机械设计的基本原理1.4
Deterministic Design
确定性设计
Everything happens for a reason, and we merely need to apply the proper resources and focus in order to discover and understand the issues that would otherwise lead to uncertainty. Minimizing uncertainty, and hence risk, makes a design more deterministic. Deterministic design1 can be facilitated through the use of a structured design process. While it might be possible to debate whether design itself is a deterministic or stochastic (shoot-from-the hip) process, it is best to focus creative and analytical forces on real design problems in order to stay on the schedule.
万物有果必有因（这个因果已经提炼为参数化的数学关系，这个是西方文明的根本），我们只需要应用合适的资源来发现和理解设计过程中遇到的问题，这样才能消除不确定性，确定前因后果。随着不确定性的降低，设计本身的风险也在降低，从而这样的设计就更具有确定性。此外，好的设计流程规划，也会有助于确定性设计的进行和完成。当然，确定设计和随机设计（不是从头开始，而是从“屁股”开始）的争议还是会不绝于耳，但是在项目节点快要临近时，我们最好还是有创造性的从分析一些实际问题开始吧。
Engineering design problems are essentially cost and performance trade-offs, and a key element of performance is time to market. It does not matter how good your solution is if you miss the market window. Consequently, engineers with a vibrant passion for success live on the (appropriate) edge. Because the edges move as cost/performance requirements change, engineers and managers must remain nimble, open-minded, and on continual lookout for disruptive technologies2 that can deliver far more performance for far less cost (e.g., integrated circuits verses vacuum tubes).
机械设计实质上是成本和功能的权衡，最重要的功能就是要快速投放市场收回现金流。如果错过产品投放市场的窗口期，那么再好的解决方案也是徒劳。所以，好的设计师还必须通过权衡功能和成本，来跟随市场的脚步。由于市场需求的变化，成本和功能的需求也在变化，工程师和项目经理必须积极进取，不停寻找颠覆性的技术，保证以最低的成本实现最大的功能（例如，真空电子管和集成电路板的区别）。
The stagnant edge is the realm of the complacent engineer who is asking a competitor to come and take away market share and the business. All too often an engineer gets good at doing something and then fails to realize that new methods have been developed that can provide better performance for less cost. This is akin to riding on the flat bottom of your snowboard while gazing at the sky. You are asking for a face plant or a tree hug!
停滞阶段特点：产品的设计停滞不前，自鸣得意的工程师坐以待毙，竞争者慢慢占有并提高市场份额。总是有工程师们仅仅满足于以往的成功经验，而忽略了新技术可以带来的低成本高性能的可能性。这就好比在滑雪板上仰望天空一样，迎接你的只有脸着地或者“猪撞树”的惨烈后果。
The leading edge is the place to be as it means that it is very difficult for a competitor to do better than you unless they spend a lot of resources, and you are likely doing better than all your competitors. The leading edge can only be maintained by constant vigilance and being ready to switch to a different technology curve. This is akin to switching between the toe and heel edge of your snowboard as you weave your way through the woods.
领先阶段产品特点：产品的设计处于同行业的前端，竞争者需要花费大量的研发资源来达到同等水平。为了保持产品一直处于该阶段，设计人员必须非常机警，随时引入新的技术来保持领先。这像滑雪的时候随时调整姿态一样，这样滑雪者才能顺利的穿过树林（这个教授很爱滑雪~）。
The bleeding edge3 is the place for paranoid engineers who refuse to change their ways and instead think that with just a little more effort, things will work out; however, soon they run out of resources and fail. Creative solutions may appear to be cleverer than solutions arrived at by analytical means; however, if analysis was not applied, it is likely that the solution rests on the bleeding edge. This is akin to the snowboarder who refuses to turn because the hill is too steep, and instead runs off into the woods. Time after time, it is shown that individuals or teams who can simultaneously harness the power of creative and analytical and computational methods outperform those who use less than all three. Only then can you consistently identify the slope with the finest possible powder and then make first tracks!
产品落后阶段的特点：偏执的工程师拒绝接受改变，而不是通过努力来实现事半功倍的效果。但是，由于资源和技术的匮乏，他们设计的产品往往会失败。创造性的设计往往只是看起来比分析式的设计更聪明，但是如果创造性设计没有进行客观分析的话，其结果很有可能是落后类的产品。这就好比滑雪者因为山坡太陡而不转弯，最后却冲进树林一样。实践证明，能够熟练的进行创新、分析和理论计算的公司和个人，其设计的产品总比那些很少使用这些原则的好。
Consider the evolution of the machines on which your parts will likely be produced. Linear actuators are key elements that determine the speed, accuracy and force with which the axes move. Sliding contact lead screws worked great for over a hundred years until they gave way to ball screws which are starting to give way to linear electric motors. Each succeeding technology costs more than the other but provides better performance. However, for the new growth area of small machine tools to make mesoscopic (cm3 sized) parts, large forces and strokes are not needed. DC voice coil actuators have all the advantages of linear electric motors yet do not require expensive commutation circuits; thus they can have lower cost and higher performance. Understanding the physics of the problem and the scaling laws is critical!
生产零件机床的技术进化就是一个很好的例子。直线驱动装置是决定机床轴运动精度、速度和力大小的关键部件。直线电机正在逐步取代滚珠丝杠驱动的机床轴，而滚珠丝杠取代了沿用一个世纪左右的滑动丝杠驱动。每一个领先的技术都更昂贵，但是其性能都更加突出。但是对于新出现的纳米制造领域（体积只有1平方厘米大小），大的驱动力和行程不再重要。所以，直流电机就更适用了，因为其有直线电机的所有性能，但是却不需要增加昂贵的换向器电路。因此，新的低成本、高性能产品诞生了。总之，理解问题的物理原理和尺度定律是非常重要的。
Create a table of the basic physical properties and capabilities of the kit parts, and a spreadsheet to study time, motion, power required to score by each different means. Forecast what might be easy and what would be difficult ways to score, and think of strategies and concepts for ideas that are not easy, yet not too difficult. Then think of strategies and concepts for the more challenging scoring methods!
针对工具箱零件的物理特性和功能列出一个表格，通过计算表单确定不同得分方式所需的时间、运动和功率。这样，可以初步判断那种得分方式更容易，哪种方式更难。但是，也要再思考一些适度难度的得分方式和最难的一些得分方式。
1.R. Donaldson, “The Deterministic Approach to Machining Accuracy”, SME Fabrication Technology Symposium, Golden, CO, Nov. 1972 (UCRL preprint 74243).
2.Clayton M. Christensen, The Innovator’s Dilemma, 1997 Harvard Business School press, Boston, MA. USA
3.The term bleeding edge was coined by Richard W. Slocum III, a gifted project manager and a key catalyst in the life of his little brother who is eternally grateful for the butt kickings he received that enabled all you are reading to come to be. Thanks Rick for keeping me focused!
