ECE 495 Project 2

Robot Design and Financial Analysis

Group 6 February 15, 2013

Emily Burns, Hunt Graydon, Madison Montgomery, Sara Bailey Stocks

Executive Summary

For Project 2, our group brainstormed several ideas for the robot and the robot actuator, also known as the device that will pick up the mine, which is a magnet with north or south polarity. We decided on a final design and built a working prototype of the actuator and a mockup of the robot. The group decided to use an electromagnet to pick up the mines and move them around to their diffusing station, which is a 1 ¼ inch hole on the game board. Our group decided PVC piping would be the best choice to place around the electromagnet so the mines would have a straight direction when picked up and put down; it also alleviated some space in between the magnet and electromagnet. The electromagnet is signaled to pick up and drop the mines, depending on the polarity of the magnet, through a command line input. After several tests with the electromagnetic, it was discovered that a voltage amplifier (Techron 5530) was needed so that there would be enough current going through it therefore it would be able to pick up the magnet at a certain distance away.

Robot Design

Customer Requirement Engineering Requirement- Play game according to “Mine Sweeper

2 Description and Rules”o For consistent timing of each

round, the robot and effector must start and stop above the rectangular well.

o Any interpretation and clarification of the rules should be done through the course instructor (not the TAs).

- Program will signal the arm to hover over the rectangular well before the start of each game.

- Camera will load QR code for the polarity of the Red and Green defusing stations.

- Use the provided game board without modification.

- No changes made to game board

- Cost < $300 for parts beyond the cost of the xPC Workstation

- Parts will be purchased as cheaply as possible.

- Use xPC workstation including Q4 board and Techron amplifier

- The provided xPC workstation will be used.

- Power Source for custom electronics:o AC powero No batteries

- All power will be controlled through the Q4 board and the Techron Amplifier. Simulink will be used to amplify the signal from the Q4 board.

- Reliable - The robot will be built in a fashion that solves the desired puzzle, if the puzzle is solvable.

- Durable - A thick metal will be used for the robot arm and a strong electromagnet will also be used.

- Safeo Low noise – no hearing

protection requiredo Guarding as necessary to protect

userso A hardware emergency stop

button to deactivate the system

- All hardware used will emit limited noise.

- A small barrier will be built around the game board to ensure the magnet cannot be tossed towards persons around the game board.

- The GUI created through Matlab will have an emergency stop button that disables all signals to the robot.

- Fast times for solving - The robot will solve the puzzle in a reasonable time. Estimated time is something less than 3 seconds per puzzle move.

- Easy to use, user friendly - The GUI will provide a simplistic approach to controlling the robot.

- Electric/electronic circuits built from basic components, e.g. resistor, inductor, capacitor, diode, transformer

- The circuitry will not involve complex circuits.

- Runs autonomously during puzzle solving mode

- An algorithm that runs until the puzzle is solved will be executing when the solve option is set through the GUI interface. No other interaction will be necessary during this time unless an emergency shutdown is required.

- Must have at least one degree of freedom that has closed loop position control where the loop is closed through the xPC target.

- The motor that rotates the actuator will be controlled in closed loop. This is to allow much quicker and accurate control of the robot arm.

Robot Idea #1

In our first Idea, as shown in figure 1, the design is to have a strong electromagnet attached to the end of a rotating arm. Only the arm will move and because the electromagnet is so strong, it will not have to lower and raise to pick up the mine. Also suspended at the top is the camera, which is used to take visual data. All designs have the same way to obtain the visual data.

Figure 1

Robot Idea #2

In our second idea, as shown in figure 2, the design is to have a robot arm with multiple moving joints that could move over the entire game board. At the end of the robot arm is a claw, which would grip and pick up the mine. This design would be a fairly complicated build.

Figure 2

Robot Idea #3

For the third idea, as shown in figure 3, the plan is to pick up the magnet with a rotating vacuum hose. The vacuum will be attached to a hose that will attach to a rotating arm. The vacuum will turn on to pick up the magnet, the arm will rotate and then the vacuum will turn off to drop the mine.

Figure 3

Robot Idea #4

For our fourth idea, as shown in figure 4, is to use an electromagnet attached to a rotating arm. Also the arm will be able to raise up and lower so that the electromagnet comes into direct contact with the magnet. This will require two motors, one to rotate the arm and one to lower and raise it.

Figure 4

Robot Idea #5

For our final idea, as shown in figure 5, the plan is to rotate the board itself. On the side of the board will be a stationary arm with a strong electromagnet attached to the end. The actuator would remain stationary at all times.

Figure 5

Weighted Matrix for Robot Design

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5Criteria Weigh

tScore

Weighted

Score

Weighted

Score

Weighted

Score

Weighted

Score

Weighted

Cost 4 3 12 1 4 2 8 1 4 4 16Weight 3 5 15 5 15 4 12 4 12 5 15Simplicity

5 5 25 3 15 3 15 5 25 3 15

Speed 4 5 20 1 4 1 4 4 16 3 12Safe 5 5 25 3 15 2 10 5 25 2 10Reliable 5 3 15 2 10 2 10 5 25 3 15Total 26 26 112 15 63 14 59 24 107 20 83Score 4.3 2.4 2.3 4.1 3.2Weighted 21.5 12 11.5 20.5 16

The robot design that we chose to use is Figure 1 because this design has the highest weighted score among the 5 robots. The cost of the robot will be rather cheap because the only thing that must be purchased will be the electromagnet. The electromagnet does not weigh much, so the only part of the robot that will weigh a decent among will be the motor that spins the arm around. The design only has one moving part, the motor, which makes it simple. The speed of the robot will be fast since the arm does not have to move up and down but just rotate around the motor. This design is safe because there are no components that pose a threat to the surroundings. The design will be reliable because the electromagnet is strong, however the only problem is that it might be too strong and make the mine bounce when released.

Actuator Design

Customer Requirements Engineering Requirements Test- Lift mine - A 30 gram electromagnet

will be used to lift the mine from the well. The voltage will have to be amplified a significant amount to allow the magnet to be picked up the required distance of 30 millimeters.

- After the mine has been successfully lifted, the voltage can be decreased to 0 V.

- A series of tests will be performed to determine how many volts will be needed to lift the mine the required 30 millimeters.

- Drop mine - The mine will be dropped by reversing the polarity of the

- A simple Simulink model will be used to send a voltage to the

electromagnet. The voltage required to do so is much less than the voltage required to lift the mine. A small reverse in polarity of about -5 V will enable to mine to disengage from the electromagnet and fall back into the well.

amplifier, which will be the opposite polarity that was used to life the mine. This will completed through Matlab, by changing the parameters of the Simulink model. The gain will be decreased and the input will be negated. This will allow our actuator to be properly tested for dropping the mines. A test will be performed to determine the minimum gain needed to drop the magnet.

- Efficiency/speed of actuator

- At least 90% of the time the actuator needs to be able to pick up the mine.

- At a minimum distance of 30 millimeters, we will attempt to pick up mines of different polarities and record how many times it picks it up versus how many times we attempt to pick it up. We will also time how long it takes the electromagnetic to pick up the mine starting the stopwatch when the matlab code is executed.

Actuator Design #1

For our first actuator design, as shown in figure 6, a strong electromagnet picks up the mine. In order to drop the mine the polarity of the electromagnet is switched. The electromagnet is simply attached to the end of the rotating arm.

Figure 6

Actuator Design #2

In the second design, as shown in figure 7, a similar setup is used as in idea #1 the difference here is that a pvc pipe is added to the end of the magnet so that when the polarity is switched to drop the mine, the mine will drop strait and not flip.

Figure 7

Actuator Design #3

For the third design, as shown in figure 8, a vacuum is used to suck up the mine. This vacuum would be attached to a hose with a nozzle at the end with roughly the same size opening as the mine so that is would quickly pick it up and keep the magnet strait in the process.

Figure 8

Actuator Design #4

For this design, as shown in figure 9, a claw is used to pick up the mine. The claw will have a motor in it, which allows for the claws to open and shut. The claw will lower onto the magnet close, pick it up, move and then drop it in is proper place.

Figure 9

Actuator Design #5

For the final design, as shown in figure 10, a metallic object, such as a washer, is used to pick up the magnet. The washer is attached to a string, which allows it to be raised and lowered. After the mine is picked up the washer will raise up until the mine hits blockers, which allow for the washer to go up but not the mine.

Figure 10

Weighted Matrix for Actuator

Figure 6 Figure 7 Figure 8 Figure 9 Figure 10Criteria Weigh

tScore

Weighted

Score

Weighted

Score

Weighted

Score

Weighted

Score

Weighted

Cost 4 3 12 3 12 2 8 1 4 5 20Weight 3 5 15 5 15 4 12 5 15 5 15Simplicity

5 5 25 5 25 3 15 3 15 1 5

Speed 4 5 20 5 20 1 4 1 4 1 4Safe 5 5 25 5 25 2 10 3 15 2 10Reliable 5 3 15 5 25 2 10 2 10 2 10Total 26 26 112 28 122 14 59 15 63 16 64Score 4.3 6.1 2.3 2.4 2.5Weighted

21.5 30.5 11.5 12 12.5

The actuator that we chose to use is Figure 7 because it has the highest weighted score among the five actuators presented. The cost of the electromagnet was fairly cheap for the team to purchase. The weight of the magnet is rather light weighing 30.8 grams, and has the ability to hold 44 pounds. The electromagnet design is simple in that it only involves one moving part. The speed in which the electromagnetic picks up the mine is an advantage of Figure 7 as well. The PVC piping placed around the actuator makes it safe so the mine does not slip off of the electromagnet. This design is reliable because the actuator has no moving parts to it; the more moving parts the design has, the bigger chance it has to fail.

Actuator Prototype Evaluation

The design that we chose for our prototype actuator was design number 2. A more detailed look at the design is shown below in figure 11.

Here in this design the main piece of the actuator is the electromagnet. Attached to the end of the electromagnet is PVC pipe. The reason for the PVC pipe is so that when the mine is dropped that it drops straight down without flipping. The electromagnet is connected to an amplifier, which in-turn, is attached to the Q4 board. When the mine needs to be picked up a strong voltage around 22Volts is put through the electromagnet. When the mine needs to be dropped a smaller voltage, around 6 Volts, is put through the magnet in the opposite direction so that the magnet will drop. It was found through experimentation that a full voltage reversal would shoot the mine out with too much force. The mine often did not make it back into the game board thus a quarter of the power was used.

Voltage Used Distance From Electromagnet to Mine12V 8mm16V 12mm20V 15mm22V 25mm24V 31mm

Table 1: Testing volts required to pick mine up at distance of 30mm

Gain Drop safely into well5 No; mine bounced out of well3 No; bounced out of well

0.7 Yes; 50% efficiency0.5 Did not drop because the mine stuck to the

electromagnetTable 2: Testing gain needed to safely drop mine into well

Conclusion

This design will continue to be developed in accordance with the specifications until the optimal prototype yields the most efficient results. After attempting several of the original designs, it was ultimately decided that the electromagnet needs to be lowered through a pvc pipe to grab the magnet. Then the electromagnet will be raised back to the top of the pvc pipe to ensure that it does not drag against the board. To do this a servo motor will be needed to raise and lower the electromagnetic with a string. As seen by test results in Table 1 and Table 2, it is apparent that we need to refine our actuator design because it only droped the mine in the well 50% of the time and the voltage required to pick up the mine was more than twice the rated voltage of the electromagnetic which is unsafe and can cause the electromagnet to break.

ECE 495 Group 6-TEK Engineering

Estimated Financial Scenario

Start-up CostsPersonnel

4 Engineers @ $55K/yr + President @ $75K/yr + Admin. Asst. @ $25K/yr = $ 320,000

Fringe Benefit (FB)

A fringe benefit is a form of pay for the performance of services. For example, you provide an employee with a fringe benefit when you allow the employee to use a business vehicle to commute to and from work. Assume Fringe Benefit Package @ 36% (incl. employee's SS tax, vacation, holidays, medical, retirement (401K), dental, life insurance, relocation, unemployment insurances, etc):

(4 x $55,000 + $75,000 + $25,000) x 0.36 = $ 115,200

Note: Federal Insurance Contributions Act (FICA) tax (Social Security and Medicare) is imposed by the federal government on both employees and employers. The entire FICA percentage of 15.3%

Employee's pay 6.2% for SS and 1.45% for the Medicare (this is not included in your cost)

The employer is liable for 6.2% Social Security and 1.45% Medicare taxes=7.65%Building Initially rent a suite of offices with 2 engineers/office (12' x 14'), an office/conference room

for President (12' x 20'), and a reception/office area of 16' x 20'.

(4 cubicles) x (12' x 14'/cubicle) + President office of (12’x 20’)

+ Reception/office area of (16' x 20') = 1,232 sq ft

Use nominal figure for office space in industrial park sectors of` Clemson area, $9.50/sq ft/mo. Then the lease rate for office space will be

$0.79/sq ft/mo x 1,232 sq ft = $973/mo. = $11,679/yr.

Furniture Rental of a desk, chair, credenza set will run about $60/mo. Need 6 sets for a total

monthly expenditure of $360/mo = $4,320/yr

The remaining equipment, furniture and software expenses are estimated to be about

6 computers @ $1,500/computer $9,000

6 sets of general software @ $1,000/set $6,000

Specialized software $18,000

Copier, printer $4,000

Table and chairs for conference room $3,888

5 telephones @ $35/ea $175

Total $45,383

Phone and Internet

According to Bell South, the cost of a combined voice/data line, is $70.00/mo for operation.

For 6 telephones the total cost will be $5,040 /year.

Assume that long distance calls add another 40% to this to get a total estimated annual phone cost of $7,056

Travel Another cost item which will be important is travel. There will have to be continual contact with potential clients, attendance at selected technical conferences and workshops, and visits to plants or other locations where potential clients might be. Assume (modestly) that this will that the cost per local trip is $200 and the cost per out-of-state trip is $3,000 there will be 2 of each trip each month

$6,400/mo for the first year, or an annual total of $76,800.

Interest Capital (i.e. money) is needed to fund these initial purchases as well as to underwrite operating expenses until a revenue stream is established by selling engineering services to customers.

Assume that through personal contacts a credit line of $800,000 has been established. This is to be repaid over the period of a year with 11 equal payments starting 1 month after the loan date. The negotiated interest rate is 5% per year. The monthly payment M is calculated from

= $74,726

Where P is the principal amount ($800,000), I is the interest rate (5%), and q is the number of payments to be made (11). From this,

Debt Service = Total interest paid in year = 11 x M - P = $21,983.

Cost Estimate

Salaries $320,000

FB @ 36% $115,200

Building $11,679

Furniture $45,383

Debt service $21,983

Travel $76,800

Internet and Phone Service $7,056

Total Costs $598,101