Event Tutorial : Inferno

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Let us see the basic problem statement :

 “  Build a manually controlled robot or a group of robots which can retrieve people (cylinders) from buildings affected by fire, bring them to the safety zone and fight fire. The tasks include those done by a normal fire rescue team.  “

In effect, your robot needs to have the following abilities:

→ Locomotion
→ Extension (Optional)
→ Collection
→ Storing (Optional)
→ Extinguish [Fire]

Before we start, here’s the key idea behind this tutorial:

“Keep it simple and sturdy”

How this Tutorial works :

This is not a step - by - step "How To Make a Firefighter Bot" tutorial but a guide for an enthusiast like you to explore your own imagination and make the ultimate HERObot. The tutorial lists out all the skills that the event requires your bot to have and tells you exactly how you can implement each of them. Look out for the words in blue because they will lead you to external pages which show exactly how to build that particular mechanism. And finally, find our ‘Tips’ to gather up all your mechanisms onto the drive base and build a winning robot!

In case you have specific doubts you need answered, we have a Forum where we'd love to hear from you.

Getting Started

And Then Troubleshooting:

To win the day,  you have to build a winning “ROBOT”. Let’s try and break that down.

R: Robust (Good soldering, tight joints, strong enough to last till the end.)

O: Open-ended (Modular i.e. made in parts which are easily repairable and replaceable so as to suit the situation.)

B: Balanced (Let physics keep your mechanical marvel from going topsy turvy.  Traversing uneven terrain (especially on an inclined plane) can be made easier by revisiting elementary textbook concepts like Centre of Gravity.)

O: Offbeat (Never hesitate to experiment, remember O is not Orthodox)

T: Tangible (Lots of ideas are good on paper. Yours has to be realistic and tangible. )


To build a ROBOT, take the following steps in word and in action.

  1. Draft your design :

    2.                       List out the tasks your bot needs to perform and then address them one at a time. Should you need a nudge in the right direction, read the section of this tutorial on Robot Skills. 

  2. Test with Trial Runs :

    3.                  To test and experiment on the Bot, it would help to simulate the actual event arena yourself to modify certain mechanisms. You will gradually understand the practical problems which may occur and need appropriate contingency measures.

  3. Get Familiar With The Controls :

    4.                 The onus of a successful run largely depends on the controller - that is you. At the end of the day what matters is how skillfully you can control your Robot. Robots with the cleverest of mechanisms have failed to perform due to bad handling and control.

  4. Analyse and Modify :

    5.                 You must always leave room for change as testing the bot on the arena may bring out new scope for modifications every time you make a practice run.

  5. Repeat the cycle till you have a HERObot!

                         Analyse, modify, test the bot, analyse again and improve.

              “ To achieve something that you have never achieved before, you must do things which you have never done before.”

     

HYDRAULIC MECHANISMS

Having delved deeper into innovative alternative mechanisms that can be used for the various tasks to be performed by the bot in the event Inferno, a fairly simple solution involves the application of the syringe mechanism.

 To explain this further, let us take for example the very popular rack and pinion mechanism. To implement this mechanism, you require a motor and of course, the ‘rack’ and the ‘pinion’, as explained earlier in the tutorial. As a result of this mechanism, circular motion is converted to translator motion.  Often, a rack and pinion arrangement is used to make a clasping mechanism. It is interesting to note how syringes may be used to achieve a similar effect.

1.       Fix two wooden arms around a pin, ensuring that they can still rotate around it.

2.       Fix the syringe’s mouth on the front arm.

3.       Fix a pipe at the end of the syringe and connect it to another syringe which you hold in your hand.

4.       Tape the end of the syringe to the back arm.

5.       When you push and pull on your hand – held syringe, the arms move back and forth.

6.       Place two such systems in opposition to each other to achieve a clasping mechanism.

For extinguishing fire, simply fix one end of a syringe to a pipe, the other end being fixed at the end of an arm on the robot. To achieve this without hindering the motion of the bot, you have to ensure that the pipe used is long enough.  To draw water from the reservoir, put the end attached to the bot in the reservoir and pull on the hand-held syringe. Point the arm to the fire and push on the syringe to douse the fire in the candles.

Here are a few links you can peruse to understand exactly how to make use of the syringe mechanism :

1.       See exactly how the connections are made :  http://www.youtube.com/watch?v=jZtL4yCK7RE

2.       This video demonstrates a clasping mechanism using syringes :  http://www.youtube.com/watch?v=jSTcMw_D7W4&feature=endscreen&NR=1

The classic water gun, explained in detail at  http://entertainment.howstuffworks.com/water-blaster1.htm , is also a design you might choose to use.  You could modify the pipe and trigger system inside the gun to suit your requirement. 

In case you decide to use such hydraulic mechanisms, or even cycle brakes for clasping,  make sure you use long enough connecting wire. 



SCOTCH YOKE MECHANISM :

Among some lesser known alternatives to the rack and pinion, and one that is definitely much easier to implement is the 'Scotch Yoke'. Let's see how to build this.
Attach a circular disk to the shaft of a DC motor and fix a chip on the other side, such that it fits into a longitudinal slot that in turn is fixed on a rod / small wooden or plastic beam that achieves to and fro motion when the circular disk rotates. The length to which the beam can move depends on the length of the slot, the radius of the disk and the position of the chip.

For an animated view of the working of this mechanism, click here

LOCOMOTION:

Though there are various kinds of drive bases, the most common drive mechanism that can be used here is a Differential Drive.

                              

For detailed information on constructing a differential drive, you may check the video tutorial Differential Drive.

                                                   

Once this is done, we are in a position to focus on the additional skills your robot must possess.

 EXTENSION:

Fire Engines use extension ladders or platforms to save people. The Robot can incorporate an extension mechanism into its system in order to reach the higher parts of the building from the ground level itself. A few extension mechanisms are illustrated below:

A Scissor Lift mechanism would consist of basically a fulcrum  which is essentially a screw to hold two rods together, single or dual arms , a base and a platform.
- High torque is required to extend the arm against gravity, so preferably use a 10 to 30 rpm motor.
- The construction of a Scissor lift is shown. The ‘Add-on’ is the mechanism to ‘Collect’ the cylinders. [See Collection]

                           

                           See this Video to understand the motion in a better way.

    A rack-pinion mechanism converts the rotating motion of a motor to linear motion.


 - All you need is two sets of racks and pinions synchronized to move in opposite directions.
 - This mechanism needs high torque motors of about 10-15 rpm.
 - This mechanism can also be used for ‘Collection’.

       Rack & Pinion [Video Link]

                                  

 

                       [For other details also visit http://en.wikipedia.org/wiki/Aerial_work_platform]

 

  COLLECTION:

The primary goal of the Robot is to save people , represented by cylinders that are hollow, made of wood with an iron disc on top with a semi-circular handle.

   Your robot should have a Flexible Arm that collects the cylinders and drop them into the safe zone. You may consider using the following approaches:

 This is an example of a Gripping Mechanism that replicates two fingers.


 - This gripper mechanism is like you ‘Pinching’ to get hold of the cylinder.
 - You just require 4 metallic pieces (or can be wooden or plastic), nut-bolts and some screws.
 - The basic gripper is finished. In order to grip, you must move the two fingers. This can be done by rotating the angular shafts by motors.

                              

Check this for a simple gripper contraption [Gripper.]- You could make this by using the parts of a pair of wire strippers. Of course, a simpler option would be to keep one of the fingers fixed (i.e, unattached to a motor) and only use one finger for movement. You could use the rack and pinion arrangement to do this.

                         

Think about using a hook lowering mechanism to lift the cylinders which already have a handle. In the arena, there are ‘windows’ for this cylinders to be lifted from by their handle.

 

               

 

 STORING:

 It could be good strategy to add an extra carrier to the body structure to collect cylinders on the bot itself since you could put all cylinders in the safety zone all at once instead of one at a time, leaving you more time to score better. The easiest way would be to create an enclosure on the chassis of the bot for this purpose.

 A container to carry the siphoned water would be beneficial as it would reduce the time taken to draw more water from the provided tank(s).

EXTINGUISHING :

There is a water tank(s) available in all the rounds in order to use the given water to put out the fire (Candles). A few suggested mechanisms.

 

  • Syringe Mechanism
    

            Basically, a mechanism replicating the use of a Syringe [Video Link]may be used. A motor would be added to the ‘Plunger’ and ‘Barrel’ junction, the suction of water by the syringe can be controlled by the direction of motion of the motor.

 While spraying the water on the candles, the reverse direction of the motor would cause the water to come out.

 

 

 

  • Scoop Mechanism:

 

                    This is a simple mechanism, where you gather the water into the ‘Scoop’ . The scoop is controlled by a rotatable motorised shaft by which the scooped water can be turned upside down and the water can be dropped onto the candles.

 

 

 

 

 

  • Suction Pump Mechanism:

      This mechanism is slightly harder to implement. It involves a vacuum suction pump which pumps the water into a container and then sprays it using a fan system.
Water Suction[Video Link].


POWER:

o        The participants will be provided power during the event in the form of power sockets of AC 230 V. You can choose to use an adaptor or build your own rectifier circuit to power your motors. Remember to use an appropriate voltage for your motors to avoid any damage during the run.

o        Participants can also choose to bring their own power source to the arena as this reduces the effort of handling too many wires. Safety is of utmost importance, so do make sure that the battery pack and all exposed wires are sufficiently insulated.

o        It is suggested that only one person handles the bot throughout the event to minimise the risk of shock.


Additional Resources

·         To prepare the controls of the robot, you need to create a switch panel. For each motor, you would need an H-Bridge circuit. To learn more, go to: http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/index.html

·         A power supply of 230 V AC will be provided to you. According to your requirement, get yourself an adaptor or else you may want to make your own rectifier circuit. To learn more, follow the link: http://www.robotix.in/rbtx09/tutorials/electronics4robotics

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