Displacement and temperature sensors for electric motorbike

During testing in early 2009, the EV-0 RR motorcycle, designed by EVO Design Solutions Ltd, utilised several different non-contact displacement and temperature sensors from Micro-Epsilon to help improve the bike's performance. All sensors and electrics used on the bike were fitted and tested by KA Sensors, a specialist provider of sensors and instrumentation equipment to the motor sports industry.

KA Sensors customised Micro-Epsilon's optoNCDT 1300 non-contact displacement sensor and mounted it to the nose of the bike's chassis, with the laser window pointing towards the ground. From here, the high-speed (500Hz) sensor is able to measure and monitor the ride height of the motorcycle. The sensor acts as an anti-wheelie device and enables the bike's designers to adjust the suspension characteristics and engine power mapping in order to optimise the performance of the bike, while reducing energy consumption.

Ride height

The optoNCDT 1300 laser sensor measures displacement against almost any target surface, including shiny black rubber. It has an integrated digital signal processor and is suitable for a wide range of applications in industrial automation and production environments, including: parts measurement; surface contour measurement; epoxy placement on integrated circuits; weld seam detection on welding robots; automotive vehicle positioning and height; tool positioning; eccentricity; shape conformance; positioning on conveyors; bending and tilt angles; part recognition; thickness; deformation and waviness.

For the EV-0 RR motorcycle, the sensor needed some customisation, as Peter Trevor, Sales Director at KA Sensors, explains: "The bike was tested on private airfield strips in Norfolk, so the conditions were pretty harsh for a standard sensor. There is a lot of vibration, heat and dirt to contend with, so we developed a special protective, anti-vibration mounting for the sensor. We also introduced a tear-off strip for the sensor's laser window to protect it from stone damage; this can be replaced after every test session.

"The performance and speed of the sensor is excellent and it is extremely compact compared to alternative displacement sensors on the market. This is important because the sensors often have to be mounted in restricted spaces on the chassis or mudguards. The sensor is very competitively priced, which is important too," explains Trevor.

On other racing bike projects, KA Sensors has used the optoNCDT 1300 sensor to measure the lean angle of the bike. For this, two identical sensors are positioned in the chassis at 45 degrees to the ground in order to monitor the change in displacement as the bike travels around the track.

Temperature measurement

In addition to the optoNCDT 1300 sensor, KA Sensors also mounted three Micro-Epsilon thermoMETER CS micro non-contact temperature sensors on the rear mudguard. These three sensors measure the temperature profile of the tyre during testing.

The thermoMETER CS micro is a miniature infrared thermometer for OEMs. With rugged silicon-coated optics, the sensor can measure temperatures from -20 up to 350degC, with the special motorsport version able to measure up to 1000degC. The sensor electronics are integrated in the cable, which saves space, with a separate controller and optional USB programming interface and software.

Peter Trevor states: "To KA Sensors, the Cs micro is a phenomenal piece of kit in terms of performance and benefits. Its compactness enables us to mount the sensor into mudguards to measure tyre temperatures. The three sensors measure the centre of the tyre, plus the inside and outside edge, giving us a very clear temperature profile of the tyre as the bike moves around the track.

"This allows us to choose the best tyres and to adjust the suspension system set up of the bike. Basically, the tyres need to be hot and sticky to do their job properly. From a laptop, we can use programming software to adjust all the parameters, such as temperature measurement range and the output voltage. We have even used the same sensors to measure the temperature profile of brake discs on motorcycles. Just as important, the software enables us to change the emissivity of the sensor to suit different target materials, such as steel, carbon or rubber.

"The measuring range of the thermoMETER CS micro is a 10:1 ratio, which means the sensor can be mounted some distance from the target. This meant that KA Sensors could mount the three sensors between 2 and 3cm from the tyre surface, without sacrificing the performance (accuracy and resolution) of the sensor and giving us more room to protect it from the harsh conditions."

KA Sensors did some customising of the CS micro by fitting a sacrificial protection lens over the laser window. In addition, the electronics, which are integrated into the cable, were given extra protection and housed in a robust carbon tube. Trevor adds; "We also need to strain relief the cable against excess vibrations and protect the electronics from the rough handling associated with many bike mechanics."

Thermal imaging

When the bike was on the test bench, KA Sensors also used Micro-Epsilon's thermoIMAGER TIM rugged, inline infrared thermal imaging camera that is not only comparable in terms of technical specification and performance to the latest inline thermal imagers, but costs around 60 per cent less.

The inline radiometric thermal imaging device provides temperature images and profiles of a target area. Included as standard is free software that enables users to both configure all the adjustable parameters of the thermoIMAGER and capture (at 100Hz full frame rate) and store images or an event for playback at a later date - which is important for R&D purposes.

Furthermore, the device has a USB 2.0 interface for real-time thermography with a 100Hz frame rate as standard (most competing cameras offer only 50Hz) and a cable length of up to 20m. Temperature measurement ranges are comparable with other inline thermal imaging cameras.

On the bike, KA Sensors uses the device to monitor hot spots on the bike's cooling system and electrical terminals. The bike has a conventional water-cooled radiator and electric motor that sits in the airflow. Trevor says: "We use the thermal imaging camera to see how warm the radiator is and whether it is dissipating the heat as it should be. If it is not doing its job, we might change the radiator itself or use a fan to increase the airflow through the radiator, or change the routing of the coolant through the radiator pipes.

"We can perform a similar exercise on the bike's electrical terminals. The bike runs on 48 volts and we have a 600-amp capacity to draw from. If we do not select the correct cable sizes and terminals, the bike will lose energy through excess heat. The thermal imaging camera allows us to identify which terminals and cables are too hot and rectify the problem."

Trevor concludes: "We have been working as Micro-Epsilon's UK motorsport partner for three years. We have integrated Micro-Epsilon sensors into numerous applications, including F1, GP2, A1 Grand Prix, World Touring Cars, British Touring Cars, Le Mans cars, GT cars, British and World Superbikes.

"Micro-Epsilon products are top-class in terms of quality and price and this has enabled us to enter new markets that were previously closed to us. Motorsport teams are looking to cut costs where they can but are always looking for innovative ways of measuring things, which is where KA Sensors' strength lies."

Follow the links for more information on Micro-Epsilon's ranges of non-contact displacement sensors and temperature sensors.