Our postage meter still needs a lot of improvements to be an actual postage meter existing in the market. The following are the improvements we had in our mind, which we could not do due to lack of time:
We were planning to use infra-red sensors to detect jamming at all times. The sensors could sense the movement of the envelope and in case it was stopped in the middle of its way, the infra-red sensor would have informed the MCU and the process would have stopped automatically and the user would be informed. The sensors were designed to be placed after each wheel and at the entrance and exit of the system.
The current system is only capable of putting one type of stamp on the envelope and it can not change the stamp according to user setting. In an actual postage meter, the user is able to set how much money to put on the stamp, i.e. $0.34. This required to use either and ink-jet or dot-matrix system to stamp which was out of our capability.
We were planning to write a java/web based user interface software to charge the postage meter for certain amount of money with credit card, so that the postage meter would have worked only there were enough money in it. This could be done through using the serial communication capabilities of the MCU. We were also thinking of adding the feature of charging the postage meter through Internet.
If we had not encountered this many mechanical problems, we would try to add more features to our postage meter. We would like to warn the future designers who are planning on building such a system: it is VERY time consuming, and it needs a lot of mechanical design. If you have friends in architecture or mechanical engineering, go for it and improve our design!