Background

In this Unit, students will modify a build to solve problems and make observations surrounding its performance.

What can be modified in a VEX GO build?

Engineers apply the principles of science and mathematics to develop solutions to a variety of  problems. One way to do this is by innovating current designs to improve performance by changing a build’s various components. 

There are many parts that students can modify on a VEX GO build:

• Structure Subsystem- These parts are the “skeleton” of the robot to which all other parts are attached. This subsystem consists of all the main structural components in the VEX GO kit. These pieces (beams, plates, connectors, standoffs, and pins) come in a variety of shapes and sizes. These pieces connect together to form the frame of the robot, usually called the chassis.
  • Center of Gravity -The build’s center of gravity is where most of the weight rests on the build. A stationary build will be most stable when the weight is centered, however engineers sometimes make modifications to  the center of gravity in order to change a build’s performance.
• The Motion Subsystem- The Motion Subsystem (gears,pulleys, wheels, motors, ropes, knobs, shafts,and shaft collars) combines with the components of the Structure Subsystem in most builds. It’s like the muscle attached to the skeleton in a human body.  Most of the VEX GO motion pieces use a square hole, which fits on the square VEX GO shafts.
  • Drivetrain- Although some build’s perform their tasks without moving, a build often needs to move from location to location.  Students will usually use some sort of wheeled component called a drivetrain to enable a build’s mobility.

• Example Modifications to the Spring Car- Students will develop and test modifications to the Spring Car in the lab. Make sure that you have enough room for testing; use a long hallway or gym floor area.

  The following are some examples of the modifications students may try and the typical results:

  • Spring Car with the rubber band doubled over the pins.

    •  The “spring” part of the car is very vital to the movement of the Spring Car. The more you stretch the rubber band, the more potential energy is stored, and the farther and faster the car should go. The thickness of the rubber band also affects the distance, because a thicker rubber band is harder to stretch than a thin rubber band. The rubber bands that come with the VEX GO kit are made of silicone enabling your intake mechanisms to grip objects easier but does not work better for elongation uses like synthetic ones do. Therefore, doubling the rubber band is not a modification that works well and may damage the buber band.

  • Spring Car with two rubber bands over the pins

    • Since the more you stretch the rubber band, and the farther and faster the car should go as explained in the previous example, students may want to use both of the rubber bands from the kit.  If they are stretching two of them, they should get  twice the force, enabling the Spring Car to move father.

  • Spring Car with front wheels replaced with Blue Wheels

    • This modification enables the Spring Car to go further because the stability of the car is improved since the wheels are wider.

What is the Engineering Design Process?

Students will use the Engineering Design Process (EDP) to modify the Spring Car to improve its performance. The EDP is a series of steps that engineers use to come up with solutions to problems. Often, the solution involves designing a product that meets certain criteria or accomplishes a certain task.
The EDP can be broken down into the following steps: DEFINE → DEVELOP SOLUTIONS → OPTIMIZE.

• Defining engineering problems involve stating the problem to be solved as clearly as possible in terms of criteria for success, and constraints or limits.
• Designing solutions to engineering problems begins with generating a number of different possible solutions, then evaluating potential solutions to see which ones best meet the criteria and constraints of the problem.
• Optimizing the design solution involves a process in which solutions are systematically tested and refined and the final design is improved by trading off less important features for those that are more important.

The EDP is cyclic or iterative in nature. It is a process of making, testing and analyzing, and refining a product or process. Based on the results of testing, new iterations are created, and continue to be modified until the design team is satisfied with the results.

In this Unit, students will use the EDP to modify the Spring Car to improve its performance.   After an initial build, groups will ask questions to improve the Spring Car’s design to increase performance. This is the same Engineering Design Process covered by the Next Generation Science Standards (NGSS).

What are good observation practices?

One of the most important steps in both the Scientific Method and the Engineering Design Process is the testing.  Scientists and engineers wouldn’t know if they were successful in their results without collecting data by making observations during the testing step.

There are two types of observations:

• Natural Observation: This type consists of watching something in its natural state without any intervention. In this type of observation, scientists watch and wait for an event to happen during an experiment.
• Staged Observation: Engineers and scientists usually surround their projects around the “what if… “ question. “What is the center of gravity on this build?” “What if I change the length of the beam on the chassis?” In this type of observation, the tester intervenes and observes the result. This type of testing can be observed many times because it can be recreated.

When conducting a staged observation, there are some guidelines to follow:

• Determine in advance what you want to observe. This should be done in the planning stage of the Engineering Design Process. A group can’t determine success if they don’t know what they are examining.
• Change only one element at a time. All others must be kept the same so that it can be determined if the element being tested is successful.
• Decide on the required number of observations. Time, supplies, and location may be a factor in determining how many times a test can be recreated.
• Form a schedule. If several groups are conducting test runs in the same space a schedule ensures that there is no confusion and everyone gets a chance to test their builds.
• Record your observations so that others can use them.  Use precise terms and accurate measurements when recording your data. 
• Decide on what tools to use. There are many types of tools engineers use when testing. 
  • These tools allow for more precise and accurate observations:
    • Rulers
    • Thermometers
    • Scales
    • Cameras