Design Brief The client, Mr. Vaughn Anderson, the Technology Coordinator at Lyndale Secondary College, has requested the design and construction a motor vehicle or other device which can be programmed using PICAXE technology. He wants to use this device to help teach students in his year 9 and 10 programming classes how to write in the BASIC programming language. He believes that having a real world application for the program scripts will make the class more interesting for his students. The client has left various specifications for the design of this unit. He has stated that the vehicle must cost no more than $80 per unit, and that it must be no larger than the size of an A4 sheet of paper (approximately 20cm x 30cm). He has also requested that, if possible, the unit be controlled by an infrared remote control, as this will further engage his students. If this is not possible, the device must be able to run forward and, on contact with a wall or other item, be able to reverse and turn in order to manoeuvre around the object. The PCB used in the unit must be enclosed so that there are no exposed wires or components, but at the same time, must be accessible via an access panel, so as to allow for repairs. The batteries must also be accessible so that they are able to be replaced easily. The only visible components may be the stereo socket, to allow for the programming of the PICAXE chip, or any other necessary components such as infrared sensors or switches. Although not directly specified, the device should be visually appealing, so a shell to enclose the vehicle should also be designed and produced. Not only will this make the buggy visually appealing, but it will help to meet the client s specification that there should be no visible unnecessary components. The shell and device should also be durable enough to withstand prolonged use. As the device will only be used during class time, it will need to be able to operate in a computer class room environment. Therefore, it must be capable of operating on carpet, table tops and possibly tiles. It should also move at a reasonable, slower speed, as it is not going to be used in an open or outdoor environment. After taking the above specifications into account, I have decided to design and construct a buggy which can be programmed to operate via either an infrared remote control, or switches mounted on the front of buggy. This way, the client can use it as a reversible buggy is desired. By making use of a PICAXE-14M chip, it will be possible for the buggy to be programmed using the BASIC programming language as specified. The base of the buggy will be made from a commercial track and wheel set and gearbox from Tamiya, whereas the shell to enclose the PCB and batteries will be designed and constructed from aluminium.
Considerations Function: As the system is a remote controlled toy car, its function is to respond to an infrared input device and move in the direction stipulated by the PICAXE program. The system can be programmed via USB port and its responses to the infrared device are editable. This is to allow the actions undertaken after an input to be altered by the user, thus making the operation of the system more flexible. The overall function of the system, however, is to convert chemical energy from the batteries, into rotational and linear motion. This is achieved by the system s gearbox, motors and wheels. Purpose: The purpose of the overall system is to help teach IT students the BASIC programming language. The system can be used by IT teachers as a real world example of how programming is used in everyday life. The students can write their own programs then download it to the buggy to see how it works in real life, instead of using on screen simulators. Having a real world application for the programs will engage students as well as help to further their understanding of software development and information technology. The purpose of the systems circuitry is to receive an infrared signal, then process it accordingly. The effect of this is generally to move the buggy in a desired direction with the use of the motors and wheels attached to the circuit. Materials: The materials used to construct the shell of the buggy need to be strong and durable enough to withstand prolonged use. However, the materials used cannot be too heavy, as this may affect the operation of the vehicle. Safety: During construction of the product, many different tools and other equipment will be used. Some of these may cause harm to the user, if not used carefully. A risk assessment criteria sheet will need to be constructed and adhered to throughout the process of constructing this device.
Australian Standards AS/NZS 4360:2004 These are the Australian Standards on risk management. They outline the process for identifying, analysing, evaluating and treating, any risks associated with the construction of this, or any other device. The Risk Management Guidelines AS/NZS 4360:2004 Booklet can be purchased from www.riskmanagement.com.au for more detailed information on risk management in Australian workplaces. AS/NZS 3000:2007 These are the Australian Standards for Wiring Rules. These rules and guidelines are mostly for electricians, but some may be applicable to this project. These guidelines can be purchased online from www.wiringrules.standards.org.au Constraints Cost: The client has requested that the overall cost of the product not exceed $80, this is so that he can afford to purchase 12 of these units for his programming class. Size: The requested size is no larger than 20cm x 30cm, approximately the size of an A4 sheet of paper. This is to allow a class set of units to be carried in a single crate. Time: There is an approximate time limit of 35 weeks from the time of receiving the client s letter to the due date of the project. Available tools and equipment include: Soldering iron, drill press, hot glue gun, computer, milling machine, metal lathes, plastic heater, and a sheet metal bending brake. for the production of the PCB include: Blank printed circuit boards, solder, insulated copper wire, heat shrink, mixed components, various types of switches, breadboards, and serial cables for programming the PICAXE chip. for building the buggy s shell include: Sheets of aluminium, coloured plastic, wheels, motors, gear boxes, track and wheel sets, glue, hinges, screws, batteries and battery housing.
Likelihood RISK ASSESSMENT MATRIX Determining the Level of Risk This document can be used to identify the level of risk and help to prioritise any control measures. Consider the consequences and likelihood for each of the identified hazards and use the table to obtain the risk level. Consequences 1 Insignificant Dealt with by in-house first aid, etc 2 Minor Medical help needed. Treatment by medical professional/hospital outpatient, etc 3 Moderate Significant non-permanent injury. Overnight hospitalisation (inpatient) 4 Major Extensive permanent injury (eg loss of finger/s) Extended hospitalisation 5 Catastrophic Death. Permanent disabling injury (eg blindness, loss of hand/s, quadriplegia) Almost certain to occur in most A - circumstances High (H) High (H) Extreme (X) Extreme (X) Extreme (X) B - Likely to occur frequently Moderate (M) High (H) High (H) Extreme (X) Extreme (X) Possible and likely to occur at some C - time Low (L) Moderate(M) High (H) Extreme (X) Extreme (X) D - Unlikely to occur but could happen Low (L) Low (L) Moderate(M) High (H) Extreme (X) May occur but only in rare and E - exceptional circumstances Low (L) Low (L) Moderate (M) High (H) High (H) How to Prioritise the Risk Rating Once the level of risk has been determined the following table may be of use in determining when to act to institute the control measures. Extreme Act immediately to mitigate the risk.either eliminate, substitute or implement engineering control measures. Remove the hazard at the source. An identified extreme risk does not allow scope for the use of administrative controls or PPE, even in the short term. High Medium Low Hierarchy of Control Elimination Substitution Engineering Controls Administrative Controls Personal Protective Equipment Act immediately to mitigate the risk. Either eliminate, substitute or implement engineering control measures. If these controls are not immediately accessible, set a timeframe for their implementation and establish interim risk reduction strategies for the period of the set timeframe. Take reasonable steps to mitigate the risk. Until elimination, substitution or engineering controls can be implemented, institute administrative or personal protective equipment controls. These lower level controls must not be considered permanent solutions. The time for which they are established must be based on risk. At the end of the time, if the risk has not been addressed by elimination, substitution or engineering controls a further risk assessment must be undertaken. Take reasonable steps to mitigate and monitor the risk. Institute permanent controls in the long term. Permanent controls may be administrative in nature if the hazard has low frequency, rare likelihood and insignificant consequence. Controls identified may be a mixture of the hierarchy in order to provide minimum operator exposure. Eliminate the hazard. Provide an alternative that is capable of performing the same task and is safer to use. Provide or construct a physical barrier or guard. An achievable timeframe must be established to ensure that elimination, substitution or engineering controls are implemented. NOTE: Risk (and not cost) must be the primary consideration in determining the timeframe. A timeframe of greater than 6 months would generally not be acceptable for any hazard identified as high risk. Interim measures until permanent solutions can be implemented: Develop administrative controls to limit the use or access. Provide supervision and specific training related to the issue of concern. below) Develop policies, procedures practices and guidelines, in consultation with employees, to mitigate the risk. Provide training, instruction and supervision about the hazard. Personal equipment designed to protect the individual from the hazard. (See Administrative Controls Health & Safety Services July 2009 1
RISK ASSESSMENT SUMMARY Topic: Date: Issue No. Review date: Identify Hazards and subsequent Risks Analyse Risks Evaluate Risks Identify and evaluate existing risk controls Further Risk Treatments Hazards/Issues/Risks Consequence Likelihood Risk level Burns from soldering iron What we are doing now to manage this risk. 2 C M Use soldering iron stand Solder in eye 5 D X Wear safety glasses Inhalation of fumes from solder 1 B M Electrical shock 3 E M Dropping tools on feet Cut by sharp objects such as saws Hair/clothing caught in drill press 1 C L 2 C M 4 D H Use solder only in well ventilated areas Check all power cords to assure there are no splits in the plastic Keep tools away from table edge Take care when using sharp objects Tie long hair back, remove hanging clothes, eg. ties Effectiveness of our strategies Mostly Effective Entirely Effective Entirely Effective Mostly Effective Partially Effective Partially Effective Mostly Effective New risk level L L L L L L L Further action needed Opportunities for improvement Wear safety gloves when working with soldering iron Wear protective shoes Wear safety gloves when using sharp objects Health & Safety Services July 2009 2
Research and Annotations
4 Wheeled Designs 1 While this design looks interesting, it has too many visible wires, components and circuitry and it does not make use of infrared technology. 2 This design uses the base of a commercial remote control car. This is a good idea and would be easy to manufacture, however it would be expensive to purchase the base, and it may operate at a speed too fast for a classroom environment. 3 While this design looks nice and simple and easy to make, its circuitry is entirely visible. This does not meet the client s specifications.
2-3 Wheeled Designs 4 This design may meet some of the specifications, however, the circuit is not covered and the materials to make it are not readily available. 5 The small plastic wheels and low standing if this design would not allow it to run properly on carpet. Meaning it does not meet the client s specifications. 6 This design scored very low on the criteria, and, as such, would not be a suitable choice for this project.
7 I really like the idea of constructing the shell out of Lego pieces, however, these pieces are not readily available. Also, this design would not be very durable 8 This design looks interesting, however, the fact that its shell is made of the circuitry, means it does not meet the clients specifications of having an enclosed circuit and components. 9 This design doesn t look too appealing, nor does it use infrared technology. Also, its circuit is not enclosed, making it a bad choice for this project.
Track Wheeled Designs 10 This design is very suitable for classroom use, however it is not very durable and the circuitry is entirely exposed. 11 This design is nice and simple, however, its circuitry is not enclosed. 12 The circuit of this design sits on top of the buggy. This does not meet the client s specifications of having an enclosed circuit and components.
13 I like this design, however, its shell is not be easily removable. This means that it will be hard to repair any faulty components. 14 This design has too many exposed wires and components to be considered for this project. 15 This design would be a good choice for this project if the circuit and batteries were enclosed.
Conclusion While I like the look of some of these designs, I have decided that I will create my own shell design. Using some of these designs as inspiration, I will design a shell and circuit myself. One of the ideas I will incorporate into my system is the tracked wheel platform. I will use the design from image 11 as the base for my system, but will create a shell to enclose it, along with the circuit and batteries, so as to make it more appealing. Sources 1 http://www.syzygytech.com/2008/11/15/infrared-robot-detection-with-obstacle-avoidance/ 2 http://letsmakerobots.com/node/798 3 http://www.dharmanitech.com/2009/01/ir-remote-controlled-car-pwm-motor.html 4 http://letsmakerobots.com/node/6417 5 http://www.active-robots.com/products/robots/robo-jr.shtml 6 http://electronics.saintjohn.nbcc.nb.ca/sumo/sumo.htm 7 http://www.techno-stuff.com/dirpd-t.htm 8 http://www.microbric.com/page.php?sid=17 9 http://robotechno.us/line-follower-robot-tutorial.html 10 http://letsmakerobots.com/node/1520 11 http://letsmakerobots.com/node/1736 12 http://www.robotshop.ca/inex-interactive-c-robot-kit-3.html 13 http://nathanbrinks.com/projects/tankesc/tankesc_phase1.php 14 http://luckylarry.co.uk/2009/08/obstacle-avoidance-robot-build-your-own-larrybot/ 15 http://letsmakerobots.com/node/6776
Product Evaluation
Selection Criteria Can the device be programmed using PICAXE technology? Does the device use the BASIC programming language? Does the device cost less than $80 per unit? Is the device smaller than 20cm x 30cm? Can the device be controlled via an infrared remote control? Is the device capable of operating on carpet and table tops? Does the device move at a reasonable, slower speed? Are the PCB, wires, and other components enclosed? Is the PCB accessible for repairs? Are the batteries accessible for changing? Is the device durable enough to withstand prolonged use?