Understanding Proximity Detection Technology for Pedestrian Detection in Warehouses
Warehouse operations present a variety of potential hazards. Despite increased awareness of these safety hazards, sadly, the fatality rate in warehouses remains higher than the average for all other industries in the U.S.
The most common accidents involve forklifts or lift trucks. About 100 employees die every year in forklift accidents and another 95,000 injuries are reported. Forklift accidents include those that have overturned or when workers have fallen off of lifts, but more than a third of these accidents involve interactions between a forklift and pedestrians.
The National Institute for Occupational Safety and Health (NIOSH) recommends physical barriers where possible, signage in facilities, audible alarms, flashing lights, and regular worker training to help improve safety in warehouses. NIOSH also recognizes the value of proximity detection technology to help reduce pedestrian accidents.
What Is Proximity Detection?
Proximity detection uses sensors to detect personnel, vehicles, and other objects that come near machines. Rather than relying on employees seeing a potential hazard, sensors on machinery and workers can detect potential collisions and provide alerts for operators and nearby personnel.
The Smart Proximity Detection System (SPDS) from Laserglow TechnologiesTM uses Ultra Wide Band (UWB) radio frequency (RF) to precisely measure distances between forklifts or other machinery and pedestrians and alert both operators and pedestrians to potential danger and hazard zones.
Workers can wear tags that provide audible and vibration alarms when they are near machines to enhance awareness. Warehouse operators can designate Danger and Hazard zones around moving vehicles which provides alerts to both parties using two-way communication between the sensors.
The Vehicle Tag creates a 360-degree detection zone that constantly monitors anything entering these zones. Zones can be configured to trigger different reactions ranging from audible, visual, or vibrations alarms to forcing vehicles to slow down or stop until obstacles are cleared.
Additional sensors can also be installed at fixed locations throughout the warehouse that are more likely to be the site of accidents, such as intersections, blind spots, crossing areas, loading docks, or high-traffic aisles. Sensors can also be used to control access to areas.
How Does Ultra Wide Band RF Work?
Ultra Wide Band technology isnâ€™t new. In the early 2000s, it was used in military radar, remote medical monitoring, and medical imaging. More recently, Apple included UWB in its iPhone 11 so that nearby users can transfer files or photos by pointing their phones at each other when theyâ€™re nearby.
Similar to Wi-Fi or Bluetooth, UWB is a short-range, wireless communication system.
UWB transmitters send billions of pulses across a wide spectrum frequency. A receiver translates these pulses into data. Since pulses are sent and received within a few nanoseconds, UWB provides real-time accuracy. Used for indoor positioning, UWB is incredibly precise. UWB can measure distances within a few centimeters while Wi-Fi, Bluetooth, and other narrowband radio systems measure proximity in feet or yards.
UWB is extremely low power but operates at a high bandwidth. This high bandwidth is an ideal way to send significant amounts of data back and forth to nearby receivers. UWB can range about 30 feet â€” more than enough to provide advance warning of potential warehouse collisions.
All of this makes UWB a perfect solution for close-range proximity detection to identify potential hazards that could lead to pedestrian accidents in warehouses.
Laserglowâ€™s SPDS can track multiple vehicles and pedestrians simultaneously with precision. When pedestrians wear active UWB tags and enter a Warning or Danger zone near a vehicle, the driver receives a Watch Out or Danger message that repeats while the pedestrian also gets a vibration or audible alarm.
When an alarm occurs, the vehicle driver must either wait for the pedestrian to clear the zone or take action to acknowledge the alarm and mute it.
Other Types of Proximity Detection
There are also other types of proximity detection available. Each has its own benefits and weaknesses.
Ultrasonic Proximity Sensor
Ultrasonic sensors use sound pulses to detect objects. Using both a transmitter and receiver, ultrasonic proximity sensors use echolocation. The transmitter chirps and then measures the time it takes for the sound to strike an object, reflect the sound, and return to the source. With additional processing, an ultrasonic sensor can not only detect other objects, but also assess distances between objects.
This technology is very accurate and can even be used in dark or poorly lit areas. Ambient noise, however, can limit effectiveness. Air temperature fluctuations can also impact accuracy.
Photoelectric Proximity Sensors
If your garage door has an electric eye that detects movement and stops doors from moving when an object crosses its path, it does so using a photoelectric sensor. Photoelectric sensors use a beam of light that travels between the light source and a detector.
With few moving parts, photoelectric sensors tend to last a long time and can have very fast response times. They are not made to calculate distances between objects and require alignment and tuning to maintain a line of sight.
Radio Frequency Identification (RFID)
RFID uses radio waves to atomically identify objects. Readers and tags both use predefined radio frequencies to exchange data. Active readers typically have a transmitter and power source while passive tags do not have power. Instead, electromagnetic waves from the reader induce a current in the passive tagâ€™s antenna so it can be read.
RFID is used most commonly to identify large system objects.
A motion sensor uses image-based technology. When it detects movement, it can trigger an action or alert. Image-based positioning technologies use cameras and software to compare video images to static images to approximate positioning.
Line of sight is required for image-based tech. Range and coverage are limited.
High-accuracy positioning, passes through walls and equipment, less susceptible to interference than other options
May be slightly higher initial costs than other options
Best for detection of large objects with hard surfaces
Very sensitive to temperature fluctuations and can have difficulty reading non-flat surfaces or small-sized objects
Fast response times and long-range capability
Requires line-of-site, sensitive to lens contamination (dust, dirt, debris)
No line-of-sight required, can penetrate solid objects
Positioning coverage is small and lacks communications capabilities
Can be less expensive than some other options
Requires line-of-sight, coverage is limited, does not provide precise positioning
Most Accidents Are Preventable
Despite safety training, investigations into worker deaths caused by forklifts and warehouse machinery show that employees often remain unaware of the potential risk of working on or in areas where forklifts operate. Often, OSHA guidelines and standards are not followed. In fact, NIOSH reports that nearly every death they investigated could have been prevented by using proper safety procedures and equipment following OSHA guidelines.
This tells us safety training simply isnâ€™t enough. No training will be effective if employees donâ€™t actively practice safety protocols. Itâ€™s just another reason why proximity detection is an important technology to create safer warehouses. Rather than relying on workers remembering to enact best practices, proximity detection provides another layer of protection to help avoid accidents.
Pedestrian accidents in warehouses can occur because of a variety of common situations, such as:
â€¢Pedestrians did not see the forklift or lift truck until it was too late.
â€¢Pedestrians did not hear the forklift above ambient noise.
â€¢Pedestrians underestimate the dangerous area around forklifts.
â€¢Pedestrians were caught off guard by sudden starts or turns.
Signs, painted lines, and active traffic management can help. So can cameras, monitors, and intersection mirrors, as well as regular safety training. However, safety training can too easily be ignored and static safety measures can quickly blend into the background.
SPDS is OEM-independent, so it is ideal for mixed fleets. The system works on robots, cobots (collaborative robots), and AGVs (automated guided vehicles), as well as forklifts and other industrial vehicles. It can be installed on new vehicles or easily retrofitted onto your existing fleet.
Contact Laserglow today to explore the benefits of the Smart Proximity Detection System and enhance your warehouse safety.