Sardar Vallabhbhai National Institute Of Technology

Sardar Vallabhbhai National Institute of Technology (SVNIT, Surat) Portfolio Abstract Report ROBOWARS

Vijay Rao B.Tech. III – Electronics +91 – 99243 47462

Chassis The primary chassis structure for the robot is as shown in the picture. It is a structure made up of steel L-flanges so as to provide strength to the unit at the basic level. The entire structure can thus be primarily deciphered as a square unit with multiple integrals mounted onto it at various points as per requirements of the weapons. The centre of the chassis has a mounting facility for the power systems, to the lower portion. This is accompanied with a locking/unlocking system, so as to ease the replacement of batteries between rounds. The basic chassis skeleton design is as indicated in the adjoining picture. It’s a steel structure designed keeping in mind the weapons and the weight of the power system. The structure also provides the freedom of switching between 2 wheel and 4 wheel drives.

The adjoining picture is the structure after adding the cutter and the flips. As can be easily deciphered, the internal structure has been covered up. The material used for this purpose will be steel sheets, with a coating of hardened rubber sheets. The picture still doesn’t show the position of the central hammer as it is yet to be accommodated into the structure.

Materials The structure consists mainly of steel (Mild Steel) to provide it with the strength to bear heavy blows from the sides and the top. The sheet thickness is 2mm. Major parts of the chassis structure are made of aluminium (from Jindal™ Aluminium, product code: 15181). The following picture shows the details. 2

Cross-section of the aluminium tube

the aluminium tubes used for the internal chassis structure However, internal machinery consists of aluminum plates in various places, to exploit the workability that it provides and also to decrease the overall weight of the robot by compromising with strength of those parts which are not exposed to external view or blows.

This picture shows the robot during the initial tests that were conducted to check the linear alignment of the motor system and the control systems

Dimensions The basic internal structure of the robot is shown in this picture which was used to conduct tests regarding motor alignment, control systems and power system endurance tests. 3

This structure is a square when viewed from the top, 40cm x 40cm. The height of the basic structure extends up to 9.5 cm. However, this is only the basic structure which will be fitted with the vertical members as shown in the previous page. The design height is 800 cm.

Weapons and Strategy The square structure of our robot facilitates a multi-faceted attack system, making our assaults four-pronged (presently, increase expected before the combination). The square structure is useful in increasing the stability of the entire integrated combination, as the weapons can be placed in strategic positions. i) Killer Cutter The leftovers from an old HITACHI™ cut off machine form what we call the Killer Cutter, although the machinery had to be changed to conform to the rules. Powered by a 150W 24V PMDC motor, using a HITACHI™ 211001 15-inch 110 tooth cutting miter/bevel saw blade, this weapon will spearhead our attack strategy. It is directly connected to an arm mechanism, which is driven via servo control to lower onto the opponents’ robots ripping them open at strategic places. This weapon is specifically designed keeping in mind the lack of strength in the chassis coverings that some of the robots might have. With the amount of power and promise for damage this weapon offers, our most preferred option is undoubtedly this weapon.

1.a

1.b

The picture 1.a shows our cutter that we have in our inventory. (The picture 1.b is of the blade that we will be extracting. 1.b is the one put up by the company for commercial purposes.)

ii) Side Flips Our next strategy aims at light-weight robots. It is anticipated here that these robots, which will be weighing very light inherently, will be so made to perk up their speeds. Hence, this strategy will be directed at exploiting the opponent’s momentum in making them jump up and falling upside down. The mechanism is materialized via thin steel sheets attached to fast motors, fixed on the front edge, to capitalize on the initial gambit. 4

iii) Drill We ripped open an ELECTREX™ hand-held impact-drill and modified the machinery (basically extraction and fitment of the chuck), constructed a few jobs using MS on the college workshop lathe and there we had a drill ready, which used a 5000 rpm 50W motor. With a drill bit of 6 mm diameter, we hope to cause a lot of damage. The positioning of this weapon is done keeping in mind that it is directly supposed to screw up the locomotion mechanism of the opponent. A tank-type tracked movement system, which we expect having maximum probability, would be most vulnerable.

iv) Central Hammer The center of the robot houses the most dangerous weapon we have been able to devise. It aims at banging the locomotion mechanism straight down, or any other vulnerable parts that might be observed during the match duration.

This picture is of the hammer that will be fitted to serve the purpose of this weapon. It is a 6 kg hammer, which will be tied onto a chassis member using nylon strings. When required to fire, it would be opened and allowed to fall down. The active impulse would be powered by gravitational force only. 5

Control Systems The control-system of the robot is a unit which consists of two distinctly placed portions, connected wirelessly. The technique used for communication is Amplitude Shift Keying (ASK), that is, a digital system is being used to serve the purpose. There is only one frequency of operation and that is 434 MHz, however, there won’t be any frequency clash problems because of the technique incorporated in the circuitry, which is as mentioned below. As had been demanded through the technical criteria put up on the site, the control system incorporates a facility to circumvent the problem that would arise because of frequency clashes. This is done by employing an address changeable mechanism on the receiving end. There are a total of 256 different addresses possible and hence two exclusive machines being controlled at the same time would not be a problem as the combinations will not be exhausted out. This allows data transmitted at the same frequency to be filtered out as required. The transmitter consists of a keyboard of a maximum of 16 keys and hence can be used for a robot that has 16 different mechanisms. Our robot presently has the following mechanisms: i) Motion of the wheels 2 ii) Weapon 1 : Cutter 1 iii) Weapon 2 : Flip 1 iv) Weapon 3 : Drill 1 v) Weapon 4 : Hammer 1 These particulars add up to a total of 6, as of now, leaving space for 10 more weapons to be added. We do plan to increase the number of weapons to utilize all the space our control system provides us with.

Power Systems The power system for the robot is primarily a sealed lead acid battery pack, which have a total voltage of 24V. The pack consists of two batteries, each of 7 Ampere hours. The powering of the electronic circuitry responsible for proper functioning of the control systems as well as the heavy solenoidal electro-mechanical loads is done with the same battery pack. However the electronic circuitry employs its own set of voltage regulators to step down the voltage to a rating demanded by the ASK modules and the logic for driving the motors. 6

Progress – Present Status Presently, the chassis is ready and the control system has been materialized and mounted. The killer cutter, side flips and drill have been developed individually as standalone devices and only remain to be mounted onto the chassis for complete operation. Testing at 24V DC has been done and therefore we do not expect any problems once the mounting has been completed. The only materialization of current plans that remains is that of the central hammer, and that is to be completed once work resumes after the winter break at college ends and the team gets back on campus. The progress report being mentioned here is of the work and planning that had been done before the semester ending winter-break started (date : 5th December, 2008). With a little more than 3 weeks remaining for the competition, we are sure the robot will be done and will certainly be capable of putting up a great show.

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