Dusk Till Dawn

Dusk Till Dawn is a 2014-2018 iRobotics Combat team.

Kraken

The Kraken was the Dusk 'till Dawn robot from 2017 robobrawl. It was only the second attempt by iRobotics at a full body spinner. Although the robot was structurally sound, taking only cosmetic damage during the competition, the spinner was never fully functioning. Some thoughts as to improvements to the functionality of full body spinners are listed below.

The full body spinner functions as armor and provides 360 degrees of attack. Another benefit is that since the weapon has such a high radius, and almost all of the mass is concentrated on the outside, it has a large moment of inertia at 541 pounds per square inches. Comparing this to the previous weapon on catastrophe, the weapon will be much harder to accelerate. When this weapon is spun up to 3000 rpm, it has an energy of 7.7KJ. This is more than double the energy of last year’s weapon. A tradeoff of this is that the weapon will take a longer time to spin up because of the high moment of inertia. The weapon was driven by two motors, mounted on a suspension system that would bring two wheels into contact with the underside of the top plate. These wheels would ride on the plate, which would cause the shell to start spinning. The suspension system helped the wheels stay in contact with the plate, as well as make the system more impact resistance as the shell takes hits from an opponent’s weapon. The suspension system that held the wheel to the plate would cause the wheel to “bounce” along, speeding the wheel up when it was off the plate, and causing it to decelerate rapidly when it came back into contact with the shell. This caused the motor to jitter and stall rapidly, which causes the average current flow to be too high and burn out the ESC. To help with this, we would would stiffen the suspension, and reorient the wheels to run along the vertical sections of the shell, rather than the top plate. We could also use a belt to drive the center shaft of the shell rather than spin it from the inside. The suspension system did not work, as it continued to draw to high of amps through the speed controllers and motors, breaking most speed controllers. Another possible solution to this would to use a sensored motor, which could allow for the motor to spin up. A better overall design would have the motors mounted so the wheels could run along the outside walls.

Continuing to iterate on the designs that worked well last year, this year our frame had walls that slotted together and into the base plate. The walls were then held down to the base plate with strategically placed aluminum brackets. The brackets were used in such a way that they only held the plates in the slots, but would not be stressed when the frame is placed under a heavy shock load. It was important the the central square of the frame, which held a stack of bearing blocks that supported the central shaft of the weapon/shell, was stiff and durable. The shell would be under large loads when it comes into contact with an enemy’s armor, or was hit hard by a weapon impact. The thick, interlocking internal walls supported the robot well, and even held up under extreme loads such as when our robot would be launched into the air from an opponent's weapon strike.