Peerless
Crossfire
EECS
373 Fall 2004
Final Project
Members:
Jason Martin
Thomas Martin
Description:
Peerless Crossfire is a converted version of Crossfire, in which one plays it without a peer (i.e. one player). Also, since this is the ruler of all Crossfire’s, it is without a peer itself. The object of the game is to rapidly shoot the target on the game board and knock it into the opposing side goal. The computer simulated opponent that runs off of the MPC823 processor, functions as an opposing player that is capable of scanning the playing surface and finding the target using an infrared distance sensor. After successfully finding the target, the simulated player is programmed to shoot the target using a trigger pulling mechanism that we created for it. A final bonus feature that the original Crossfire did not have is that, Peerless Crossfire can keep track of the score of who get to 15 points first and wins the game. Light Amplification by Stimulated Emission of Radiation (Lasers) are placed at each goal line of the game board and pointed at infrared photo transistors directly across from them. When the laser beam is broken for a particular side of the game board, the opposite sides player receives a point. The score keeping is displayed on the seven segment LED display.
Components
and Use:
o Hitec HS-322HD servo used to control gun rotation. PWM output (from the MPC) is controlled with two RISC timers set up for PWM use
- Hobbico super torque CS-70 servo used to control firing of the gun. PWM output (from the MPC) is controlled with two RISC timers set up for PWM use
- SHARP GP2D12 infrared distance sensor used to find the target. Analog input (to the MPC) signal is processed with the ADC808.
- Two LASER pointers aimed at infrared photo transistors to be triggered when someone scores. The outputs of the diodes are sent to two testpoints on the MPC823 daughter board, which are then processed to generate an interrupt to the core.
- 7 segment displays are used to display each players score
- push button S1 is used to continue game play after a side has scored (which causes game play to cease and give us time to reset the target and reload).
Difficulties:
The most difficult aspect of this project was firing the gun. The force to push the ball through the final spring loaded “shooter” was too high for all the actuators we tired. We finally ended up adding a long lever and a heavy duty servo. This allowed us to get the force needed to shoot the ball. Another, less difficult, but more pestering aspect was making the infrared distance sensor locate the center of the target. With the “peripheral” vision of the sensor, it would find the target before “center” and hence miss the target when shooting. We alleviated this problem by mounting the sensor vertically, which turned the “peripheral” side-to-side vision to a vertical orientation (which is the same orientation as our target). Finally, the distance sensor was picking up the other gun at the outer limits of its range. This would cause our algorithm to continuously shoot at the other gun. Black tape over the front of the other gun decreased the visibility of the gun, and fixed this problem.
Conclusion:
Peerless Crossfire was a successful project and a practical application that could be marketed in the real world towards only child kids that do not have any anyone to play the game with. We were able to successfully complete all the functionality requirements that our team originally planed to do. Through this project, our team was capable in showing our good understanding of the fundamental concepts taught in this class and our ability to implement a few things that EECS 373 does not focus on.
Pictures of Peerless
Crossfire:
Simulation of Peerless Crossfire: