1/29/08

Today we decided to attempt direct control over the motors instead of using connections on the circuit board within the vehicle.  The connections within the vehicle were not easily available and were difficult to decipher, so we attempted a direct connection to the motors with a PWM signal.  Our initial test was successful in driving the motors, so we proceeded to develop circuitry to connect an LMD 182009 H-Bridge chip as the drive circuitry.  We were unable to get the H-Bridge circuitry working at this time.  We also began looking into the circuitry required for the GRB1134 - a reflective sensor to gage wheel position/velocity.

2/5/08

We decided to use the L293 quadruple half-H driver for the drive circuitry.  Using this chip, we were able to drive the motors via a PWM signal in either direction.  We next looked into options to mount the GRB1134 reflective sensor in combination with a black and white pinwheel on the inner side of a wheel.  We also tested the ultrasonic pinger - SRF05 - at the position on the vehicle it will likely be located.  By mounting it on the underneath of the top of the cab, we were able to detect objects without false positives.

2/12/08

We conducted a crude preliminary power dissipation test on the L293 half-H drivers.  We used the chip to drive the motors for an extended period of time to ensure that it did not engage the auto-shutdown due to temperature.  The chip did not become hot even when utilized significantly more than will be done during actual operation.  After determining that the GRB1134 reflective sensor will be too large to easily fit on the inside of the wheel, we decided to order the HOA0149 reflective sensor due to its low profile and modest range.  We proceeded to test the infrared transmitters/receivers at the positions they will likely be located during operation.  In these positions, the range is reduced to around 1.5 ft, but should still be enough for actual operation.  We then developed protective circuitry for the bucket tilt and arm lift motors to prevent driving the motor past the end of arm operation.

2/19/08

Today we continued work on the infrared beacons.  We found that the combination of L14C1 and QED123 that we had previously utilized no longer had the range that we had seen.  We substituted PNZ109L-ND and LED's of TSAL6100 and were able to once again have a range of over 3 feet.  Since we got a second compass, we retested both to ensure that they functioned in the same manner and found that they operated as expected.  To clean up the signal from the infrared beacons, we decided to use an inverter with Schmitt trigger.  This gave us an output from 5V to 0V that was a smooth output for a PWM input to the LED.  We also tested the HOA0149 reflective sensors that we had ordered due to their low profile.  Using a pinwheel, we were able to get a pulse train output which when connected to the inverter with Schmitt trigger, generated a smooth output.  We also decided to use the 4345A voltage translator to communicate between the board and the items using 5V.  It was also found that the MC7805 voltage regulator will generate a 5V output from the 7.2V battery on board.

 

2/26/08

With the final circuitry in place, we worked on wire-wrapping and soldering our circuitry today.  In the 'Documents' section our final layout and circuitry can be seen.  We use perforated boards and were able to connect a large portion of our circuitry today.

 

3/04/08

Today we presented our project progress to the faculty.  We then continued connecting our circuit board using wire-wrapping and soldering.  We then tested the compass as connected in the circuit board and it operated as expected.  Next we tested the motors when connected to the H-bridge circuitry we had constructed and were able to operate them via a PWM signal.  We continued learning how to utilize SDCC as the compiler and used some test code to ensure we could control various ports.

 

3/11/08

We will be changing voltage regulators to LM2940CT due to stock issues.  We spent much of the day continuing the construct the circuit board and making circuit connections.  The infrared beacon circuitry was tested and found to operate as expected on the circuit board.  We also worked on the connectors for the motor circuit board.

 

3/25/08

Today we finished up some hardware assembly issues.  The cab was raised to accommodate the boards better.  We also mounted the infrared wheel sensors inside of the wheels.  We used a pinwheel to be able to tell distance and velocity.  We then reassembled the vehicle and continued work on the IR receiver, the compass, and the ultrasonic software development.

 

4/1/08

Software development continued today.  We decided to utilize SPI0 for the compass instead of the previously determined timer.  The SPI0 code makes for an easier coding process and more accurate results.  We also worked on the infrared code and were able to get it to interrupt to determine which (if any) beacon we are facing.  Ultrasonic code was also developed and found to be functioning as expected as was the motor PWM code.

 

4/8/08

Today we wired the 50-pin connector from the microcontroller to our circuit board.  Since port 4 was found to be only byte addressable, we will mostly use the other ports.  We then worked on testing our code, beginning with rotating the vehicle to find an infrared beacon of interest.  We were able to rotate the vehicle but were having trouble finding the beacon.

4/15/08

Today we continued working on code.  Everything is now functional except the ultrasonic code which appears to have an overflow issue.  To combat the frequent problem of translator chips making poor connections, we inserted new sockets into the old sockets.  This was done to prevent having to rewire the new sockets.  Since the insertion of new sockets made good connections, we did not need to remove the old sockets.

 

4/22/08

The ultrasonic code was completed today.  The issue was a software overflow, fixed by casting the variables used in mathematics into larger variables.  We are developing a new navigation routine which will use the compass and ultrasonic to retrieve data to allow for the use of trigonometry based navigation.  This will allow the vehicle to initially start at a position not directly centered between the beacons.  We also found that the compass will not allow us to use the MISO pin with a direct toggle, so we re-wired our compass enable to another pin.

 

4/29/08

Today we finished the navigation software.  We were having issues with the motor and sensor connectors, but replaced the connectors and have achieved the desired results.  All software is now finished and functions as expected.  The vehicle is able to locate and navigate to the load and then scoop the load.  The vehicle then locates and navigates to the truck and proceeds to dump the load into the truck.