Typical aluminum machined design
 
#Typical aluminum machined design
 
##Pros:
 
##Pros:
 +
###Sturdy
 
##Cons:
 
##Cons:
 +
###Manufacture time
 +
###CAM setup time
 
#Thinned and heat treated steel machined design
 
#Thinned and heat treated steel machined design
 
##Pros:
 
##Pros:
 
##Cons:
 
##Cons:
 +
 +
=== Roller Rubber ===
 +
 +
#Round o-rings
 +
##Pros:
 +
###Simple
 +
###The most inexpensive option
 +
###Same as what we've done in the past, so it the easiest to re-imple
 +
##Cons:
 +
###Smallest contact area ("point" contact)
 +
###Most effectively seated via a semi-circular groove on the roller - this was an outsourced job in the past
 +
#Double seal o-rings
 +
##Pros:
 +
###More contact area = more grip
 +
###Relatively cheap
 +
##Cons:
 +
###Slightly more expensive than round rings
 +
#Custom rubber rings
 +
##Pros:
 +
###Easily designed to have high contact area
 +
##Cons:
 +
###Not a commercial-of-the-shelf product and would require our team to manufacture it (more development time)
 +
###Potential inconsistencies with our in-house manfacturing process (the waterjet cutter may leave a slight flap on the edge at the "lead-in/lead-out" locations.
  
 
== Chosen Design ==
 
== Chosen Design ==
Line 42: Line 70:
  
 
== Materials ==
 
== Materials ==
<ul style="line-height: 20.7999992370605px;">
 
<li>Body
 
#Aluminum 7075
 
#*1/2"
 
#*1/16"</li>
 
  
*Rollers
+
{| width="735" border="1" cellpadding="1" cellspacing="1"
*#Neoprene O-Rings
+
|-
*#*McMaster: Neoprene O-Ring AS568A Dash Number 012 (94115K012)
+
| style="text-align: center" | '''Item'''<br/>
*#**Pks of 100 for $2.87
+
| style="text-align: center" | '''Material'''<br/>
*#**Total Needed = (15*4*5)/100 = 3 + 1 = 4pks
+
| style="text-align: center" | '''Fleet Quantity'''<br/>
*#Aluminum 7075
+
| style="text-align: center" | <u>Stock Material</u><br/>
*#*1/8"
+
| style="text-align: center" | <u>Cost per part</u><br/>
 +
| style="text-align: center" | <u>Total Cost</u><br/>
 +
| style="text-align: center" | <u>Vendor</u><br/>
 +
| style="text-align: center" | <u>Part Number</u><br/>
 +
| style="text-align: center" | Manufacturing Method<br/>
 +
| style="text-align: center" | Notes<br/>
 +
|-
 +
| style="text-align: center" | Body<br/>
 +
| style="text-align: center" | Aluminum 7075<br/>
 +
| style="text-align: center" | 32<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | McMaster<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | CNC Mill<br/>
 +
| style="text-align: center" | <br/>
 +
|-
 +
| style="text-align: center" | Cap<br/>
 +
| style="text-align: center" | Hardened Steel<br/>
 +
| style="text-align: center" | 32<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | McMaster<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | Waterjet<br/>
 +
| style="text-align: center" | <br/>
 +
|-
 +
| style="text-align: center" | Pin<br/>
 +
| style="text-align: center" | Stainless Steel<br/>
 +
| style="text-align: center" | 576<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | McMaster<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | (Stock component)<br/>
 +
| style="text-align: center" | <br/>
 +
|-
 +
| style="text-align: center" | Roller Core<br/>
 +
| style="text-align: center" | Carbon Steel<br/>
 +
| style="text-align: center" | 576<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | McMaster<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | Waterjet<br/>
 +
| style="text-align: center" | Hardened after cut<br/>
 +
|-
 +
| style="text-align: center" | Roller Rubber<br/>
 +
| style="text-align: center" | Rubber<br/>
 +
| style="text-align: center" | 576<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | McMaster<br/>
 +
| style="text-align: center" | <br/>
 +
| style="text-align: center" | Waterjet<br/>
 +
| style="text-align: center" | <br/>
 +
|}
  
 
== Assembly Structure ==
 
== Assembly Structure ==
Line 63: Line 147:
 
#1 - O-Ring (RC-2008-01-01)
 
#1 - O-Ring (RC-2008-01-01)
 
#1 - Roller Hub (RC-2008-01-02)</li>
 
#1 - Roller Hub (RC-2008-01-02)</li>
 +
  
 
#1 - Wheel Body (RC-2008-02-01)
 
#1 - Wheel Body (RC-2008-02-01)
Line 77: Line 162:
 
<li>Fasten using RC-2008-07-04</li>
 
<li>Fasten using RC-2008-07-04</li>
 
</ol>
 
</ol>
 
== Parts & Components ==
 
 
Amounts are based on per robot. Materials are in sizes for prototyping not lowest cost per amount.
 
 
=== Stock ===
 
 
===== Plate - Wheel Plate =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 8885K13
 
:Cost - $21.63
 
:Description - Alloy 7075 Aluminum Sheet .063" Thick, 12" X 12"
 
 
===== Plate - Wheel Body =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 9037K21
 
:Cost - $158.77
 
:Description - Alloy 7075 Aluminum Sheet .500" Thick, 12" X 12"
 
:''Note: will look at thinner and optimize sheet size to a per robot amount''
 
 
===== Shaft - Rollers =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 9063K243
 
:Cost - $17.48
 
:Description - Alloy 7075 Aluminum Precision Ground Rod 1/8" Diameter, 3' Length
 
:''Note: Usually ships within 2 weeks.''
 
 
=== Fasteners ===
 
 
===== 6-32 Low Head Socket Cap Screw =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 92220A141
 
:Cost - $7.42 (packs of 25)
 
:Description - Alloy Steel Low Head Socket Cap Screw 6-32 Thread, 1/4" Length
 
 
===== 3/16" Dowel Pin =====
 
 
:Vendor - MSC
 
:Part No. - 88231758
 
:Cost - $43.08 (per 100)
 
:Description - Precision Ground Dowel Pins - Stainless Steel Type: Dowel Pin Diameter: 3/16 Overall Length: 1/4 Material: Stainless Steel - 416 SS Finish/Coating: Bright
 
 
=== Other ===
 
 
===== O-Ring (option 1) =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 94115K012
 
:Cost - $2.87 (Pks of 100)
 
:Quantity -
 
:Description - Neoprene O-Ring AS568A Dash Number 012
 
 
===== O-Ring (option 2) =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 90025K137
 
:Cost - $9.70 (Pks 100)
 
:Quantity -
 
:Description - Double Seal Buna-N O-Ring AS568A Dash Number 012
 
 
===== Axel / Wire =====
 
 
:Vendor - McMaster-Carr
 
:Part No. - 9666K69
 
:Cost - $2.93
 
:Description - 1080-1090 Carbon Steel Wire .059" Diameter, 1/4-lb Coil, 27' Coil
 
 
== Fabrication ==
 
 
===== Omni Plates =====
 
 
:Primary - Water Jetting (Outsourced)
 
:Notes
 
::Alignment holes will need to be reamed out.
 
 
===== Omni Bodies =====
 
 
:Primary - Milling (Outsourced)
 
:Notes -
 
::Hex broaching
 
::Press fitting in dowel pins.
 
 
===== Omni Rollers =====
 
 
:Primary - Turning / Lathing (Outsourced)
 
:Notes
 
::We will apply o-rings.
 
  
 
== Cost Estimates ==
 
== Cost Estimates ==
Line 182: Line 176:
  
 
== Action Log ==
 
== Action Log ==
<ol style="line-height: 20.7999992370605px;">
 
<li>12/04/2007 - RC-2008-PO-02 - Purchase Order for Omni Roller Hub Samples (Option A & B).</li>
 
<li>12/14/2007 - RC-2008-PO-01 - Purchase Order for Omni Body Prototypes.</li>
 
<li>12/28/2007 - Fabrication of Omni Plates completed.</li>
 
<li>12/28/2007 - Full omni prototype completed.
 
:Notes - Very hard to get axle wire in to omni bodies must find new material.</li>
 
<li>12/28/2007 - Roller Option A revised and selected for prototype set.
 
:Notes - Option B (square) is cheaper and requires a costs analysis change in dimension and different roller material may be required.</li>
 
<li>12/29/2007 - RC-2008-PO-03 - Purchase Order for Omni Roller Hub (Rev 2).</li>
 
<li>12/31/2007 - Looking at 8867K25, 9495K92 for alternate wire.</li>
 
<li>01/29/2007 - Keeping original wire.</li>
 
<li>03/05/2007 - Omni rollers finalized.</li>
 
<li>03/08/2008 - Omni rollers sent out. (20 cents each)</li>
 
<li>03/17/2008 - Investigating the use dowel pins to cut down on machining costs.</li>
 
<li>03/30/2008 - Designs for body are finalized and sent out to supplier.
 
:Notes - Dowel / locating pins, relaxing tolerances, a new supplier, and hex broaching our selves have brought down the machining cost to around $4 per body (prototype $53).</li>
 
<li>04/13/2008 - Fleet rollers arrive and are fitted with o-rings.</li>
 
<li>05/14/2008 - Fleet bodies arrive, are hex'd, and have locating pins pressed in.
 
:Notes - A few were damaged in process a fitting for press was made, and replacements ordered.</li>
 
</ol>
 
  
[[Category:RoboCup]]<br/>[[Category:Mechanical]]<br/>[[Category:Year: 2007-2008|Year:_2007-2008]]
+
== <br/>Manufacturing ==
 +
 
 +
=== WaterJetting ===
 +
 
 +
WaterJet proved to have loose tolerances innitially however it can be adjusted to reduce taper utilizing the A-Jet settings. So far the best outcome has been setting the A-Jet tilt to -2.02174 degrees and tool offset of .02175. (Original settings for comparison tilt: 0 degrees and offset: .021).<br/><br/><br/><br/>
 +
[[Category:RoboCup]]
 +
[[Category:2007-2008|2007-2008]]
 +
[[Category: 2014-2015]]

Latest revision as of 21:51, 13 June 2018

This page is a sub-section of the RoboCup 2015 Mechanical page. Specifically, the Omni Wheels allow the robots to move in any direction at anytime.

Background

The omni wheel serves the purpose of allowing the robot to move in any direction at any time. This is important for having highly dynamic robots that can execute their plays as fast as possible.

The 2008 fleet of robots designed by the team utilized a 

The 2011 fleet of robots utilized rollers supported by individual pins which proved to be easier to assemble despite the increased part count. Additionally, the omni wheel had an internal ring gear mounted on the rear to engage the spur gear mounted on the 30W motors. This design proved to be compact, allowing for more internal space on the robot. 

Both the 2008 and 2011 fleet of robots use wheels that are mounted on 1 radial bearing. While this design works, it allows for a lot of out of plane motion of the wheel, which has resulted in significant rubbing and reduced performance. Both designs use simple o-rings as contacts for the ground. The 2011 robots utilized an outsourced aluminum core to seat the o-ring.

Requirements

  1. In-house manufacturable (including ease of manufacturability)
  2. Provide more grip/contact than previous designs
  3. Must be able to mount the internal ring gear for a more compact design
  4. Ground clearance of 0.XX inches
  5. Must include more rollers for smoother driving performance.

Potential Design Variants

Body/Housing

  1. Injection molded design
    1. Pros:
      1. Highly geared towards mass manufacturing. Saves development time
      2. Significantly more freedom with design parameters than a purely machined design
      3. Potentially lighter if designed and analyzed correctly
    2. Cons:
      1. Relatively unknown realm of manufacturing
      2. Generally weaker material than most metals
      3. Development of the mold is time consuming and not easy
  2. Typical aluminum machined design
    1. Pros:
      1. Sturdy
    2. Cons:
      1. Manufacture time
      2. CAM setup time
  3. Thinned and heat treated steel machined design
    1. Pros:
    2. Cons:

Roller Rubber

  1. Round o-rings
    1. Pros:
      1. Simple
      2. The most inexpensive option
      3. Same as what we've done in the past, so it the easiest to re-imple
    2. Cons:
      1. Smallest contact area ("point" contact)
      2. Most effectively seated via a semi-circular groove on the roller - this was an outsourced job in the past
  2. Double seal o-rings
    1. Pros:
      1. More contact area = more grip
      2. Relatively cheap
    2. Cons:
      1. Slightly more expensive than round rings
  3. Custom rubber rings
    1. Pros:
      1. Easily designed to have high contact area
    2. Cons:
      1. Not a commercial-of-the-shelf product and would require our team to manufacture it (more development time)
      2. Potential inconsistencies with our in-house manfacturing process (the waterjet cutter may leave a slight flap on the edge at the "lead-in/lead-out" locations.

Chosen Design

Drawings

Materials

Item
Material
Fleet Quantity
Stock Material
Cost per part
Total Cost
Vendor
Part Number
Manufacturing Method
Notes
Body
Aluminum 7075
32



McMaster

CNC Mill

Cap
Hardened Steel
32



McMaster

Waterjet

Pin
Stainless Steel
576



McMaster

(Stock component)

Roller Core
Carbon Steel
576



McMaster

Waterjet
Hardened after cut
Roller Rubber
Rubber
576



McMaster

Waterjet

Assembly Structure

Parts List

  1. 15 - Rollers (RC-2008-01-00)
    1. 1 - O-Ring (RC-2008-01-01)
    2. 1 - Roller Hub (RC-2008-01-02)
    1. 1 - Wheel Body (RC-2008-02-01)
    2. 1 - Plate (RC-2008-02-02)
    3. 1 - Ring / Axel (RC-2008-02-03)
    4. 3 - 6-32 1/4" Long (RC-2008-07-04)

    Instructions

    1. Place 15 rollers on wire axle.
    2. Bend to circular shape.
    3. Drop in omni body.
    4. Place omni plate on omni body.
    5. Fasten using RC-2008-07-04

    Cost Estimates

    1. Rollers - $0.42 x 15 = $6.30
    2. Body - $4.00
    3. O-rings - $0.03 x 15 = $0.45
    4. Plate -
    5. Fasteners - $0.30 x 3 = $0.90
    Total - $11.65 (missing plate)
    Note - Shipping is included in per unit cost.

    Action Log


    Manufacturing

    WaterJetting

    WaterJet proved to have loose tolerances innitially however it can be adjusted to reduce taper utilizing the A-Jet settings. So far the best outcome has been setting the A-Jet tilt to -2.02174 degrees and tool offset of .02175. (Original settings for comparison tilt: 0 degrees and offset: .021).