Projekt rapporter, første udgaver

til oversigten

Her er de rapporter, og artikler jeg har skrevet ind til videre.
De er næsten alle sat op som .pdf så husk at få dig en pdf-reader ;) .

(P9 and P10)Master Thesis

One Step Closer; Towards Dynamic Walking on AAU-BOT1 The thesis treats the development of a dynamic walk controller for AAUBOT1. AAU-BOT1 is a biped robot developed at Aalborg University. A Biped Robot system, can be described as a hybrid system, as long time spans of the gait are governed by continous motions, and the impacts with the ground can be considered discrete events. Planning a trajectory, and applying it on the system must take this into account. AAU-BOT1 is physically unable to walk statically, this is partly due to kinematics, and weight distribution, and partly due to the combination of small actuators and large frictions in the joints. It has been suggested numerous times during the development, that a traditional PID regulator can be used as a servo controller, and that all the nonlinear effects, both discrete as well as continuous can be suppressed on the robot. This claim is put to the test in this thesis, as a traditional PID regulator is tuned and applied for the physical system. The gait is generated on line, based on model prediction, and numeric integration, of a nonlinear inverted 3d pendulum. Applying the trajectory to the robot requires that the implemented PID controller can handle the system suficiently well, it is however shown that non-linearity's can occur which can destabilize a PID regulator. Slowing down the trajectory, and keeping the knees stretched counters the problems, and a stable quasi-static gait is achieved. artikel (året før vi overtog projektet)

(P8) IAS preparing:

Robots with wheels or tracks are currently used for exploring dangerous areas in search and rescue missions. To improve the abillity to traverse terrains it is proposed to use a walking robot. A random generated terrain is set up to represent a search and rescue terrain, and a hexapod walking robot is applied. A kinematic model is set up of the hexapod robot, and it is determined how the robot can be moved while sustaining static stabillity. A gait generator for tripedal walk is developed using artificial potential functions, and a trigonometric inverse kinematics solver is used for translating the gait into servo angles. Collisions with the surface are detected using a 3D model, and a system is set up to avoid unwanted terrain contacts. The robot is controlled in open loop to evaluate the models. While traversing the terrain singularities can appear when solving inverse kinematics. It was attempted to modify the gait to avoid the singularities, this was however not achieved satisfactory.

(P7) Netværks teori:

This particular project did not produce a report. Instead a Poster and an article was produced, and shown at a local seminar, and evaluated against demands to compile the project to the article form.

You may download the article and the poster, though, note that the article is only present in .dvi, ghostscript can be used to see this format.

In short the project concerns the implementation of a small ethernet, using a 100mbit router, and 10 mbit embedded processors. The application level was set up to allow retrieving, logging and wireless transfer of sensor data. The speed and reliabillity of the network is tested, and it is determined that motor controls and other crucial data can be transmitted sufficienty fast over ethernet.

- after project was ended, the system was succesfully deployed on the unicorn car by another member, and is still in operation (2009).

(P6) Regulerings teknik:

This report concerns the development of the Attitude and Determination Control System for AAUSAT3. Initially the the space environment is ana- lyzed, concerning the ADCS system and how positioning is done in space. It is decided to use magnetorquers to control the attitude, therefore an analysis of different models of the Earth’s geomagnetic field and how to generate a magnetic torque is investigated. Different sensors for determining attitude and position in space are analyzed. An experimental setup for controlling a proto- type satellite in one axis is made. For control- ling the prototype a PID controller is imple- mented to prove the functionality of the mag- netorquers and the sensors. The controller in the experimental setup is verified and a com- parison against the results from the simulation is made to provide an idea of the reliabillity of the simulations. The one-axis PID controller is able to con- trol the satellite wihthin the specified require- ments. A state-space model is made of the system, to provide insight into this method for reaching the next step which is to develop a controller in three dimensions. State-space models are ideal for systems with multiple outputs and inputs.

(P5) Realtids feedback control:

A problem is set up that requires feedback controlled movements of a robot. The robot is constructed with LEGO bricks and is based on the LEGO Mindstorms NXT. A web camera is used as position sensor. The task of the robot is to reach multiple targets within a given field. The field contain obstacles that must be avoided. The targets are plastic cups that can be stacked by the robot when it collects them. The behavior of LEGO Mindstorms NXT motors are modeled and, by loading these with properties of the robot, the movements performed are simulated in the regulation software. To recognize items on the field, “EyesWeb” is used as the image processing program for item detection on the images from the web camera. The coordinates of the detected items are then converted from image to world coordinates. The control software is developed in Java and controls the robot by planning a route to the nearest target, and then steers the robot to follow the route. By using a simulator for the movements of the robot and the data from image processing, the correct location and direction of the robot is estimated. The software then decides how the robot should be regulated by driving in circular motions of different ratios. The system has proven to be able to pick up all cups and avoid all obstacles at the set-ups tested.

(P4) Digitale Kredsløb:

As a feasibility study for the future AAUSAT-III satellite, it is investigated which requirements should be taken into consideration when designing a camera system for a pico satellite traveling in Low Earth Orbit.
The requirements lead to the design of a camera subsystem that provides an interface between an onboard computer and the chosen image sensor.
The image sensor used in the project is supplied as a stabilized module by Devitech ApS, and outputs parallel data.
To achieve the necessary speed for collecting the data a FPGA is inserted to act as a DMA controller.
The software controlling the camera system is based on eCos and is designed to compress, save, delete, produce thumbnails of, and list up to five images captured.
It is also possible to store one raw image to make it optional if the image processing happens on the satellite or on Earth.
The camera system communicates with the rest of the satellite using the existing protocol that is implemented on AAUSAT-II.
Furthermore, the software of the camera system can be updated using the RS-232 debug interface.
The PCB design of the prototype attempts to have EMC and follows ESA space graded standards; the PCB is manufactured by GPV Printca A/S.
The camera system was successfully tested by fetching test data from the image sensor; yet no image with a recognizable motive is captured due to lack of time for adjusting the lens system used for testing.

(P3) Diskrete Kredsløb:

For eksisterende audioforstærkere på markedet er nyttevirkningen meget lav når der ikke spilles højt.
Da det er meget sjældent at forstærkerne spiller ved fuld volumen, men oftere ved laveste, går der meget energi til spilde.
Med ”bedre nyttevirkning“ som udgangspunkt er der lavet en forstærker med et klasse G effektforstærkertrin, samt 3 indgange, henholdsvis CD indgang, Line indgang og en Phono indgang.
Derudover er der lavet en tilhørende volumenkontrol, tonekontrol samt en kanalvælger.
Teoretisk set skal en forstærker med et klasse G trin, kunne opnå en nyttevirkning på over 80%, når der spilles højest.
Dette er dog meget svært at opnå i praksis.
Forstærkeren er blevet lavet med 2 plus-minus-forsyninger til effekttrinet, til henholdsvis når der spilles højt og når der spilles lavt.
Trinet skifter automatisk mellem forsyningerne når det er nødvendigt.
Ved den laveste spændingsforsyning er den største opnåede nyttevirkning for hele forstærkeren på 32% og ved den højeste spændingsforsyning er nyttevirkningen oppe på 64%.

(P2) Grundlæggende Elektronik:

I forbindelse med forelæsninger i auditorier er det et problem for visse forelæsere at høre spørgsmål stillet af tilhørerne.
Problemet er naturligvis størst i store auditorier og/eller for hørehæmmede forelæsere og kan hæmme brugen af spørgsmål i en undervisningssituation, men det kan også være et problem for andre tilhørere at høre spørgsmålene.
Efter kontakt til en forelæser og indkøber af av-udstyr, er der opstillet funktionskrav til et system, der kan forbedre situationen.
Dette skal bl.a. være simpelt at betjene og maksimalt koste 5000 kr.
Der tages udgangspunkt i konstruktion af et såkaldt mikrofonarray.
Den valgte løsning anvender 5 mikrofoner og teoretisk kan den løsning forbedre signal-støj-forholdet ca. 7 dB i forhold til kun at anvende en enkelt mikrofon.
I praksis opnås en forbedring på ca. 6,5 dB.
Dette medfører en mærkbar forbedret taleforståelighed for forelæseren.
Systemet styres ved at forelæseren kan trykke på en knap og derved vælge den ønskede lytteretning.
Produktet kan videreudvikles på forskellige måder, så det f.eks. kan anvendes i andre miljøer.
Der er endvidere mulighed for forskellige tekniske optimeringer, der bl.a. kan forbedre lydkvaliteten.

(P1) Kontekst arbejde:

For danske hjem er der ingen konkret lovgivning vedrørende luftfugtighed.
Rapporten belyser nogle af de problemer, der kan opstå for menneskers helbred og for de mest anvendte byggematerialer, når de udsættes for forkert luftfugtighed.
Gældende lovgivning indenfor indeklima i boliger sammenlignes med den tilsvarende på arbejdspladsen.
De mest anvendte måder at måle luftfugtigheden på beskrives.
Der er udført en spørgeskemaundersøgelse for at indhente krav til luftfugtighedsmåleren og give indblik i befolkningens viden om luftfugtighed.
Resultaterne af undersøgelsen vurderes, og kravet til produktets præcision sættes til værende bedre end +/-5%RH.
For at leve op til kravene baseres luftfugtighedsmåleren på en kondensator.
Luftfugtighedsmåleren simuleres i programmet LTspice, og fremstilles derefter som prototype.
Resultaterne fra simuleringen holdes op imod målinger på prototypen.
Der bliver fundet mindre afvigelser, der tilskrives prototypens opbygning på fumlebræt.
I rapporten forsøges vurderet, hvad den fremstillede teknologi kan videreudvikles til.

(P0) Introduktions projekt:

I dette P0-projekt er der arbejdet med strømbesparelse på lysanlæg.
I problemanalysen er miljømæssige og økonomiske aspekter blevet undersøgt.
Endvidere er der arbejdet med teknologien bag armaturer.
Her er konventionelle reaktorer og højfrekvente forkoblinger blevet undersøgt.
Herefter er der foretaget et forsøg hvor effektforbrug og belysningsstyrke er målt.
Desuden er der gennemført interviews med institutioner som har skiftet lysanlæg.
Til slut er der konkluderet på om det kan betale sig at bruge højfrekvente forkoblinger.

Henrik Dalsager Christensen · Ranunkelvej 211 8471 Sabro · (safemail)