结论：选装件不是附加品，它改变的是整机的性能参数
轮椅的选装件很多——增厚坐垫、头枕、餐桌板、侧支撑、防倾轮、氧气瓶架、拐杖架、扩展电池。
企业常把选装件当成独立的配件，整机检测用基础配置，选装件另外提供数据或者不提供。
但选装件装上去之后，整机的性能参数会改变： 重量增加、重心位置变化、受力路径改变、尺寸改变。这些变化可能使基础配置的检测结论不再适用。
最典型的是稳定性 ——装了头枕和高靠背，重心升高，倾翻阈值下降；装了餐桌板，前方重心外移。
影响的类型
| 选装件 | 主要影响 |
|---|---|
| 增厚坐垫 | 座位升高、重心上移、护栏相对高度下降 |
| 头枕与高靠背 | 重心上移、后向稳定性 |
| 餐桌板 | 前向重心、整机重量 |
| 侧支撑 | 宽度、重量、接触压力 |
| 防倾轮 | 稳定性改善、越障能力下降 |
| 扩展电池 | 重量、重心、续航 |
| 氧气瓶架 | 重量、重心、偏载 |
| 拐杖架 | 重量、宽度 |
| 坐姿系统 | 重心、重量、尺寸 |
「增厚坐垫」的影响常被低估。 坐垫加厚使使用者位置升高，重心随之上移，同时扶手和护栏的相对高度下降，防坠效果变差。
需要重新验证的情形
稳定性。 几乎所有改变重量或重心的选装件都影响稳定性。这是最需要重新验证的项目。
强度。 选装件的安装点承受新的载荷，安装点及周边结构的强度要验证。
尺寸参数。 总宽、总长、折叠尺寸可能改变，影响通过性。
重量。 整机重量改变，影响搬运和运输。
续航（电动）。 重量增加导致续航下降。
制动（电动）。 重量增加影响制动距离。
电气安全（电动选装件）。 电动的选装件（电动靠背、电动腿托）涉及电气项目。
「安装点的强度」容易被忽略。 选装件本身可能很结实，但它固定在车架上的那个点，原设计时可能没有考虑承受这个载荷。
组合的处理
选装件可以组合，组合数量可能很大：
全组合测试不现实。 如果有十种选装件，组合数量是天文数字。
按最不利组合测试。 找出对各项目最不利的组合。
分项分析。 分析每个选装件对各项目的影响方向，据此推断最不利组合。
限制组合。 在资料中规定哪些组合不允许。
分别验证关键项。 对影响大的选装件单独验证。
「找出最不利组合」需要分析。 比如稳定性的最不利组合，是所有使重心上移和外移的选装件同时装上；而强度的最不利组合可能是另一套。
分析的方法
逐项列出选装件的影响。 重量变化、重心变化方向、尺寸变化、受力变化。
按项目汇总影响。 对某个测试项目，哪些选装件有不利影响。
叠加分析。 不利影响能否叠加。
确定最不利组合。 叠加后最不利的组合。
验证该组合。 用最不利组合做验证。
论证其余组合被覆盖。 说明为什么其余组合不会更差。
这个分析做一次，可以覆盖整个选装件体系，后续新增选装件时只需分析新增的影响。
不能组合的情形
某些组合可能造成问题，应当在资料中明确禁止：
超出稳定性限值的组合。 几个使重心上移的选装件同时装。
超出重量限值的组合。 整机重量超出设计上限。
功能冲突的组合。 两个选装件占用同一位置或相互干涉。
超出安装点承载的组合。 同一安装点装多个选装件。
影响其他功能的组合。 比如某选装件妨碍折叠。
「禁止的组合」要在说明书中明确列出，而不是笼统说「注意兼容性」。使用者和经销商需要明确的清单。
资料上的表述
选装件清单。 所有可选装的部件及规格。
兼容性说明。 哪些选装件可以同时使用。
性能参数的变化。 装了某选装件后，哪些参数会改变、改变多少。
使用限制。 某些组合下的使用限制。
安装说明。 正确的安装方法和扭矩。
检查要点。 选装件安装后的检查。
「性能参数的变化」建议给出具体数据。 比如「加装扩展电池后整机重量增加多少、续航增加多少、后向稳定角减小多少」——这类具体信息对使用者和处方者有实际价值。
选装件自身的验证
除了对整机的影响，选装件本身也要验证：
强度。 选装件承受的载荷。
功能。 调节、固定、使用功能。
材料。 与人体接触的部件的生物相容性与阻燃。
耐久。 反复使用和调节。
安装可靠性。 安装后不应松动或脱落。
误装防护。 能否装错方向或装到错误位置。
「误装防护」值得考虑，因为选装件通常由经销商或使用者安装，装错的可能性实际存在。
第三方选装件的处理
市场上可能有第三方生产的兼容选装件，这带来问题：
第三方件的质量不受控；装上后整机性能可能改变；出现问题时的责任划分；以及是否在说明书中说明。
建议在资料中明确说明：只应使用制造商提供或认可的选装件，使用其他部件可能影响安全和性能，并可能影响保修。
采购与处方中的应用
选装件的性能数据对采购和处方有实际价值：明确加装后的参数变化，便于判断是否仍满足使用者需求；便于比较不同产品在同等配置下的表现；以及避免加装后超出安全限值。
建议企业把「基础配置 + 各选装件」的参数变化整理成表，随产品资料提供，这对专业人员的配置决策有直接帮助。
我们的做法
承接带选装件的轮椅委托时，我们会先要选装件清单和兼容性说明，据此分析各项目的最不利组合，而不是只测基础配置。
稳定性是我们建议重点重新验证的项目，因为几乎所有选装件都会影响它，而基础配置的稳定性数据在加装之后可能不再适用。
对于有电动选装件的产品，我们会把这些部件纳入电气安全和电磁兼容的测试范围。
如果你有带选装件的产品需要安排检测，可以把选装件清单和兼容性说明发过来一起讨论测试组合，或者直接联系：132 4819 8029。检测能力见服务介绍，产品分类见手动轮椅检测与电动轮椅检测，案例见案例。
English version
Conclusion. Wheelchairs carry many optional items: thicker cushions, headrests, trays, lateral supports, anti-tip wheels, oxygen cylinder holders, crutch holders and extended batteries. Manufacturers commonly treat options as separate accessories, testing the whole product in base configuration and supplying separate data for options or none at all. Once fitted, however, options change the whole product's performance parameters: weight increases, the centre of gravity moves, load paths change and dimensions change. Those changes may render the base configuration conclusions inapplicable. Stability is the clearest case: a headrest and high backrest raise the centre of gravity and lower the tipping threshold, while a tray moves the centre of gravity forward.
Types of effect. A thicker cushion raises the seat and centre of gravity and reduces the relative height of rails. A headrest and high backrest raise the centre of gravity and affect rearward stability. A tray affects forward centre of gravity and overall weight. Lateral supports affect width, weight and contact pressure. Anti-tip wheels improve stability while reducing obstacle negotiation. An extended battery affects weight, centre of gravity and range. An oxygen cylinder holder affects weight, centre of gravity and offset loading. A crutch holder affects weight and width. And a seating system affects centre of gravity, weight and dimensions. The thicker cushion is the most underestimated: it raises the user's position and with it the centre of gravity, while lowering the relative height of armrests and rails and weakening protection against falling.
When re-verification is needed. Stability is affected by almost any option changing weight or centre of gravity and is the item most needing re-verification. Strength requires verifying the mounting point and surrounding structure, which now carry new loads. Dimensional parameters may change in overall width, length and folded size, affecting access. Weight changes, affecting handling and transport. Range on powered chairs falls with added weight. Braking on powered chairs is affected by added weight. And electrical safety applies where powered options such as powered backrests or leg rests are fitted. Mounting point strength is easily overlooked: the option itself may be robust while the point at which it attaches to the frame was never designed to carry that load.
Handling combinations. Options combine, and the number of combinations can be very large. Testing every combination is impractical: ten options produce an astronomical number. Test the least favourable combination, identified for each item. Analyse item by item, establishing the direction in which each option affects each test item and inferring the least favourable combination. Restrict combinations, stating in the documentation which are not permitted. And verify key items separately for options with large effects. Identifying the least favourable combination requires analysis: for stability it is every option that raises and moves the centre of gravity fitted together, while for strength it may be a different set.
The analytical method. List each option's effects on weight, direction of centre of gravity movement, dimensions and loading. Aggregate by test item, establishing which options affect each unfavourably. Analyse superposition, determining whether unfavourable effects add. Determine the least favourable combination from the superposition. Verify that combination. And argue that the remainder are covered, explaining why no other combination is worse. Performed once, this analysis covers the whole option range, and adding an option later requires analysing only its own contribution.
Prohibited combinations. Certain combinations cause problems and should be explicitly prohibited in the documentation. Combinations exceeding stability limits, where several options raise the centre of gravity together. Combinations exceeding weight limits, taking the whole product above its design maximum. Functionally conflicting combinations, where two options occupy the same position or interfere. Combinations exceeding mounting point capacity, where several options attach at one point. And combinations affecting other functions, such as an option preventing folding. List prohibited combinations explicitly rather than issuing a general caution about compatibility: users and dealers need a definite list.
What the documentation should state. An options list with specifications. Compatibility statements showing which options may be used together. Changes in performance parameters, stating which parameters change and by how much when an option is fitted. Use limitations under certain combinations. Installation instructions covering method and torque. And check points after installation. Give specific figures for parameter changes: stating how much an extended battery adds to weight, how much it adds to range and how much it reduces the rearward stability angle gives users and prescribers practical information.
How we handle it. For wheelchairs with options we ask for the options list and compatibility statement first and analyse the least favourable combination for each item, rather than testing the base configuration alone. Stability is the item we suggest re-verifying as a priority, since almost every option affects it and base configuration data may no longer apply once options are fitted. For products with powered options we bring those components into the electrical safety and electromagnetic compatibility scope.
Send us the options list and compatibility statement and we will work through the test combinations. Phone or WeChat: +86 132 4819 8029.