Run down any standing-desk quote sheet and you will find the line "anti-collision: yes." It is the least informative "yes" in the category. Behind it sit two genuinely different sensing technologies, a sensitivity setting that changes what the desk will and will not notice, and a stop-and-reverse behaviour that is either tuned or it is not. Since we build height-adjustable desks and field the warranty claims when a desktop meets a windowsill, here is what that one word actually contains.
Method one: watching the motor current
The baseline method costs nothing extra, which is why it is everywhere. The control box continuously watches the current each motor draws. When the desktop hits something, the motors work harder, current spikes past a threshold, and the controller cuts power and reverses. No additional hardware — the sensing is firmware in a control box the desk needed anyway.
The catch is in the physics. Current only rises after the obstacle is already resisting the desk, so force has to build before anything triggers. Against a hard obstacle — a windowsill, a cabinet top — the spike is sharp and detection is quick. Against something compliant, like the padded arm of a chair, the desk compresses it for a noticeable distance before the current climbs enough to trip. The threshold also has to sit above normal operating noise: a frame carrying a heavy desktop, or running stiff in a cold room on day one, draws more current doing nothing wrong, so the threshold is set with margin — and that margin is exactly the force the obstacle absorbs before the stop. Decent firmware compensates by learning the load and watching the rate of change rather than the absolute value, which is part of what separates a good control box from a cheap one with the same motor count — the same lesson as in our note on dual- versus single-motor frames.
Method two: a gyro in the control box
The second method adds a small gyroscope/accelerometer module that senses the desktop itself. A collision — especially an uneven one, where one side of the top catches before the other — tilts and judders the desktop in a way the chip reads immediately, before much force has built. That is the practical difference: current sensing waits for resistance, the gyro feels the disturbance. Glancing hits and one-sided snags, the cases current sensing handles worst, are where the gyro earns its few dollars of added cost.
It has its own blind spot: a perfectly square, slow, soft contact that barely disturbs the desktop can stay under the gyro's radar, which is why better frames run both — gyro for fast asymmetric events, current monitoring as the backstop. On our frames the module lives in the control box, and where it sits matters; a sensor on a flexing corner of a wide top reads vibration that is not a crash, so mounting position is part of the design, not an afterthought.
Sensitivity settings: the trade-off nobody documents
Most controllers expose two or three sensitivity levels. High sensitivity trips on light contact — good around children, glass shelves, pets. Low sensitivity tolerates more resistance before stopping — necessary on desks carrying heavy, slightly flexing tops, where high sensitivity produces phantom stops halfway up and the user, infuriated, turns the feature off entirely. That last part is the real-world failure mode: an anti-collision system tuned so twitchy that users disable it protects nobody. When we configure a contract order we set the shipping default against the actual desktop weight and size on the PO, not the bare-frame value from the firmware image.
The second tunable is reverse travel. On trigger, the desk should not merely stop — stopping leaves the obstacle pinched. It should back off, typically by a couple of centimetres, enough to free a trapped object or hand. Ask for both numbers: trigger setting and reverse distance. A supplier who cannot state them has not tuned them.
What anti-collision cannot do
Honesty section. Every system above is reactive — it acts after contact, never before. There is no proximity sensing on a normal desk; the top must touch the obstacle, with some force, before anything happens. So a sharp edge meeting a soft obstacle still dents it; a slow squeeze against something compliant can progress further than a buyer imagines; and no setting turns a moving desktop into a child-safe surface. We will not print "pinch-proof" on a desk, and we advise our buyers not to either. For households with small children, the controller's lock function — disabling movement entirely — is the honest answer, and it is a feature worth speccing alongside the collision system rather than instead of it.
How it is actually tested
The test is unglamorous: a rigid obstacle — in practice a wood block or a load cell on a stand — is placed under the crossbeam or the desktop edge, the desk is driven down at full speed, and three things are recorded: that the desk stops, how much force it applied before stopping, and how far it reversed. Then the same in reverse, driving up under a fixed shelf. A thorough protocol repeats this at minimum and maximum load, at several heights, and on one corner rather than the centre, because asymmetric contact is the common field case and the hard one for current-only sensing. On the standards side, EN 527-2 sets squeeze- and shear-point requirements for power-operated desks and EN 60335 thinking governs the electrics; our frames are built and tested to those methods and to BIFMA X5.5 durability cycling, and third-party testing of the collision behaviour — with the force trace in the report — can be arranged per order. If you want to see it before you commit, ask for a video of the block test on your configuration; it is twenty minutes of work and we would rather send it than argue about a dented cabinet later.
What to put on the PO
Four lines: sensing method (current-only or current + gyro), default sensitivity matched to your desktop spec, reverse travel in millimetres, and a block-test report or video at your load. That converts "anti-collision: yes" from a checkbox into a behaviour you can hold a factory to. Send your frame spec and desktop sizes through our contact form, or read how we run private-label desk programs on the ODM / OEM page — we will come back with the settings we would actually ship.