Week10/12 - 10/19

According to the bogie team and the track development team, the distance between the inner and the outer tacks is 2 in (50.8 mm). The width of the part of the bogie in between the two tracks is 33.5 mm. Thus the distance between the bogie and the track is about 0.5*(50.8-33.5) = 8.65 mm. The height of the magnetic switches on the bogie is 7.5mm from datasheet, and it will scratch the track while turning. Thus, the height of the peak for the corrugated metal strip is design as 5 mm. See Figure 1.

Figure 1 Space between Tracks

The ground came up with three kinds of corrugated metal strip we might be using. They are square wave, sinusoid wave and trapezoid wave corrugated metal strips (See figure 2). Square wave will be our first choice because the sudden change of height will allow the Hall Effect senor to have clear digital output. The distance between peaks (d) is depended on the speed of the podcar and the resolution of the data acquisition device, which is the Arduino board in the SuperWay project. The team have to find out the maximum speed of the podcar in order to find the minimum distance between peaks.

Figure 2 Designs for Shapes of Corrugated Metal Strip

Moreover, the team had decided to put the Hall Effect sensor on a ski which extent out of the bogie in order to keep proper distance between the corrugated metal strip and the sensor. The team is also looking for a magnet with proper size and magnetic strength.

week 10/05 to 10/11

In this this week, we tried to determine the size of the ferrous strip. According to the control team and the bogie team, the magnets detector on the bogie will be kept. Keeping the magnet detector will allow us to stay with digital ouput sensor. However, the magnet detectors are occupying too much sapce on the bogie, which became a problem for us to install the metal strip on the track. We came up with a proposing solution for this, that is to cut out the upper part of the magnet detector, and we will attach the corrugated metal strip just right above the position of the magnet detector. The upper part of the magnet dector is for placing the screws, but currently the detector are mounted using glue. Thus, the screw holes are no longer needed.

The team also examinize the track, and found that the distance between the two side of the tracks are different every where, it is a big problem for us to decide the size of the corrugated metal strip in this case.

We already found a nice size hall effect sensor. The rest thing depended on how small of the strip we can make.

Week 9/29 to 10/04

This week, it is because we have to prepare for our presentation, so we do not have that much time spend on our project.
Overall, our team tried to ask some workshop in San Francisco to make the ferrous strip this week. Unfortunately, none of them can make for us. It is because the ferrous strip we expect is the distance between peak to peak and the distance between upward peak and downward peak have to be very accuracy. Probably, we have to ask help from some more workshops or companies in the coming week.
Moreover, we will test the new hall sensor in the coming week.

We also found some of the small bussiness websites which might be able to manufacture the corrugated metal strip we want, and we will contact them for more information.

http://www.builders-in-scale.com/bis/parts-metal.html
https://www.mechanicalmetals.com/accessory-items/foam-closure-strips-and-plugs/

Week 9/21 to 9/28

This week, our team met up with the vehicle control team to discuss about the feasibility of the Hall Effect sensors on both positioning and switching. Both team came up with the idea of using the Hall Effect sensor’s digital output as the positioning tool and using a second sensor for switching and detecting the magnets on the track. Originally we would like to keep the design of the Korean team. However, this idea was rejected by the Track development and Bogie team because the magnetic detector on the podcar will contact with the track. And the hold system needs to be redesigned if the control team wants to keep the magnetic detector. We tested the RFID sensor, but fail to make it work properly. Our team started searching some of the smaller Hall Effect sensors. And we are getting an A3144 Hall Effect sensor in recent days.

The team is also working on searching possible corrugated metal strip supplier on the market. We are looking for products similar to the metal strip that we want, and trying to contact the manufacturer of the product to search for possible assistance.

Vehicle Position Sensing Team Week 9/14/2016 – 9/21/2016

The week, the team was focus on testing the Hall Effect sensor, the test was done on Arduino base test environment. The circuit was constructed as shown: 

The Arduino was programmed using the following simple code:

#define hall 0

void setup() {

  pinMode(hall,INPUT);

  Serial.begin(9600);

}

void loop() {

  sensorValue = analogRead(analogInPin);

  Serial.print(sensorValue);

  delay(2);

}

Conclusion for Testing:

• The Sensor only can only detect ferrous object inside a 3mm range.
• The sensor we used for testing only outputs digital signal, which means its reading might not be effected by the magnets on the track.
•  The team tested the sensor with a magnets, the result confirmed that the sensor is not affected by magnets.

Recent plans

• The team need to find new corrugated ferrous strips with much narrower spacing between peaks.
• The team is looking for a new type of Hall Effect sensor which is able to provide analog output.

Vehicle Position Sensing Team Week 9/7/2016 – 9/14/2016

This week, our team has talked to Dr. Furman about the feasibility of using Hall or GMR sensors and corrugated ferrous strip to build the position sensing system. Dr. Furman has introduced the Hall Effect sensors and his idea about accurate position sensing system for the 1/12 scale model. After the discussion with Dr. Furman, our team listed out some difficulties and key parts of our plan.

1. The team has to test if the sensors are able to detect the ferrous strip and give correct feedbacks as we expected. And the test will be done using a large scale ferrous strip and sensor.
2. If the idea work, the team should figure out the size of the ferrous strips in order to achieve a high resolution sensor feedback.
3. There is limiting space between the vehicle and the track, the team have to figure out a way to attach the ferrous strip and the sensors on the track and the car.
4. The team must find the manufacturers which are able to provide us assistance on manufacturing high quality ferrous strips, otherwise we have to make it ourselves.

In conclusion, Dr. Furman provided plenty of useful information for our team, and the team has start working on the testing of sensors.

Configuration of Hall Effect Sensor and Ferrous Strip

Testing Circuit

Team Blog Assignment #1

• Members:
• Name: Qihuan (Kevin) Miao
• Skills: Matlab, Arduino coding, CAD drawing, C++
• Contact: Cell: 415-4268953 Email: miaokevin@hotmail.com
• Responsibilities: Coding, sensor testing, researching

• Name: Zhiwei Li (Alex)
• Skill: Arduino coding, Solid Work, CAD drawing
• Contact: Cell: 415-216-6084 Email: zli52@mail.ccsf.edu
• Responsibilities: Mechanical Part, Researching, sensor testing

• The Position sensing team is supposed to work with other vehicle control teams to develop a “smart” and autonomous multiple-podcar system. The main focus of the team is to solve the positioning problem in order to create an accurate and reliable podcar positioning system for the twelfth scale model this year. The team is supposed to work out position sensing system with linear magnetic encoders systems. The linear magnetic encoder system will be created by implement hall effect sensors and neodymium magnets with a corrugated piece of sheet metal on the guide way.

• Major task in recent weeks:

• Budget Estimate: Between $100 - $300