Why radar‑based safety sensors matter
In modern industrial automation, where machines and robots operate in increasingly dynamic and confined environments, reliable detection of person presence or access is crucial. Traditional safety measures, such as light curtains, safety mats or physical guards, may fail under certain conditions: light curtains need a clear, uninterrupted line‑of‑sight; safety mats restrict only floor‑level access; physical guards limit flexibility, require mechanical modifications, or can hamper productivity.
Radar-based safety sensors overcome many of these limitations. The radar sensors emit continuous electromagnetic waves and measure reflections to detect objects or persons within a defined volume. In particular, the type of radar used by Inxpect is Frequency‑Modulated Continuous Wave (FMCW) radar at 60 GHz. This FMCW radar emits low‑power waves with continuously changing frequency, enabling the sensor to measure very small distances and detect multiple objects simultaneously.
Because radar penetrates dust, smoke, dirt, and is insensitive to ambient light or visual obstructions, radar-based sensors remain reliable even in demanding industrial environments e.g., dusty, smoky, or poorly lit machine halls.
From a safety perspective, radar‑based sensors facilitate “presence detection” and “access control” functions, helping to prevent accidental machine restarts or unauthorized access to hazardous zones, thereby reducing risk to personnel while allowing flexible machine operation.
S202A-MV the presence sensing safety radar
The S202A-MV uses 60 GHz FMCW radar to generate a three-dimensional sensing field capable of detecting human presence, even when the target remains nearly motionless. Unlike optical or infrared systems, the MV variant measures frequency shifts in the reflected radar signal. These shifts allow the sensor to identify micro-movements such as chest expansion during breathing, enabling highly reliable occupancy detection.
The radar module continuously evaluates the return signal for amplitude, phase and frequency variations, ensuring precise discrimination between a static object and a person present inside a hazardous zone. This is a key requirement for maintenance tasks, cleaning procedures or diagnostics inside machines where movement may be limited.
Detection Volume
The MV sensor can supervise a fully configurable volumetric zone up to approximately 48 m³. Engineers define the zone based on three values height, width, and length. This allows adaptation to virtually any geometry, from narrow robot cells to deep processing cabinets or complex machinery layouts. The volumetric approach avoids “dead zones” that occur with 2D sensing devices.
Safety Function
The MV model is designed for ‘Presence Sensing Device – PS(D)’ functionality. It prevents hazardous motion as long as an individual remains within the cell. Even if the operator is seated, kneeling, or performing stationary inspection work, the FMCW radar reliably maintains the stop command. This makes the MV variant highly suitable for:
- Robot cells with manual intervention steps
- CNC or machining islands where operators enter the enclosure
- Packaging lines requiring manual clearing or adjustments
- Systems where residual risks from blind spots must be mitigated
- Environmental Robustness
Because radar operation is uninfluenced by: coolant mist, welding fumes, sawdust or metal dust, high-intensity lighting, and shadows or reflections. The MV maintains detection reliability where optical systems typically fail. For HSE-managers, this provides predictable risk reduction regardless of environmental disturbances.
S202A-MS the access protection radar
The S202A-MS provides 2D area safeguarding, functioning as a virtual safety barrier that detects entry into a defined protection field. While it also uses 60 GHz FMCW radar, the MS version is optimised for boundary penetration detection rather than static human presence. It constantly monitors specific zones and triggers a safe stop when an operator crosses the boundary. Whereas the MV model measures a large volume, the MS model supervises a more directional surface area, similar to an optical light curtain but without requiring a visible beam.
Detection Field Configuration
The safeguarded zone requires configuration of two parameters: height (typical mounting 100–250 cm from ground level) and length (up to 4 m of horizontal coverage).This enables deployment of “virtual walls” in front of robot cells, along conveyor stations, or in areas where installing a physical guard would reduce operability or accessibility.
Safety Function
The MS variant executes “Safeguarding Device – S(D)” functionality. When an operator enters the defined zone, it either prevents the machine from starting, or triggers an immediate safe stop depending on the safety architecture. Typical applications include:
- Areas where operators need frequent but controlled access
- AGV/AMR pathways requiring safeguarded pedestrian boundaries
- Zones where light curtains fail due to contamination or reflections
- Retrofitting older machinery lacking space for physical barriers
- Environmental and Operational Reliability
The MS radar sensor is immune to common sources of false triggering such as dust clouds, smoke, steam, sparks, water spray or fluctuating lighting. This stability often results in: fewer nuisance stops, reduced maintenance, and consistent compliance with performance level and SIL requirements. For buyers and maintenance engineers, this translates to lower operational costs, longer uptime and reduced troubleshooting overhead.
Radar‑based safety sensors such as those in the Inxpect Plug & Safe Line address many limitations of traditional safety systems. Their FMCW‑radar technology ensures reliable detection even in dusty or visually challenging environments. For engineers, purchasers and HSE‑managers, the Plug & Safe Line represents a technically sound and pragmatic safety choice.
