Equipment

Lab Equipment

The Srivastava Senior Design Lab has a wide selection of equipment that provides nearly all of the capabilities of the other ECE teaching labs in one place. Although the equipment may not be identical to that found in these other teaching labs, similar functionality is offered. Use the experience of learning new equipment as a way to expand your horizons. If you are using a piece of equipment for the first time, ask a TA for assistance, to make sure you understand how to safely use it. If the available equipment does not meet the needs of your project, talk to the course staff, and we will help you find what you need elsewhere on campus, consider purchasing it for the senior design lab (if it would be used by many groups), or brainstorm alternate ways to solve your problem.

Lab Kits

Each team is provided with at least one lockable storage drawer in the lab as well as a portable lab kit. An additional drawer and/or kit may be issued as need arises and facilities allow.

The lab kit includes a box with carrying handle and contains a wiring board for prototyping circuit projects, a multiple-output power supply, a digital multimeter, and a set of 8 cables (2 bnc/bnc, 2bnc/pin, 2 banana/banana, and 2 banana/pin). This is checked out to you by your TA at the beginning of the semester and must be returned undamaged at the end of the semester. Missing lab kits will result in an encumbrance or withheld diploma and a charge of $500.00, so always be sure to lock your lockers! Also, do not store any cables from the lab in your kit. Doing so will result in a loss of points.

Test Equipment

Most equipment is connected to the PCs via HPIB cables. Below is a sampling of the test equipment available:

Specific setups at the various lab benches can be in the listing at the bottom of this page.

Computers

The lab has PCs with enough processing power for the needs of nearly any senior design project. These machines are networked to a high-capacity laser printer (printing will count against your standard print quota). Each has an Ethernet connection to the campus network, an HPIB interface card connecting it to all of the standard instruments on its bench, and a sound card. The computers are maintained by Engineering IT, located in 3080 ECE Building.

The PCs are presently configured with the software shown here. Their primary uses include:

Test Equipment (Listed by lab bench)

 
Bench: A
Oscilloscope Rohde & Schwarz RTE 1054
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
 
Bench: B
Oscilloscope Agilent DSO7104B
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
 
Bench: C
Oscilloscope Agilent DSO-X 3034A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
Dual Output Power Supply Hewlett-Packard 6234A
 
Bench: D (Power)
Oscilloscope Agilent DSO-X 6004A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
Triple Output Power Supply Hewlett-Packard 6235A
Digital Power Analyzer Valhalla Scientific 2101
DC Power Supply Hewlett-Packard 6632A
DC Electronic Load Agilent 6060B
kW Power Supply Sorensen DCS 20-50
 
Bench: E
Oscilloscope Agilent DSO-X 3034A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
 
Bench: F
Oscilloscope and Logic Analyzer Teledyne LeCroy HDO 4054-MS
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
 
Bench: G (power)
Oscilloscope Agilent DSO-X 6004A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Triple Output Power Supply Hewlett-Packard 6235A
DC Power Supply Hewlett-Packard 6632A
DC Electronic Load Hewlett-Packard 6060B
Current Probe Amplifier Tektronix AM 503
 
Bench: H (RF)
Mixed Domain Oscilloscope Tektronix MDO4054B-3
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
S-Parameter Network Analyzer Hewlett-Packard 8753ES
S-Parameter Test Set Hewlett-Packard 85047A
Pulse Generator Hewlett-Packard 8011A
Signal Generator Hewlett-Packard 8657B
 
Bench: I
Oscilloscope Agilent DSO7104B
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
Dual Output Power Supply Hewlett-Packard 6234A
 
Bench: J (RF)
Oscilloscope Agilent DSO7104B
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Triple Output Power Supply Hewlett-Packard 6235A
DC Power Supply Hewlett-Packard 6632A
Network Analyzer Hewlett-Packard 8751A
S-Parameter Test Set Hewlett-Packard 87511A
 
Bench: K
Oscilloscope and Logic Analyzer Teledyne LeCroy HDO 4054-MS
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Dual Output Power Supply Hewlett-Packard 6234A
 
Bench: L (RF)
Mixed Domain Oscilloscope Tektronix MDO4054B-3
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Vector Signal Analyzer Agilent 89441A
RF Section Hewlett-Packard 89440A
Signal Generator Hewlett-Packard 8657B
Precision LCR Meter Hewlett-Packard 4284A
 
Bench: M
Oscilloscope Agilent DSO7104B
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
 
Bench: N
Oscilloscope Agilent DSO-X 3034A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
 
Bench: O
Oscilloscope Agilent DSO-X 3034A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series
Pulse Generator Hewlett-Packard 8011A
Triple Output Power Supply Hewlett-Packard 6235A
Communications Receiver AOR AR5000
 
Bench: P
Oscilloscope Agilent DSO-X 3034A
Digital Multimeter Keysight 34461A
Triple Output DC Power Supply Keysight E3631A
Waveform Generator Agilent 33500B Series

ATTITUDE DETERMINATION AND CONTROL MODULE FOR UIUC NANOSATELLITES

Shamith Achanta, Rick Eason, Srikar Nalamalapu

Featured Project

Team Members:

- Rick Eason (reason2)

- Srikar Nalamalapu (svn3)

- Shamith Achanta (shamith2)

# Problem

The Aerospace Engineering department's Laboratory for Advanced Space Systems at Illinois (LASSI) develops nanosatellites for the University of Illinois. Their next-generation satellite architecture is currently in development, however the core bus does not contain an Attitude Determination and Control (ADCS) system.

In order for an ADCS system to be useful to LASSI, the system must be compliant with their modular spacecraft bus architecture.

# Solution

Design, build, and test an IlliniSat-0 spec compliant ADCS module. This requires being able to:

- Sense and process the Earth's weak magnetic field as it passes through the module.

- Sense and process the spacecraft body's <30 dps rotation rate.

- Execute control algorithms to command magnetorquer coil current drivers.

- Drive current through magnetorquer coils.

As well as being compliant to LASSI specification for:

- Mechanical design.

- Electrical power interfaces.

- Serial data interfaces.

- Material properties.

- Serial communications protocol.

# Solution Components

## Sensing

Using the Rohm BM1422AGMV 3-axis magnetometer we can accurately sense 0.042 microTesla per LSB, which gives very good overhead for sensing Earth's field. Furthermore, this sensor is designed for use in wearable electronics as a compass, so it also contains programable low-pass filters. This will reduce MCU processing load.

Using the Bosch BMI270 3-axis gyroscope we can accurately sense rotation rate at between ~16 and ~260 LSB per dps, which gives very good overhead to sense low-rate rotation of the spacecraft body. This sensor also contains a programable low-pass filter, which will help reduce MCU processing load.

Both sensors will communicate over I2C to the MCU.

## Serial Communications

The LASSI spec for this module requires the inclusion of the following serial communications processes:

- CAN-FD

- RS422

- Differential I2C

The CAN-FD interface is provided from the STM-32 MCU through a SN65HVD234-Q1 transceiver. It supports all CAN speeds and is used on all other devices on the CAN bus, providing increased reliability.

The RS422 interface is provided through GPIO from the STM-32 MCU and uses the TI THVD1451 transceiver. RS422 is a twisted-pair differential serial interface that provides high noise rejection and high data rates.

The Differential I2C is provided by a specialized transceiver from NXP, which allows I2C to be used reliably in high-noise and board-to-board situations. The device is the PCA9615.

I2C between the sensors and the MCU is provided by the GPIO on the MCU and does not require a transceiver.

## MCU

The MCU will be an STM32L552, exact variant and package is TBD due to parts availability. This MCU provides significant processing power, good GPIO, and excellent build and development tools. Firmware will be written in either C or Rust, depending on some initial testing.

We have access to debugging and flashing tools that are compatible with this MCU.

## Magnetics Coils and Constant Current Drivers

We are going to wind our own copper wire around coil mandrels to produce magnetorquers that are useful geometries for the device. A 3d printed mandrel will be designed and produced for each of the three coils. We do not believe this to be a significant risk of project failure because the geometries involved are extremely simple and the coil does not need to be extremely precise. Mounting of the coils to the board will be handled by 3d printed clips that we will design. The coils will be soldered into the board through plated through-holes.

Driving the inductors will be the MAX8560 500mA buck converter. This converter allows the MCU to toggle the activity of the individual coils separately through GPIO pins, as well as good soft-start characteristics for the large current draw of the coils.

## Board Design

This project requires significant work in the board layout phase. A 4-layer PCB is anticipated and due to LASSI compliance requirements the board outline, mounting hole placement, part keep-out zones, and a large stack-through connector (Samtec ERM/F-8) are already defined.

Unless constrained by part availability or required for other reasons, all parts will be SMD and will be selected for minimum footprint area.

# Criterion For Success

Success for our project will be broken into several parts:

- Electronics

- Firmware

- Compatibility

Compatibility success is the easiest to test. The device must be compatible with LASSI specifications for IlliniSat-0 modules. This is verifiable through mechanical measurement, board design review, and integration with other test articles.

Firmware success will be determined by meeting the following criteria:

- The capability to initialize, configure, and read accurate data from the IMU sensors. This is a test of I2C interfacing and will be tested using external test equipment in the LASSI lab. (We have approval to use and access to this equipment)

- The capability to control the output states of the magnetorquer coils. This is a test of GPIO interfacing in firmware.

- The capability to move through different control modes, including: IDLE, FAULT, DETUMBLE, SLEW, and TEST. This will be validated through debugger interfacing, as there is no visual indication system on this device to reduce power waste.

- The capability to self-test and to identify faults. This will be validated through debugger interfacing, as there is no visual indication system on this device to reduce power waste.

- The capability to communicate to other modules on the bus over CAN or RS422 using LASSI-compatible serial protocols. This will be validated through the use of external test equipment designed for IlliniSat-0 module testing.

**Note:** the development of the actual detumble and pointing algorithms that will be used in orbital flight fall outside the reasonable scope of electrical engineering as a field. We are explicitly designing this system such that an aerospace engineering team can develop control algorithms and drop them into our firmware stack for use.

Electronics success will be determined through the successful operation of the other criteria, if the board layout is faulty or a part was poorly selected, the system will not work as intended and will fail other tests. Electronics success will also be validated by measuring the current consumption of the device when operating. The device is required not to exceed 2 amps of total current draw from its dedicated power rail at 3.3 volts. This can be verified by observing the benchtop power supply used to run the device in the lab.