By: Rickeisha Brown (Manufacturing Engineer)

As a level one requirement, the customer requests to refrain from exceeding a total of 6 hours 3D printing time and not to exceed two hours per printed component. The customer has a project total budget of which ultimately limits the amount of spending power per division. Printing Cost estimates which is of total budget.

Maker’s Society is the organization handling our 3D prints. Their printers can print multiple parts at a time, they’re conveniently located on the campus of CSULB, and are reasonably priced to $5 per hour. Visit their website for more details regarding Maker’s Society and the services they offer: http://lbmakersociety.org/about-us/.

I submitted my design to Carlos Vergara¹, the AESB representative, and informed him of my 6 hour printing requirement. He uploaded the parts to a program which examines each component and estimates total printing time down, to the minute.

Figure 1: The table above shows the trade-offs between strength, quality, low cost, speed vs. layer height. ²

Figure 2: Maker’s Society printing time estimates for the original body with 0.3 mm layer height: 8 hours and 24 minutes.

Figure 2 shows the results for total printing time of Goliath components with 0.3 mm layer height, with 0.2 mm being an ideal layer height based on Figure 1.

This does not meet level one requirement, so we must revert to Plan B: reducing the amount of components which make up our body from 6 to 3 components, sides (2), and cellphone and periscope compartment (1).

Here are the results:

To my surprise, the printing time did not decrease!

I requested that Carlos increase the layer height to 0.4 mm which will decrease printing time and help our team meet the 6 hour printing time requirement. Here are the results:

For 3 components, the total time still exceeds 6 hours. Therefore, I will go back to the drawing board readjust components thickness.

References:

^1-Carlos Vergara, AESB Representative for Maker’s Society, E-mail: carloslbvergara@gmail.com

^2- “What Is the Influence of Infill %, Layer Height and Infill Pattern on My 3D Prints?” 3D Matter. N.p., 10 Mar. 2015. Web. 23 Mar. 2016.

By:  Tae Min Lee (Mission, Systems, and Testing Engineer)

In order to use the Arxterra control panel we need to first implement the Arxterra firmware for the Goliath.  After testing the Arxterra firmware we encountered a problem with the motor control.  Since, the Arxterra firmware is implemented to using TB6612FNG motor control we had to make a few changes to the firmware to use the Arduino motor shield.

The following changes were made to implement the basic movements of the Goliath:

The run_AMS function is responsible for setting the direction and brakes on a motor.  In this case we treated IN1 of controlling the direction on the motor and IN2 to controlling the brakes.

The following table will indicate the movement of the Goliath:

Setting a HIGH value for IN1 will make the motor move forward.  While setting a LOW value for IN1 makes the motor go backward.  In addition, the brakes are activated when we set IN2 variable to HIGH on the motors and setting a INT2 to LOW we will disable the brakes.

To make a right turn on the Goliath we made the motor on the left side to go forward while the motor on the right go backward.  This provides a faster method of turning the Goliath to the right.  A similar action can be performed for the left turn by having the motor on the right go backward and the motor on the left go forward.

Sources:

1. https://www.arduino.cc/en/Main/ArduinoMotorShieldR3
2. https://www.arduino.cc/en/Tutorial/DueMotorShieldDC

By: Tae Lee (Systems Engineer)

IR Sensor Code

To implement the laser tag game we have to show an indication of when the Goliath gets hit by the enemy’s IR LED. This will be shown through the three LEDs we will be using to indicate the number of hits.

The following code shown below will be used to implement the three hit indicator:

The general idea of how this code operates will be shown by the block diagram below:

The code will start by checking if a signal is received at the detector. If the detector detects the IR emitter it will light up one of the LEDs and increases the count. The count will be used to indicate the number of hits received by the enemy. As we get hit the count will increase to power each LED until it reaches 3 hits. The if statement will be used to check if the Goliath receives 3 hits, which will disable the Goliath. Otherwise, it will do nothing and it will repeat the program through a loop.