CanSat 2012 PDR: Team 2134 (IEEE UCSD)1 CanSat 2012 Preliminary Design Review Team 2134 - IEEE UCSD

CanSat 2012 PDR: Team 2134 (IEEE UCSD) 1

CanSat 2012

Preliminary Design Review

Team 2134 - IEEE UCSD

CanSat 2012 PDR: Team 2134 (IEEE UCSD) 2Presenter: Chris Warren

Presentation Outline

Introduction / Team Organization — Chris Warren

Systems Overview — Chris Warren, Jeff Wurzbach

Sensor Subsystem Design — Alex Forencich

Descent Control Design — Jeff Wurzbach

Mechanical Subsystem Design — Jeff Wurzbach

Communication and Data Handling Subsystem Design — Alex Forencich

Electrical Power Subsystem Design — Alex Forencich

Flight Software Design — Chris Warren, Alex Forencich

Ground Control System Design — Chris Warren, Alex Forencich

CanSat Integration and Test — Jeff Wurzbach

Mission Operations & Analysis — Chris Warren

Management — Chris Warren


Team Organization

Presenter: Chris Warren


Acronyms


AGL – Above Ground Level

BPS – Barometric Pressure Sensor

CAN – CanSat System

CAR – Carrier Subsystem

DCS – Descent Control System

IMU – Inertial Measurement System

LAN – Lander Subsystem

MCU – Microcontroller Unit

PCBA – Printed Circuit Board Assembly

RTV – Room-temperature Vulcanizing Rubber

FSW – Flight Software

GSW – Ground Station Software

OTA – Over the Air

GCS –Ground Control Station


Systems Overview

Chris Warren

Jeff Wurzbach


Mission Summary

• CanSat Objectives– Successfully leave the Payload Envelope of the rocket

– Record and transmit telemetry every two seconds

– Passively control descent rate as specified

– Autonomously seperate into Carrier and Lander units at 91 meters above the ground

• Carrier Objectives– Maintain a descent rate of 5 meters per second

– Record atmospheric and position data onboard

– Send recorded telemetry data to ground station

• Lander Objectives– Maintain a descent rate of 5 meters per second

– Record atmospheric and position data onboard

– Land a large grade A hen's egg safelyPresenters: Chris Warren Jeff Wurzbach


Mission Summary (cont'd.)

• Selectable Objective– Lander shall measure the force of impact on the ground at a

sampling rate of 100 Hz

– This data will be stored onboard for post-processing

– Due to space and weight constraints, this is the easiest bonus objective to attempt

• External Objectives– As a team, we wish to release as much open-source data,

programming, and other system information as possible

– We will publish information and experimental findings that proved to be important and useful in our project

– This will serve as an aid and inspiration for other individuals/teams attempting similar system objectives

Presenters: Chris Warren Jeff Wurzbach


System Requirements – Cansat Mission


ID Requirement Rationale Priority ChildrenVM

A I T D

CAN-01Total mass of Cansat shall not exceed 750 grams / be less than 400 grams (excluding egg)

Mass is an expensive property concerning rockets and flight HIGH X X

CAN-02 Cansat shall fit inside payload envelope 130mm in diameter and 152mm in length

Systems will have to be constructed around space available in a transport vessel HIGH X X

CAN-03No protrusions beyond the envelope of the rocket allowed until the Cansat is deployed

Many cansats fail to eject properly, this will aid in ensuring a proper ejection HIGH X

CAN-04The rocket airframe cannot be used to restrain any deployable parts of the Cansat

The rocket is only for transport; systems must work independently MEDUIM X

CAN-05The rocket airframe and payload sections shall not be used as a part of Cansat operations

Systems must work independently MEDIUM X

CAN-06 The Cansat shall deploy from the rocket payload section

Important to have a successful flight with proper telemetry HIGH X

CAN-07 The descent control system shall not use any flammable or pyrotechnic devices We will be launching in a fire-risk area MEDIUM

CAR-06LAN-06DCS-04

X

CAN-08 Prior to lander deployment, Cansat shall descend as a single unit Competition Requirement MEDIUM X X

CAN-09Cansat descent rate shall be 10 m/s above 200 meters AGL, and 5 m/s below 200 meters AGL

Competition Requirement MEDIUMCAR-01LAN-01DCS-01

X X X

CAN-10 The Cansat (Carrier+Lander) shall separate at an altitude of 91 meters Competition Requirement MEDIUM LAN-08 X X

CAN-11 All descent control systems must be capable of handling a 30G shock force

The deployment of recovery parachutes could tear apart the Cansat airframe if it is not strong enough

HIGHCAR-03LAN-03DCS-05

X X


System Requirements –Cansat Mission (cont’d.)


ID Requirement Rationale Priority ChildrenVM

A I T D

CAN-12Carrier and lander both shall include an audible locating device rated at 80dB or higher, independently powered with a dedicated power switch

Cansat could be lost in the launch area after landing; audible locating is more reliable than visual in this situation

HIGH CAR-09LAN-10 X

CAN-13Cansat communications shall use the XBEE radio modules, with the NETID/PANID set to the team number, and the modules NOT in broadcast mode

Reliable data handling and communications with no interference is key for this satellite flight HIGH X

CAN-14 Cansat shall not transmit telemetry until commanded by the ground control station

Preserves onboard memory and battery life for mission critical data MEDIUM X X

CAN-15Ground station must be developed that shall display telemetry in real-time and in engineering units

Prevents messy conversions or accidental miscalculations MEDIUM X

CAN-16 Ground control station antenna must be elevated a minimum of 3.5 meters

Allows for clearer and more reliable radio transmissions HIGH X

CAN-17Carrier and lander both shall have battery capacity to support a one-hour delay on the launch pad as well as flight time, with an external power control

There is a good chance that there will be launch delays due to wind or other events; an external power switch will allow for easy power control without tearing apart the Cansat

HIGH X X

CAN-18 Cansat shall not use LiPo batteries Competition Requirement LOW X

CAN-19 Cansat fight hardware budget shall be limited to $1000

All projects must work within their approved budgets MEDIUM X

CAN-20 Cansat shall be launched within the assigned launch window Delays are costly, and must be avoided MEDUIM X

CAN-21The Cansat and associated operations shall comply with all published field safety regulations

Safety is key when dealing with rocket launches, projectiles, and possibly-free-falling objects

HIGH X X


System Requirements – Carrier


ID Requirement Rationale Priority Parents ChildrenVM

A I T D

CAR-01 Average descent rate of Carrier after Cansat separation shall be 5 m/s Competition Requirement MEDIUM CAN-09 DCS-02 X X X

CAR-02 Parachutes / parafoils shall be florescent pink or orange Aids visibility of the Carrier when in the sky MEDIUM DCS-06 X

CAR-03

Structure must support 10G acceleration force and 30G shock force, with the descent control attachment points to be easily inspected

Structure must not deform under expected launch, flight, and descent forces HIGH CAN-11 X X X

CAR-04 Mechanisms must be able to maintain their configuration under any loading

Structure must maintain its configuration in order to reliably work HIGH X X X

CAR-05All electronic circuit boards must be properly mounted and enclosed/shielded from the environment

Proper design and mounting of PCBs will ensure reliable electronic functioning MEDIUM X

CAR-06Mechanisms must not use pyrotechnics or chemicals, and any use of heat must not be exposed to the outside environment

We are operating in a fire-risk area; safety is key HIGH CAN-07 X

CAR-07Contact information and identifying marks must be places on the Carrier structure

In case the Carrier travels off-range, there is more of a chance of it being returned MEDIUM X

CAR-08

Telemetry must be transmitted every two seconds, and shall consist of GPS fix data, altitude from a non-GPS sensor, air temperature, and battery voltage

Telemetry data is a large part of the competition HIGH X X

CAR-09Carrier shall activate an audible beacon only following landing, and for at least three hours thereafter

After landing, visual contact will most likely be lost; audible contact will be much more reliable

HIGH CAN-12 X


System Requirements – Lander



A I T D

LAN-01 Average descent rate of Lander after Cansat separation shall be 5 m/s Competition Requirement MEDIUM CAN-09 DCS-03 X X X

LAN-02 Parachutes / parafoils shall be florescent pink or orange Aids visibility of the Lander when in the sky MEDIUM DCS-06 X

LAN-03

Structure must support 10G acceleration force and 30G shock force, with the descent control attachment points to be easily inspected

Structure must not deform under expected launch, flight, and descent forces HIGH CAN-11 X X X

LAN-04 Mechanisms must be able to maintain their configuration under any loading

Structure must maintain its configuration in order to reliably work HIGH X X X

LAN-05All electronic circuit boards must be properly mounted and enclosed/shielded from the environment

Proper design and mounting of PCBs will ensure reliable electronic functioning MEDIUM X

LAN-06Mechanisms must not use pyrotechnics or chemicals, and any use of heat must not be exposed to the outside environment

We are operating in a fire-risk area; safety is key HIGH CAN-07 X

LAN-07Contact information and identifying marks must be places on the Lander structure

In case the Lander travels off-range, there is more of a chance of it being returned MEDIUM X

LAN-08 Lander shall safely land a single large Grade A egg from 91 meters AGL Competition Requirement HIGH CAN-10 X X X

LAN-09Lander shall measure the force of impact with the ground at a rate of 100 Hz, with data stored onboard

Bonus Objective HIGH X X

LAN-10Lander shall activate an audible beacon only following landing, and for at least three hours thereafter

After landing, visual contact will most likely be lost; audible contact will be much more reliable

HIGH CAN-12 X


System Level CanSat Configuration Trade & Selection

• Stacked Module Design (Selected)• Proven design

• Easily constructed

• Lower risk of binding during release phase

• 360° antenna coverage is straight forward to accomplish

• Sliding Module Design (Not used)• Simple retention mechanism

• Higher sensitivity to tolerance stack up and misalignment

• Possible antenna occlusion due to asymmetric design

• Concentric Module Design (Not used)• High complexity geometry

• Requires exotic PCB substrate to accommodate electronics

• If designed correctly center of mass will not change dramatically after release

• Parachute mount to inner module is simple, the outer module mount is comparatively complex



System Concept of Operations


Pre-Launch

Cansat will listen to XBEE, waiting for ground station to signal telemetry

start

Sleep

Sleep

MCU SENSOR (IMU / BPS / TMP) GPS

Lander

Carrier

OFF

BUZZ XBEE

Active


OFF

BUZZ XBEE

Active

SleepSleep

Sleep

Sleep Sleep

Sleep SleepActive

Active


System Concept of Operations (cont’d)


Launch

MCU will cycle, pulling necessary information

from SENSOR package. Data

retrieval and storage will be interrupt-based

Sleep

SleepActive


Active

Lander

Carrier

OFF

BUZZ XBEE

Active

Active

Active


Active

OFF

BUZZ XBEE

Active

Active

Carrier and Lander will have near-exact flight hardware. Telemetry data from both units

will be separated and parsed by the ground

station


System Concept of Operations(cont’d)


Apex / Deployment

SENSOR data still polled, stored onboard,

and sent via XBEESleep

SleepActive


Active

Lander

Carrier

OFF

BUZZ XBEE

Active

Active

Active


Active

OFF

BUZZ XBEE

Active

Active

CanSat will fall out of payload envelope. Drag chute (resting

inside payload bay) will release, keeping

CanSat at required descent rate




Descent A

SENSOR data still polled, stored onboard, and sent via XBEE.

Sleep

SleepActive


Active

Lander

Carrier

OFF

BUZZ XBEE

Active

Active

Active


Active

OFF

BUZZ XBEE

Active

Active

Once altitude transitions past 200

meters AGL, the secondary drag chute attached to the Carrier

will be released

BPS pressure altitude will be monitored




Lander

CarrierDescent B


Once altitude transitions past 91

meters AGL, the Carrier and Lander will

separate

BPS pressure altitude will be monitored

Active


Active

OFF

BUZZ XBEE

Active

Active

Active


Active

OFF

BUZZ XBEE

Active

Active

Lander chute will deploy during separation




Lander

CarrierLanding / Post-flight


IMU (containing the accelerometer) will be monitored at 100 Hz

Sleep


Active

ON

BUZZ XBEE

Sleep

Active

Sleep


Active

ON

BUZZ XBEE

Sleep

Active

After impact data is stored, Buzzer will be

turned on, sensor package will be turned off, and the MCU and

XBEE will sleep

OFF OFF

OFF OFF

ON

ON

MCU and XBEE will wake periodically to

ping the ground station


Physical Layout


Isometric view of the Complete CanSat

(covers not shown)

Sectioned Front view of the Complete CanSat

(covers not shown)127mm

145mm


Physical Layout


Carrier (cover not shown) Lander (cover not shown)


Physical Layout


Front view of Carrier (cover shown) Carrier (cover shown)

Note: Lander cover design is incomplete.


Launch Vehicle Compatibility

• CanSat (Carrier + Lander) will be inserted into the payload envelope upside-down, with the initial drag chute closest to the base of the rocket stack• This allows the CanSat to fall out in the proper orientation

• The CanSat dimensions will be within the required envelope, and will have a factor of safety built in such that the CanSat will fall out smoothly• 127mm• 145mm

• We have ordered and received a LOC/Precision Minie-Magg rocket body• We will use this prior to our flight to ensure proper CanSat – Rocket

integration and fit



Launch Vehicle Compatibility


This rendering shows the Cansat assembly inside the specified reference payload envelope

CanSat 2012 PDR: Team ### (Team Name) 24

Sensor Subsystem Design

Alex Forencich


Sensor Subsystem Overview

Presenter: Name goes here

Subsystem Component Chosen Purpose

ALT DEV-100/BMP085 Measure barometric pressure

TEM DEV-100/BMP085 Measure open-air temperature

ACL DEV-100/ADXL345 Measure acceleration

GYR DEV-100/ITG-3200 Measure rotation rate

MAG DEV-100/HMC5883L Measure heading

GPS MT3329 Calculate Altitude, Latitude, Longitude, and Time

SCP DEV-100/ATMEGA328P

Coprocessor to assist in sensor data acquision and processing


Sensor Subsystem Requirements


ID Requirement Rationale Priority ParentVM

A I T D

SEN-01 Telemetry shall be displayed at GCS Competition requirement HIGH X X

SEN-02 Position shall be recorded via GPS Competition requirement HIGH SEN-01 X

SEN-02 Altitude shall be recorded via non-GPS sensor Competition requirement HIGH SEN-01 X

SEN-03 Air temperature shall be recorded Competition requirement HIGH SEN-01 X

SEN-04 Accelerometer shall measure impact force Competition requirement HIGH X

SEN-05 Accelerometer shall be sampled at a minimum of 100 Hz Competition requirement HIGH X

SEN-06 GPS shall operate at 3.3 volts Hardware requirement MEDIUM EPS-04 X X

SEN-07 IMU sensors shall operate at 3.3 volts Hardware requirement MEDIUM EPS-07 X X


Carrier GPS Trade & Selection


Model Power Channels Accuracy Mass Frequency

MT3329 3.3V/42mA 66 2.5m 6g 10Hz

LS20031 3.3V/41mA 66 10m 9g 5Hz

Venus634FLPx 3.3V/28mA 14 <2.5m 2g 10Hz

• Selection: MT3329

• Extremely compact and lightweight

• Internal antenna

• High update rate

• Binary protocol support for efficient storage and transmission of GPS data with no reprocessing


Carrier Non-GPS Altitude Sensor Trade & Selection


Model Voltage/Current

Range Accuracy

Mass Interface

BMP085 3.3V/5A 30kPa-110kPa 100Pa .09g I2C

MPL115A1

(3.3V or 5V)/10A

50kPa-115kPa 1000Pa <1g SPI

SCP1000 3.3V/25A 30kPA-120kPa 1.5Pa <1g SPI

• Selection: BMP085


• Very accurate

• Built in pressure sensor

• Included in Mongoose IMU board


Carrier Air Temperature Trade & Selection



Range Accuracy

Mass Interface

BMP085 3.3V/5A -40 to +85°C ±0.1°C <1g I2C

TMP36 (3.3V/5V)/50A –40°C to +125°C

±1°C <1g Analog

DS18B20 (3.3V/5V)/NA –55°C to +125°C

±0.5°C <1g Digital



• Very accurate

• Built in temperature sensor



Lander Altitude Sensor Trade & Selection



Range Accuracy

Mass Interface

BMP085 3.3V/5A 30kPa-110kPa 100Pa .09g I2C

MPL115A1

(3.3V or 5V)/10A

50kPa-115kPa 1000Pa <1g SPI

SCP1000 3.3V/25A 30kPA-120kPa 1.5Pa <1g SPI



• Very accurate

• Built in pressure sensor


CanSat 2012 PDR: Team ### (Team Name) 31Presenter: Name goes here

Lander Impact Force Sensor Trade & Selection

Model Voltage Current (active/sleep)

Range Frequency Interface

ADXL345 3.3V 40A/.1A 2, 4,8,16g 3200Hz I2C

MMA7361 3.3V 440A /3A 1.5, 6g 400Hz (x,y)300Hz (z)

Analog

SCA3000 3.3V 300-650ANo Sleep Mode

2g 300Hz SPI

ADXL320 3.3V/5.0V 350-480ANo Sleep Mode

5g 500Hz Analog

• Selection: ADXL345


• Very accurate



Descent Control Design

Jeff Wurzbach


Descent Control Overview

Presenter: Jeff Wurzbach

• Carrier and Lander descent control will be accomplished with a parachute.

• A hemispherical or an elliptical configuration shall be used ration to minimize mass, material, and volume.

• A spill hole may be used for improved stability.• Rip-stop Nylon fabric will be used cut into gores and stitched

into desired geometry.• Nylon cords will be used for suspension lines


Descent Control Requirements



A I T D

DCS-01CanSat descent rate shall be 10 m/s above 200 meters AGL, 5 m/s below 200 meters AGL

Competition Requirement MEDIUM CAN-09 X X

DCS-02 Carrier descent rate shall be 5m/s after separation Competition Requirement MEDIUM CAR-01 X X

DCS-03 Lander descent rate shall be 5m/s below 91 meters AGL Competition Requirement MEDIUM LAN-01 X X

DCS-04 Descent control system shall not use and flammable or pyrotechnic devices

Safety is key, as we are launching in a fire-risk area HIGH CAN-07 X

DCS-05 All descent control systems must be capable of handling a 30G shock force

The deployment of parachutes must not teat apart the CanSat structure HIGH CAN-11 X X

DCS-06 Parachutes / parafoils shall be florescent pink or orange

High visibility of descending carrier and lander MEDIUM CAR-02

LAN-02 X


Carrier Descent Control Strategy Selection and Trade

• Material Selection – Rip Stop Nylon

• Lightweight

• Strong– proven to hold up humans when skydiving

• Easy to work with

• Bright orange is easily procured• We used nylon in last year’s competition

• Parachute design performed marginally well• Flaws in last year’s implementation

• Edges of the parachute crept up the shroud lines• Packing error caused the canopies to collapse during release

phase• Using data / experience from last year to design and fabricate higher

performance descent control parachutes



Lander Descent Control Strategy Selection and Trade

• Using Rip Stop Nylon for Lander descent control• It makes sense for us to use only one material

• Simplifies manufacturability• Nylon, as stated before, is proven to work• Bright pink selected for Lander descent control parachute


Descent Rate Estimates

Assumptions

Maximum system mass of 750 g

Mass split equally between Carrier and Lander

Mass of egg neglected for estimations

Pieces falling at terminal velocity

Air density at standard temperature and pressure

Configurations Estimates

Since mass of Carrier + Lander is double that of just the Carrier (or Lander), we can assume that the descent speed of the combined configuration is double that of the single pieces

CanSat 2012 PDR: Team 2134 (IEEE UCSD) 37Presenter: Jeff Wurzbach

Descent Rate Estimates (cont’d)

Thus, we have decided to use the same parachute for both halves of the Cansat assembly

This will simplify design and manufacturability

However, since our CAD model has not yet been refined, we have not focused on nailing down the descent control design

The governing equations for parachute decent are well documented

The final mass budget we get from our final CAD design will drive those equations, the solution of which will be our finalized parachute design

All we really need is the parachute dimensions from those equations to move forward


Descent Rate Estimates (cont’d)




Mechanical Subsystem Design

Jeff Wurzbach


Mechanical Subsystem Overview

Summary• Carrier design overview• Lander design overview• Egg Container and Protection System overview• PCBAs and electrical components• Material Selections



Mechanical System Requirements



A I T D

MEC-01 Structure must support a 10G loadThe Cansat must not deform; it must stay strong throughout the mission

HIGH X X X

MEC-02 Structure must support a 30G shock force

Parchute deployment can be violent HIGH X X X

MEC-03 Structure must have an enclosureProtects electronic components; adds strength

MEDIUM X

MEC-04 Cansat structure must have a mass between 400 and 750 grams

Mass is a valuble “resource” in space misions

HIGH X


Lander Egg Protection Trade & Selection

• Selection: Neoprene Rubber and Expanding Foam (formed in the field, around egg to be launched)


Material Cost Weight Comments

Closed Cell Foam (thin) Medium Low Observed effectiveness is low (used in last year’s scheme)

Neoprene Rubber High High Whole sheets are very costly

Polystyrene Beads N/A (left over from last year) Low Observed effectiveness is low

Expanding Foam Medium-High Medium Expanding foam to be contained so that it does not stick to the egg or container the egg is in.

Peanut Butter Low High Almost as dense as water. Eliminated as the primary cushion material due to high density

44

Mechanical Layout of Components Trade & Selection

• Principle metric for judging materials is workability. • This metric is key based on last year’s experiences of

building the structures at the last minute• Parts have to machine-able with the tooling we have on

hand

• Table below shows the metrics considered and a brief description of the metric

Material Workability Cost Strength/Weight Other

Name of the material Overall ease of machining and forming processes

Cost of the raw material

Strength of the material divided by its weight.

Notes and comments

CanSat 2012 PDR: Team 2134 (IEEE UCSD)Presenter: Jeff Wurzbach

45

Mechanical Layout of Components Trade & Selection

Material Workability Cost Strength/Weight Other

6061-T6 Alloy Aluminum

Medium Low-Medium Medium Tears easily when bent

7075-T6 Alloy Aluminum

Medium Low-Medium Medium Tears easily when bent

3003 Alloy Aluminum Easy-Medium Low Low-Medium Used last year

Carbon Fiber/Other Composites

Medium High High Dust is very annoying

Nickel Based Alloys (such as Inconel)

Difficult Astronomical High No prior knowledge of working with material

High Impact Polystyrene

Easy Low Low For use on non structural parts. No prior experience with vacuum forming process

Expanding Foam Medium (messy) Medium-High N/A (used for cushioning)

Expanding foam to be contained so that it does not stick to the egg or container the egg is in.

Peanut Butter Medium (messy) Low N/A (used for cushioning)

Almost as dense as water.

CanSat 2012 PDR: Team 2134 (IEEE UCSD)Presenter: Jeff Wurzbach

Material Selections

• 3003 Aluminum sheet metal

• Easy to work with (machines easily, takes bends well)

• Readily available (carried by Home Depot and other local vendors)

• Good strength to weight ratio

• 40 mil High Impact Polystyrene

• Vacuum formable

• Allows low weight non-structural and low strength parts to be made

• Low density foam

• Low weight

• Easily custom formable

• Readily available

• Neoprene/similar Rubber

• Good shock absorption

• Moderate weight

• Augments the expanding foam

46CanSat 2012 PDR: Team 2134 (IEEE UCSD)Presenter: Jeff Wurzbach


Carrier-Lander InterfaceOperational Model

• 4 locking tabs hold the lander to the carrier• The carrier has a plate that turns and releases the

locking tabs. • There are alignment tabs and pins that ensure the

Lander does not rotate with the Carrier• Rotation is accomplished by rotary solenoid

• Considering swapping a servo in to save weight.• Parachute for the lander will be stowed to the side of

the lander • Pulled out during the separation phase by a drag line

taped to the Carrier• Stowed here to prevent damage from moving parts



Carrier-Lander InterfaceParts


Rotary Solenoid

Alignment Bracket

Release Tabs

Rotating Arm

Lander Top Plate

Carrier Parachute Foundation Mounting Nuts and Washers

Planned Alignment Pins on Lander (not modeled yet)


Carrier-Lander InterfaceOperation Part


Planned Motion of the Solenoid and Arm


Carrier-Lander InterfaceParachute Storage


Parachute wrapped around the enclosure.

Drag line (yellow) taped to the bottom of the Carrier

Structure Survivability Trades

• PCBAs mounted with 4-40 hardware to core structures– Lander: Mounted to Egg Protection Cup– Carrier: Mounted to Parachute Foundation

• PCBAs will be covered with enclosures made from high impact polystyrene on both Lander and Carrier– Enclosures will cover entire module.

• Batteries adhered to PCBAs with zip tie and adhesive based RTV

• GPS will be secured with adhesive based RTV to top of enclosure (not modeled in CAD yet)


Structure Survivability Trades

• 10G Acceleration and 30G shock force verification– Conduct FEA simulations in Solidworks to verify. – Requires a more complete CAD model than we

presently have.– Learning How to use the bolt and screw joint modeling

feature



Mass Budget

• Table(s) providing the following:– Mass of all components– Mass of all structural elements– Sources/uncertainties – whether the masses are

estimates, from data sheets, measured values, etc.– Total mass– Margins

• Must clearly distinguish between carrier and lander masses– Include allocated mass for egg payload



Mass Budget (Carrier, Lander, Egg and Margin)


Module Estimated Mass (grams) Percent of System Mass

Carrier 300.71 40%

Lander 217.78 29%

Margin/unallocated 231.51 31%

Egg 63.19 N/A

Note 1: Margin/unallocated mass accounts for parts not yet modeled. This number will change as the design matures.Note 2: Egg model was created last year. Measurements of eggs purchased in the past 30 days validates the model, with margin.


Mass Budget(Electronics)


Electronics Estimated Mass (grams) Notes

PCBA-CPU 37.18 Includes CR123A Battery

PCBA-Sensor 37.18 Includes CR123A Battery

GPS 15 Manufacturer’s Website. Mass not captured in Integrated CAD model.

Xbee 3 Manufacturer’s Website.Mass partially captured in Integrated CAD model.

Antenna 4 Average mass of 4 units.

PCBA-RF Power Divider 2 Estimate based on density of FR4 substrate and estimated dimensions of PBCA. Mass not captured in Integrated CAD model.

Note: Electronics configuration is identical on the Lander and Carrier


Mass Budget(Wiring and Interconnects)



Carrier Interconnects 50 Target Value

Lander Interconnects 50 Target Value

Note: Final weight of interconnects will be driven by the CAD model


Mass Budget(Carrier Structure)



Baseplate 54 CAD Model estimate from material properties

Parachute Foundation 15 CAD Model estimate from material properties

Servo 9 Manufacturer’s Website

Parachute Retention Mechanism 23 CAD Model estimate from material properties

Release Mechanism 75 CAD Model estimate from material properties

Antenna Bracket (x2) 1.2 CAD Model estimate from material properties. Given mass is for both brackets

Fasteners 30 Target value. Not Captured in the CAD model yet

Enclosure/Cover 40 CAD Model estimate from material properties


Mass Budget(Lander Structure)



Baseplate 31 CAD Model estimate from material properties

Parachute Foundation 16 CAD Model estimate from material properties

Top Plate 27 Manufacturer’s Website

Release Tabs (x4) 10 CAD Model estimate from material properties. Mass given is for all 4 parts

Antenna Bracket 1 CAD Model estimate from material properties

Fasteners 30 Target value. Not Captured in the CAD model yet

Enclosure/Cover 40 Target value. Not Captured in the CAD model yet


Mass Budget(Egg Protection)



Cover 19 CAD Model estimate from material properties

Neoprene 32 CAD Model estimate from material properties

Foam Half (x2) 1.7 CAD Model estimate from material properties. Given mass is for both brackets

PCBA Mounts 10 Target value. Not Captured in the CAD model yet


Communication and Data Handling Subsystem Design

Alex Forencich


CDH Overview

Presenter: Alex Forencich

CarrierCarrier

XBeeXBee

TransponderTransponder

XBeeXBee

XBeeXBee

• XMEGA processors in Carrier and Lander will packetize telemetry data for transmission via the XBee radios

• Transponder XMEGA will process received packets and pass them to the ground station computer via RS485

• Multiple ground receive radios with overlapping antenna patterns allow for seamless sky and long range ground coverage

• Ground station software will format and display data in real time

XMEGAXMEGA

LanderLander

XBeeXBeeXMEGAXMEGA

XMEGAXMEGA

Ground Station Computer

Ground Station Computer


CDH Requirements



A I T D

CDH-01 Radios used shall be Digi XBP24-AUI-001 and XBP24-ASI-001 Competition requirement HIGH CAN-13 X

CDH-02 Communications shall be carried out through the XBee API Necessary for robust packetized telemetry HIGH CAN-13 X X X

CDH-02 XBee PAN ID shall be the team number, 2134

Competition requirement, necessary to prevent interference HIGH CAN-13 X

CDH-03 Telemetry data shall be transmitted at a rate of 0.5 Hz Competition requirement HIGH CAR-08 X X

CDH-04 Telemetry data shall be backed up on board in real time Accurate analysis of flight data HIGH X X

CDH-05 Primary processor shall be Atmel ATXMEGA128A1 running at 32 MHz

Internal oscillator and lots of serial IO for communicating with internal peripherals MEDIUM X

CDH-06 Auxillary sensor processor shall be Atmel ATMEGA328P running at 16 MHz

On integrated IMU board, offload sensor data acquisition and processing MEDIUM X


Processor & Memory Trade & Selection

• Selection: XMEGA128A1 for communications processing, MEGA328 for sensor processing

• Easy to use, widely available, open source toolchain

• XMEGA has numerous serial ports for comms, data acquisition, control, and logging

• IMU board contains an ATMEGA328, convenient for off-loading high rate sensor data acquisition and processing

• Interrupt support allows for easy multitasking

• Low power


Model Voltage Clock SRAM UART / I2C / SPI Flash

ATXMEGA128A1 3.3 V 32 MHz 8 KB 8 / 4 / 4 128 KB

ATMEGA328 3.3 V 16 MHz 2 KB 1 / 1 / 1 32 KB

AT91SAM7X512 3.3V 55 MHz 128 KB 2 / 1 / 2 512 KB


Carrier Antenna Trade & Selection


• Selection: ANT-2.4-CW-RH

• Very small size, light weight, economical

• Low gain

• Correct frequency band

Model Gain Center F BW Length Weight

ANT-2.4-CW-RH 2 dBi 2.45 GHz 80 MHz 27 mm 4 g

GW.15.2113 2 dBi 2.45 GHz 50 MHz 109 mm unknown

W5001 1.5 dBi 2.45 GHz 50 MHz 128 mm unknown


Radio Configuration

• Radios will be configured in API mode• Radio PAN ID will be set to the team number• Radio configuration parameters will be stored in nonvolatile

memory making them immune to unexpected resets• Radio data frames will be encapsulated in XBee transmit request

packets and sent to the XBee radio for transmission• XBee radio will be connected to a buffered, interrupt driven USART

in the XMEGA controller to enable efficient asynchronous transfers of packet data while allowing minimally interrupted processing

• Packets for transmission will be enabled or disabled based on internal mission phase selection



Carrier Telemetry Format

• Data will be sent in packet format• Data frames will be encapsulated inside ZigBee packets• Data frames will include high precision timestamps,

source, and type information• Data frames will have different formats for different

sensors• Data will be transmitted in binary to conserve

transmitted wireless data• Communication to ZigBee module will take place at

115200 baud• Radio data rate will be 250000 baud



Activation of Telemetry Transmissions

• Telemetry transmissions will be controlled as part of a mission phase state machine

• State change will be triggered by onboard interpretation of sensor data in addition to command packets sent by the ground station software

• Data will be logged before and during telemetry transmission during all phases of flight

• Radios and sensors will enter a low power state after landing to preserve battery life



Locator Device Trade & Selection

• Selection: CEM-1203• Produces audible sound• Much smaller and lighter than alternative speakers• FSW onboard carrier will enable buzzer once the lander

mission phase has switched from descent to landed• State change should be triggered by sensor data, but

could be manually actuated by a radio command


Model Frequency Impedence Mass

CEM-1203 2 kHz 42 Ohm 1.4g

COM-09151 Unknown 8 Ohm 10g

ZSP99023A 400 Hz-8 kHz 4 Ohm >30g


Electrical Power Subsystem Design

Alex Forencich


EPS Overview


• Components require 3.3 volts• Chose 3.7 volt RCR123A 880 mAh Li-Ion cells• 2 series cells, 7.4 volts total

• Components require 3.3 volts• Chose 3.7 volt RCR123A 880 mAh Li-Ion cells• 2 series cells, 7.4 volts total

Carrier components include:•XBee Radio•XMEGA CPU•GPS•IMU 328/Acc/Gyro/BPS•Temperature Sensor•Release Solenoid•Servo•Buzzer

Carrier components include:•XBee Radio•XMEGA CPU•GPS•IMU 328/Acc/Gyro/BPS•Temperature Sensor•Release Solenoid•Servo•Buzzer

Lander components include:•XBee Radio•XMEGA CPU•GPS•IMU 328/Acc/Gyro/BPS•Temperature Sensor•Servo•Buzzer

Lander components include:•XBee Radio•XMEGA CPU•GPS•IMU 328/Acc/Gyro/BPS•Temperature Sensor•Servo•Buzzer


EPS Requirements



A I T D

EPS-01 High efficiency switching regulator will generate 3.3 volts from batteries Hardware Requirement HIGH X X

EPS-02 XMEGA MCU shall operate at 3.3 v Hardware Requirement MEDIUM EPS-01 X X

EPS-03 XBee radio shall operate at 3.3 v Hardware Requirement MEDIUM EPS-01 X X

EPS-04 MTK GPS shall operate at 3.3 v Hardware Requirement MEDIUM EPS-01 X X

EPS-05 Parachute release servo shall operate at 3.3 v Hardware Requirement MEDIUM EPS-01 X X

EPS-06 Separation solenoid shall operate at 35 v provided by a step-up converter Hardware Requirement MEDIUM X X

EPS-07 IMU module shall operate at 3.3 v Hardware Requirement MEDIUM EPS-01 X X


Carrier Electrical Block Diagram

• Carrier will be put in sleep mode with a pin actuated switch

• Verification will be an on board LED in addition to XBee radio packets


7.4v Li-Ion Pack

7.4v Li-Ion Pack

3.3 VSwitcher3.3 V

Switcher XMEGAXMEGA XBeeXBee

IMUIMUMicro SDMicro SDStep up switcherStep up switcher BuzzerBuzzer

ServoServo

SolenoidActuator

SolenoidActuator


Lander Electrical Block Diagram


• Lander will be put in sleep mode with a pin actuated switch

• Verification will be an on board LED in addition to XBee radio packets

7.4v Li-Ion Pack

7.4v Li-Ion Pack

3.3 VSwitcher3.3 V

Switcher XMEGAXMEGA XBeeXBee

IMUIMUMicro SDMicro SD BuzzerBuzzer

ServoServo


Power Budget


Device Source Typ. I (A) Max I (A) Stdby I (A)

Qty Total Typ. I Total Max I Total Stdby I

V Typ. P (W) Max P (W) Stdby P (W)

xmega Logic 3.3 0.022 0.022 0.0095 1 0.022 0.022 0.0095 3.3 0.0726 0.0726 0.03135

mega368 Logic 3.3 0.006 0.006 0.0015 1 0.006 0.006 0.0015 3.3 0.0198 0.0198 0.00495

led Logic 3.3 0.01 0.02 0 4 0.04 0.08 0 3.3 0.132 0.264 0

max3468 Logic 3.3 0.004 0.004 0.004 1 0.004 0.004 0.004 3.3 0.0132 0.0132 0.0132

adxl345 Logic 3.3 0.000145 0.000145 0.000145 1 0.000145 0.000145 0.000145 3.3 0.0004785 0.0004785 0.0004785

hmc5883l Logic 3.3 0.000002 0.000002 0.000002 1 0.000002 0.000002 0.000002 3.3 0.0000066 0.0000066 0.0000066

Ps-itg-3200

Logic 3.3 0.0066 0.0066 0.0066 1 0.0066 0.0066 0.0066 3.3 0.02178 0.02178 0.02178

bmp085 Logic 3.3 0.00005 0.00005 0.00005 1 0.00005 0.00005 0.00005 3.3 0.000165 0.000165 0.000165

XBee Radio

Radio 3.3 0.148 0.25 0.015 1 0.148 0.25 0.015 3.3 0.4884 0.825 0.0495

MTK GPS Radio 3.3 0.042 0.053 0 1 0.042 0.053 0 3.3 0.1386 0.1749 0

• Power figures drawn from datasheets• Maximum values used for current and minimum values

used for efficiency for worst case calculation• Assuming radio typically transmits 50% of the time

(overestimate)

Rail Name Source Voltage

Efficiency

Typ. Load P

Max Load P

Stdby Load P

Typ. P Max P Stdby P Typ. Load I

Max Load I

Stdby Load I

Logic battery

7.4 1 0.985 1.546 0.134 0.985 1.546 0.134 0.133 0.208 0.0182

Logic 3.3 Logic battery

3.3 0.9 0.260 0.392 0.0719 0.288 0.435 0.0799 0.0787 0.118 0.0217

Radio 3.3 Logic battery

3.3 0.9 0.627 0.999 0.0495 0.696 1.111 0.055 0.19 0.303 0.015

Source Voltage

Typ. P Max P Stdby P

Typ % Max % Stdby %

Approx P

Capacity Ah

Capacity Wh

Typ. Life (h)

Max Life (h)

Stdby Life (h)

Approx Life

Logic Battery

7.4 0.985 1.546 0.134 1 0.25 8 0.254 0.88 6.512 6.607 4.210 48.264 24.567

Power Budget

• Power figures drawn from datasheets• Maximum values used for current and minimum values

used for efficiency for worst case calculation• Figures include 15 minutes at max current draw, 1 hour

regular telemetry transmission, and 8 hours standby

CanSat 2012 PDR: Team 2134 (IEEE UCSD)Presenter: Alex Forencich 75


Power Source Trade & Selection


Model Voltage Capacity Weight Dimension Type

16340 (CR123A) 3.7 V 880 mAh 17 g 16 x 34mm Li-ion

14500 (AA) 3.7 V 800 mAh 16.2 g 14 x 50mm Li-ion

9 volt 9 V 565 mAh 47 g 49 x 27 x 18 mm Alkaline• Selection: 16340 Li-ion cell

• Physically short so easier to fit into CanSat body

• Large capacity cylindrical cell

• Relatively easy to obtain


Battery Voltage MeasurementTrade & Selection

• Battery voltage measurements will be made with a voltage divider

• The output of the divider will be connected to an analog input of the XMEGA MCU

• ADC has 12 bits of resolution• Carrier and lander use same measurement method



Flight Software Design

Chris Warren

Alex Forencich


FSW Overview

• FSW will be essentially the same for both the Carrier and Lander

• While the Carrier and Lander will function separately, the code running on each will be taking care of roughly the same things, however:• The Carrier will be the only subsystem monitoring

barometric pressure altitude, and will be controlling the release of drag chutes and system separation

• The Lander will be more of a data-logging unit, as it has no separation or chute release• Lander shall record impact forces at 100 Hz

• FSW will be written for the Atmel XMEGA processor– Based off of the C programming language

Presenters: Chris Warren Alex Forencich


FSW Requirements



A I T D

FSW-01Software shall control the gathering and sending of telemetry data over the Zigbee protocol

CARRIER ONLY – Competition Requirement; Ensures the availability of necessary flight data

HIGH X X X

FSW-02Software shall store any telemetry data onboard for post-processing and risk reduction

Storing the data sent to ground onboard as well reduces the risk of lost flight data

HIGH X X X

FSW-03 Software shall control the release and control of descent control methods

Control of descent speed is necessary for a successful flight

HIGH X X X

FSW-04 Software shall measure impact force at a rate of 100 Hz

LANDER ONLY – This is our chosen bonus objective

MEDIUM X X X

FSW-05Both instances of software (Carrier and Lander) shall operate independently and autonomously

Following the physical separation of subsystems, the Carrier and Lander must operate on their own for the flight to be a success

HIGH X X X


CanSat FSW Overview


• Our plan for the flight software is an interrupt-driven state machine• It isn’t terribly efficient to outline this program style with a

standard flowchart• This state machine will change its behavior based

mainly on its altitude read from the pressure sensor• It will also “begin” its flight sequence from a command

sent from the ground control station to initialize telemetry


Carrier CanSat FSW Overview


• The Carrier FSW states are as follows:

• Pre-Launch• Carrier listens for “Telemetry Go” signal from ground station

• Launch• Carrier polls sensor packages for GPS location, pressure altitude and other

telemetry

• Deployment• Sensors are still polled, Carrier now waits for pressure altitude checkpoints

• Descent• Carrier releases main descent chute at 200 meters AGL

• Carrier separates from Lander at 91 meters AGL

• Landing / Post-Flight• Sensor data continues to be polled until landing on ground

• Carrier will then relay the final GPS location, turn on the buzzer, and go into sleep mode waiting for signals from ground station


Lander CanSat FSW Overview


• The Lander FSW states are as follows:

• Pre-Launch• Lander listens for “Telemetry Go” signal from ground station

• Launch• Lander polls sensor packages for GPS location, pressure altitude and other

telemetry – sensor packages are polled continuously until the Landing / Post-Flight state

• Deployment• Sensors are still polled

• Descent• Sensors are still polled

• Landing / Post-Flight• Sensor data continues to be polled until landing on ground

• Lander records impact force data at 100 Hz and stores data onboard

• Lander will then relay the final GPS location, turn on the buzzer, and go into sleep mode waiting for signals from ground station


Software Development Plan

• We are already in the process of writing our flight software• We have obtained and are using XMEGA development

boards to test and prototype our code• We are using Git as source control to allow team members

to write, edit, and maintain our software independentlya• We plan to test our code after major changes

• Tests will occur many times throughout our software development stage



Ground Control System Design

Chris Warren

Alex Forencich


GCS Overview


LAPTOPS SIGNAL ROUTER

ANTENNA MAST W/ GUY

WIRES

SPARE PARTS


GCS Requirements



A I T D

GCS-01 Antenna shall be 3.5 meters above the ground (or greater)

Allows for clearer / more reliable signal transmission

HIGH X X

GCS-02Communications shall use the XBEE module, with PANID set to the team number

Prevents crosstalk between different teams / systems

HIGH X X

GCS-03 GCS User Interface will allow for real-time viewing of telemetry data

The ability to view real-time data allows for a better understanding of the mission at hand

MEDIUM X

GCS-04 GCS will communicate with both the Carrier and Lander units

Gives a better picture of the mission by capturing data from two sources

MEDIUM X


GCS Antenna Trade & Selection


• The antenna mast will consist of 1.5” (diameter) fiberglass/aluminum poles in 4 foot sections

• This is easily obtainable from various military surplus sources

• The mast will be 24-32 feet tall

• We will use three antennas

• One 3dBi antenna

• One 8dBi antenna

• One patch antenna

• We have chosen these three antennas due to the various signal ranges and strengths they give us

• We will be able to automatically select the strongest signal

GCS Software

• Telemetry will be displayed via live graphs drawn on screen

• No commercial packages will be used in the GCS• We wish to keep this design purely open-source• Allows more fine control of our software

• Data from the antenna array will be directly logged to SD card• Data will also be logged to a simple text file on the

laptop(s)• Command interface will be built into the telemetry

viewer and data logger• We wish to create a unified user interface

CanSat 2012 PDR: Team 2134 (IEEE UCSD) 89Presenters: Chris Warren Alex Forencich


CanSat Integration and Test

Jeff Wurzbach


CanSat Integration and Test Overview

• 3D CAD Model integration prior to fabrication of parts• Integrated system tests on flight unit representative parts• Testing of flight representative radio configurations with ground

station setup (small scale tests have been completed already).• Long term (hours to days) testing of software systems to ensure

stability• Progressive testing during production to ensure problems are

identified prior to installation into CanSat.• Design reuse wherever possible



CanSat Integration and TestSystem and Subsystem Integration

• Systems Integration prior to fabrication via “In the box design”• Design system in Solidworks prior to fabrication and detailed design

of the flight PCBAs to ensure that all components fit and mass budgets are observed

• 3D CAD allows immediate feedback on system level impacts of changes

• Use/Creation of accurate 3D models in Solidworks ensures that our team meets specs

• Proven method used last year and by other IEEE UCSD projects

• Design validated as a whole before production begins via simulations in Solidworks

• Technical Drawings made for dimensional verification of fabricated parts to the 3D CAD model.

• Parallel development of hardware and software systems by using non-flight unit prototypes• Identifies electronic interface issues before long lead items are

purchased.Presenter: Jeff Wurzbach


CanSat Integration and Test Integrated System testing

• Fully Integrated System Testing• Drop testing—Drop Cansat from 6th floor Service elevator balcony down to

the east loading dock (6+ story drop)• Checkout operation of separation method

• Checkout operation of main parachute retainer

• Checkout landing software sequence

• Overall structural checkout of design

• Long distance radio testing• Setup Ground station mast on Warren field

• Move CanSat away from mast until the connection drops.



CanSat Integration and Test Module/Major Subassembly Level Testing

• Module Level Testing• Assembled modules tested for basic functionality prior to integration into

CanSat Assembly

• Each module to be drop tested to ensure that each DCS performs as expected

• GPS testing accomplished by long term logging tests (road trip).• Major Subassembly Testing

• Shared configuration of electronics between Lander and Carrier

• Sensors system tested for electrical functionality after soldering into PCBA

• Software tested by running the system for long periods to verify logging tests, long term system stability (no counter overflows, etc), and battery life testing.

• Software updates can be completed OTA using xboot boot loader• xboot installed on all microcontrollers in the system (flight and ground)



CanSat Integration and Test Test Equipment

• Electronics testing accomplished with standard test equipment• Oscilloscope

• Voltmeter

• Debugging terminal on computer• Mechanical parts verified via measurement and inspection against CAD

model• Calipers

• Ruler

• Scale

• Many tests can be completed with sensors on board the CanSat modules.• Data logging code within FSW is already verified

• GPS testing is underway



Mission Operations & Analysis

Chris Warren


Overview of Mission Sequence of Events

• Arrive at launch Site• Check in with Flight Line Judge

– Weigh Cansat– Perform fit-check of CanSat using sample payload– Receive Egg– Receive Rocket Payload

• Prep and test CanSat for flight• Wait for launch window

– Request flight from Flight Coordinator• Set up CanSat on launch pad• Give Flight Coordinator “GO” for launch• Monitor Telemetry of descent following Rocket Separation• Update Flight Day scoring card• Coordinate CanSat recovery with Flight Line judge and Field judges

– Recover CanSat ONLY when final approval is given by Field judge



Mission Operations Manual Development Plan

• Development of our Operations Manual has only somewhat begun

• We have only included the basic launch day requirements and activities included in the Competition Guidelines

• As the team progresses through our final design plans and begins on the testing, verification, and manufacture phases of this project, we will add to our Operations Manual any interesting, important, and/or useful things we come across

• Ideally, by our demo flight, the Operations Manual will be the ultimate guide to running, repairing, and managing our project

• This “ultimate guide” will be a great addition to our plan to release our project data as open-source



CanSat Location and Recovery

• Upon landing onboard buzzers will activate for 3 hours• Carrier can be found by the last GPS location

transmitted over the Xbee radios• While one team member stays behind at the ground

station, two people will become “scouts”, using any data relayed over handheld/shortwave radios



Management

Chris Warren


CanSat Budget – Hardware


Model Cost (US Dollars)

SCP1000 (x2) 25.00

CR123A (x4) 8.00

Buzzer (x2) 15.00

IMU (x2) 200.00

XBEE Module (x2) 70.00

GPS Module (x2) 74.00

Power divider (RF) (x2) 20.00

Casing (exterior) UNK

Micro-servo 12.00

Casing (other) 50.00 (allocated)

Descent Control 50.00 (allocated)

Egg Protection 20.00 (allocated)

Custom PCB 100.00

Total: 644.00


CanSat Budget – Other Costs


Item Cost (US Dollars)

XBEE Modules $70.00

Antenna $30.00

Computers $0.00

Software $0.00

Miscellaneous Other $50.00

Total $150.00

Item Cost (US Dollars)

Flight Hotel and Car $2400 (Estimate)

Food $720 (Estimate)

Prototyping $400 (Estimate)

Total $3520 (Estimate)

Ground Station Costs

Travel and Other Costs

Total Budget Cost (US Dollars)

Cansat $644

Ground Station $150

Travel & Other $3520

Total $4314

Total Budget Costs


Program Schedule



Program Schedule (cont’d)



Conclusions

Major Accomplishments• Mechanical design is essentially finalized

• Only a few minor details need to be worked out before we enter the prototyping and manufacturing phases

• Radio communications are proven in the lab•Need trials in the field to test fully

Major Unfinished Work• Need to finalize plans for descent control• Need to work on flight software• Need to finalize the design, and test, our ground station setup

Why We’re Ready for The Next Step• We have a very dedicated team• Energy and motivation to move forward• We have the history and experience to take this project to the next level and beyond


Documents

CanSat 2012 PDR: Team 2134 (IEEE UCSD)1 CanSat 2012 Preliminary Design Review Team 2134 - IEEE UCSD