On the radar: How Battle of Britain technology is appearing on 2021’s motorcycles

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Acronyms have long been a familiar way for bike firms to crow about tech but long before terms like SRAD or DCT became familiar on two wheels the term RADAR – RAdio Direction And Ranging – had been coined.

Dating back to the 1930s and famously used by the RAF to fend off the Luftwaffe, radar’s use has spread from the military to civilian world and now is finding its way into vast numbers of cars and, from 2021, motorcycles.

Why? To let bikes fitted with the systems build a real-time picture of their surroundings, monitoring other vehicles in the vicinity and enabling technologies including Adaptive Cruise Control (ACC) and blind-spot monitoring.

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The radar sensors are made up of two main components: a transmitter and a receiver. The transmitter emits high-frequency radio wave 'chirps' in the 77GHz spectrum along a focused, fan shaped pattern.

These waves bounce off anything they hit inside that area, reflecting back to the receiver. By measuring those reflections – their width, the direction they came from and the time it took for them to return – the radar 'sees' objects, including registering how fast they’re moving and in what direction.

The Bosch-developed radar sensors that are first to appear on in motorcycles – with Ducati’s Multistrada V4 and BMW’s R1250RT having the system as an option in 2021 – can 'see' around 120 metres in front of the bike with a field of view of about 60 degrees. The Ducati also gets a rear radar with a shorter range to monitor vehicles approaching from behind.

The radar sensors themselves are just part of the system, though. The picture they build is useless without the ability to interpret it, and that requires all the information that’s become available to motorcycle computer systems in recent years thanks to inertial measurement units, so the bike knows how fast it’s going, its lean angle and rate of acceleration – allowing it to compare those with the objects the radar senses to tell how they’re moving in relation to the bike.

The systems only work with a specific speed range – between 30kmh and 160kmh. Because they are set not to turn on at lower speeds, they can be programmed to ignore stationary objects such as lamp posts or parked cars that might otherwise interrupt or confuse the system.

Close cooperation between the radars, IMU, ABS system and electronic throttles means that when the ACC is engaged a bike fitted with the system can maintain a constant distance – selected by the rider – from the vehicle ahead, accelerating and braking (gently) to keep pace with it and return to the preselected cruising speed when the road ahead is clear.

Because so much of the kit needed for ACC is already in many modern bikes, the system isn’t a vast additional expense. BMW’s front-only radar is a £500 add-on for the R1250RT, while Ducati’s front-and-rear system adds around £700 although it can only be had with £1250-worth of other kit at the moment, making it a £1950 option.

Rear radar will also feature on motorcycles

Radar technology explored:

  • Display and controls Buttons on the left-hand bar controls let you activate the ACC system and select the distance you want to keep from vehicles ahead, shown on the dash.
  • Rear radar Bosch’s rear radar is smaller than the front one, with less range, and monitors blind spots. Unlike ultrasonic blind spot monitors (as on BMW’s C650 scooter), the radar monitors the speed differential from vehicles approaching from behind. It activates with the indicators, illuminating warning lights in the appropriate mirror if there’s a vehicle in the blind spot.
  • ACC computer Bosch’s system merges this with the ABS computer, which is already connected to the IMU, speed sensors and the electronic throttle.
  • IMU Needed so fan-shaped radar signal doesn’t pick up the road surface when you turn into a corner. The radar range is also reduced when you lean over, so the system is programmed not to accelerate if the vehicle in front drops out of its field during a corner.
  • Front radar Emits a fan-shaped signal of high-frequency radio waves and senses their reflections. Multiple measurements every second mean that interference, for instance from other bikes or cars with similar radars, can be filtered out.


Keep your distance: BMW to launch radar-guided cruise control

First published on October 16, 2020 by Ben Clarke

BMW will put radar cruise control on bikes in 2021

BMW have joined the list of manufacturers working to release a radar-guided cruise control function for motorcycles. Following Ducati’s announcement that they will be first to market and spyshots showing a similar system used by KTM and BMW themselves, the Bavarian brand have released details of how their system will work.

The Active Cruise Control (ACC) system has been developed with Bosch and will allow the rider to set not only a cruising speed but also a distance from the vehicle ahead, which is detected using a radar sensor at the front of the bike.

The radar unit uses this information, plus yaw rate and current vehicle speed to calculate the likely path the motorcycle will take in the next 100m and then, if necessary, modulate speed.

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A required adjustment is sent via the bike’s CAN bus to the ABS, which can add revs to the engine or apply the brakes depending on what is needed.

Both the distance to the car in front and maximum vehicle speed can be set in three stages at the touch of a button and will be displayed on the dash. ACC features two riding modes, comfortable or dynamic, which alter how aggressively the bike accelerates and decelerates.

Radar technology will feature on bikes in 2021

The system also incorporates ‘curve speed control’, which manages your speed in a turn to maintain a ‘comfortable lean angle’. As you lean further, the bike limits its interventions to avoid unsettling the rider.

This feature will also prevent unexpected acceleration while you are leaning in a bend if, for example, the radar loses sight of the vehicle ahead (BMW say the radar’s capability is limited while you’re cornering).

The system doesn’t respond to stationary vehicles, either, so if you are approaching the back of a queue of traffic you have to do your own braking.

Expect BMW R1250RT models to feature the tech in 2021

If the system is unable to operate, a symbol on the dash will let you know that you are in full control of your bike. There is also a second warning to let you know you are in a situation where emergency braking may be necessary because the braking capabilities of the system are limited for safety reasons.

BMW say that the rider will take an active role in the effectiveness of ACC by riding in the centre of their lane, making lane changes and overtakes clear (the system reacts to the use of indicators) and adopting a calm riding style.

BMW haven't confirmed when the system will arrive, how much it will cost or which models will receive this technology but mock-up images from BMW feature their touring K1600GT model.

Watch our video review of the existing BMW R1250RT below:

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Ben Purvis

By Ben Purvis