Difference between revisions of "Bucki"

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(→‎Bucki V1.0)
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| Drive Motor Controllers
 
| Drive Motor Controllers
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| HobbyKing Brushless Car ESC 2S-4S
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| HobbyKing Brushless Car ESC 2S-4S (This was based on lessons learned at Motorama. Original ESCs were not Car ESC)
 
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| Weapon Motor
 
| Weapon Motor
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====Design Overview====
 
====Design Overview====
−
The chassis for Apachi had to solve a couple of problems. First, it had to be contained within the bounding circle made by the bent bar weapon. Second, the chassis needed to securely hold the weapon due to the high loads from our large moment arm. Third, we wanted to have easy access to the foot modules in order to troubleshoot problems.
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====Design Decisions====
 
====Design Decisions====
−
*For the first problem, the geometry of our feet had a large impact on our chassis shape. our feet were long straight lines that we wanted as far as we could get to the outside. We considered making a plus shaped chassis to maximize our space, but were concerned it would increase our wobble which would be especially bad because of our weapon hitting the ground. We chose a rectangular design.
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*In order to secure the weapon, we added two steel supporting bars to hold the weapon shaft. We don't have much evidence that this worked because our weapon snapped every time we hit something full force, but these supports did not fail.
 
−
 
 
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*In order to access our feet modules, we considered two options. The first option was to create a modular bounding box that could easily connect or be replaced. This would require a more complex interface between the module and the internal drive motor and geartrain. The main benefit of this is the plug-and-play nature leading to easy swaps. The second option, which we opted for, was to primarily focus on the side plates being easily removable and the feet accessible from there. While this meant the robot would be down whenever we needed to access the feet, it simplified the rest of the design and number of parts.
 
  
 
====Evaluation====
 
====Evaluation====
−
Some main chassis takeaways from our experience were:
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BLANK
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*Pre-planning electronics could have saved a lot of pain
 
−
*Integrating a center bar with a shuffler heavily constrains design
 
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*Using nonstandard dimensions to save a tiny amount of weight is annoying during machining
 
−
*It is worth double checking electronics hole dimensions
 
  
 
=== Drive Assembly ===
 
=== Drive Assembly ===
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====Design Decisions====
 
====Design Decisions====
−
There were none.
+
We made the incorrect assumption that our drive ESCs were reversible. That was not true, and even further we did not learn this until <i>AT</i> Motorama.  
  
 
====Calculations====
 
====Calculations====
−
[https://drive.google.com/file/d/1180Qxw9OBa18za8L7Cr7c5LujhyiaMad/view?usp=sharing Link to spreadsheet]
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We only matched the supported output ampage to the max current draw of our drive motors. Physical dimensions were the most relevent to our calculations.
−
Our calculations showed that a 4 foot design would be very slightly better, but we opted for the 6 foot design because we thought that the hex shaft would be easier to machine
 
  
 
====Evaluation====
 
====Evaluation====
−
*The shuffler drive worked a lot better than expected. Its mobility and controllability were much better than initially thought, and our weapon choice in hindsight did not need to be so driven by our perceived lack of mobility. The cam manufacturing was harder than expected. Due to the thickness of the cams and the necessary straightness of the hex cutouts, the Invention Studio’s 5 axis waterjet was required, including testing and cutting with an angle to compensate for the taper. In future designs, looking into EDMing the cams would be a good idea. The manufacturing of the hex shafts was also difficult, due to the rotating hex the tools took a lot of stress until the points were turned away. Looking back, a design with 4 feet per side could have also been used. While complicating parts, its weight savings, bearing savings, and potential easing of manufacturing would potentially be beneficial. Overall, the design exceeded expectations, while the manufacturing could have been optimized.
+
BLANK
 +
 
 +
===Weapon Assembly===
 +
====Overview====
 +
BLANK
  
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*As for performance in competition, the vibration caused by the drive system during competition caused screws to come loose very often. Systems using shufflers in the future should attempt to minimize screws for other fastening methods when possible.
+
====Design Decisions====
 +
BLANK
  
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*When adding additional weight on top of Apachi, it was determined that Apachi could drive with up to a total of 45-50 pounds. (insufficient)
+
====Calculations====
 +
BLANK
  
 +
====Evaluation====
 +
BLANK
  
−
===Weapon Assembly===
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===Electronics===
 
====Overview====
 
====Overview====
−
Apachi utilized an overhead bent bar weapon, which is a bar situated above the robot with bent sections that would descend toward the floor to a level where it could strike other robots. Advantages of this style of weapon are a high moment arm, 360 degree strike area, and potential to act as armor in the event of a hit. Disadvantages are a high mass arm requiring reinforcement at the point of rotation, non invertibility of the weapon, and a tall system. The weapon transmission consisted of an outrunner motor with a V belt and pulley, which interfaced with a pulley on a central shaft held by a key and set screw. The central shaft attached to the weapon through another key.
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BLANK
  
 
====Design Decisions====
 
====Design Decisions====
−
The selection of an overhead bar was due to the unknown mobility of our shuffler module. With our ability to move and have our weapon facing the opponent in question, it was decided to make up for the potential vulnerability with a weapon that was dangerous from all sides. A ring was discarded due to the rectangular nature of shuffle modules, and an overhead bar was selected as a weapon. The lack of invertibility was not considered a problem. The weapon transmission system was largely designed around space concerns, with the outrunner motor having its pulley mounted on top and using keys and set-screws instead of profiles for more robust connections.
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BLANK
  
 
====Calculations====
 
====Calculations====
−
Get angry at Cory and make him fill this in
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BLANK
 +
 
 
====Evaluation====
 
====Evaluation====
−
Multiple weaknesses made it into the design that ultimately resulted in catastrophic failure at multiple points. Specific design failures were selection of a weapon that required stable movement, as the overhead bar (even with a half inch of clearance) would impact the ground due to how a shuffler moves, and massive underestimation of the forces involved with such a high moment weapon. The main drive shaft proved to be too thin to handle the impact of the weapon, and there wasn't enough reinforcement to the connection point between the shaft and weapon to absorb the impact, resulting in the bending of the exposed section of shaft (roughly 0.5”) and the fracture of the weapon. Another point of failure was the level of hardening to the weapon; the bar was over hardened to withstand the subjected forces, resulting in fractures originating in the keyway of the shaft. The key of the shaft itself surprisingly survived the impacts, as it was believed that would be the point of failure. The weapon transmission also presented some weaknesses, with the double set screw attachment on the weapon motor a decision made out of necessity as opposed to being a robust connection. Overall the weapon system had some major design flaws that were not caught or excused due to the design constraints already in place. In a new iteration a new weapon design would be recommended.
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BLANK
  
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When a flail becomes a viable alternative, you have made a <strike>mistake</strike> beautiful robot
+
=== Pneumatics ===
  
−
===Electronics===
+
====Design Overview====
−
====Overview====
+
As a flipper, Bucki launches its opponents into the air using rapid, impulsive force. To this end, it utilizes a liquid CO2 system to power an air cylinder and actuate its flipping motion. The liquid CO2 is stored in pre-filled 20 gram cartridges, which are inserted into a specialty regulator to reduce the operating pressure to an amount manageable by the most fragile elements of the design.
−
Apachi’s electrical system consisted of two 4 cell lithium polymer batteries, two brushless electronic speed controllers (ESCs) designed for RC cars which controlled the drive motors, and a different brushless ESC which controlled the weapon motor. The circuits for the weapon system and the drive system were isolated with each having its own battery and power switch. There was also a receiver which sent pwm signals to the speed controllers.
+
 
 +
Upon exiting the regulator, the decompressed CO2 is held upstream of a 3 port/2 state solenoid valve, which allows for intake of air into the piston and exhaust following the end of its stroke. This solenoid is controlled using signals from a standard RC controller interpreted by a microcontroller.
 +
 
 +
Also upstream of the solenoid valve, the system features a bleed valve to empty the system following operation and a pressure gauge to monitor the regulator’s output. These components are connected with a variety of connectors and lengths of tubing.
 +
 
 +
A full component list can be found in the safety documentation below.
 +
 
 +
[[File:BuckiPneumaticSystem.png|thumb|center|400px|Bucki Pneumatics Diagram]]
  
 
====Design Decisions====
 
====Design Decisions====
−
Multiple batteries were used in order to most efficiently utilize the space inside of the robot while providing the large current required by the motors. RC car ESCs were selected for the drive motors due to their ability to run motors in reverse which is not a standard feature of brushless ESCs. The ability to reverse was not necessary for the weapon so a standard ESC was chosen. The specific voltage, capacity, and maximum current for the batteries were determined based on the drive and weapon calculation spreadsheets discussed earlier. The ESC specifications were determined based on the voltage of the batteries and the maximum current draw of the motors.
+
*A liquid CO2 system was chosen for its small form factor and reduced weight relative to the standard HPA design.
 +
**HPA necessitates a larger tank that needs to be recharged, while CO2 cartridges can be switched out rapidly.
 +
**Recharging a HPA tank would require a more powerful air compressor (such as a SCUBA or paintball one) than the ones that are easily available on campus.
 +
**HPA operates at pressures and capacities that are excessive for the other limits imposed on the system.
 +
*The specialty regulator was chosen for its ability to pierce CO2 cartridges and convert their input to a standard NPT size.
 +
*The solenoid valve chosen was decided based on its low weight and size, but other options (such as some valves from Parker) would have been superior in terms of pressure and power.
 +
*Tube adapters were used on components expected to be moved by operators or during weapon actuation (piston, gauge and regulator).
 +
*The system was primarily constrained by weight and size and would've been better served with a larger piston and greater pressure.
 +
*NERC rules were relatively loose, but they required the use of a gauge and a method to bleed the system.
 +
*Liquid CO2 when decompressing to a gaseous state undergoes an endothermic reaction that rapidly cools the components and reduces the tank pressure.
  
 
====Calculations====
 
====Calculations====
−
See the other calculation sections
+
I need to go hunt these down lmao
  
 
====Evaluation====
 
====Evaluation====
−
Based on the voltage level of the batteries after running for an entire match, they seem to be appropriately specced. More in depth testing was going to be done to determine whether battery specs, and therefore size and weight, could be decreased but these tests were unable to be completed. Additionally there were concerns about the weapon being underpowered due to the inability to spin such a large moment to high speeds. This could potentially be solved by some creative wiring solutions that were going to be tested but again were not. The wiring of this robot was somewhat tricky due to there being many spinning things inside the robot that the wires needed to avoid.
+
*Pneumatics are incredibly difficult at a 12lb weight class according to officials at Motorama, so it existing is kind of impressive.
 +
*The system was able to actuate more than 15 times rapidly without issue.
 +
*It was never used to flip anything and it is still unknown whether it matched the calculation or was sufficiently powerful.
 +
*It had various issues that made assembly difficult:
 +
**Some components did not match spec sheets and required the system to be modified.
 +
**Modifications required deviation from initial placement plan which made fitting system in chassis difficult.
 +
**Chassis had no systems to aid in assembly or constrain parts.
 +
*Future robots using pneumatics should use HPA at a higher weight class.
 +
 
 +
====Links====
 +
[https://docs.google.com/document/d/1vJr__bwY3fGl827ZOihG8hrwaWbd_oc0wv8mEKBof2Q/edit?usp=sharing Safety Documentation]
  
 
= See also =
 
= See also =
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<span style="line-height: 20.7999992370605px">Naming Inspiration: Nothing good; should've been Topsi Turvi</span>
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<span style="line-height: 20.7999992370605px">Naming Inspiration: Metal arm similar to the Marvel character Bucki, also bucks other bots like a rodeo bull; should've been Topsi Turvi</span>
  
 
<span style="line-height: 20.7999992370605px">Took least amount of damage of any bot in Motorama history</span>
 
<span style="line-height: 20.7999992370605px">Took least amount of damage of any bot in Motorama history</span>
 +
[[Category:BattleBots]]
 
[[Category:HobbyWeights]]
 
[[Category:HobbyWeights]]
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[[Category:BigBots]]

Latest revision as of 19:27, 28 May 2022

Bucki
(Highlight text)
Year Of Creation 2021-2022
Versions
Current Version V 1.0
Update Year 2021-2022
Wins/Losses 0/2
Information and Statistics
Weight Class Hobbyweight
Weapon Class Pneumatic Flipper
Combined Wins/Losses 0/2
Weapon Speed Around 80000?
Other Never moved lol

Bucki is not the first iteration of a 18 lb Bent Bar Shuffler. Bucki is unfortunately the first iteration of the 12 lb pneumatic flipper. The purpose of this guide is to explain all of the reasoning behind the design decisions during the creation of Bucki. This guide will go in depth on why certain designs were chosen as well as explaining some of the calculations used to support those decisions.

Competitions

Motorama 2022

  • Results:
    • Bracket Style: Double Elimination
      • Loss vs Hocki lmao
        • Bot did not move and we immediately gave up
        • "Victory by intimidation"
      • Loss vs Who Knows?
        • Bot did not fire and we immediately gave up

Bucki V1.0

Created by: Daniel Johnson, Martha Leach, Mesum Zaidi, Natalie Van Slyke, Scott Janssen, Keaton Sadoski, Samuel Alzate, Anthony DeCesaris, Paul Barsa

Drive Motors Turnigy 540L V-Spec Inrunner 810kv
Drive Motor Controllers HobbyKing Brushless Car ESC 2S-4S (This was based on lessons learned at Motorama. Original ESCs were not Car ESC)
Weapon Motor wind
Weapon Motor Controllers YEP 100A (2~6S) SBEC Brushless Speed Controller
Receiver Hobby King 2.4Ghz Receiver 6Ch V2
Remote Control Hobby King 2.4Ghz 6Ch Tx and Rx V2
Battery 2x Turnigy 2200mAh 4S 30C Lipo Pack
(OTHER:) MS-05 Switch

Chassis

Design Overview

BLANK

Design Decisions

BLANK

Evaluation

BLANK

Drive Assembly

Overview

Bucki’s Drive system was not.

Design Decisions

We made the incorrect assumption that our drive ESCs were reversible. That was not true, and even further we did not learn this until AT Motorama.

Calculations

We only matched the supported output ampage to the max current draw of our drive motors. Physical dimensions were the most relevent to our calculations.

Evaluation

BLANK

Weapon Assembly

Overview

BLANK

Design Decisions

BLANK

Calculations

BLANK

Evaluation

BLANK

Electronics

Overview

BLANK

Design Decisions

BLANK

Calculations

BLANK

Evaluation

BLANK

Pneumatics

Design Overview

As a flipper, Bucki launches its opponents into the air using rapid, impulsive force. To this end, it utilizes a liquid CO2 system to power an air cylinder and actuate its flipping motion. The liquid CO2 is stored in pre-filled 20 gram cartridges, which are inserted into a specialty regulator to reduce the operating pressure to an amount manageable by the most fragile elements of the design.

Upon exiting the regulator, the decompressed CO2 is held upstream of a 3 port/2 state solenoid valve, which allows for intake of air into the piston and exhaust following the end of its stroke. This solenoid is controlled using signals from a standard RC controller interpreted by a microcontroller.

Also upstream of the solenoid valve, the system features a bleed valve to empty the system following operation and a pressure gauge to monitor the regulator’s output. These components are connected with a variety of connectors and lengths of tubing.

A full component list can be found in the safety documentation below.

Bucki Pneumatics Diagram

Design Decisions

  • A liquid CO2 system was chosen for its small form factor and reduced weight relative to the standard HPA design.
    • HPA necessitates a larger tank that needs to be recharged, while CO2 cartridges can be switched out rapidly.
    • Recharging a HPA tank would require a more powerful air compressor (such as a SCUBA or paintball one) than the ones that are easily available on campus.
    • HPA operates at pressures and capacities that are excessive for the other limits imposed on the system.
  • The specialty regulator was chosen for its ability to pierce CO2 cartridges and convert their input to a standard NPT size.
  • The solenoid valve chosen was decided based on its low weight and size, but other options (such as some valves from Parker) would have been superior in terms of pressure and power.
  • Tube adapters were used on components expected to be moved by operators or during weapon actuation (piston, gauge and regulator).
  • The system was primarily constrained by weight and size and would've been better served with a larger piston and greater pressure.
  • NERC rules were relatively loose, but they required the use of a gauge and a method to bleed the system.
  • Liquid CO2 when decompressing to a gaseous state undergoes an endothermic reaction that rapidly cools the components and reduces the tank pressure.

Calculations

I need to go hunt these down lmao

Evaluation

  • Pneumatics are incredibly difficult at a 12lb weight class according to officials at Motorama, so it existing is kind of impressive.
  • The system was able to actuate more than 15 times rapidly without issue.
  • It was never used to flip anything and it is still unknown whether it matched the calculation or was sufficiently powerful.
  • It had various issues that made assembly difficult:
    • Some components did not match spec sheets and required the system to be modified.
    • Modifications required deviation from initial placement plan which made fitting system in chassis difficult.
    • Chassis had no systems to aid in assembly or constrain parts.
  • Future robots using pneumatics should use HPA at a higher weight class.

Links

Safety Documentation

See also

  • [(link to other bot made this year) (Name of other bot made this year)]

Notes:

Naming Inspiration: Metal arm similar to the Marvel character Bucki, also bucks other bots like a rodeo bull; should've been Topsi Turvi

Took least amount of damage of any bot in Motorama history

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