Weekly Report Updates:
March 25, 2013:
At the beginning of spring break, the parts were ordered. As we have been still waiting for all of them to arrive, most of our work was on hold waiting for this. Kevin and Nick went over to Black, where last-semester's car was located, and connected an oscilloscope to the Hall-effect sensor to determine its output waveform. It was found that the signal needs no amplification at all to be read by the microcontroller.
March 11, 2013:
The two small teams responsible for the solar panel and LCD user interface began to build our PCB layouts in EAGLE this week. This proved to be more time consuming than it had originally been thought. Parts selection was, however, finalized, and materials lists started to be put together. Draft layouts of the required boards were built. A deadline of Thursday, March 14 was set for ordering parts and boards, so that we can build and test the systems after Spring Break.
March 4, 2013:
This week the group continued with subsystem design. Most importantly, we selected parts for our systems. We finalized our schematics and started the process of laying out the circuit boards in CadSoft EAGLE. Lawrence and Andy finalized and ordere the solar panel. Chris selected two pre-built audio amplifier ciscuits to use in the audio system. Nick revamped the website. Kevin made a block diagram of the code to roughly diagram how the MCU will be programmed once we have obtained it. In addition, on Friday the group made a short presentation of Dr. Amariucai detailing our plans and what our deliverables will be.
February 25, 2013:
This week our group began to design the schematics for each of the systems we are working on. Lawrence instructed the team on the program Eagle to build our schematics and convert them into PCB layouts. Also due to excess current use, Lawrence will be redesigning the headlamp configuration to help with power consumption. Chris consolidated the logic circuit for his audio system and has began choosing parts. Andy focused on picking out capacitors, inductors, resistors and diodes for the solar panel. Andy also talked with the ME and Industrial Design groups about the exact size of the solar panel how they wanted to put the panel on the kart. Nick and Kevin have begun to outline the programing of the micro controller for the user interface and have created a buck converter to power the micro controller. For the next week the team will have the schematics and PCB layouts finished and part selection finalized.
February 17, 2013:
During the week of the career fair, progress has been slower but Chris is looking into different ways of creating the audio system due to the initial bluetooth device not having the functionality that was desired. Andy has been talking with the Industrial Engineering team about the different size options of solar panels and their power capabilities to help the team decide what they would like on the kart. Nick and Kevin are looking at different buck converters to power their system and it's sensors. Our team has also begun to create schematics for the systems to put in Eagle with the help of Woody. Next week will be Eagle schematic finalization.
February 10, 2013:
This week the team members created block diagrams to describe the systems that they are building. Andy, who is working on the solar panel, also calculated the energy that the solar panels collects at different sizes to give to the industrial design team so they can decide how much of the roof of the car will be used for the solar panel. Nick and Kevin have decided on parts including the micro controller, the LCD screen for the UI and the different sensors needed and will discuss their parts selection with Lawrence next week. Also the team will start building the schematics in Eagle next week.
February 3, 2013:
This week our group met with Prof. Bigelow to discuss the schedule for the semester and designate tasks for each group member. This semester our group will be adding a solar panel, a Bluetooth P.A. system, and a User Interface to the kart. Andy will be in charge of integrating the solar panel into the system, Chris design the P.A. system, Nick and Kevin will design the U.I. and program the micro controller, and Lawrence will be helping each team member.
Here is what our schedule will be like:
| Week | Task |
| 1-2 | Design (ideas, schematics) |
| 3 | Parts selection/Eagle schematic building |
| 4 | PCB design |
| 5 | Order boards/Make up week |
| 6-7 | Power-train Finalization |
| 8 | Board population/ Coding |
| 9-10 | Finalize and Testing |
| 11 | Installation |
| 12-13 | Make up weeks/ Presentation Prep |
To elaborate on the tasks, Chris will be designing a P.A. system that can connect to a users phone via Bluetooth for hands free calling and a music player. The internal mic and music player will also be used with external speakers to communicate with people outside the kart. Andy will be integrating a solar panel to either power the auxiliary systems of the kart or charge the battery, which has yet to be determined. Nick and Kevin will be designing a user interface to relay information to the user like speed, battery life, temperature, distance of objects behind kart when in reverse, karts current mode(turtle/rabbit) and more.
Block diagram of the microcontroller system: 
microcontroller system block diagram.docx (47 kB)
Block diagram of the audio system: 
Audio System Block Diagram.pdf (136 kB)
November 25, 2012:
The week before break we moved the drivetrain circuit to the Mechtronics lab in Hoover hall to assemble our design on the paragon prototype car. It was important that this be completed so the other engineering teams could test the cart before thanksgiving break. We recieved a new motor controller on Wednesday and with the drivetrain circuit assembled we were able to program it. Some of the parameters of the motor controller we set were the max current, we set to 100 A which we wanted to set to 70 A due to battery life but 100 A was the lowest setting. The max speed of the motor was also set to be below 20 mph.
With the motor controller programed we tested it the circuit. We tested the motor in both forward and reverse (including the reverse buzzer), the rabbit and turtle modes, and our key and kill switch. While testing we discovered that the computer program that sets the motor controllers parameters also has a data logger for trouble shooting, which the other engineering teams were asking us for.
To measure our speed we decided to use a bicycle speedometer to measure the speed of the cart instead of the motor controller's capability. The reason for this was due to the differential between the motor and the wheels has two gears and would change from what we had set it to be in the motor controller parameters. We also do not have an interface to display the speed from the motor controller, but the bicycle speedometer has a separate interface that can be used even if the cart's circuit is turned off.
Next week we will be working on the lighting circuit on the cart.
November 11, 2012:
Last week we built, tested, and did troubleshooting on the circuit to operate the motor controller. We wired up the circuit using ring and spade terminals in accordance with the wire gauge connected to each terminal. We also switched from 00-gauge wire to 2-gauge for practical purposes, as we are going to be limiting the motor current to around 100 amps and don't need so much current capacity. We were also unable to locally procure crimp-on connectors for 00-gauge wire.
When the circuit was first completed, it didn't work, and after correcting the fault codes that the motor controller helpfully displayed to us, we attempted to run the motor controller and it didn't work. The motor controller at this point flashed an error code indicating (according to its manual) low battery voltage. The thought was that since the controller had been programmed to work in the bubble car with a 48V battery, then it might not work at the lower voltage (36V) that we were using.
Nick disassembled the throttle and found that it uses a sensor and a magnet to vary an output voltage with respect to the position of the twist handle when 5V is applied across its red and black wires. It puts out between 0.8 and 4.6V depending on the position of the handle. This will work satisfactorily for a throttle until the ME team constructs a foot pedal for the accelerator.
After more troubleshooting and repair, the motor controller was finally able to make the motor spin both forwards and reverse, however the motor would slow down after a few seconds of motion in either direction, presumably due to the low voltage sensed at the motor terminals. When we attempted to connect the programmer to the controller it would not connect. We thought that perhaps the low voltage was preventing it from connecting, and we resolved to get the 48V battery out of the bubble car and try with the correct voltage, once the lab in the armory was open.
When we brought the battery from the bubble car, it was in a very low state of charge and could not be used, which was unfortunate. This is also a very low-capacity, low-current battery. We also discussed the matter with an engineer from Curtis. He told us that the voltage was not an issue, and as long as the controller was given a voltage between 24V and 48V that the logic would operate, and it would be able to be programmed. For troubleshooting, Woody suggested taking it to a golf cart dealer and the engineer agreed.
When Chris and Nick returned the bubble car battery to the bubble car, they stopped and examined the large four-seet National Guard golf cart in the Armory. It uses a bank of eight normal-sized flooded lead-acid batteries, much higher capacity than what we have, but with thinner wire. When we improve the design of our cart next semester, we may want to look into changing the batteries out to these type, rather than the valve-regulated batteries we are currently using.
The golf carts at the dealership to which Woody, Chris, and Andy travelled in order to test the controller were powered by four very large flooded lead-acid batteries, and with a very similar motor controller. We were able to connect our programmer up to the controller in the golf cart, and it was immediately able to connect and communicate. We came to the conclusion that the motor controller we have is defective and unable to communicate with the programmer via its serial link. Jim Heise is ordering a new unit.
Left to do this week is to build the circuit into the car with the fuses and other safety components added, along with a more permanent wiring style (including a proper wiring harness for the motor controller connections). The keyswitch we purchased was of very low quality and it broke on us, so we will need to get a new one to use as an ignition switch for the car.
November 1, 2012:
This week we took pictures of all the group members, then went over a replacement for the mosfet in the circuit due to its power consumption. We will also be adding a diode for redundant protection of the contactor that will replace the mosfet. Also we needed a way to measure the current coming out of the battery so we chose to use current clamps to acheive this.
The Parts will be ordered by the end of this week and we will be building our circuit that we have designed and testing it. We will also be presenting our design in class on Tuesday.
The draft of our presentation is here: 
EE 491 Group May13-22 Kart.ppt (711kB)
October 25, 2012:
This week we went over the final schematic for the motor controller circuit which included the redesign for the main contactor relay being replaced with a MOSFET (due to cost). Also we decided what was going to be included in the design document and delegated sections of it to each group member. Chris Larson will be going over the datasheets, Kevin Flynn will be going over the standards that we are using, Lawrence Woody will be drawing the final schematic, Andy Goiffon will be summarizing and organizing the document and Nick Marquardt will be posting it to the website and going over the details motor controller program. We also will be calling an engineer of the company that built the motor that we are using to get some more info about it including the torque vs. RPM chart, electrical characteristics and fault conditions.
Next week we will hopefully be receiving the components and building a test circuit for the motor. Also we will be working on a powerpoint presentation to show the class that following week.
Some design drawings:
 |
 |
| Motor contactor overview (168kB JPEG) | Instrumentation amplifier for contactor (175kB JPEG) |
October 18, 2012:
This week our group made a parts list for everything we need to get the motor controller operating the motor and integrated into the vehicle. We will be typing this list into a spreed sheet and it will be given to Prof Bigalow to order. We also discussed standards that apply to our portion of the project for the homework. For next week we will be reviewing what will be in the design document and if we get the parts by then we will start to build the motor controller schematic and integrate it into the vehicle.
October 14, 2012:
This week we met with some of the other team leads in the Mechtronics lab in Hoover to discuss our part of the project and what needs to be done in the coming weeks. The goal is to have a working prototype of the vehicle by the end of the semester, which means that our team needs to start working on the motor controller to drive the motor and integrate it into the other groups user interface. First we had to track down the motor controller that the other teams had already purchased, which we found in the bubble car (Chinese vehicle Paragon wants theirs model after) in the armory workspace. Now that we have it and access to the documentation for it we will be designing a way to test the motor and the motor controller next week.