Currently most advanced robots are custom made for a particular task and expensive to produce. Other robots are designed simplistically as toys or gadgets, and as such are mass produced and relatively cheap to produce. The MIRC which has been produced as a result of this project combines these factors by using mass produced components to create a technically advanced robotic system which has the additional capacity for customisation, giving endless flexibility. Ultimately it could allow the consumer to purchase a MIRC and then to create a robot custom built for their needs from standard components without the need for extensive knowledge of robotics or expensive outlay.

1.2 Rationale

This project was chosen because this area of the technological industry is not being fully exploited. Whilst researching the availability of robots for adaptation to be used in the home, only one type of labour saving robot was found to be available. This is the autonomous vacuum cleaner [2]. It is a small robot that will map out the floor of a house and then vacuum it without the need for human interaction (apart from emptying the bag). This was an important technological breakthrough, but a cost of around £1000 per unit, makes it outside the price range of the average consumer. The high cost of such robots is mainly due to the costs of developing its custom computer hardware and software.

1.3 Current position

Moore’s law states that computing power doubles every 18 months [3]. Although according to Dylan Tweny, this is probably not true [4], computer technology is currently at a point where processing power on a small sized pc is large enough to deal with extensive real time data e.g. web cam image processing. These computers are now cheaply manufactured and available in most homes. People are already customising their personal computers to their own needs. The logical next step would appear to be extending or combining technologies to create a whole new product, which had potential for a new way of conducting tasks currently conducted by people. This gave rise to the idea for the MIRC. 
PCs today are much faster than they used to be. So much so, that the average computer has enough processing power to adequately analyse sensor data such as stereo video images in real time. Due to the PCs huge variety of applications and its popularity across the world it seemed clear that a robot could be based on this technology. This would allow for USB devices and component upgrades to come from the same sources as normal PC equipment. The same manufacturers could also make the products, allowing it to reach world markets very quickly.
A fully constructed model could be capable of many things. If many different manufacturers created USB and FireWire upgrades, the robots could have a huge range of functions. Devices like robot arms, vacuum cleaners, paint sprayers, even robotic legs could be added simply by attaching them in the correct place and installing the software. Wireless networking would enable robots to communicate with each other from almost anywhere and the owner to control them all via the internet.

1.4 Literature review

In embarking on the project to create the MIRC it was necessary to conduct extensive research into both the current situation re the development of similar technologies and specific research into aspects necessary to design and build the MIRC.
There are surprisingly few PC based mobile robots in existence today. When searching the internet for PC controlled robots, mainly static workstations were discovered. 
Arrick Robotics [5] sells various robotic products. Their Robotic Work cells can be joined with XYZ positioning tables to create the work cell of your preference.
Kuka Robotics [6] also sells PC controlled robots. These are large industrial robotic limbs that are fixed to the ground, used for welding and press-linking. 
Another project found was called “Robotics Engineering Task Force” [7]. Here they were working on creating standard interchangeable robot parts so that industrial robots could be easily constructed. The idea of creating an ‘Industry Standard’ is progressive as it allows other manufacturers to create a wider range of devices and helps to boost the market. This indicates that if the MIRC were to be manufactured, standardised fittings for adding hardware or changing parts could be made. 
Whilst conducting the literature review, it was surprising to find only two other projects similar to the MIRC. One is a project known as the ‘Open Automation Project’ [8]. This project bares a striking resemblance to project MIRC. This project not only involves a PC based robotic system, but it also uses some of the exact same electronics, such as sensors and the I2C BUS to communicate with them. The OAP aims to create a PC based mobile robot for the cost of a standard PC.

“The objective is to use readily available “off-the-shelf” low-cost consumer components where possible, and to design electronic subsystems where such components are either not readily available or are too expensive. In terms of affordability, the overall goal is to design a robot that can be made for around the price of a PC (US,500 to ,000 is the target, but the actual cost of building a robot can vary greatly depending on how many of the electromechanical components are made in your own workshop versus purchased pre-fabricated).” (ibid)

This is almost identical to the objectives of this project, but with one main difference. The Open Automation project (OAP) involves using a built in PC motherboard and processor to control all the hardware. The MIRC does not have any on board processing. It relies solely on the computer it is linked to. The first obvious advantage of this is the final cost of a finished MIRC would be greatly reduced. It is assumed that by the time the MIRC would be ready to be manufactured and sold, the majority of people will own some type of mobile computing device. This could be anything from a laptop or PDA to a modern mobile telephone. It is intended that any such devices could be used to control a MIRC depending on how much processor power was required. Standard PC motherboards could also be used as this would mean a better processor power to cost ratio could be achieved.
Another project is the ER1 [9]. This has actually reached the manufacturing stage and is on sale in America for 0. The ER1 makers have very similar aims to that of project MIRC. They also decided that by excluding the computer from the finished product the final cost can be dramatically reduced. The main differences between the ER1 and the MIRC is that the ER1 is specifically designed for use with a laptop where as the MIRC is intended for use with any type of computer. The ER1 needs to be trained using quite specific instructions whereas the MIRC will use more of a fuzzy learning method.

“’Training’ an ER1 requires the owner to use very simple ‘if/then’ logic, to be very literal with the poor machine” © 2004 MSNBC Interactive [9]

This ‘if/then’ type of training will enable a user to get the robot to perform tasks quite quickly after opening the box, but this also greatly limits what the robot is capable of doing. With the fuzzy learning approach proposed for the MIRC, it will take much longer to train a MIRC and it may be quite repetitive, but the end result would be much more effective. This is because it would be able to use what it has learned in being trained for one task, and apply it to other relevant tasks helping it to learn more quickly. Just like when training a dog for example.

1.4.1 Acquiring new skills

Having only brief training in electronics or mechanical engineering created the need for the author to gain some knowledge in this field. There is no shortage of information available on these subjects, therefore learning these new skills was quite productive. Some of the information on the mechanical hardware requirements was collected from a book named ‘The Robot Builders Bonanza’ [10]. This book contains basic plans and descriptions of mechanical systems involved in robot building. It also contains some information on linking sensors and motors to controllers such as the Leggo Mindstorms kits. This book provided most of the information needed to create the drive system.
Information on electronic components was found available in ‘The Forrest Mims Circuit Scrapbook’ [11]. This book provides various example circuits and descriptions of how all the components are working. This book particularly useful when linking the I/O ports of various pieces of hardware as it shows various ways of altering signals using electronic components.
Information on the various interfacing methods was harder to find. Most information was obtained from the web shops that sold them. The Information on USB interfacing was obtained from ‘PC Interfacing Using USB’ [12]. This book mainly contains details describing how to use the USB IO24 module to control motors and capture data.

1.4.2 Programming

Programming information was taken from various sources. For C++ programming ’Sams Teach Yourself Visual C++ 6 in 21 days’ [13] was very useful. This book contains simple step by step tutorials which teach the basics of using Visual C++. Although this book provided information on creating some programs in C++, It was unhelpful in understanding how to use it to control the hardware. To solve this, a Yahoo group [14] that had been set up for people needed information on the K8000 interface board proved useful. The K8000 Yahoo group was an invaluable resource throughout this project, one person in particular was Christian Allegre. He was able to advise me how to program the K8000 using C++ with Windows XP.
For QBASIC programming ‘Programming In QuickBasic’ [15] was invaluable. This book provides most of the information needed to create QBasic Programs used for controlling hardware.

1.5 Objectives

The aim of this project was to create a prototype MIRC to show how a PC based robot could be developed. The objective was to produce a basic model with four wheels, standard sensors and a web cam forming the centre around which an individual could create their own custom robot with extra USB devices.
It was intended that the structure of the robot should be simple to facilitate easy adaptation and upgrading. The housing was designed to create three distinct layers within the MIRC to separate elements of the robot, thus leaving room to add more devices and a laptop computer when complete. The bottom layer would be designed for battery housing and mechanical hardware, such as wheels and sprockets, the middle layer to contain the main interface electronics, and the top layer to be for the external devices.
The MIRC was developed over a period of eight months. Initially research was conducted into robotic control systems, pc interfaces, sensors and actuators. A K8000 interface board formed the basis of the project, as it allowed for the connection of analogue sensors and actuators to the pc. The PC was chosen rather than built in micro processor because it was far more powerful and customisable.

1.6 Limitations

The actual MIRC produced was limited by a variety of factors. Processing power of the laptop used (90MHz) limited the amount of data that could be captured and processed within a given time; laptop batteries were defective which meant that larger batteries had to be used which affected the overall weight and ultimately the manoeuvrability of the MIRC. Lack of modern ports such as USB stopped connection of modern hardware with a high data or bandwidth capability. Mechanical engineering knowledge and access to tools, materials and equipment were very limited which caused time delays and construction problems. It also added to costs due to the need to purchase tools. The authors’ knowledge of high level programming languages such as C++ was initially limited and meant time had to be spent learning the basics. A decision was made to use QBASIC as it is very easy to learn and it would run properly on the aging laptop used. Financing the project was also problematic. The author had to take on a part time job to cover some costs. Conveniently this job was in an electronics shop which staff discount was available on some of the required hardware.

2. Project Management

Project management was generally done on a step by step basis. This was because all the required parts could not be purchased together so that the costs were spread out over the entire project. This also meant that individual pieces of hardware were tested and developed as they arrived. The main influencing factor in choosing the hardware at the development stage was the cost. Finding the most effective parts within a limited budget proved very difficult. The software was developed along side the hardware as new parts were added to the MIRC. This makes describing construction chronologically very difficult. The table shown in Appendix A shows the progress made in comparison with the original plan.

2.1 Interfacing

The versatility of the PC in part comes from the variety of IO ports it is able to use. This allows it to connect to many different types of hardware, and with ever growing processor power the bandwidth capabilities of the ports grows too. The most important part of the MIRC was the sensors, so a good interface for these was essential. It needed to have the capability of capturing analogue and digital sensor data and also outputting in the same way.
This section describes the options available for interfacing a computer with robot hardware. Where appropriate it also gives an indication of strengths and weaknesses of the various components in relation to project development.

2.1.1 K8000

The K8000 [16] is a PC interface board which connects to the parallel port. This board consists of several analogue and digital I/O ports that are connected by a bus system known as the I2C BUS. The connected PC can communicate with the K8000 using RS232 data sent via the parallel port. This board formed the main interface between the computer and the sensors and actuators. This board can be controlled using RS232 data, giving it the possibility to connect it to almost any microcontroller. The K8000 can be used under Linux as someone has created drivers for it. An example of this is shown on the libK8000 house alarm website [17].
The K8000 is designed to run from a mains outlet, which is obviously not suitable for a mobile robot. To overcome this problem the transformers were removed and dc voltages were applied where the transformer output used to be. The small transformer was easily replaced by 6V from a lead acid battery, but the larger one required at least 15V. As the largest battery on the MIRC is 12V a step up inverter, normally meant for running a laptop in a car, was used.

2.1.2 I2C BUS

This is a commonly used bus system [18] for electronic devices such as televisions, but is now becoming quite common in the robotics field. This is mainly due to the large amount of hardware that is already available for use on an I2C bus. On web shops for robot hardware [19] there are various types of sensors that use the I2C BUS. These range from ultrasonic range finders to electronic compasses.

2.1.3 USB IO24

This device is simply a board with 24 digital i/o pins that can be individually set as an input or output [12]. This is done with software on the PC when the device is connected to the USB port. These pins can then be connected to different electronics such as analogue to digital converters. There are also many other versions of this device available [20], most of them are not much bigger than the USB plug its self. This was not implemented in the MIRC as the laptop used was not USB compatible.

2.1.4 Wireless Interfacing

A wireless interface would mean that the MIRC would not have to carry around any bulky computer hardware, as all the sensor data and instructions for the MIRC would be transmitted wirelessly between the MIRC and a desktop PC. Wireless interfacing could greatly reduce the size and weight of a MIRC based robot, but it also has it drawbacks. First of all the bandwidth of wireless connections is much more limited than when using wires. This is not really a problem for the majority of sensor data as it does not require a high data rate, but this does greatly limit the amount of more advanced hardware that could be used. USB2 data rates are much higher than currently available from standard wireless links. This means that good quality real time images could not be transmitted wirelessly without adding too much cost. Not only is bandwidth a problem but so is the transmitter range. A robot under wireless control would be limited to the area covered by the transmitters and could also be subject to interference which would effect both the range and the data rate.

2.2. Hardware

The MIRC consists of many different pieces of hardware working together. This section describes the various electronic systems that make up the MIRC and how they were constructed.

2.2.1 Sensors

Having to buy only the cheapest sensors was frustrating as they are the main factor that will affect MIRC performance. The first type of sensors needed was proximity detectors. The sensors chosen for this were simple photo reflective IR devices. These sensors consist of an infra red LED and phototransistor in a plastic case; they would output a voltage that was dependant on the amount of IR light hitting the detector. Using analogue sensors enabled development of fuzzy logic to control how the robot avoided objects. These sensors worked well at short range as long as there was no ambient sunlight. It wasn’t until the weather got sunnier that it was realised how much the sunlight would affect operation. Sunshine affected the photo reflective sensors outputs by increasing output to about ¾ of maximum. Adding sunshine sensor and adjusting the other sensor values relative to it stopped the sunshine from making the outputs go too high but it reduced the range so much that they were useless.

A much better type of sensor is the Sharp GPD-12 Infra red range finder. It is much larger in size than the photo reflective sensors but is much more accurate as it measures the angle of the reflected light as well as the intensity. On board signal processing then converts this to an analogue output voltage. The downside to this sensor is that it costs over £10. The GPD-12 is one in a range of infra red range finders by Sharp. They come with various output types and ranges.
One sensor on the MIRC is an ultrasonic proximity detector. This is the Velleman K3502 parking radar kit. This kit usually sounds a buzzer when an object passes a preset distance from the sensor. To connect this sensor to the K8000 the buzzer was removed and the buzzer output was connected to a digital input on the K8000. There was no need to alter the voltage or the buzzer output, as the K8000 can tolerate a wide range of voltages (5-20V DC).

The head module on the MIRC contains several sensors, one of which is an ultrasonic range finder by Milford instruments [21]. This sensor uses the Polaroid transducer system, which has a single transducer for sending and receiving echoes. This is mounted on a servo for panning and is controlled by a board connected to the computers serial port. Another sensor in the head is a USB webcam of 640*480 pixels. Currently this has not been used in the project as the laptop being used does not support USB. With a more modern laptop this camera could be utilized for many functions, such as object recognition, motion tracking and remote avatar web conferencing.

2.2.2 Actuators

The main actuators of the MIRC are the two drive motors. Each motor drives one wheel independently. The original design involved using a four wheel drive system. Steering was done using he ‘tank drive’ method. This allows for a zero turning circle and therefore greater manoeuvrability in a small space. This method was found to be insufficient due to large amounts of slippage and torque requirements. The current method employs two large back drive wheels and castors at the front. The steering is done in the same way as the ‘tank drive’, but as the wheels are on the back the turning circle is increased to twice the length of the MIRC. The great reduction in slippage with this method meant that less torque was required and therefore better performance was achieved. The speed and direction of the motors can be controlled via the K8000 and H-Bridge driver board [22]. The motors are fitted with a 148:1 gear box to give greater torque, but this was still insufficient for the ‘tank drive’.
The other actuators are the pan and tilt servos for the head assembly. The panning servo is controlled by the same board that controls the Polaroid transducer range finder. The tilt servo is controlled by a separate board [21] which is capable of controlling up to 8 servos. This board is not currently connected due to the lack of ports on the laptop used in development.

2.2.3 Body

The body of the MIRC consists of three layers. The bottom layer is for the drive mechanics and batteries, the middle layer is for the interface electronics and the top layer for the computer and room for expansion. The base was initially made from an aluminium sheet with aluminium shelving brackets along the sides for strength. This eventually had to be changed as the original base did not prove sturdy once the heavy batteries were added. Rapid acceleration and turning caused the whole base to flex, which eventually caused the chains between the motors and wheels to slip, and one of the gearboxes to break. This was one of the main obstacles that was overcome as it slowed progress and wasted funds. The new base is made from a piece of thick MDF with wooden supports for the bearings, and performs much more effectively.

2.2.4 Multiplexer

The K8000 is limited to four analogue inputs. This problem was solved by creating a sensor multiplexer. This device was able to allow the computer to capture data from several sensors using a single analogue input on the K8000. To do this it was necessary to create a device that could switch eight digital outputs one at a time and be controlled by 1 digital input from K8000. This is very similar to ‘running lights’ where several LED’s run in sequence and start again. To keep the multiplexer small it was decided that a PIC microcontroller would be used, as this would greatly reduce the number of required components. Having had very little experience using PICs this activity proved a valuable learning experience. The chosen PIC was the 12F675 because of its small size (8 pin) and the low cost of the chip programmer. This PIC has only four digital outputs so these also needed to be multiplexed. The digital outputs when low can be used like a ground connection, allowing LEDs to be connected directly across two outputs (fig 1)