5.1 - Personal Factory: Requirements

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System Requirements[edit]

This section lists the initial set of system requirements for the Personal Factory project. It is the first step in the Systems Engineering process described in Section 4.0. It puts into measurable and specific terms what we want the Factory to do. They are organized into categories, and numbered for later reference. The requirements are written in terms of the Mature Factory when it has reached full capacity. The Seed Factory design, which will be the starting point for growth, is determined later in the design process from what is needed to reach that final capacity.

Following the text of each requirement we discuss how they were arrived at, but there is no "right answer" to setting requirements, they are a matter of the end user's goals and choices. In fact, this particular set of requirements was derived from a larger goal of improving the quality of life for an expanding civilization. Parts of that larger goal will be addressed in the other design examples, but they only affect the Personal Factory as far as providing a source for the requirements below. Just because we want the factory to meet these requirements is no guarantee they are possible or economically feasible. This is why we call them the initial set of requirements. As the design progresses they will most likely need adjustment to what is practical or help identify areas that require more development.


1. Objectives


  • 1.1 Project Goal - The project shall provide a locally owned and operated Personal Factory System which supports the physical needs of the owners.

This sets the operating regime and basic design function that the system will perform. It is a binary (Yes/No or True/False) type requirement. The requirement is either met or not met. Locally broadly means "within several hours travel time", or approximately a metropolitan area and surroundings. This will be made more explicit later.

  • 1.2 Project Scale - The system shall support 75 people the first year, and 75 additional people/year until a full capacity of 660 people.

A target size is needed so you can work towards definite designs. The particular goal of 660 people is somewhat arbitrary, but is based on historical examples of settling new communities. The idea is that 660 people would have enough different skills to operate the various parts of the factory. If later design work shows this number is either too small, or larger than necessary, it can be changed. But we need starting values for numerical requirements for the first cycle of design.

  • 1.3 Choice - The specific physical locations for the project, and their internal organization, function, and operation shall be chosen by program participants and location residents within the limits of design constraints.

The intent of this requirement is that the owner-operators of the factory will choose where it is built and how it is operated, rather than these decisions being made from the outside. Completed designs for the factory elements gives them a starting point to work from, but the final choices will be theirs.


2. Performance


  • 2.1 Location - The system shall be designed to operate in a temperate environment, as defined by the middle 90% of world population.

We want it to operate under the range of conditions where the majority of people actually live. The outer 5% on each end of the environment range are left out for this first-generation design. Setting a range establishes definite design limits. Later versions may be adapted to more difficult conditions.

  • 2.2 Growth - The system shall be able to increase capacity for production, transport, and habitation by 11% per year after initial start-up.

To make the design desirable for the owners, it should be able to more than just maintain itself, and have a generous margin for growth. The extra capacity could be used to increase the community size, start up new locations, or make products for sale. Initial start-up refers growth phases before supporting 75 people the first year, when the system is expanding from starter set to mature capacity.

  • 2.3 Improved Technology - The system shall increase the levels of self-production, cyclic flows, and autonomy in a progressive manner.

We do not expect the starter set to have the same abilities as a mature system supporting 660 people. This requirement sets a gradual increase in technical performance as the factory grows. To put it in more concrete terms, we divide this requirement into more detailed ones. The final level is set to 85% for the various detailed requirements as a reasonable goal for a first-generation design.

  • 2.3.1 Local Resources - Provide 85% of continuing matter and energy needs from local resources, as measured by economic value.

This meets the design goal of "supports most of the physical needs". 85% is for a mature factory. The remaining 15% would include rare or hard-to-make items which would be difficult for a small-scale local factory. We expect the parent requirement of progressive improvement would be met at a decreasing rate vs size. The easiest items that contribute most to the 85% goal will likely be added first to the factory.

  • 2.3.2 Self Production - Provide 85% of the total economic value for the owners internally, with the remainder from outside work.

The previous requirement covers physical needs, this one is economic value which the factory generates, including work by the owners as operators. Again, we think 85% is a reasonable level for a mature system, with a gradual increase as the factory grows. The remaining 15% would be conventional outside work elsewhere. A corollary of this requirement is that the early stages from the starter set would only support part-time operation or a few full-time people, while meeting only some local needs. Most participants would be doing conventional outside work at that point. We think a gradual shift as each person individually transitions from outside work is more feasible than doing so all at once.

  • 2.3.3 Cyclic Flows - The system shall recycle and reprocess 85% by mass of local waste flows from production, transport, and habitation.

This requirement comes from several sources. Closed cycle flows are more sustainable in the long term. They have lower input costs because you do not need as many new inputs. They also have lower disposal costs than linear flows produce. We expect that the factory's ability to work from raw materials and level of automation will make the recycling economically inexpensive. The 85% goal is again for the mature factory.

  • 2.3.4 Automation - The system shall reduce human labor requirements by 85% relative to the US average.

Automation is desirable from a quality of life standpoint - more output for less work. The factory owners do not have to worry about automation putting themselves out of jobs, since they own the production. Less work and economic security are key parts of making the Personal Factory something people will want. We think 85% automation is a reasonable level for a first generation mature factory. It assumes the factory as a whole is integrated, so that transfers between production steps can be automated, as well as the individual steps.

  • 2.3.5 Autonomy - The system shall be capable of controlling at least 85% of production, operations, and maintenance functions locally.

This flows partly from the desire for owner choice and ability to run things under control of the people who live with the results. Having the capability does not require it be used. Participants or specialists who are not in the local area can operate parts of the factory by remote control as an option.

  • 2.3.6 Complexity - The starter set shall include not more than 7 major production elements, not counting attachments.

One of the growth paths for the Personal Factory is diversifying to new equipment and processes out of the hundreds of types available. We wish to start with a reduced set to lower initial cost and design complexity. On the other hand we do not want to start with too little. For example, we could in theory start with zero production elements and rebuild technology starting from rocks, sticks and fire made by hand, but that is not very practical. A compromise is to start with about one piece of equipment per major production function, so that a reasonably complete production chain is possible within the factory. Attachments, bits, consumable supplies, tooling, and small shop tools will be needed to outfit any operating factory, but are not counted as major elements.

  • 2.4 Improved Quality of Life - The system shall support an equivalent GDP/person of $156,000 referenced to January 2013.

The goal of supporting physical needs does not say at what level of quality for food, shelter, and utilities. Naturally we would like a high level of quality, and we think with automation and self-production this can be reached. The GDP equivalence sets a target well above the US average, and is in terms of what it would cost to reproduce the lifestyle and income in 2013 dollars. Cash income will be much less, since most items will be supplied directly from the factory. As with other requirements, this is a goal for the mature factory, early versions will not reach this high.

  • 2.5 Data - The system shall share project experience and data with the local community and beyond.

As a first of it's kind project, we would like others to build on the knowledge gained and hopefully feed back their own experience. Including it as a system requirement ensures a process for collecting and then sharing the data will be included in the design. We recognize that personal data will need to be carefully protected. This requirement is about technical features like solar collector power output.

  • 2.6 Resources - The system shall produce at least 10.5 times internal needs for materials and energy.

This comes from a desire for a highly productive design that comfortably produces above it's own maintenance and support needs. It also supports a high quality of life either by directly supplying items to the owners, growth of the factory, or surplus production for sale. This is measured for the mature factory, after building facilities and equipment, and community residences have reached 660 capacity. It is related to the concept of "energy return on energy invested" (EROEI) for energy sources, but extended to also cover material resources.


3. Time

  • 3.1 Completion Time - [Not Applicable]

A project schedule or completion date is often used as a time-based requirement. In this set of requirements it is already implicit under 1.2 Project Scale as 660 person final size/(75 people/year growth) = 9 years from start of full construction to completion. We mark 3.1 Completion Time as "Not Applicable", at the system level, since we try not to have duplicate requirements. At more detailed levels of the project, we may set time and schedule requirements, and reserve this requirement number (3.1) for that purpose.

  • 3.2 Operating Life - The system will be designed for an indefinite life with maintenance, repair, and replacement of parts.

This project is intended as a permanent source to supply the owner's needs. Therefore it will not have a finite life or wear out date. Since the individual elements cannot be designed to last forever, a consequence of this requirement is the need for maintenance and repair tasks.


4. Cost


  • 4.1 Total Development Cost - Development cost for the project shall be less than $66 million for a capacity of 75 people per year, net of sales.

We use January 2013 US dollars, adjusted for inflation. Cost requirements put a bound on how much effort goes into designing and building the system. Total costs are divided into Development - the one-time costs for technology, prototypes, and design; and Location - the repeating costs for each added unit or copy you build. The agricultural, construction, and utility industries, which our factory outputs fall within, typically do not invest a lot in research and development. Since we want to apply modern automation to these areas, we assume a relatively high development cost. The specific number is a multiple of the expected unit cost. This is justified if many personal factories are eventually built based on the design. The Personal Factory prototypes, and early expansion phases are able to make items for sale. Any items sold during the development period are credited against the cost, so $66 million would be the maximum net outlay.

  • 4.2 Location Cost - The unit location cost after development shall be less than $76,000 per person supported.

This covers the repeating cost for the food production, housing, and utilities capacity for each person supported per the other requirements. This is a relatively low number because automation and self-production is intended to make these things at low cost. The $76,000 is intended to cover the outside raw materials, parts, and labor which still need to be purchased. It is an average number per person when the factory is mature, and may be higher to start with. Some individual elements may be more expensive, but serve multiple people.


5. Technical Risk


  • 5.1 Risk Allowances - The system design shall include allowances for performance and design uncertainties of less than 7.5% when complete.

No engineering design is perfectly understood, or built and operated exactly as intended. Therefore there will always be some uncertainty in performance, failure rate, and other parameters. A technical risk allowance is a design margin above the required performance to account for this uncertainty. In other words, we design for slightly more than we need. It is measured at the point the design is finished and building the equipment starts. Once the system is built and operating, you will find out the actual performance. The margin is intended to insure the final performance is at least at the required level. The uncertainties will be higher at the start of design, especially for something new like self-expanding factories. The intent to lower the uncertainties by methods like simulation, component tests, and prototypes. Note that technical performance risk is distinct from failures and safety hazards.


6. Safety


  • 6.1 Location Risk - The system shall have a location life and property risk of less than 38% of the US 2013 average.

Safe operation is a desirable feature, so we include it as a requirement. This is to be met at the full 660 person population goal, and applies at the project-owned land and improvements. A 5/8 reduction is an ambitious goal, but we think it can be met by automation (which removes people from work hazards) and design for safety (prevent risks at the design stage).

  • 6.2 Population Risk - The system shall reduce natural and human-made risks to the nearby population by 17%, including external risks created by the system.

The previous requirement was for risks of the project to it's owners and property. This one is for risks to others outside the project. We would like to have a positive impact on the nearby community. We define nearby as zones 20 km wide around the location, with 50% of the risk reduction applied in the nearest zone, 25% in the next zone, and so on. The population of the nearest zone determines the total number of people we reduce the risks for.


7. Sustainability


  • 7.1 Biosphere Security - The system shall preserve 89 species outside their normal environment range, either stored or living.

In addition to present safety, we want to contribute to long term sustainability of the biosphere. The number of species is scaled to the size of the project, so we use a relatively small number here. By preserving species outside their normal range, recovery from hazards to the original population, like climate shift or human development is possible.

  • 7.2 Survivability - The system shall provide 0.0085% compensation for civilization level critical risks.

Besides the biosphere, we want to contribute to the long term survival of human civilization. A project this size can only be expected to make a small contribution, therefore the requirement value is small. Examples would be helping address resource depletion or atmospheric carbon accumulation. We acknowledge this is a challenging requirement, but we think it is worth at least trying to meet it.


8. Openness

  • 8.1 Open Design - Technology and design methods developed within the project shall be open for others to use. Specific instances of a design and produced items may be proprietary.

Our larger intent is not just to support one local community, but to demonstrate Personal Factories are possible and enable others to use them. We need to balance sharing the underlying technology with rewards for people who do the work. So we allow people to keep specific hardware designs and physical items private if they choose.


Measures of Effectiveness[edit]

During the design process, attempts to meet the various requirements often affect more than one at a time. For example, higher performance and reliability often come at the expense of higher cost. To optimize a design when this happens, we use measures derived from and strongly related to the requirements, but converted to a common scoring system. How well each requirement is being met is converted by formula to a numerical score. The scores are combined, and the better design is then the one with the highest total score. For this project we will use a 100 point scale and assign a certain number of points (their weight) to each requirement according to their relative importance. The score by formula is found for each criterion, and the total score is the sum of weight x percent score for all the requirements. Note that some requirements are fixed, like the fact the project is designed to support the physical needs of a certain number of people, and thus do not get a variable score.

The measures as a whole are a mathematical model of what we think is better in a design. Like the requirements in the previous section, there is no "right answer", since they are based on human goals and choices. What the measures do is allow different people, or one person working on different parts of the project, to reach a consistent solution based on the same assumptions. In the table below we list our selected scoring items and formulas. The individual items only total to 78% because some items from a more comprehensive project are not included here. They will be included in the later design examples, and we want to be able to easily compare across projects. Therefore the total is adjusted by 100/78 to bring the score for this example to a nominal 100 point score for meeting all the targeted measures.


Criterion Weight (points) Scoring Formula (percent) Notes
2.2 Growth (rate/yr) 5.0 (equivalent % annual GDP growth of all locations -2.5%) x 10 Goal = 11%. Internal production valued as if sold at market rates
2.3 Improved Technology (local resources) 1.0  % of local resources from program locations Goal = 85%. Measure by kg (mass) or Joules (energy)
2.3 Improved Technology (self production) 1.0  % of finished products from program locations Goal = 85% by economic value
2.3 Improved Technology (cyclic flow) 1.0  % of location mass flows reused Goal = 85%. Includes local use but not production for growth or sale
2.3 Improved Technology (automation) 1.0  % reduction human labor hours Goal = 85% lower relative to current technology
2.3 Improved Technology (autonomy) 1.0  % required labor and control supplied locally Goal = 85% of necessary functions can be supplied
2.4 Quality of Life (GDP) 5.0 (equivalent GDP - $20,000)/1600 Goal = $156,000/capita. Includes value of internal production and labor
2.6 Resources (surplus) 5.0 ln(material & energy output/internal use)/ln(2) x 25% Goal = 10.5 over program life cycle. Clip at -100%
4.1 Total development cost 14.0 (avg unit cost/total development cost) x 1000% Goal = 11.7 x location cost = $890,000/capita
4.2 New Location Cost 14.0 [(ln(0.25xUS capital per person/location cost))/ln(2) x 25%]+100% Goal = $76,000/capita
5.1 Technical Risk Allowance (%) 5.0 (50% - technical uncertainty allowance) x 2 Goal = 7.5% technical allowance
6.1 New Location Risk (relative) 7.5 [ln(0.25x general casualty risk/location risk)/ln(2) x 25%] +100% Goal = 38% relative risk. Includes life and property risks
6.2 Population Risk (relative) 7.5 (% reduction to general population risk) x 5 Goal = -17% from natural and program causes. Increased risk not allowed.
7.1 Biosphere Security (species-locations) 5.0 [(log(species maintained outside natural range x locations)) - 1] x 20% Goal = 89 in vivo or stored, humans are a species
7.2 Survivability (relative) 5.0 (% compensation for critical risks) x 10,000 Goal = 0.0085%. includes all civilization level risks
Total 100 Sum partial scores x weight from each line above x 100/78