Difference between revisions of "Team 1640 2010 Summer Program"

From DEW Robotics
Jump to: navigation, search
(Mirror photo gallery)
(8-August)
 
(45 intermediate revisions by 4 users not shown)
Line 1: Line 1:
 +
[[Image:DB6_Paul_100711_csm.jpg|350px|right|thumb|Paul & [[DEWBOT VI]]]]
 
==Objectives==
 
==Objectives==
 
Objectives for the 2010 Summer Program are focused on our desire to perform well at IRI. Towards this end, we are:
 
Objectives for the 2010 Summer Program are focused on our desire to perform well at IRI. Towards this end, we are:
Line 47: Line 48:
  
 
==Possessor==
 
==Possessor==
We've got a adequate possessor for demonstrations.  At [[DEWBOT VI PARC XIII | PARC]], [[DEWBOT VI Monty Madness | Monty Madness]] and [[DEWBOT VI Bridgewater Battle | (BR)<sup>2</sup>]], we were dissatisfied with our possessor's performance.  While it seemed to perform well enough at the [[STEM Defined]] demonstration, in the heat of competition, it tends to either fail to possess the ball, or to cause or allow the robot to drive over the ball.  We really cannot effectively herd balls into the goal either (because of a tendency to drive over them).  This is an area which needs work for IRI. Options seem to be:
+
At [[DEWBOT VI PARC XIII | PARC]], [[DEWBOT VI Monty Madness | Monty Madness]] and [[DEWBOT VI Bridgewater Battle | (BR)<sup>2</sup>]], we were dissatisfied with our possessor's performance.  While it seemed to perform well enough at the [[STEM Defined]] demonstration, in the heat of competition, it tends to either fail to possess the ball, or to cause or allow the robot to drive over the ball.  We really could not effectively herd balls into the goal either (because of a tendency to drive over them).  This was addressed for IRI. Original options included:
 
:# A vacuum possessor (like Team 25's)
 
:# A vacuum possessor (like Team 25's)
 
:# A Possessor with a low roller
 
:# A Possessor with a low roller
:# Adapt the possessor to grab the ball by pinching it (without lifting it off the floor) rather than just applying a backwards spin
+
:# Adapt the possessor to grab the ball by pinching it (without lifting it off the floor) rather than just applying a backwards spin. [In virtually all benchmarking cases, this involves a low roller/bar anyway.]
  
 
===Vacuum Possessor===
 
===Vacuum Possessor===
 
:Preliminary analysis in Inventor indicates that it is feasible to accommodate a vacuum-type possessor similar to Team 25's in the DEWBOT VI chassis.  The driver would have to accurately center the ball.  Analysis and design were not pursued past this point.
 
:Preliminary analysis in Inventor indicates that it is feasible to accommodate a vacuum-type possessor similar to Team 25's in the DEWBOT VI chassis.  The driver would have to accurately center the ball.  Analysis and design were not pursued past this point.
  
===Low roller Possessor===
+
===Low Roller Possessor===
:We've observed that robots with effective possessors often have passive rollers at or below the ball centerpoint.  Installing such a low roller on DEWBOT VI without a major redesign is not trivial.  Key challenges are:
+
:We've observed that robots with effective possessors often have passive rollers at or below the ball centerpoint.  Installing such a low roller on DEWBOT VI without a major redesign was not trivial.  Key challenges were:
 
::# Avoiding interference with the kicker
 
::# Avoiding interference with the kicker
 
::# Avoiding interference with the pivots
 
::# Avoiding interference with the pivots
Line 62: Line 63:
  
 
===Trirol Possessor Design===
 
===Trirol Possessor Design===
:A possessor was designed having an articulated, low, 3<sup>rd</sup> roller.
+
:A possessor was designed having an articulated, low, 3<sup>rd</sup> roller. Kicking clearance requires some non-structural kicker modification. Articulation is needed to clear the bump. For full specifications, see [[DEWBOT VI Possessor Development#Trirol Possessor Design | Trirol Possessor Design Specifications]] and [[media:Dewbot_VI_new_possessor.pdf | Detailed Drawings]].<br>
::* The low roller is a ½" steel rod (like the middle roller)
 
::* The low roller is set in needle (roller) bearings for free rotation
 
::* The low roller articulates by pivoting forward and up out of the way for bump crossing.
 
::* Two 3/4" diameter x 4" stroke pneumatic cylinders provide the actuation. Both run from a single solenoid.  Restrictor valves will need to be installed on the solenoid vents.
 
::* A hard stop is provided for the possessor in the lowered, working position (the design does not rely on the pneumatic cylinders to provide this stop).  This hard stop is necessarily quite close to the pivot axis.
 
::* While rotating between the deployed and retracted states, the low possessor assembly does not break the frame perimeter.
 
::* It is proposed that the low possessor will automatically retract when the operator relaxes the kicker to cross a bump; and automatically deploy when the kicker is armed; normal kicking will not change the possessor state.
 
::* In addition, it is likely that the combination of reversing the driven possessor and retracting the lower possessor roller would be a useful, low-velocity means to positively eject balls into the goal from the goal's ramp (without having to drive the robot entirely into the goal).
 
::* The kicker is modified by having its lower portions cut away so that it clears over the 3<sup>rd</sup> roller.
 
 
 
 
As designed, this is a back-rolling possessor, not a pinching possessor.  It could in principle be converted to a pinching possessor if the low roller bearings were removed or disabled.
 
As designed, this is a back-rolling possessor, not a pinching possessor.  It could in principle be converted to a pinching possessor if the low roller bearings were removed or disabled.
 
View the [[media:Dewbot_VI_new_possessor.pdf | detailed drawings]].
 
  
 
<gallery widths=250 heights=250 perrow=3>
 
<gallery widths=250 heights=250 perrow=3>
Line 88: Line 77:
 
Image:DB6_new_possessor_close_3.jpg|Kicker close approach to 3<sup>rd</sup> roller - 3/3 - maximum extension
 
Image:DB6_new_possessor_close_3.jpg|Kicker close approach to 3<sup>rd</sup> roller - 3/3 - maximum extension
 
</gallery>
 
</gallery>
 
+
====Testing====
===Prototype Testing===
 
 
:[[image:DB6_3rd_roll_prototype_100630_csm.jpg|400px|right|thumb|3rd roll prototype installed on [[DEWBOT VI]]]]At Jon Davis's suggestion, a fixed 3<sup>rd</sup> roll prototype was installed and tested on 30-June.  Key observations:
 
:[[image:DB6_3rd_roll_prototype_100630_csm.jpg|400px|right|thumb|3rd roll prototype installed on [[DEWBOT VI]]]]At Jon Davis's suggestion, a fixed 3<sup>rd</sup> roll prototype was installed and tested on 30-June.  Key observations:
 
::* Possession performance appears unaffected by the 3<sup>rd</sup> roller - poor-to-mediocre
 
::* Possession performance appears unaffected by the 3<sup>rd</sup> roller - poor-to-mediocre
Line 99: Line 87:
 
:Adding friction tape to the bottom roller resulted in no observable improvement.
 
:Adding friction tape to the bottom roller resulted in no observable improvement.
  
===Hi/Lo Roller Pinching Possessor test===
+
====Hi/Lo Possessor====
:We were planning to replace the middle steel roller with fiberglass, but before installing the fiberglass rod, we tested the possessor without the middle roller.  This provided a phenomenal improvement in possessing performance.  ''This Hi/Lo 2-roller possessor really works!''  It hangs on to the ball.  The Hi/Lo 2-roller possessor is definitely a pincher. The bottom roller needs to be high-friction and needs to not roll easily (or at all). The bottom roller also needs to be stiff (so steel is better than fiberglass).  No ball overdriving problem. The possessor will lose the ball if the ball touches the Ball Dam Gusset on either side. Transverse driving is therefore a problem if taken too far, but it can also serve to center the ball. We tested filling in the top roll spiral gaps with friction tape, but this had no obvious effect.  Existing spirals are definitely not beneficial (they do not center the ball), but don't seem to hurt performance either.
+
:We were planning to replace the middle steel roller with fiberglass, but before installing the fiberglass rod, we tested the possessor without the middle roller.  This provided a phenomenal improvement in possessing performance.  ''This Hi/Lo 2-roller possessor really works!''  With a stiff (steel, not fiberglass) and frictive Lo Bar, it's definitely a pincher. It makes no attempt to center the ball (but we're ok with that). No ball overdriving problem. Further development produced even better results. We have a Vulcan death grip (and it doesn't just convince the Romulans). The ball goes in. The robot goes forwards, backwards, sideways, slantways, longways, backways, and spinways. The ball stays in--approximately 2.75" but not more than 3", and not off the floor. It passes the ruler test, the paper test, and (most importantly) the Rizzo-the-Ref test. The only way to release the ball is to turn off/run backwards the possessor or kick. We don't even need to reduce the torque, though we can, since the vertical IR ball sensors work. The death grip doesn't visibly affect the kick range or arc (both of which are quite nice). The only way to pick up another ball is to get rid of the first--no way to possess two a once since the first on stop the top roller.<br>
  
 
<gallery widths=250 heights=250 perrow=3>
 
<gallery widths=250 heights=250 perrow=3>
Line 108: Line 96:
 
Image:DB6_Heather_100702_csm.jpg|Heather McKown cutting parts
 
Image:DB6_Heather_100702_csm.jpg|Heather McKown cutting parts
 
Image:DB6_Paul_Kenneth_Siri_DJ_100702_csm.jpg|Paul, Kenneth, Siri Maley & DJ testing the possessor (some more than others)
 
Image:DB6_Paul_Kenneth_Siri_DJ_100702_csm.jpg|Paul, Kenneth, Siri Maley & DJ testing the possessor (some more than others)
 +
Image:DB6_modified_kicker_100711_csm.jpg|Modified kicker
 +
Image:DB6_Maley_applying_friction_tape_100711_csm.jpg|Siri Maley applying friction tape to the lower rod
 +
Image:DB6_possessing_100711_csm.jpg|Robot possessing
 +
Image:DB6_whirling_dervish_100711_csm.jpg|''Whirling Dervish'' - spinning about wheelbase center - we hold on to the ball
 +
Image:DB6_kicking_100711_csm.jpg|Kicking (teleop)
 +
Image:DB6_possessor_right_100711_csm.jpg|Possessor mechanism detail - right
 +
Image:DB6_possessor_left_100711_csm.jpg|Possessor mechanism detail -left
 +
Image:DB6_front_elevation_100711_csm.jpg|Robot front elevation showing possessor (& photographer)
 +
Image:DB6_paper_test_100711_csm.jpg|''We pass the paper test!''
 
</gallery>
 
</gallery>
  
===Back to the Drawing Board (3 & 4-July)===
+
===Back to the Drawing Board (July 3 & 4) - Articulation Redesign===
:The elimination of the middle roller makes access for actuation of the low roller simpler.  Narrowing the top roller is no longer necessary.  A design with this change was started, then abandoned.  The possessor went through two major redesigns in two days.
+
:The elimination of the middle roller made access for actuation of the low roller simpler.  Narrowing the top roller is no longer necessary.  A design with this change was started, then abandoned.  The possessor went through two major redesigns in two days. In addition, our tests make it clear that a great deal of backwards force is applied on the low roller.  The Trirol's low roller mount was not designed with this sort of force in mind.  We therefore needed a more robust approach for the articulated low roller.
 
+
:After prototyping and CAD work, the final design emerged to be vertical retraction actuated by (2) 3/4" diameter x 4" stroke pneumatic cylinders. For full details, see [[DEWBOT VI Possessor Development#Back to the Drawing Board (3 & 4-July) - Articulation Redesign | Hi/Lo Vertical Retraction Details]].
:Our tests make it clear that a great deal of backwards force is applied on the low roller.  The Trirol's low roller mount was not designed with this sort of force in mind.  We therefore need a more robust approach for the articulated low roller.
+
:The kicker still needed to be modified slightly (cut down from 15" to 13"), and the possessor system is effectively narrower. Neither of these significantly limit possessor or kicking.
 
+
:The excessive load on the possessor motor & drive presented some damage issues. Possible solutions pursued included:
:In light of this need for robustness, we started investigating vertical retraction (linear motion) design.  Robust linear motion 80/20 roller wheel assemblies (80/20 part # 2751) were gallantly ''liberated'' from [[DEWBOT IV]].  Mounted on the existing 80/20 kicker spring mounts, a quick prototype test indicated promise.  CAD design and physical prototyping and testing ran together in parallel.  The revised design is simpler, more easily executed and more robust.  Things are still tight and require careful design and fabrication.  Key points:
+
::* Limit current to the motor via a current-based feedback loop (a control/electronic solution)
::* The low roller is no longer intended to roll.  No bearings provided.
+
::* Reduced the frictional coefficient or the normal load between the possessor drive belt and either the motor pulley or the possessor tube, turning this into a ''poor man's clutch''.
::* The (2) 3/4" diam x 4" stroke pneumatic cylinders will still be employed (they have already shipped, so this is good)
+
The first option requires implementing CAN. We did switch the possessor motor from a Victor to a black Jag, but development stopped there given the complexities in adding CAN at this point. The second option proved more practical provided the final solution. Looser polycord belts (from 8% reduction to 6%) reduced the normal loads. Adding friction tape to the motor pulley (in addition to the Lo Bar) increased the pulley-belt frictional coefficient relative to the Hi Roller-belt coefficient, inducing the belt to slip only on the Hi Roller. This is also much less taxing on the polycord.
::* The actuators will act in the direction of linear motion.  Actuators will be hard-mounted (not pivoting).
 
::* Actuator mounts are moderately complex and must be welded to the chassis frame
 
::* The low roller is further forward and, when lowered, expected to occupy a lower position than the Trirol low roller
 
::* The height of the low roller will be mechanically adjustable
 
::* When retracted, the low roller mechanism will be entirely within the ball dam gusset envelope and therefore protected from impact with the bump
 
::* The kicker width will be reduced from 15" to 13".  The cutting of the lower extremities of the possessor for clearance will be less extreme than for the Trirol design
 
::* The pinching design puts a lot of stress on the possessor drive motor and the polycord drive belts.  We destroyed the original motor in testing.
 
 
 
:Regarding the last of these points (the excessive load on the possessor motor & drive):
 
::* Our first thought was to limit current to the motor via a current-based feedback loop (a control/electronic solution)
 
::* but an alternative approach would be to reduce the friction coefficient or the normal load between the possessor drive belt and either the motor pulley or the possessor tube, turning this into a ''poor man's clutch''. This would continue to apply pinching force while at the same time avoiding motor stall, motor burn-out, excessive battery drain, and polycord melting. for example:
 
:::* reducing polycord tension by slightly increasing the belt length would reduce normal loads; while
 
:::* a different surface on either the pulley or possessor tube could reduce the friction coefficient;
 
:::* this approach could allow us to keep unloaded possessor velocity high, provide force for pinching; preserve the motors and drive parts; save battery power; and limit force on the low roller.
 
 
 
:The Possessor is effectively narrower.
 
  
 
:Additionally, benchmarking of other successful bottom rollers (which neither roll nor facilitate rolling) revealed an inordinate number of teams using 1/2" angle. Prototyping (with aluminum) seems to reveal why. The ball tends to roll (and thus fall out) much less than with even the misnamed bottom roller bar, and holds somewhat better in snake and much better in strafing. (Strafing is a beneficial aspect of our drivetrain could prove ''very'' helpful on defense against a certain looper bot at IRI.) The system isn't yet to death-grip standard, but I (Siri) wouldn't be overly surprised if changing the roller(s) surface(s) and/or speed (recommended at 2x robot speed) got us quite close.
 
:Additionally, benchmarking of other successful bottom rollers (which neither roll nor facilitate rolling) revealed an inordinate number of teams using 1/2" angle. Prototyping (with aluminum) seems to reveal why. The ball tends to roll (and thus fall out) much less than with even the misnamed bottom roller bar, and holds somewhat better in snake and much better in strafing. (Strafing is a beneficial aspect of our drivetrain could prove ''very'' helpful on defense against a certain looper bot at IRI.) The system isn't yet to death-grip standard, but I (Siri) wouldn't be overly surprised if changing the roller(s) surface(s) and/or speed (recommended at 2x robot speed) got us quite close.
Line 154: Line 135:
 
</gallery>
 
</gallery>
  
===Hi/Lo Possessor Installation & Testing===
+
===Final Designing Photo Gallery===
:''Tempus fugit!.''  Only a week and a bit before IRI!  Time to finish our work and test it all out.
 
 
 
:Almost like a week taken from build season. 
 
 
 
:Mother nature played a little joke on 10-July.  Morning rain was so intense that it flooded the robot shop via the outside door (at the bottom of a ramp).  Fortunatly, we arrrived at the start of the flood and were ably to stay ahead of the water, so no damage was done.  We pulled over 30 gallons of water off the shop floor.  Opportunity was taken to organize the shop.
 
 
 
 
<gallery widths=250 heights=250 perrow=3>
 
<gallery widths=250 heights=250 perrow=3>
 
Image:DB6_Heather_cutting_metal_100706_csm.jpg|Heather cutting possessor actuator mount
 
Image:DB6_Heather_cutting_metal_100706_csm.jpg|Heather cutting possessor actuator mount
Line 171: Line 146:
 
Image:DB6_possessor_&_actuators_100707_csm.jpg|Possessor installed with pneumatic actuators & plumbing
 
Image:DB6_possessor_&_actuators_100707_csm.jpg|Possessor installed with pneumatic actuators & plumbing
 
Image:DB6_possessor_work_team_100707_csm.jpg|Possessor work team
 
Image:DB6_possessor_work_team_100707_csm.jpg|Possessor work team
Image:DB6_flood_100710_csm.jpg|Flooded robot shop
 
Image:DB4_in_water_100710_csm.jpg|[[DEWBOT IV]] remains in water
 
Image:DB6_Deaver_emptying_shopvac_100710_csm.jpg|Gary Deaver emptying the shopvac
 
Image:DB6_Rizzo_ready_for_the_flood_100710_csm.jpg|Mike Rizzo ready for the flood
 
Image:DB6_Maley_wringing_100710_csm.jpg|Siri Maley wringing water from towels
 
Image:DB6_empty_shop_100710_csm.jpg|Empty shop - ''where's all the junk?''
 
Image:DB6_drying_out_100710_csm.jpg|Shop drying out
 
 
Image:DB6_Matt_Heather_lathe_100710_csm.jpg|Matt & Heather McKown work the lathe
 
Image:DB6_Matt_Heather_lathe_100710_csm.jpg|Matt & Heather McKown work the lathe
Image:DB6_Cole_prepping_cabinet_100710_csm.jpg|Cole prepping the cabinet for painting
 
 
Image:DB6_Douglas_100710_csm.jpg|Douglas changing possessor belts
 
Image:DB6_Douglas_100710_csm.jpg|Douglas changing possessor belts
 
Image:DB6_Jen_lathe_100710_csm.jpg|Jen turning a spare possessor rod on the lathe
 
Image:DB6_Jen_lathe_100710_csm.jpg|Jen turning a spare possessor rod on the lathe
 
Image:DB6_Possessor_lathe_100710_csm.jpg|spare possessor rod on the lathe
 
Image:DB6_Possessor_lathe_100710_csm.jpg|spare possessor rod on the lathe
Image:DB6_ready_to_paint_100710_csm.jpg|Matt & Faith McKown with cabinet ready to paint
 
 
Image:DB6_Deaver_Rizzo_Maley_100710_csm.jpg|Gary Deaver, Mike Rizzo & Siri Maley with robot
 
Image:DB6_Deaver_Rizzo_Maley_100710_csm.jpg|Gary Deaver, Mike Rizzo & Siri Maley with robot
 
Image:DB6_possessing_100710_csm.jpg|robot possessing
 
Image:DB6_possessing_100710_csm.jpg|robot possessing
Image:DB6_Ben_Paul_100710_csm.jpg|Ben & Paul
+
</gallery>
Image:DB6_modified_kicker_100711_csm.jpg|Modified kicker
+
 
Image:DB6_Maley_applying_friction_tape_100711_csm.jpg|Siri Maley applying friction tape to the lower rod
+
===Testing & Driving Practice (12-July)===
Image:DB6_possessing_100711_csm.jpg|Robot possessing
+
We encountered several problems during driver practice & testing on 12-July. View the night's log [[DEWBOT VI Possessor Development#Meeting Logs: Hi/Lo Possessor Installation & Testing#12-July Update | here]]. In summary, we've got some practicing to do. Most of the work will focus around increasing competency with the new possessor, practicing 2 robot (thanks, DEWBOT V) interactions on defense and offense, and addressing any maintenance issues that arise (including training the pit crew).
Image:DB6_whirling_dervish_100711_csm.jpg|''Whirling Dervish'' - spinning about wheelbase center - we hold on to the ball
+
<gallery widths=250 heights=250 perrow=3>
Image:DB6_kicking_100711_csm.jpg|Kicking (teleop)
+
Image:DB6_drive_teams_100712_csm.jpg|Drive teams at practice
Image:DB6_possessor_right_100711_csm.jpg|Possessor mechanism detail - right
+
Image:DB6_Nichole_Jack_100712_csm.jpg|Nicole & Jack
Image:DB6_possessor_left_100711_csm.jpg|Possessor mechanism detail -left
+
Image:DB6_Kenneth_Ben_100712_csm.jpg|Kenneth & Ben
Image:DB6_front_elevation_100711_csm.jpg|Robot front elevation showing possessor (& photgrapher)
+
</gallery>
Image:DB6_Paul_100711_csm.jpg|Paul & [[DEWBOT VI]]
+
 
Image:DB6_paper_test_100711_csm.jpg|''We pass the paper test!''
+
===Post-IRI (28-July)===
 +
We persued the action plan from the [[DEWBOT VI IRI Post-Mortem | IRI Post-Mortem]] to further improve the possessor.
 +
:* Replaced broker cylinder
 +
:* Replaced standard clevises with ball joint rod ends to provide additional degrees of freedom thereby reducing the prospect of bending cylinder rods or binding action
 +
:* Replaced 80/20 roller brackets with Kellom-custom 4-wheel keyed brackets
 +
:* Installed ½" ID latex tubing on bottom rod in lieu of friction tape
 +
:* Installed Deaver magnetic clutch in lieu of crude belt-tension friction "clutch" on possessor drive
 +
 
 +
<gallery widths=250 heights=250 perrow=3>
 +
Image:DB6_mechanical_100728_csm.jpg|Mechanical team working on possessor
 +
Image:DB6_mag_clutch_100728_csm.jpg|Deaver's magnetic clutch on possessor motor/gearbox
 +
Image:DB6_possessor_bracket_100728_csm.jpg|Kellom's possessor bracket - designed to replace (2) 80/20 brackets and thereby eliminate bracket canting & binding.  Bracket back has key fitting tight into 80/20 slot, assuring alignment.
 +
</gallery>
 +
 
 +
The magnetic cluch created a lot of vibration, which keeps the possessor from working.  We will continue development and test again next week.
 +
 
 +
===4-August===
 +
Gary Deaver revised the magnetic clutch by adding a 2<sup>nd</sup> drive disk with magnets out of phase with the 1<sup>st</sup> drive disk.  The thought was that this arrangement would reduce possessor roller vibrations to the point where the possessor would work.  This modification was ineffective and we went back to the crude friction clutch used at IRI.
 +
 
 +
The issue is that disengagement of the magnets (slippage of the clutch) forces a short period of reverse direction drive before the clutch magnets reengage at the next coupling.
 +
 
 +
A plate type friction clutch would work. The problem with friction clutches is heat and wear. Also we only have a 1.5 x 1.5" cylinder to fit it into. For now the slipping belts will have to do.
 +
 
 +
<gallery widths=250 heights=250 perrow=3>
 +
Image:DB6_Deaver_Garrison_100805_csm.jpg|Gary Deaver & Garrison installing revised magnetic clutch
 +
Image:DB6_mag_clutch_100805_csm.jpg|Deaver's magnetic revised clutch on possessor motor/gearbox
 +
Image:DB6_drive_disk_100804_csm.jpg|2<sup>nd</sup> clutch drive disk
 
</gallery>
 
</gallery>
  
Line 218: Line 210:
  
 
====11-July Update====
 
====11-July Update====
We've loosened the second latex tube to prevent the mirror from re-extending outside the frame perimeter. We've also added a simple latch (a deliberately damaged wire tie to allowed unlatching) to hold the mirror down during maintenance. The mirror is not raised during autonomous, though it can start up. Retrospectively, the servo placement makes bumper wingnut and lifting handhold access a bit more complicated. (The non-possessor motor side would have been better.) We'll live, though. We've realized that we've gained some primo advertising real estate on the back of the mirror.
+
We've loosened the second latex tube to prevent the mirror from re-extending outside the frame perimeter. We've also added a simple latch (a deliberately damaged wire tie to allowed unlatching) to hold the mirror down during maintenance. The mirror is not raised during autonomous, though it can start up. Retrospectively, the servo placement makes bumper wingnut and lifting handhold access a bit more complicated. (The non-possessor motor side would have been better.) We'll live, though. We've also realized that we've gained some primo advertising real estate on the back of the mirror, and that we can add a polycarbonate back shield for the same reason. This is good, especially since we'll have to cover up some of the current sponsor logo space with our autonomous tape guides. Plus, this new space is vertical.
  
 
====Mirror photo gallery====
 
====Mirror photo gallery====
Line 226: Line 218:
 
Image:DB6_Matt_Stumpo_Douglas_100704_csm.jpg|Matt, John Stumpo & Douglas working on mirror lift
 
Image:DB6_Matt_Stumpo_Douglas_100704_csm.jpg|Matt, John Stumpo & Douglas working on mirror lift
 
Image:DB6_Douglas_doing_the_math_100704_csm.jpg|Douglas doing the math behind the mirror lift
 
Image:DB6_Douglas_doing_the_math_100704_csm.jpg|Douglas doing the math behind the mirror lift
Image:DB6_servo_talk_100706_csm.jpg|Forster Schucker talks about servos
+
Image:DB6_servo_talk_100706_csm.jpg|Foster Schucker talks about servos
 
Image:DB6_servo_100711_csm.jpg|Working servo lift for mirror!
 
Image:DB6_servo_100711_csm.jpg|Working servo lift for mirror!
 
</gallery>
 
</gallery>
  
==Programming==
+
==Programming Version Control==
 +
Implement and use version control to enhance communication and collaboration.
 
===Programmer Jobs===
 
===Programmer Jobs===
 
#Review the final code specs (below).
 
#Review the final code specs (below).
Line 245: Line 238:
 
#Create a text file in the "wall" directory announcing your presence.  (Hint: You will need to let Mercurial know about the new file by "add"ing it.)
 
#Create a text file in the "wall" directory announcing your presence.  (Hint: You will need to let Mercurial know about the new file by "add"ing it.)
 
#Get your new file to the repository.
 
#Get your new file to the repository.
===Final Functional Specifications for Code===
+
===Photo Gallery===
[[Media:DEWbot VI Controller Map.pdf | Current Driver's Interface File]]<br>
+
<gallery widths=250 heights=250 perrow=3>
Key:<br>
+
Image:DB6_Paul_100704_csm.jpg|Paul writing code
P#=Priority (number), this code is not tested<br>
+
Image:DB6_programming_team_100706_csm.jpg|Programming Team
D#=Done (number), untested (number indicates debug priority order)<br>
+
Image:DB6_Ben_Paul_100710_csm.jpg|Ben & Paul
T=Tested individually, but not in consolidated code<br>
+
Image:DB6_auto_kick_0_100711_csm.jpg|Autonomous kick from far field
W=Working, tested in consolidated code<br>
+
Image:DB6_auto_30_100711_csm.jpg|Autonomous in near field (just prior to kick)
C=Confirmed in competition (but not in not-yet existent IRI consolidated code)
+
Image:DB6_programming_&_CAD_100728_csm.jpg|Programming & CAD teams at work (port-IRI)
====Pre-Match Routine====
+
</gallery>
Update: As of 11 July 2010, 1-3 happens in autonomous.
 
The overall routine does not need to be hard coded, just the individual steps. (Though if you're bored...P6.)<br>
 
1. (C) Calibrate wheels<br>
 
2. (W) Set wheel angles
 
:Home zone, n = 1, implies 30° CW (really cool)
 
:Mid zone, n = 2, implies 9.5° CW (quite possible)
 
:Away zone, n = 3, implies 0° CW (marginally problematic)<br>
 
2. (C) Check if kicker is fully armed (cocking arms down, latch closed, limit switch triggered)
 
:Arm if necessary
 
::Ensure limit switch triggers
 
::(P4) If limit switch still does not trigger<span style="color:red">...</span>
 
3. (W) Extend Lo bar if necessary<br>
 
4. (C) Ensure upstream air pressure is 120 psi (minimum <span style="color:red">xx</span>) and downstream is 60 psi (minimum <span style="color:red">yy</span>)
 
  
====Autonomous====
+
==Shop Organization==
;(W) Forward-Sensor Mode
+
Starting essentially on 10-July, we started reorganizing the shop in earnest. Why 10-July? Well, Mother Nature played a little joke that day. Morning rain was so intense that it flooded the robot shop via the outside door (at the bottom of a ramp).  Fortunately, we arrived at the start of the flood and were ably to stay ahead of the water, so no damage was done.  We pulled over 30 gallons of water off the shop floor.  Opportunity was taken to organize the shop.
1. (C) Link up, turn on<br>
+
<gallery widths=250 heights=250 perrow=3>
2. Prepare robot
+
Image:DB6_flood_100710_csm.jpg|Flooded robot shop
:Check that kicker is armed; arm if necessary
+
Image:DB4_in_water_100710_csm.jpg|[[DEWBOT IV]] remains in water
:Calibrate wheels
+
Image:DB6_Deaver_emptying_shopvac_100710_csm.jpg|Gary Deaver emptying the shopvac
:Set infrared sensors' baselines
+
Image:DB6_Rizzo_ready_for_the_flood_100710_csm.jpg|Mike Rizzo ready for the flood
:Turn on possessor going inwards<span style="color:red">?</span>
+
Image:DB6_Maley_wringing_100710_csm.jpg|Siri Maley wringing water from towels
3. Drive
+
Image:DB6_empty_shop_100710_csm.jpg|Empty shop - ''where's all the junk?''
:Drive forward at <span style="color:red">xx</span> ft/s (current autonomous speed)
+
Image:DB6_drying_out_100710_csm.jpg|Shop drying out
:Read IR sensors
+
Image:DB6_Cole_prepping_cabinet_100710_csm.jpg|Cole prepping the cabinet for painting
4. Wait for one or both values (or the average of several readings) to change by <span style="color:red">yy</span> tolerance
+
Image:DB6_ready_to_paint_100710_csm.jpg|Matt & Faith McKown with cabinet ready to paint
:Do not kick until 0.25s after arming.
+
</gallery>
:If the value doesn't change during autonomous, don't worry.
 
::(P2) Is there a way to know this didn't happen after the fact<span style="color:red">?</span> In order to diagnose the issue if and when we don't kick. This could also be helpful in telop (P3). Initial answer (Paul): Theoretically? don't know, maybe. Now? no so much.
 
5. (C) Fire (unlatch kicker)
 
:Ignore IR sensor values when the kicker is unlatched
 
6. (C) Rearm (raise cocking arms, wait for limit switch to trigger, close latch, lower arms)<br>
 
7. Loop from step 3 to 6 for duration of autonomous
 
:<span style="color:red">Need to confirm</span> we won't run into anything.
 
  
;(W) ''n''-Ball & Angled Drive Autonomous (Default)<br>
+
==Glick - 31-July==
Differentiation is based on pre-set wheel angles and robot & ball placement.<br>
+
Ben Kellom introduced me (Clem) to [http://www.mbglick.com Moses B. Glick LLC] today. Basically a salvage yard in Fleetwood PA (East-nor-east of Reading). Glick specializes in metals, tools and machinery. I picked up six sturdy work benches for our remaining time in DEC and of course our new home. Glick has a wide selection aluminum, steel, stainless steel, nylon,... stock in various sizes and shapes. Sold by weight. Aluminum is $1.50/lb. We should definitely look here before placing orders with our traditional supplier.
1-2. Same as Forward-Sensor. Also in 2:
+
<gallery widths=250 heights=250 perrow=3>
:Read ''n'' switch (specifies number of balls, 1-3, based on starting zone/autonomous plans)
+
Image:DB6_Glick_trailers_100731_csm.jpg|Glick trailers
:(W) Set/confirm wheel angles
+
Image:DB6_Glick_benches_100731_csm_1.jpg|Work benches found
::Home zone, ''n'' = 1, implies 30° CW (really cool)
+
Image:DB6_Glick_pneumatics_100731_csm.jpg|pneumatics trailer
::Mid zone, ''n'' = 2, implies 9.5° CW (quite possible)
+
Image:DB6_Glick_Al_100731_csm.jpg|Aluminum stock
::Away zone, ''n'' = 3, implies 0° CW (marginally problematic)<br>
+
Image:DB6_Glick_machines_100731_csm.jpg|mills
3-6. Same as Forward-Sensor
+
Image:DB6_Glick_benches_100731_csm_2.jpg|Work benches loaded
7. (D4?) Stop 3-6 loop after 1<''n''<3 completions.<br>
+
</gallery>
:Is this really necessary?
 
<span style="color:red">Non-Code:</span> Drive team needs to practice placement of robot and soccer balls. Need to add tape guides.
 
 
 
;(P6) Anti-469<br>
 
Just an idea...<br>
 
1-2. Same as Forward-Sensor<br>
 
2. Move rightward at a 45 degree angle, wedge in the tunnel enough to block to block but not enough to fully cross the line. (Can the line sensors work?)<br>
 
i.e. Do what the mid zone blue robot does [http://www.thebluealliance.net/tbatv/match/2010gl_qf1m1 here]. (The red robot is 469. Blue still lost, but by much less than most did. 11-14 instead of 18-5, 13-0, 21-0, 26-1...)
 
--[[User:Siri|Siri]] 16:17, 8 July 2010 (UTC)
 
 
 
;(P5) Other Nice Versions
 
:Be able to delay the start of driving (step 3).
 
 
 
====(C) Drive Modes====
 
Ability to specify mode.<br>
 
Crab mode: angle all wheels based on arcade joystick input<br>
 
Snake mode: angle back and front wheels sets based on dual arcade joystick inputs<br>
 
Rotate mode: angle wheels to rotate around the front of the robot/ball
 
 
 
====Kicker Modes====
 
Ability to specify mode. (4<span style="color:red">?</span> on Joystick)<br>
 
 
 
;(W) Semi-Auto (default - great!)<br>
 
:1. Wait for broken beam and fire inputs<br>
 
:2. When one happens...
 
::Check that kicker is armed and arm if necessary
 
:::<span style="color:red">Possible Issue:</span> If something triggers the beam break on the bump, the kicker will arm. So maybe don't do this...<br>
 
:3. When the beam breaks...
 
:4. When the beam is broken and the driver has pressed fire...
 
::Wait until at least 0.25s after arming to fire.
 
::Fire
 
::Do not read beam break sensor while the kicker is unlatched<br>
 
:5. Rearm<br>
 
;(C) Manual Override<br>
 
:1. Receive fire input<br>
 
:2. Check that kicker is armed, arm if necessary<br>
 
:3. Fire<br>
 
:4. Rearm<br>
 
;Relax Kicker Routine
 
:1. (W) Retract Lo Bar
 
:2. (C) Relax Kicker: Raise cocking arms, unlatch kicker, lower arms<br>
 
;Arm Kicker Routine
 
:1. (C) Arm Kicker: raise cocking arms, wait for limit switch to trigger, lower cocking arms
 
:2. (W) Check that Lo Bar is extended, extend Lo Bar (or only run extension routine when exiting relaxed mode)
 
 
 
====Possessor Modes====
 
Indicate possessor status: in/out/off and ball possession: ball/no ball on the dashboard throughout telop.<br>
 
Default possessor speed: <span style="color:red">xx</span> f/s<br>
 
(C) Gather & Hold ball: run inwards at <span style="color:red">xx</span> f/s<br>
 
(C) Release ball(s): run outwards<br>
 
(W) Raise Lo bar manually<br>
 
(W) Raise Lo bar when kicker relaxes (see kicker modes)<br>
 
 
 
====Issues/Questions====
 
What we know but should to write down (preferably here):
 
#Minimum starting up- and downstream psi
 
#We need a map of the operator joystick.
 
#Which way did we settle on for the possessor on the xbox: right=in or left=in?
 
#Current drive speed in autonomous<br>
 
What we need to determine
 
#Possessor speed/use in autonomous (can vary by ''n'' switch)
 
#Desired drive speed in autonomous (can vary by ''n'' switch)
 
#When to stop/do we run into anything?
 
#Practice robot and ball placement for all three zones.
 
#Do/when do we want to check the status of the kicker (armed/relaxed), Lo Bar (extended, retracted), wheels (calibration/angles in autonomous), etc? What (processing power, time, etc) does this take?<br>
 
Answered
 
#Possessor intake speed/torque. Answer: 3/4 on joystick.
 
#Possessor holding torque/duty cycle. Answer: None!
 
#Pre-kicking possessor status (do we need to grip it less?) Answer: Nope.
 
 
 
====Item List====
 
;Confirmed in Competition
 
:(Re)Arm kicker
 
:Calibrate wheels
 
:Drive modes (crab, snake, rotate)
 
:Check air pressure
 
:Fire
 
:Gather & hold balls (possessor in, <span style="color:red">need speed</span>)
 
:Link up, turn on
 
:Manual (override) kicking
 
:Relax kicker
 
:Release ball (run possessor outwards, <span style="color:red">need speed</span>)
 
 
 
;Working in Consolidated Code:
 
:Extend Lo Bar manually
 
:Retract Lo Bar manually
 
:Retract Lo bar when kicker relaxes
 
:Extend Lo bar when kicker relaxes
 
:Forward-sensor mode
 
:Semi-auto kicking
 
:''n''-ball & angled drive autonomous
 
:Set wheel angles pre-match
 
:Ignore ''n'' switch after initial reading (ensure a stray ball hitting it does not affect autonomous plans)
 
Also done: pre-programming code into the spare cRio.
 
 
 
;Priority (not done)
 
:2. Procedure to know beam break values during autonomous after the match
 
:3. Procedure to know beam break values during teleop after the match.
 
:4. Procedure if limit switch will not trigger
 
:5. Anti-469 autonomous
 
:5. Hard-coded pre-match routine
 
 
 
===Current Autonomous Critique===
 
Not effective yet.  Main points seem to be:
 
:* Sensor for kicking does not seem to be reliable.
 
:* Angles for off-axis shooting need to be checked.  They appear to shoot off-field is the robot is aligned to drive along the central ball column.  I'll check, but we should test too.
 
:* Keeping in a straight line by blind dead reckoning is often ineffective.
 
:* Keeping the possessor off seems to work better (insofar as something which doesn't work can be said to work better).<br>
 
 
 
:My initial angle calculations for autonomous were incorrect, as observed at (BR)<sup>2</sup>.  ''My bad.''  the real angles can be found (with math) in [[media:DB6_auto_angles.xls | Auto Angles (xls format)]].
 
  
:Without special (BR)<sup>2</sup> rules, reasonable autonomous sequences are:
+
===8-August===
::* Autonomous Near Field - choice of either:
 
:::# Set ball C2-R1
 
:::# Set wheels to 30° CW
 
:::# Set robot to drive down C(olumn)2 (use tape guide on robot top for alignment)
 
:::# Stop after 1 kick (not critical)
 
:::or:
 
:::# Set ball C2-R1
 
:::# Set wheels straight with Calibration (delay is beneficial here)
 
:::# Set robot to drive through ball towards goal
 
:::# Stop after 1 kick (critical)
 
::* Autonomous Mid-Field:
 
:::# Set balls at C2-R1 & C2-R2
 
:::# Set wheels to 9.5° CW
 
:::# Set robot to drive down C2 (using a 2<sup>nd</sup> guide tape)
 
::* Autonomous Far-Field
 
:::# Set balls at C1-R3, C1-R2 & C1-R1
 
:::# Set wheels to 0° (mathematically, this is 2.5° CW, but this proves negligible. Or rather it would, if it didn't appear to confuse the bot.)
 
:::# Set robot to drive down C1
 
 
 
:Where not specified, wheels should be pre-calibrated, wheel angles pre-set, and kicker pre-armed by tether prior to the match.  ''This requires planning with alliance partners before queuing up for the next match.''--[[User:MaiKangWei|Clem]] 1-June-2010
 
::*As of 11 July 2010, we have to set wheel angles in autonomous because wheels won't retain robot orientation without active PID control. <br>
 
 
 
===Version Control===
 
 
 
===Photo Gallery===
 
 
<gallery widths=250 heights=250 perrow=3>
 
<gallery widths=250 heights=250 perrow=3>
Image:DB6_Paul_100704_csm.jpg|Paul writing code
+
Image:DB6_bench_work_100804_csm.jpg|Garrison, Drew & Cole flipping tops on the work benches
Image:DB6_programming_team_100706_csm.jpg|Programming Team
+
Image:DB6_Cole_100805_csm.jpg|Cole & work benches
 +
Image:DB6_benches_100804_csm.jpg|1640's work benches
 
</gallery>
 
</gallery>
 +
  
 
----
 
----
 
Catch up on other team information at [[FRC Team 1640]]
 
Catch up on other team information at [[FRC Team 1640]]
[[Category:Robot]][[Category:DEWBOT VI]][[Category:Photo Galleries]]
+
[[Category:Robot]][[Category:DEWBOT VI]][[Category:Summer Program]][[Category:Photo Galleries]]

Latest revision as of 01:06, 10 August 2011

Paul & DEWBOT VI

Objectives

Objectives for the 2010 Summer Program are focused on our desire to perform well at IRI. Towards this end, we are:

  1. Performing basic maintenance on the robot, especially the drive-train to compensate for the wear and tear of our competitions and demonstrations;
  2. Developing and implementing a possessor which really works;
  3. Getting the control code right & tested, including the angle-drive autonomous; and
  4. Adding a mechanism to raise the mirror.

Necessary Repairs & Maintenance & Drive-Train

Basic maintenance & upgrade work started 2-June and comprised:

  • Pull all pivots. Add spacers between driven sprocket lower 1" bearing. Check condition and refurbish as needed. All treads will need to be changed (they're beat). I will order more treads.
  • Replace Steering Jaguars with Victors and test.
On Wednesday, 2-June, we followed the above plan, without finishing.
  • Pivots removed
  • (4) 0.520" PVC Spacers cut from 1" PVC pipe (we've got miles) - thanks, Douglas & John
  • General cleaning & tread replacement. Steering sprockets pulled from pivots.
  • Drilled holes for Jaguar > Victor switch. We made a template first, so that holes were drilled in the correct spots.
Generally, pivots are in good condition excluding tread wear and carpet fiber accumulation on the transfer axle. No "broken" pivots as at PARC. All steering sprockets are 0.52" above lower bearing (same as model dimension - 0.521") except Pivot #3 at 0.33" (thereby our steering chain problem). Pivot #3 steering sprocket set screws were loose (not quite finger tight).
The Pivot Replacement Process was documented.
On Wednesday, 16-June, we continued:
  • Molly & Garrison joined us - welcome!
  • Steering Jaguars replaced with Victors. All drive Jaguars are black.
  • Pivots 1 & 4 reinstalled. 2 & 3 still in service.
  • PVC spacers installed.
Work was completed on 19-June, just in time for the Upper Uwchlan Block Party.

Possessor

At PARC, Monty Madness and (BR)2, we were dissatisfied with our possessor's performance. While it seemed to perform well enough at the STEM Defined demonstration, in the heat of competition, it tends to either fail to possess the ball, or to cause or allow the robot to drive over the ball. We really could not effectively herd balls into the goal either (because of a tendency to drive over them). This was addressed for IRI. Original options included:

  1. A vacuum possessor (like Team 25's)
  2. A Possessor with a low roller
  3. Adapt the possessor to grab the ball by pinching it (without lifting it off the floor) rather than just applying a backwards spin. [In virtually all benchmarking cases, this involves a low roller/bar anyway.]

Vacuum Possessor

Preliminary analysis in Inventor indicates that it is feasible to accommodate a vacuum-type possessor similar to Team 25's in the DEWBOT VI chassis. The driver would have to accurately center the ball. Analysis and design were not pursued past this point.

Low Roller Possessor

We've observed that robots with effective possessors often have passive rollers at or below the ball centerpoint. Installing such a low roller on DEWBOT VI without a major redesign was not trivial. Key challenges were:
  1. Avoiding interference with the kicker
  2. Avoiding interference with the pivots
  3. Maintaining our ability to cross bumps without difficulty. A low-position roller intrinsically is in the way when climbing a bump

Trirol Possessor Design

A possessor was designed having an articulated, low, 3rd roller. Kicking clearance requires some non-structural kicker modification. Articulation is needed to clear the bump. For full specifications, see Trirol Possessor Design Specifications and Detailed Drawings.

As designed, this is a back-rolling possessor, not a pinching possessor. It could in principle be converted to a pinching possessor if the low roller bearings were removed or disabled.

Testing

3rd roll prototype installed on DEWBOT VI
At Jon Davis's suggestion, a fixed 3rd roll prototype was installed and tested on 30-June. Key observations:
  • Possession performance appears unaffected by the 3rd roller - poor-to-mediocre
  • On the other hand, it is now impossible to override the ball
  • and herding now works very well, possessor on or off
Overall, some small improvement, but not at all what we were hoping for.
Adding friction tape to the bottom roller resulted in no observable improvement.

Hi/Lo Possessor

We were planning to replace the middle steel roller with fiberglass, but before installing the fiberglass rod, we tested the possessor without the middle roller. This provided a phenomenal improvement in possessing performance. This Hi/Lo 2-roller possessor really works! With a stiff (steel, not fiberglass) and frictive Lo Bar, it's definitely a pincher. It makes no attempt to center the ball (but we're ok with that). No ball overdriving problem. Further development produced even better results. We have a Vulcan death grip (and it doesn't just convince the Romulans). The ball goes in. The robot goes forwards, backwards, sideways, slantways, longways, backways, and spinways. The ball stays in--approximately 2.75" but not more than 3", and not off the floor. It passes the ruler test, the paper test, and (most importantly) the Rizzo-the-Ref test. The only way to release the ball is to turn off/run backwards the possessor or kick. We don't even need to reduce the torque, though we can, since the vertical IR ball sensors work. The death grip doesn't visibly affect the kick range or arc (both of which are quite nice). The only way to pick up another ball is to get rid of the first--no way to possess two a once since the first on stop the top roller.

Back to the Drawing Board (July 3 & 4) - Articulation Redesign

The elimination of the middle roller made access for actuation of the low roller simpler. Narrowing the top roller is no longer necessary. A design with this change was started, then abandoned. The possessor went through two major redesigns in two days. In addition, our tests make it clear that a great deal of backwards force is applied on the low roller. The Trirol's low roller mount was not designed with this sort of force in mind. We therefore needed a more robust approach for the articulated low roller.
After prototyping and CAD work, the final design emerged to be vertical retraction actuated by (2) 3/4" diameter x 4" stroke pneumatic cylinders. For full details, see Hi/Lo Vertical Retraction Details.
The kicker still needed to be modified slightly (cut down from 15" to 13"), and the possessor system is effectively narrower. Neither of these significantly limit possessor or kicking.
The excessive load on the possessor motor & drive presented some damage issues. Possible solutions pursued included:
  • Limit current to the motor via a current-based feedback loop (a control/electronic solution)
  • Reduced the frictional coefficient or the normal load between the possessor drive belt and either the motor pulley or the possessor tube, turning this into a poor man's clutch.

The first option requires implementing CAN. We did switch the possessor motor from a Victor to a black Jag, but development stopped there given the complexities in adding CAN at this point. The second option proved more practical provided the final solution. Looser polycord belts (from 8% reduction to 6%) reduced the normal loads. Adding friction tape to the motor pulley (in addition to the Lo Bar) increased the pulley-belt frictional coefficient relative to the Hi Roller-belt coefficient, inducing the belt to slip only on the Hi Roller. This is also much less taxing on the polycord.

Additionally, benchmarking of other successful bottom rollers (which neither roll nor facilitate rolling) revealed an inordinate number of teams using 1/2" angle. Prototyping (with aluminum) seems to reveal why. The ball tends to roll (and thus fall out) much less than with even the misnamed bottom roller bar, and holds somewhat better in snake and much better in strafing. (Strafing is a beneficial aspect of our drivetrain could prove very helpful on defense against a certain looper bot at IRI.) The system isn't yet to death-grip standard, but I (Siri) wouldn't be overly surprised if changing the roller(s) surface(s) and/or speed (recommended at 2x robot speed) got us quite close.
We appear to be having sporadic DS-robot communication malfunctions, both during bootup and randomly mid-test. It'd be great to determine the root cause(s).

Final Designing Photo Gallery

Testing & Driving Practice (12-July)

We encountered several problems during driver practice & testing on 12-July. View the night's log here. In summary, we've got some practicing to do. Most of the work will focus around increasing competency with the new possessor, practicing 2 robot (thanks, DEWBOT V) interactions on defense and offense, and addressing any maintenance issues that arise (including training the pit crew).

Post-IRI (28-July)

We persued the action plan from the IRI Post-Mortem to further improve the possessor.

  • Replaced broker cylinder
  • Replaced standard clevises with ball joint rod ends to provide additional degrees of freedom thereby reducing the prospect of bending cylinder rods or binding action
  • Replaced 80/20 roller brackets with Kellom-custom 4-wheel keyed brackets
  • Installed ½" ID latex tubing on bottom rod in lieu of friction tape
  • Installed Deaver magnetic clutch in lieu of crude belt-tension friction "clutch" on possessor drive

The magnetic cluch created a lot of vibration, which keeps the possessor from working. We will continue development and test again next week.

4-August

Gary Deaver revised the magnetic clutch by adding a 2nd drive disk with magnets out of phase with the 1st drive disk. The thought was that this arrangement would reduce possessor roller vibrations to the point where the possessor would work. This modification was ineffective and we went back to the crude friction clutch used at IRI.

The issue is that disengagement of the magnets (slippage of the clutch) forces a short period of reverse direction drive before the clutch magnets reengage at the next coupling.

A plate type friction clutch would work. The problem with friction clutches is heat and wear. Also we only have a 1.5 x 1.5" cylinder to fit it into. For now the slipping belts will have to do.

Mirror

Looks really good, but we should:

  • Verify that it stays within the frame perimeter.
  • It would be good to have a means of raising it during competition. A servo might be adequate.
  • A working possessor, or a sensor to kick automatically would be a benefit now that we can find the hidden balls.

3-July Update

  • The mirror was moved back 1" to keep it within the frame perimeter (Jen).
  • Initial prototyping and CAD took place for a servo raise/lower mechanism (DJ).

4-July Update

Much effort - little progress. Servos do not appear to have the necessary torque to raise the mirror.

Plan B would be to use a 3/4" pneumatic actuator.

7?-July Update

It works! With a little help from Foster and his VEXing, the servo pushes the mirror up with ease. It does not bring the mirror down. That's ok (in fact, it was in the functional specs), we'd rather have it up. A second latex tube has been added to the other side to prevent torquing.

11-July Update

We've loosened the second latex tube to prevent the mirror from re-extending outside the frame perimeter. We've also added a simple latch (a deliberately damaged wire tie to allowed unlatching) to hold the mirror down during maintenance. The mirror is not raised during autonomous, though it can start up. Retrospectively, the servo placement makes bumper wingnut and lifting handhold access a bit more complicated. (The non-possessor motor side would have been better.) We'll live, though. We've also realized that we've gained some primo advertising real estate on the back of the mirror, and that we can add a polycarbonate back shield for the same reason. This is good, especially since we'll have to cover up some of the current sponsor logo space with our autonomous tape guides. Plus, this new space is vertical.

Mirror photo gallery

Programming Version Control

Implement and use version control to enhance communication and collaboration.

Programmer Jobs

  1. Review the final code specs (below).
  2. Communicate and distribute assignments. Ensure team knows what you are working on and when your draft will be done.
  3. Indicate on meeting work plans what you will be doing during the meeting. Check off items (and upload your code) when you complete them.
  4. Use the Mercurial version control. Ensure versions are kept up-to-date and well labeled. Store code locally before competition (don't rely on internet at competition venues).
  5. Write, debug, and comment (describe how it works, possible issues/changes, etc) on your code.
  6. Ask questions as needed.
  7. Meet your deadlines and/or inform the team of issues.
  8. Inform the design team/meeting management what you need to test your code and how long you think it will take.
  9. Consolidate individual assignments into a single code body. Upload and test this as well.

Current Mercurial Assignment

  1. Create a local working copy of the repository on your own computer.
  2. Create a text file in the "wall" directory announcing your presence. (Hint: You will need to let Mercurial know about the new file by "add"ing it.)
  3. Get your new file to the repository.

Photo Gallery

Shop Organization

Starting essentially on 10-July, we started reorganizing the shop in earnest. Why 10-July? Well, Mother Nature played a little joke that day. Morning rain was so intense that it flooded the robot shop via the outside door (at the bottom of a ramp). Fortunately, we arrived at the start of the flood and were ably to stay ahead of the water, so no damage was done. We pulled over 30 gallons of water off the shop floor. Opportunity was taken to organize the shop.

Glick - 31-July

Ben Kellom introduced me (Clem) to Moses B. Glick LLC today. Basically a salvage yard in Fleetwood PA (East-nor-east of Reading). Glick specializes in metals, tools and machinery. I picked up six sturdy work benches for our remaining time in DEC and of course our new home. Glick has a wide selection aluminum, steel, stainless steel, nylon,... stock in various sizes and shapes. Sold by weight. Aluminum is $1.50/lb. We should definitely look here before placing orders with our traditional supplier.

8-August



Catch up on other team information at FRC Team 1640