Project
# | Title | Team Members | TA | Documents | Sponsor |
---|---|---|---|---|---|
28 | Universal PoE Stepper Motor Driver for Argonne National Lab |
Armando Rodea Bryan Monk Putra Firmansyah |
Evan Widloski | design_document4.pdf final_paper1.pdf photo2.jpg photo1.jpg presentation1.pptx proposal1.pdf |
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# Universal PoE Stepper Motor Driver for Argonne National Lab Team Members: - Bryan Logan Monk (blmonk2) - Putra Derindra Firmansyah (pdf2) - Armando Rodea (rodea3) # PROBLEM We are working with Argonne National Laboratory in the Advanced Photon Source. In the beamline where they conduct x-ray diffraction experiments, they use countless stepper motors for alignment, automation, etc. However, the drivers they use are bulky, expensive, and somewhat outdated. There is also a limited number, so they have to use ports sparingly. A compact, scalable driver would be ideal, but current solutions would require a power supply for each added driver in addition to wiring for serial communication. # SOLUTION We plan to create a driver that uses power over ethernet (PoE) to communicate with a stepper driver and to power it as well. There will be an input to the ethernet port then a circuit will separate the power and the data being transmitted. Afterward, we will use a voltage step-down circuit to input an appropriate amount of power into the stepper motor. The ethernet data will then be interpreted by an MCU that interfaces with a Motion Controller IC. This will produce step/dir signals for a driver IC which drives a MOSFET stage to properly drive the motor. We intend to make this module universal to stepper motors with different current requirements while being relatively low cost. # SOLUTION COMPONENTS ## Subsystem 1: PoE Interface This first consists of a PoE input through an RJ-45 port. The PoE control interface needs to be set up and communicate which power standard we are using (for example PoE++ which provides 60W), so we will use a power delivery controller IC such as the Analog Devices LT4293. Next, the ethernet data will be routed to an Ethernet PHY which communicates with the central MCU, and the power will be routed to the step-down circuit. ## Subsystem 2: Central MCU A central microcontroller will be used to interpret the data from the Ethernet PHY and convert it to SPI commands to send to the driver circuit. This should also be able to allow the user to program different current values and set a static IP address. We might also need some external memory to store settings, although we are unsure of this at this time. As far as a specific MCU, we are currently looking at the STM32F107 which has integrated ethernet MAC, but still requires an external PHY IC. ## Subsystem 3: Voltage Step Down Circuit PoE typically uses 48VDC to transmit power. To drive the stepper motors, we will need to step down this voltage to 12V, and further step it down to 3.3V for the digital logic. ## Subsystem 4: Stepper Motor driver circuit This subsystem consists of three components. The first is a motion controller IC that the MCU sends commands to over SPI. This generates step/dir pulses which is the standard communication protocol for stepper motors. Additionally, this chip accepts inputs from limit switches which are used to stop the motor if they are activated. A tentative chip to use for this would be the Trinamic TMC429. Next is the actual stepper motor driver IC, such as the Trinamic TMC262. This takes the input step/dir pulses and converts them into signals to drive the MOSFET bridge, limiting the current to a specified amount. A bridge of 8 MOSFETs is used to drive the four wires used in bipolar stepper motors. # CRITERION FOR SUCCESS The main goal of this project is to ensure that the driver works perfectly between an input that controls the motor as well as making sure the motor takes the appropriate direction and that it can be powered accordingly. Hence, we will measure its accuracy as well. To measure its accuracy, we will micro-step the motor and see if it moves correctly. E.g for a stepper motor with 200 steps for every revolution then, it should only move by 1.8 degrees per micro step. We will also test this for multiple stepper motors ranging in size and current requirements as well to make sure that the driver is indeed universal. Finally, reliability is key for use in a scientific lab, so the ethernet communication should never drop out and response should be quick. |