Project

# Title Team Members TA Documents Sponsor
30 Sensing Instrument for Generating Haptic Touch - SIGHT
 Dip Patel
Jamiel Abed
John Lee
 Dushyant Singh Udawat design_document1.pdf
final_paper1.pdf
photo1.jpg
photo2.jpg
presentation1.pptx
proposal1.pdf
video1.MOV
# SIGHT Team Members: Jamiel Abed (jabed2), Dip Patel (dippp2), Seung Lee (seungpl2)

## Problem

There are 39 million people that are visually impaired who may face hardships related to sensing objects near them. Currently the most common solutions to mobility would be a walking cane, a guide dog, or a human guide. A walking cane requires the person to thoroughly and constantly sweep for obstacles as well as having a limited range. The problems with a guide dog and a human guide would be that not everyone has access to those resources.

## Solution overview

I'm proposing we create a alternative tool for the visually impaired. The SIGHT would warn the user of a potential nearby obstacle that might pose a tripping or crashing hazard.

Using an array of ultrasonic sensors we create a zone that can detect these obstacles and send signals that will be routed to a mesh of haptic pads which will be placed on the user. The SIGHT will give directional haptic feedback that will let the user know in which direction the potential hazard lies. Using a doppler based filter we would also be able to only send haptic feedback if an object is approaching you.

The SIGHT will be better then the current alternatives since it will be more reliable and requires less physical effort from the user.

The POV of the user is reflected through the XY plane of the haptic mesh (i.e. Object that you see in the top left of your view is represented by the top left of the haptic mesh). The Z dimension of the user's POV (depth of objects relative to the user) is characterized by the strength of the haptic touch.

Case Examples: Approaching a wall-

The haptic touch will lightly activate on all pads if a wall is far but approaching you. As you get closer the pads will release a stronger touch indicating the wall is getting closer to you.

Standing in front of wall (Not moving)-

The haptic touch wouldn't not activate in this case since relative to you the wall is not moving.

## Solution Components

Ultrasonic Array: A square array of ultrasonic sensors (Likely 3x3)

Haptic Mesh: A square array of haptic motor pads (Likely 4x4)

Doppler Module: A doppler module that can detect relative velocities of objects for filtering purposes.

## Criterions for Success
Criterion 1: The ultrasonic sensors must to a degree accurately determine the general direction and depth of the hazard.

Criterion 2: The haptic mesh must work in conjunction with the filtered sensor data and accurately activate the appropriate haptic pads.

Criterion 3: The processing must be able to filter out objects that are stationary relative to you as well objects moving away from you using the doppler effect.

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.