Design Issues ECE480 Design Team 7 Mike Zito; Shaun Eisenmenger; Gu Enwei; Adam Rogacki

Transcription

1 Design Issues ECE480 Design Team 7 Mike Zito; Shaun Eisenmenger; Gu Enwei; Adam Rogacki Product lifecycle management (PLM) refers to the engineering aspect of preparing for and managing a product for the entirety of its lifecycle. This includes raw material extraction, design, manufacturing & production, transport, utilization, and finally, disposal and reuse. Care should be taken so that the usable product lifecycle is maximized, while at the same time, the amount of resources consumed by the product and processes related to the manufacturing of the product are minimized. Many of the concerns addressed in PLM are directly related to Environmental concerns, so those will also be covered in this section. A major PLM concern for our Laptop Based Radar system is the length of the product s usable life. Since the radar system was designed for use by students, its components were chosen to be low cost. This leads directly to quality concerns. For instance, the breadboards used to construct the amplifiers and pulse generators can get crowded with components causing short circuits, and confusing assembly. The breadboard circuits are also not meant in any way to be permanent fixtures, so electronic components may be accidently removed during transportation or improper storage. This was an issue that directly affected our team during the design process. Because of the relatively fragile nature of the circuitry, the expected usable lifetime of the product is very short. Some ways to extend the product usable lifetime would be to construct the breadboard circuitry on a solder board or even obtain custom PCBs from a third party vendor. These possible solutions would add much needed robustness to the electronic components. Another method that may be used in conjunction with solderable circuit boards would be to create a protective enclosure for the electronics. Both of these methods would initially add complexity and cost to the product, but would both directly contribute to lengthening the usable product lifetime. Our project uses a variety of recyclable and reusable materials. For instance, the antenna waveguides are aluminum coffee cans, and the amplifier and pulse generating circuitry is mounted on a 1ft x 1ft piece of scrap wood. Both of those components can be obtained from normal household use and are easily recycled or reused in future electronics or even household projects. The breadboard that contains the radar circuitry can be reused in future projects. In future versions of the Laptop Based Radar system, the negative environmental impacts of the product can be further minimized via a variety of means. The first would be to utilize

2 Page 2 lead-free solder when connecting the RF circuitry to the amplifier & pulse generating circuitry on the breadboard. Another method of minimizing the negative environmental impact would be to choose component vendors that that in close proximity to us, the manufacturers of this device. Finally, instead of using traditional AA batteries to power the device, the user should be encouraged to use rechargeable batteries. Some components of our project however cannot be reused at the end of the product lifetime or are tremendously difficult and expensive to properly recycle. Unfortunately, the OP- AMP chips and function generator chips as well as the passive electronic components (resistors and capacitors) will most likely end up in a landfill. If possible, the user should be made aware of proper electronics disposal. Many local governments offer specialized waste disposal programs, and we as manufacturers should attempt to increase customer awareness about such programs. If budgets allow, perhaps, a mail-back program could be implemented so that customers could mail electronic components back to the manufacturer at the end of the product life. Our Doppler Ranging Radar system has a lot of radio frequency and communication parameters that require proper protocol in order to be operational. We will next look into the standards which were implemented in order to complete our project as well as the improvement of standards we could implement within our design. Let s first analyze our cantennas. They operate at 2.4Ghz in the ISM band of frequency. ISM stands for Industrial, Scientific and Medical. With this being said, this specific radio spectrum is reserved for radio frequency energy for ISM purposes other than communication. The emission of this particular frequency band can create electromagnetic interference and disrupt radio communication. However, as of recently, the ISM band has been used more for short-range, low power communication systems such as Bluetooth devices. Since we are operating at a center frequency of 2.45GHz, we will be following ISM standards while emitting our Bluetooth frequency-similar signal through our cantennas. Secondly, let us analyze our communication with our MSP430 and a computer. We will be sending our data information as a digital signal to our pc in order to perform FFTs and plotting. We need a method of communication between the computer and our electronic devices. We landed on using the industry standard that defines the cables and connectors for this type of communication. USB is the standard in connecting computers to its peripherals. We are using a

3 Page 3 USB 2.0 B-type plug to output our data to our computer via an USB 2.0 A-type plug. Using USB standards will reduce complication and provide accessible solutions to communicate among devices. Lastly, let s analyze the architecture of our circuitry. There are many electronic device packages that are available to use, however we had to use practical connections so that we could prototype our circuitry. The standard package we used to make our circuitry was a DIP package. Dual In-line Packages are defined as a rectangular housing with two parallel rows of electrical connecting pins. These connections can either be through-hole mounted to a printed circuit board or inserted into a socket. Additionally, DIPs are useful with breadboards for temporary mounting. In addition to DIP, we also had our ADC component, which was MSOP type package. Since we needed a chip that was consistent with our DIP packaging, we needed to purchase an MSOP to DIP adapter. With all of these standards that we ve used in our design, there is still room for improvement of our standards. For example, we could use Ethernet connection rather than USB for faster communication. USB typically transfers data at around 480Mbit/s whereas Ethernet, at its highest can reach up to 1Gbit/s. Ethernet is standardized using 802 protocols for local area networks. Secondly, if we operated at a higher frequency band to increase the gain of our radar, we could move from our 2.45 center frequency to a higher center frequency within the ISM band. If these two areas are improved, our product would yield a higher level of standard. Another possibility to increase data throughput would be to conform to the USB 3.0 Standard, which has the possibility to provide a 3.2 Gbit/s bus. Product safety is not only a requirement, or responsibility, of the safety regulatory commissions, but also the responsibility of every product designer. This is especially true for designers working on distributing electrically based products to the consumers. Some potential risks to consider are radiation poisoning, fire, and child safety. Electromagnetic radiation hazards are related to two parameters: frequency and power. High frequencies, such as X-rays and gamma rays are ionizing radiation. They are capable of ionizing atoms and breaking chemical bonds, which may cause cancer or other radiation based syndromes. Also, high power electromagnetic fields may lead to dielectric heating. For example, touching or standing around on an antenna while a high-power transmitter is in operation can cause severe burns. Meanwhile, high power electromagnetic radiation can cause electric current

4 Page 4 strong enough to create sparks (electrical arcs) when an induced voltage exceeds the breakdown voltage of the surrounding medium. These sparks can then ignite flammable materials and result in a fire. For our product, we take two steps to make sure electromagnetic radiation is safe to human beings and animals. First, the transmitter and receiver of our product are working on the frequency of 2.4GHz, which is in the ISM (industrial, scientific and medical) band. This frequency is far lower than ionizing radiation frequency, and safe to human beings and animals. Second, the radiation power of our battery-based system is lower than 1W. So, the heating effect of our low power system is negligible, and equally negligible are the possibility of sparks as well as burns. Child safety is another concern to address during our designing process. The fundamental principle of design for children is to avoid small demountable parts in our product. Children, especially for those who lower than age of 8, have a nature to taste and swallow the stuff they can touch and hold. Circuit elements like resistors, capacitors and chips are small enough that they may be grabbed and swallowed by children. In order to avoid those dangers, every element is properly soldered and therefore non-removable by hand. Besides, the circuit board would also be covered by an aluminum case, so it could only be open by screwdriver. With these design considerations, we are confident that our product is safe to children, adults, and animals. One last large design consideration to take into account is to ensure that our product can be adequately used by all people, regardless of disability. This can be oftentimes difficult to implement. For example, our RADAR system relies on a GUI to interface with the user, telling the user with a graph the distances and speeds at which targets are located. Someone who is blind would not be able to take advantage of a GUI, and thus would not be able to take advantage of what our system would have to offer. However, since the data is already being processed in order to locate targets, it should be relatively easy to add an Accessibility Mode to the GUI. This mode could provide more audio cues, either in the form of speech synthesis, or tonal patterns. Tonal patterns could be used to relay the two pieces of information being relayed to the user, namely range and velocity. Range could be given by the pulse rate of the tone (faster pulse rates would indicate a closer target, and slower rates a more distant target), and speed could be contained within the pitch of the sound (higher pitch for faster moving targets). However,

5 Page 5 another thing to keep in mind is noise in the received data. This is oftentimes easy to overcome if one is looking at a graph, since you can compare present data to previous data very easy. However, with an audible mode, the noise could distort how a disabled user would analyze the data coming in. Thus, more efficient and rigorous noise reducing methods and techniques would have to be implemented. These are only a few examples of how to make this RADAR system universally accessible to more people.