SafeStop - Wireless Emergency Stop System for Unmanned Vehicles

SafeStop – Wireless Emergency Stop System for Unmanned Vehicles

Safety is an extremely important aspect to fielding and testing unmanned systems, which is why every unmanned vehicle should be equipped with an independent, fail-safe emergency stop system. For the protection of humans and equipment in the operating area, as well as your invested time, money and resources, it is imperative that unmanned systems are capable of being disabled at any time and in the event of onboard failures.

The SafeStop™ is a thoroughly tested, industry proven wireless fail safe emergency stop system that easily integrates with your unmanned vehicle platform. The SafeStop provides the ability to remotely pause or disable unmanned ground and surface vehicles from a safe location.

Quickly becoming the industry’s leading off-the-shelf emergency stop system, the SafeStop features:

  • Multi-Level Control Provides Pause and Stop Functionality
  • Independent Encrypted Communication over 900 MHZ Spread Spectrum Radio
  • Convenient Handheld Design is Lightweight and Portable
  • Units Provide Visual and Audible Operator Feedback
  • Long Range Operation & Extended Battery Life
  • 32 Channels Allows Multiple Systems to Operate Concurrently

System Overview

safestop wireless estop

The transmitter is a conveniently designed handheld unit that controls independent pause or stop contacts on the SafeStop receiver. Featuring audio and visual feedback, a rechargeable battery pack with up to 30 hours of untethered use, and a line-of-sight operation of up to 6 miles, the SafeStop transmitter’s simplified controls are easy to operate in the field while testing or operating unmanned vehicles.

The receiver unit is mounted on the unmanned vehicle and translates the emergency stop information sent by the transmitter to the vehicle’s failsafe mechanisms via two high current contacts. The unit also includes a wired serial port for communicating to the onboard computing, such as the ByWire.

In addition to the transmitter and receiver units detailed above, the SafeStop kit includes:

SafeStop Transmitter Unit (ES-220T)

  • ES-220T-RDA: Flexible Antenna
  • ES-220T-ACC: 100 – 240 VAC Charger
  • ES-220T-DCC: 12 VDC Automotive Charger

SafeStop Receiver Unit (ES-220R)

  • ES-220R-MMA: Magnetic Mount Antenna
  • ES-220R-PSC: Power / Serial Cable
  • ES-220R-PRC: Pause / Stop Relay Cable

Multi-Level Control

The SafeStop is a multi-level emergency stop system, meaning the pause and stop switches on the handheld transmitter control independent remote contacts.

A common implementation for the multi-level control can be used for:

  • An easy to integrate serial software pause that will allow for a graceful computer controlled stop of the vehicle.
  • A failsafe estop contact to disable the vehicle by applying 100% brake, and shutting down power to the vehicles engine.

This multi-level control is very helpful because a complete system shutdown is not needed in all situations, which can be extremely inconvenient when controlling the system remotely and having to manually reset or restart your computer systems. The pause feature allows you to bring your unmanned system to a controlled stop where you can simply flip the switch to resume operation without further intervention.

Independent Operation

The SafeStop transmitter links to the receiver over 900 MHZ spread spectrum radios, providing superior range, reliability, and resistance to interference. The SafeStop link is completely independent from your system’s other communications and computer equipment. Keeping this link independent from other system failures is critical to providing fail-safe, emergency shutdown functionality.

In the event of a lost link between the transmitter and receiver, the unmanned vehicle can be configured to automatically disable and come to a complete stop.

Convenient Handheld Design

The design of the SafeStop takes into account features that provide for a better user experience. The lightweight wireless transmitter can easily be held in one hand during use and slipped into a cargo pocket while between uses. Both the transmitter and receiver units are approximately 4”x4”x2”. This lightweight, handheld design makes the unit easily portable – no need to carry around large battery packs or other bulky accessories.

Visual and Audible Operator Feedback

Indicator lights on both the transmitter and receiver units display the state of the SafeStop, so the remote operator can always feel safe knowing which mode the system is in. An audible alarm on the transmitter will sound continuously if the link is lost or periodically if the battery needs to be recharged. TORC recommends additional safety measures be added to unmanned vehicles, such as the addition of external lights and audible sirens to clearly indicate when an unmanned vehicle is operating under computer or autonomous control.

Long Range & Extended Battery Life

The SafeStop has an operating range of up to 6 miles line-of-sight, with the transmitter’s rechargeable battery providing up to 30 hours of untethered use. Whether you are in need of a safety system for long days of testing or fielded missions, the SafeStop’s operating range and battery life provide an ideal combination for nearly all situations.

 

 

Specifications

Performance

Operating Distance 6 mi. (line-of-sight)*
Update Rate 25 Hz

Wireless Link

Frequency Band 902 - 928 MHz
Transmit Power 1W
Modulation FHSS FSK
Channels 32
Encryption 56-bit DES Key
FCC Approved Yes

Electrical

ES-220T Battery Life 30 hours*
ES-220R Input Voltage 9-30 VDC
ES-220R Max Power Consumption 9 Watts

Vehicle Interface / Contact Ratings

Digital Communications RS-232
Data Rate 9,600 baud
Run/Stop Contact Rating 24VDC, 5A
Run/Pause Contact Rating 24VDC, 5A

Audible Alarm

Link Lost Continuous Tone
Low Battery Three Beeps

Visual Indicators

Power Bicolor LED
Link Status
Bicolor LED
Pause Relay Bicolor LED
Stop Relay Bicolor LED
Charging (ES-220T) Bicolor LED

Environmental

Dust / Water Resistance IP50
Operating Temperature 0°C to +70°C
Operational Shock Rating 10g

Product Contents / Optional Accessories

ES-220T Transmitter Unit

ES-220T-RDA Flexible Antenna
ES-220T-ACC 100 - 240 VAC Charger
ES-220T-DCC 12 VDC Automotive Charger

ES-220R Receiver Unit

ES-220R-MMA Magnetic Mount Antenna
ES-220R-PSC Power / Serial Cable
ES-220R-PSC Pause / Stop Relay Cable

*Range and performance data based on optimal conditions.

Frequently Asked Questions

Will other 900Mhz devices affect the operation of the SafeStop?

The SafeStop systems use Frequency Hopping Spread Spectrum (FHSS) technology. FHSS transmissions switch frequencies in a psuedo random sequence over a wide frequency band. By spreading communications over a large bandwidth, interference from other devices in the same band is minimized.

Can multiple SafeStop units operate simultaniously in the same area?

TORC's SafeStop systems communicate on one of 32 different channels. Each channel implements a unique channel hopping sequence within the same frequency band. Multiple SafeStop systems can operate simultaneously in the same area when configured with distinct channels. If a particular channel is required, please specify this when ordering.

How do I know when the battery needs to be recharged?

The SafeStop transmitter uses lithium-ion battery technology, so it may be charged at any time without the "memory effect" common to other types of batteries. The transmitter will indicate a low battery condition by changing the power LED from green to red and sounding the audible alarm three times every 10 seconds. At this point the transmitter should be connected to external power to recharge the battery.

What action does the SafeStop take when the transmitter loses communications with the receiver, and can this action be changed by the user?

The SafeStop systems are, by default, configured to both pause and disable a vehicle in the event of a communication loss between the transmitter and receiver. The behavior of the latest SafeStop model, the ES-220, can be easily configured by the user via external input. For previous models, see Application Note "AN-001, Changing the Loss-of-Link Behavior of the SafeStop" on the Support page.