P17221: FSAE Composite Tube Fabrication/public/
Table of Contents
List of Functions from the System Architecture
- Zero Machine
- Decode G-Code
- Instruct Motor Controllers
- Send Signals to Motors
- Is the Machine Running Normally
Overview of the Electrical System
New Risks Added
- Incompatibilities between GRBL's expected input and
- This is a very high priority task.
- Generation of ComposicaD output is still pending.
- Mitigation would be to write code to pre-process ComposicaD's output and feed it into GRBL.
- All of the documentation indicates that the system should work. However, there is much that could go wrong, particularly in the interface between ComposicaD and the Arduino. The only way to be able to evaluate what the problems are would be to actually prototype the system with the Arduino, the motor shield, a motor, a PSU, and the ComposicaD output. This prototyping will occur as soon as we are able to get all of the parts.
- Motors don't have enough power.
- To mitigate this risk, we are over estimating the amount of power required in order to not have a situation where the motors stall or don't have sufficient holding torque.
- Additionally, we will meet with Dr. Lyshevski to get his opinion on identifying stepper motor power requirements early in detailed design phase.
- Not enough space on the Arduino for G code to be
loaded because GRBL is taking up too much space.
- This is something that we will have to explore once we get some parts are start testing.
- To mitigate this risk, we may have to purchase a Arduino board with more memory.
- Cannot obtain a winding GUI for free. This risk has been resolved as we have obtained ComposicaD.
Requirements FlowThe chart below shows how the customer requirements flow into the engineering requirements which dictate subsystem requirements.
Electrical Components Preliminary BOM
- The motors have been recently selected and this BOM does not reflect that. This BOM is using two NEMA 34 motors. We are going to use a NEMA 34 for the mandrel and a NEMA 17 for the crossfeed.
- Because the motors in the BOM are larger than required, the drivers are more powerful and more expensive than the final drivers.
- This BOM also does not account for the power supply. This is entirely dependent on the motors selected.
- The motor selected determines the drivers. The drivers will determine the power supply. We know the size of the motors that will be used, but we need to be careful to pick the right drivers and power supply. This is not so much an power/feasibility issue as it is a cost/purchasing issue (i.e. getting motors and drivers from the same brand from the same store).
GRBL FeasibilityWe set up an Arduino with GRBL on it. With GRBL, we were able to send motor commands in G-code to the Arduino. Using an oscilloscope, we measured the output of the Arduino. These signals would go the motor drivers which will drive the stepper motors.
Test Plans for Next Phase
- Many tests are for testing our system's core
functionality, and therefore don't map to specific
- Motor direction test, Motor sweep, Max file size
- Determine where to purchase/obtain the motors, drivers, and power supply. Possibly get more SME feedback for this process.
- Test the interface between ComposicaD and GRBL by
prototyping a sample system consisting of ComposicaD, an
Arduino, and a motor/driver/power supply setup.
- Test basic G code.
- Test G code files.
- Many tests from our test plan can be run on this prototype system.
- Design e-stop.
- We have determined that we need an estop, but are currently determining the best way to implement the estop. We will be able to better assess this after purchasing motors and drivers and testing the electrical system. Currently, there are too many variables; including uncertainty about the motor drivers, interfacing between the different electrical blocks, among others; to determine where the best place would be to put the estop.