Pre- Grading Session Update

As of Wednesday, 5/29, all systems are fully functional and should be able to accomplish the tasks outlined for the grading session.

As an update after the last post, the connection LED and ROAMER select switch were implemented, and our POD and ROAMER successfully connect to and run with the PODs and ROAMERs of other teams. The castors (made from PVC) on the bottom of the ROAMER were decreased in height, allowing the ROAMER more flexibility to take bumps on the carpet, and friction problems were addressed in the drive trains; this fix appears to address the issue of difficulty driving on carpet. Gripper height was increased, which fixed the problem of losing the box when dragging it over the door threshold. SPECIAL mount was attached to the top of the ROAMER. The bottom of each castor was sanded. A nonlinear mapping was applied to the incoming voltage received by the ROAMER before outputting the PWM frequency in order to make for increased sensitivity/ turning ability at low voltages. Vinyl was applied. The POD and ROAMER can now drive on carpet, drag a box out of the larger box, and control/ be controlled by other teams' ROAMERs and PODs. POD and ROAMER are ready for grading.

Update 5/27

5/27/12 Update:

The POD and ROAMER have achieved basic functionality, with some adjustments still to be made.

Circuits have been in their final state since 5/23, with a final decision to implement an H-bridge in the gripper circuit to allow additional current to flow for greater grip strength.

Software is largely finished with some minor tweaks to be made. There are still occasional problems upon connection with the ROAMER: the POD does not always register a connection immediately, and the connection occasionally breaks. These issues were largely mitigated, however, in the last couple of days, and additional fixes targeting unwanted incoming signals will be implemented as well. A major bug involving the POD software getting stuck in a while loop during the AD conversion sequence was fixed, eliminating most of the break-mid-connection problems. Connection LED and ROAMER select input will be implemented in the next day or two.

The POD mechanical structure is in its final form. The ROAMER has been built, and minor adjustments outlined after initial testing remain: the ROAMER does not drive well on the carpet, has trouble going up hills, has trouble with fine gripper movements, and fails to drag the box over the door threshold because the gripper height is limited. Fixes will be designed and implemented in the next two days.

Design Review

Tuesday, May 7

Went over design proposal and slides with Ed and Jeff
General mechanical design and communications layout approved
Communications layout:
- POD side: Two PICs (One serving as the Brain in order to increase output pins, one communicating with the XBee to relay data between Brain and XBee); Two PICs communicate through SPI
- ROAMER: Two PICs (One relaying data between XBee and E128 via EUSART, one relaying data between SPECIAL and E128 via SPI) and one E128. E128 communicates with XBee PIC via EUSART and with SPECIAL PIC via SPI

***Update 5/11: It was decided that the ROAMER XBee will be accessed directly from the E128 using EUSART, as the relay PIC can be eliminated with no issues, and the SPECIAL PIC can use Slave Select to communicate via SPI with both the E128 and the SPECIAL.

Initial Design