Week 3

Successes

This week, we demonstrated the functionality of a stepper motor that will be used for our reloading mechanism. The stepper motor shown is controlled via Arduino to rotate 90 degrees and then wait for one second. The arduino sends the step and direction commands to a stepper motor driver board, which is powered by the power supply shown and then supplies the necessary power to the stepper motor to induce the rotation. The stepper motor is shown to be able to provide sufficient torque to rotate two bean bags on a

We have also almost finished the CAD model of the different subsystems. The launch subsystem model is completed (shown below). The surgical tubing (springs) that will attach to the two moving carriages are not shown.

The chassis is also completed, shown right. We still need to complete the CAD files for the reloading mechanism, the mount for the reloading mechanism, and the mount for the launch mechanism.

We have ordered many of our initial parts; basic chassis and rack and pinion parts have already arrived. Items that are expected to arrive in the next couple of days are: Arduino bluetooth receiver, batteries, laser range finder, and v-slot components. With the parts that have arrived, we should be able to have prototypes of the chassis and launcher systems either ready or close to finished by the end of next week.

We also identified a Python library which interprets Xbox controller commands that we will use to issue commands to the robot via Bluetooth.

We performed a design calculation to spec out the spring stiffness and throw length required to propel a bean bag to a required distance and elevation. The picture shown is the surface of required spring stiffnesses for a given bean bag rail travel distance and launch angle.

Challenges

Metal springs available for purchase do not have sufficient stretch length for what we need. We’re going to try surgical tubing instead; however, we can’t really spec out the tubing since the tubing is a nonlinear spring and its characteristics are not well defined.

We're waiting on parts to be able to construct our launcher and chassis prototypes.

Plan for Next Week

This upcoming week, Kurt will focus on finalizing the design and manufacturing parts for the shooter mechanism. Lisa will build the chassis prototype from the parts we've received and test their functionality. Zach will write and test Xbox controller teleoperation code for driving the chassis and test controlling actuators via Bluetooth.

For our sensor demo next week, we will demonstrate the use of limit switches for our shooter mechanism. Time permitting, we will also demonstrate functionality of the laser rangefinder we will use to determine distance from the robot to the cornhole board.

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