Encoders

After looking for encoders in the University we found that all the encoders were borrowed and that they had little resolution. Also the Dr. Ajelandro Pineda showed us a webpage where we could buy some encoders on the US but they were very expensive and the shipment would last too much time.

So for now we will try to with the potentiometers, we hope the response and resolution will be good enough.javascript:void(0)

Trip to República del Salvador Street.

Last Tuesday we went to a street on the center of our capital city called República del Salvador in order to search for sensors for determining the angular position of the base motor and the pendulum. First se seek for some kind of potentiometer like the posted below or another one that can take infinite turns and make an specific reading on a particular angular position. But on any little store we asked for it they didn't have anything like it, the closest things they had was a precision potentiometer that had 10 turns but had different resistive values con each part of the 10 turns.

Then we decided to look for an encoder, but almost anybody had one. We encountered a place where repaired CD and DVD readers and they showed us the encoders they had, but the problem was that they were designed to suit a DVD reader and the circuit that read the encoder was part of an entire solution for many tasks. Also we had the option to use only the sensor and the wheel but the sensor didn't have any code number so it could be a hard task to find the way to understand the encoder.

Finally as the price of the encoder was very expensive and we had little time till down we decided to buy two precision potentiometers.

We hope they will be enough to sense the rotatory movement of the motor and the pendulum, nonetheless we will still try to find an encoder.

Sensors and Actuators.

After searching for different options of actuators and sensors we found the following as the best option to use so far.

For the base motor we decided to use the Pololu Metal Gearmotor of 8 Kg-cm of torque and 350 RPM. It has enough torque to move the pendulum and enough speed to make the control, it has a bidirectional rotation and has an operation voltage of 12 VDC. All it's main parts are made of metal so it is also strong enough to make fast direction changes. It also has a group of screw holes on the front, so we can fix the motor to the base platform.


Image 1: Mteal Motorgear and main characteristics.


Image 2: Dimensions diagram.

The sensor we decided as the best option so far is a circular potentiometer that will help us to know the angular position of the pendulum. It is a flat potentiometer with a little pointer and when the pointer touches the surface of the flat potentiometer it exercises an specific resistence so we will have a specific voltage to each position of the potenciometer.


Image 3: Circular flat potentiometer and characteristics and price.


Image 4: Spring actuated pointer.

Other sensors for the angular position are the following:


Image 5: PH1116 Sensor, it has up to 10 turns capacity.

PH 1116 Datasheet: http://www.electronicaestudio.com/docs/PH1116.pdf


Imnage 6: Rotary morion sensor CI-6538.

CI-6538 Datasheet: http://www.google.com/search?client=safari&rls=en&q=CI-6538&ie=UTF-8&oe=UTF-8

We will search for more sensors next Tuesday on Repulblica del Salvador Steet on the centrla part of the DF. And we are also going to but our metal gear motor in a shop called Robodacta.

These are the links of some special stores of electronic and robotics components near our college.

AG Electronica
URL: http://www.agelectronica.com/

Robodacta
URL: http://www.robodacta.com.mx/

Previous Research - Furuta Pendulum

First we introduce the concept of the Furuta Pendulum. A very accurate explanation of it is as follows:

"The Furuta pendulum consists of a driven arm which rotates in the horizontal plane and a pendulum attached to that arm which is free to rotate in the vertical plane". (1)





Resources:

(1) Technical Report: On the dynamics of the Furuta pendulum
Ben S. Cazzolato and Zebb Prime
University of Adelaide, SA 5005, Australia
URL: http://data.mecheng.adelaide.edu.au/robotics_novell/projects/2004/Pendulum/Furuta_Pedulum_Internal_report.pdf

DESARROLLO Y CONTROL DE UN PÉNDULO DE FURUTA
A. Valera, M. Vallés, M. Cardo Dpto. Ingeniería de Sistemas y Automática Universidad Politécnica de Valencia
URL: http://www.cea-ifac.es/actividades/jornadas/XXIV/documentos/ro/77.pdf

The Furuta Pendulum - Wikipedia Encyclopedia
URL: http://en.wikipedia.org/wiki/Furuta_pendulum

Coriolis Effect - Wikipedia Encyclopedia
URL: http://en.wikipedia.org/wiki/Coriolis_effect

Centripetal Force - Wikipedia Encyclopedia
URL: http://en.wikipedia.org/wiki/Centripetal_force

Video: Pendulo Invertido Rotacional o Pendulo de Furuta
URL: http://www.youtube.com/watch?v=IIuntmibhoA

Welcome!

Welcome!! You are visiting our blogg about our Final Project of the Control Laboratory course of the ITESM CEM Jan-May 2011.

This blogg will be the log file of our project, and will have all the technical affairs and progress of our team. The team is integrated by:

Profesor:
Dr. Virgilio Lopez Vazquez

Students:
Oscar Rodrigo Hernández Panczenko
Elena Cherit Mendoza
Yamara Sinahí Ríos León
Polet Lopez Lopez

Regards!