Difference between revisions of "RC08-Dribbler"
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*Maxon motor, the same CMU uses, was chosen for the fleet. This was based on 4wk shorter lead time, $60 cheaper per motor, and significantly greater performance as can be seen from the figures generated by a Matlab script | *Maxon motor, the same CMU uses, was chosen for the fleet. This was based on 4wk shorter lead time, $60 cheaper per motor, and significantly greater performance as can be seen from the figures generated by a Matlab script | ||
| − | [[ | + | [[image:motor_comparison.jpg|800 px|Dribbler motor comparison]] |
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===Gears=== | ===Gears=== | ||
Revision as of 23:13, 6 February 2008
This page contains the information and documentation of the 2008 dribbler system
Contents
Assembly Structure
| PART NAME | PART NUMBER | QUANTITY |
|---|---|---|
| Mounting Block | RC-2008-04-01 | 2 |
| Swing | RC-2008-04-02 | 2 |
| Motor Plate | RC-2008-04-03 | 1 |
| Standoff | RC-2008-04-04 | 2 |
| Hinge Shaft | RC-2008-04-05 | 1 |
| 8-32 Lock Nut | RC-2008-04-06 | 4 |
| 2" Hex Standoff | RC-2008-04-07 | 1 |
| Dribbler Motor | RC-2008-04-08 | 1 |
| M2x5 Screw | RC-2008-04-09 | 2 |
| Dribbler Motor Gear | RC-2008-04-10 | 1 |
| 6-32 x 3/4 Screw | RC-2008-04-11 | 1 |
| Cross Plate | RC-2008-04-12 | 1 |
| 4mm Snap Bearing | RC-2008-04-13 | 2 |
| Dribbler Shaft | RC-2008-04-14 | 1 |
| Dribbler Roller | RC-2008-04-15 | 1 |
| Dribbler Roller Gear | RC-2008-04-16 | 1 |
| Left Torsion Spring | RC-2008-04-17 | 1 |
| Right Torsion Spring | RC-2008-04-18 | 1 |
| 6-32 x 1/4 Screw | RC-2008-04-19 | 1 |
| 3/8" Washer | RC-2008-04-20 | 1 |
| Neoprene Rubber Tube | RC-2008-04-21 | 1 |
| 4-40 Set Screw | RC-2008-04-22 | 1 |
Parts & Components
Motor
Vendor: MicroMo
- Motor: 12V DC brushless servo motor #E-1628B
- $147.10 each
- Planetary gearhead: #E-167 gear reduction: 14
- Complete assembly 1628-V-0003
Cost: $200.40 each
- Electrical specification
- 12 Volts
- must have position or speed encoders
- brushless DC
- Maxon motor, the same CMU uses, was chosen for the fleet. This was based on 4wk shorter lead time, $60 cheaper per motor, and significantly greater performance as can be seen from the figures generated by a Matlab script
Gears
Motor gear
- Vendor: SDP/SI
- Part No.: A 1B 2MYK05030H
- Description: 3mm bore, 30 teeth, 15mm pitch diameter, brass gear with set screw
- Cost: $6.72
- Drawing:Motor Gear Spec Sheet
- Connects directly to output of motor and powers dribbler roller
Roller gear
- Vendor: SDP/SI
- Part No.: A 1B 2MYK08020
- Description: 4mm bore, 20 teeth, 16mm pitch diameter, brass gear with set screw
- Cost: $9.12
- Drawing:Dribbler Gear Spec Sheet
- Roller gear needs be turned down from 7mm face to 2mm face width
- Powers the dribbler roller - is recessed into the roller itself
Plates
Swing
- Vendor: McMaster-Carr
- Part No.: 8885K13
- Description: Alloy 7075 Aluminum Sheet .063" Thick, 12" X 12"
- Cost: $21.73
- Contains the roller shaft, the motor mounts, spacers, and hinge shafts
- Material is same and shared with Omniwheel plates
- Left and right swings are identical
Motor plate
- Vendor: McMaster-Carr
- Part No.: 8885K13
- Description: Alloy 7075 Aluminum Sheet .063" Thick, 12" X 12"
- Cost: $21.73
- Supports motor and connects to the 2 spacers in assembly
- Material is same and shared with Omniwheel plates
Cross Plate
- Vendor: McMaster-Carr
- Part No.: 8885K13
- Description: Alloy 7075 Aluminum Sheet .063" Thick, 12" X 12"
- Cost: $21.73
- Connects both mounting blocks and provides mechanical limitation for swing and torsion springs
- Material is same and shared with Omniwheel plates
Standoffs
Standoff
- Vendor: McMaster-Carr
- Part No.: 9062K271
- Description: Alloy 6061 Aluminum Precision-Ground Rod 5/16" Diameter, 1' Length
- Cost: $9.10
- Standoff between swing and motor plate
2" Hex Standoff
- Vendor: McMaster-Carr
- Part No.: 91780A339
- Description: Aluminum Female Threaded Hex Standoff 1/4" Hex, 2" Length, 6-32 Screw Size
- Cost: $.88
- Hex standoff between motor plate and swing
- Both torsion springs anchor into the standoff
Fasteners
6-32 x 1/4" socket cap screw
- Vendor: McMaster-Carr
- Part No.: 92220A141
- Description: 6-32 x 1/4" steel, low profile, socket cap screw
- Cost: $7.22 for 25
- Connects the swing and hex standoff
6-32 x 3/4" socket cap screw
- Vendor: McMaster-Carr
- Part No.: 93615A217
- Description: 6-32 x 3/4" 18-8 stainless steel, low profile, socket cap screw
- Cost: $12.72 for 25
- Connects the swing, motor plate, and hex standoff
8-32 Lock Nut
- Vendor: McMaster-Carr
- Part No.: 90633A009
- Description: Steel Hex Nylon-Insert Locknut, 8-32 Screw Size, 11/32" W, 11/64" H
- Cost: $2.21 each - STOCK
- Constrains the dribbler and hinge shafts
4-40 Set Screw
- Vendor: McMaster-Carr
- Part No.: 91375A105
- Description: Alloy Steel Cup Point Socket Set Screw 4-40 Thread, 3/16" Length
- Cost: $7.99 for pack of 100
- Pins dribbler roller to the dribbler shaft
Shaft
Hinge shaft
- Vendor: McMaster-Carr
- Part No.: 8116K3
- Description: A2 Tool Steel Tight-Tolerance Metric Rod 4 mm Diameter, 3' Length
- Cost: $6.10
- Joint between swings and mounting blocks
Dribbler shaft
- Vendor: McMaster-Carr
- Part No.: 8116K3
- Description: A2 Tool Steel Tight-Tolerance Metric Rod 4 mm Diameter, 3' Length
- Cost: $6.10
- Roller and dribbler gear spin on dribbler shaft
- Material is shared with the hinge shaft
Springs
Left Torsion Spring
- Vendor: McMaster-Carr
- Part No.: 9271K35
- Description: 1.375 lbf-in of torque. Music Wire Torsion Spring 90 Deg Angle, .309" Coil OD, .040" Wire, Cw/Lh, Packs of 6
- Cost: $6.56 for 6
- Left hand wound torsion spring
- Rests on hinge shaft and provides cushioning for ball impact
Right Torsion Spring
- Vendor: McMaster-Carr
- Part No.: 9271K33
- Description: 1.375 lbf-in of torque. Music Wire Torsion Spring 90 Deg Angle, .309" Coil OD, .040" Wire, Cw/Rh, Packs of 6
- Cost: $6.56 for 6
- Right hand wound torsion spring
- Rests on hinge shaft and provides cushioning for ball impact
Other
Mounting block
- Vendor: McMaster-Carr
- Part No.: 3511T11
- Description: Alloy 6061 Aluminum Ground Flat Stock .250" Thick, 6" X 6" Size
- Cost: $45.44 each - STOCK
- Connects entire dribbler assembly to the robot
4mm snap thrust bearing
- Vendor: McMaster-Carr
- Part No.: 7817K33
- Description: Metric Nylon Snap-in Thrust Bearing for 4mm Shaft Dia, 1.45-2.34 mm Sheet Metal Thick
- Cost: $1.32 each
- supports dribbler shaft in the swing
3/8" Washer
- Vendor: McMaster-Carr
- Part No.: 93286A009
- Description: Aluminum washer 3/8" OD,.175" ID, 1/32" thick
- Cost: $3.52 for 100
- Washer between the swing and hex standoff
Neoprene Rubber Tube
- Vendor: McMaster-Carr
- Part No.: 7505K86
- Description: Ultra-Flex Neoprene Rubber Heat-Shrink Tubing 3/4" Expanded ID, 3/8" Shrunken ID,
- Cost: $8.97
- Roller and dribbler gear spin on dribbler shaft
- Material is shared with the hinge shaft
Calculations
Torsion Spring
- Analysis was done using the Work-Energy Principle with the assumption that the only work done is from the torsion spring and gravity. Because the dribbler assembly swings and has zero velocity at both positions, only the kinetic energy of the ball was used, at its maximum value of 10 m/s
Roller Speed
- Gears were selected for a gear ratio lower than 2007. The 2008 ratio is 1.5. This was with the hope of having more torque available for the roller to grip the ball.
Notes
- 4mm steel shaft chosen to increase strength to prevent bending of dribbler shaft when hit with a ball
- roller diameter - .5"
- dribbler shaft still slides free in between two snap-in thrust bearings and can be removed to allow the roller to be changed out
Dribbler bar prototypes
- shaft diameter on ends of bar - 3mm
- maximum diameter of dribbler - .75"
- the dribbler bar prototypes will be lathed and done coated with neoprene heat shrink
dribbler bar prototypes
- 3/4" diameter aluminum bar stock
- $8.34
- McMaster part number 6750K181
- 3mm diameter aluminum bar stock
- $6.94
- McMaster part number 1681T21
- 3/4" neoprene heat shrink
- pack of 5 for $8.97
- McMaster part number 7505K86
- 3mm e-clips
- pack of 100 for $3.03
- McMaster part number 98543A101
2007 Dribbler
Drive gear
- attached to the motor
- SDP/SI A-1B-2MYK05045 Data sheet
- 45 teeth, 3mm bore, 22.5mm pitch diameter
Dribbler gear
- attached to the roller. This is done by pressing having a set screw in the gear interfere with the roller. Both the gear and roller are free to spin on the shaft, which permitting easy change.
- SDP/SI A-1B-2MYKO5020H Data sheet
- 20 teeth, 3mm bore, 10mm pitch diameter
- gear ratio from motor to drilbber = 2.25
Motor
- 15.9mm diameter, 3mm output shaft
Specs from CMU
- Dribbler motor gear from SDP-SI: S10T05M042A0303 Module 0.5, 42 Teeth, 20° Pressure Angle , 2024 Aluminum alloy Gear
- Dribbler bar gear from SDP-SI: S10T05M028A0305 Module 0.5, 28 Teeth, 20° Pressure Angle , 2024 Aluminum alloy Gear
- spur gear reduction 1:1.5
- Dribbler Motor - Maxon
- 266521
- http://test.maxonmotor.com/docsx/Download/catalog_2007/Pdf/07_154_e.pdf
- nominal speed 28200 rpm
- Gearhead
- 118184 - Maxon
- http://test.maxonmotor.com/docsx/Download/catalog_2007/Pdf/07_215_e.pdf
- reduction 5.4:1
- nominal dribbler bar speed = 28200/5.4*1.5 = 7833 RPM. It is, of course, adjustable by software.
