结论：站立过程是重心持续升高的过程，稳定裕度在过程中变化
站立架（站立床、站立轮椅的站立功能）让使用者从坐姿或卧姿转为站姿。这个过程中，使用者的重心持续升高，整机的重心也随之升高，稳定裕度相应变化。
同时，使用者在站立位无法自主维持平衡（否则也不需要这个设备），全靠约束部件和支撑结构保持姿态。约束失效意味着使用者从站立高度跌落。
所以这类产品的两个核心安全项是：整个体位变化过程中的稳定性，以及约束部件的可靠性。
受力的变化
重心高度变化。 从坐姿到站姿，使用者重心升高相当可观，整机的抗倾翻能力下降。
支撑点转移。 坐姿时体重主要由座面承担，站立位主要由足板和膝托承担，中间过程是渐变的。
约束受力增加。 站立位时，胸带、膝托、足部固定承担的力比坐姿大得多。
动态因素。 使用者的痉挛、身体晃动会产生额外的侧向力。
外部因素。 站立位时使用者可能够取物品、前倾、转身，产生偏心载荷。
最后一项容易被忽略，但它正是站立架的使用目的之一 ——让使用者能够进行站立位的活动。所以评价时应当包含使用者在站立位活动的工况。
稳定性评价
| 评价状态 | 要点 |
|---|---|
| 坐姿位 | 起始状态 |
| 转换过程中各角度 | 按间隔扫描，找裕度最小点 |
| 完全站立位 | 重心较高的状态 |
| 站立位加前倾载荷 | 模拟使用者前倾取物 |
| 站立位加侧向载荷 | 模拟侧身或痉挛 |
| 斜面上 | 四个方向 |
「按间隔扫描」与移位机的情况类似 ——只测起点和终点会漏掉中间的不利位置。建议按角度间隔逐点评价。
前倾和侧向载荷的工况必须包含。 因为站立架的使用者在站立位会做活动，这是设备的功能之一，不是误用。
约束部件的验证
约束部件包括胸带、髋带、膝托、足部固定等。验证内容：
强度。 按使用者体重的相应分量加上动态系数确定载荷。
连接强度。 约束带与机架的连接处，与前面讲的织带类似，多数失效在连接处。
调节机构的保持。 调节后在载荷和振动下不应滑移。滑移会导致约束逐渐松脱。
快速解除。 紧急情况下应当能快速解除约束，而日常使用中不应误解除。
接触面的压力。 约束部件承受较大的力，接触面的压力分布关系到舒适和皮肤安全。胸带、膝托的接触面应当有足够的面积和适当的衬垫。
老化后复测。 清洗和使用会降低织物强度。
「调节机构的保持」这一项在实际中问题较多。 调节扣在反复受力后逐渐滑移，约束慢慢变松，而这个过程是渐进的，照护人员不容易察觉。建议做加载下的滑移试验。
驱动与控制
电动站立架还要考察：
速度。 体位变化的速度应当适中。过快会让使用者不适甚至引起血压变化。
平滑性。 启动和停止应当平滑，避免冲击。
中途停止。 应当能在任意角度停止并保持。
断电保护。 停电时应当保持当前位置，不应失控下降。同时要有应急下降方式。
操作防误触。 控制器应当防止意外触发。
限位可靠性。 上下限位应当可靠，超行程可能造成机构损坏或使用者受伤。
「速度」这一项与使用者的生理反应相关。 长期卧床或坐位的人突然站立可能出现体位性低血压，所以缓慢升起是有医学理由的，不只是舒适问题。
使用场景中的风险
使用者状态变化。 站立过程中出现头晕、不适，需要能快速降下。
约束调节不当。 过松导致下滑，过紧导致压迫。说明书应当给出判断方法。
单人操作。 说明书要求两人时实际只有一人。
地面条件。 不平地面或地毯影响稳定性。
使用时长。 站立时间过长可能造成不适或压力性损伤，应当给出建议时长。
足部受力。 站立位时足部承受体重，足板的面积、角度、衬垫都影响足部安全。
与使用目的的关系
站立架的使用目的包括改善循环、维持骨密度、预防挛缩、改善消化功能等。这些目的对产品性能有具体要求：
站立角度的可调性。 渐进式训练需要角度可调，从小角度逐步增加。
角度的准确性与可重复性。 训练需要记录角度，角度指示应当准确。
站立时长的支持。 需要能维持较长时间，这对约束的舒适性提出要求。
足部承重的调节。 部分使用者需要控制足部承重的比例。
这些功能性要求与安全要求同样需要验证，因为它们关系到设备能否实现预期用途。
尺寸适配
站立架需要与使用者身体尺寸匹配，不匹配会带来安全和效果两方面的问题：
膝托位置。 位置不当会压迫膝关节或者无法有效支撑。
胸带高度。 过高影响呼吸，过低支撑不足。
足板位置。 决定足部承重和姿态。
整体高度范围。 适用的身高范围要明确。
调节范围的验证。 各调节部位的行程和锁定可靠性。
建议在资料中明确适用的身高体重范围，并说明各调节部位的设定方法。设定不当的站立架既不安全也达不到训练效果。
我们的做法
做站立架测试时，我们会按角度间隔扫描整个体位变化过程的稳定性，并把前倾和侧向载荷作为独立的评价工况 ——因为站立位活动是这类设备的使用目的，不能按静止站立评价。
约束部件方面，我们建议做加载下的调节机构滑移试验和老化后的强度复测。这两项对应的是实际使用中渐进发生的失效，新品静态数据反映不出来。
如果你有站立类设备需要安排验证，想先理清评价工况，可以把产品资料和使用方式发过来一起讨论，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，标准信息见标准查询。
English version
Conclusion. Standing frames, standing beds and the standing function of standing wheelchairs move a user from sitting or lying to standing. Through that movement the user's centre of gravity rises considerably, the machine's centre of gravity rises with it, and the stability margin changes accordingly. At the same time the user cannot maintain balance independently, or the equipment would not be needed, and posture is held entirely by restraints and supporting structure. Restraint failure means falling from standing height. The two core safety items are therefore stability throughout the postural change and reliability of the restraints.
How loading changes. Centre of gravity height changes substantially between sitting and standing, reducing resistance to overturning. Support points shift, from the seat carrying most of the weight when seated to the footplate and knee supports carrying it when standing, with a gradual transition between. Restraint loading increases, with chest strap, knee supports and foot fixings carrying far more when standing. Dynamic factors arise from spasm and body sway generating lateral force. And external factors arise as a standing user reaches for objects, leans forward or turns, producing eccentric load. The last is easily overlooked yet is one of the purposes of a standing frame, namely enabling activity in standing, so assessment should include those conditions.
Assessing stability. Assess the seated starting position. Scan intermediate angles through the transition to find the smallest margin. Assess the fully standing position with its higher centre of gravity. Assess standing with a forward load simulating reaching. Assess standing with a lateral load simulating turning or spasm. And assess on a slope in four directions. Scanning at intervals matters here as with hoists: testing only the start and end points can miss an unfavourable intermediate position. Forward and lateral loading conditions must be included, because activity while standing is a function of the equipment rather than misuse.
Verifying restraints. Restraints include chest and hip straps, knee supports and foot fixings. Strength is verified against the relevant share of user weight with a dynamic factor. Connection strength at the attachment to the frame behaves as with webbing generally, with most failures at connections. Adjuster retention must prevent slipping under load and vibration, since slipping progressively loosens the restraint. Quick release must allow rapid release in an emergency without releasing inadvertently in normal use. Contact pressure matters, since restraints carry substantial force and the distribution over the contact area affects comfort and skin safety, so chest straps and knee supports need adequate area and appropriate padding. And strength should be re-measured after ageing, since laundering and use reduce textile strength. Adjuster retention causes particular trouble in practice: buckles creep under repeated loading, the restraint gradually slackens, and because the process is progressive carers do not readily notice. Test for slippage under load.
Drive and control. Powered standing frames need further assessment. Speed of postural change should be moderate, since moving too quickly causes discomfort and can affect blood pressure. Motion should be smooth, starting and stopping without shock. Stopping mid-travel should be possible at any angle, holding position. Power failure protection should hold position rather than allowing uncontrolled descent, with an emergency lowering provision. Control should resist inadvertent operation. And travel limits should be reliable, since overtravel can damage the mechanism or injure the user. Speed relates to physiology: a person long confined to bed or chair may experience postural hypotension on sudden standing, so raising slowly has a medical rationale beyond comfort.
Risks in use. The user's condition may change, with dizziness or discomfort during standing requiring rapid lowering. Restraints may be adjusted poorly, too loose allowing the user to slide and too tight causing compression, so the instructions should explain how to judge. Single-person operation may occur where two are required. Floor conditions including unevenness and carpet affect stability. Standing duration that is too long can cause discomfort or pressure injury, so recommended durations should be given. And foot loading matters, since the feet carry body weight in standing and footplate area, angle and padding all affect foot safety.
How we handle it. We scan stability at angular intervals across the whole postural change, and treat forward and lateral loading as separate assessment conditions, because activity in standing is what the equipment is for and assessment against static standing alone is inadequate. For restraints we suggest adjuster slippage testing under load and strength re-measurement after ageing, both addressing failures that develop progressively in use and that static new-product data cannot reveal.
Send us the product information and manner of use and we will define the assessment conditions. Phone or WeChat: +86 132 4819 8029.