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Advanced Testing of the
motoinno TS³prototype
Data Acquisition results and FindingsFebruary 2014
Prepared by: Stephen McDowall
3 Debbie Way Carrara QLD 4211M: 0411 519 994
Table of Contents
Page 1: Introduction 1
2: Background: Hub-Centre Steering and the motoinno TS³ 2
3: Goals and Methods Employed for Testing the motoinno TS³ 4
4: TrackMotion Inertia Data Analysis System 6
5: Analysis of Test Data 8
6: Observations Drawn from Test Data 8
7: Comments from Test Rider 13
8: Conclusion 15
Introduction
The motoinno TS³ triangulated steering and suspension system is an advanced new design that promises a significant advantage in the arena of motorcycle suspension and steering technology.
Previous testing of the TS³ technology has provided very useful feedback to the designer, but a structured and controlled comparison test between the motoinno prototype and a production motorcycle - widely accepted as a well-balanced and superior handling machine - was required to determine if the motoinno prototype had definitely achieved its design goals.
The following test results were gathered from strictly controlled performance conditions in February 2014 and the subsequent report is a summary of the findings of that testing program.
It must be understood that neither the data analyst or test rider claim to be qualified mechanical engineers and that this report is not intended as an engi-neering report on the design, construction, or relative geometric and mechani-cal merits there of.
This report is based on information supplied by the designer, technical informa-tion freely available on all facets of motorcycle steering and suspension, obser-vations of the handling data collected from the two motorcycles during testing and subjective feedback from the test rider.
In that regard the experience and qualifications of the data analyst and test rider are highly relevant and valuable to the data acquired and presented below.
This report also represents a summary of the data and highlights of the findings. More detailed data is available to the designers for future development of the motoinno TS³ project.
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motoinno TS3 prototype on track
Background: Hub-Centre Steering and the motoinno TS³More than 90% of all motorcycles currently use a telescopic fork front end suspension and steering system. Whilst this design is well accepted and understood, it does present a number of problems in the areas of steering, suspension, braking and handling.
Telescopic forks are basically 30 inch (75cm) long unbalanced levers that magnify any front wheel shock and oscillation load three fold and transfer them into the headstock of the mo-torcycle which is forward of and high above the centre of gravity of the bike.
Braking forces in telescopics are put through the suspension stanchions causing the suspen-sion to compress under load. This compression changes the steering geometry, reducing the rake and trail and making the motorcycle more nervous. Under acceleration the forks are extended, rake and trail are increased and the motorcycle’s ability to steer becomes more sluggish.
Under braking this suspension compression also moves the suspension out of its optimal op-erating range and reduces its ability to deal with bumps and other road irregularities. In cases of extreme deceleration such as an emergency stop, telescopic forks will collapse or “bottom out”, rendering the suspension completely incapable of dealing with any further road anoma-lies. This unbalanced lack of further suspension travel can end in catastrophic results for both the motorcycle and rider.
These issues themselves are well understood by designers and engineers and measures have been developed to minimise the effects of each issue. These measures have included larger and heavier forks, more complex damping systems and heavier and stronger headstocks, all adding to the overall weight of the vehicle.
However, the fundamental issues remain, and motorcycle handling is still dictated by the in-herent handling characteristics and limitations of a telescopic fork system.
A compliant motorcycle will have stability in a straight line, during cornering and especially during rapid changes of direction under braking or acceleration loads. In a telescopic fork front end all of these qualities are difficult, if not impossible to achieve at the same time be-cause one characteristic must be sacrificed in order to achieve another.
Over the years many other suspension and steering systems have been proposed and hub-centre steering appears to offer the best alternative to a telescopic fork front end.
Hub-centre steering (HCS) is a type of front end suspension and steering mechanism charac-terised by some form of swing-arm that extends from the bottom of the engine or frame to the steered centre of the front wheel.
Compared to conventional steering and suspension models, hub-centre steering is recog-nised as a fundamentally more stable front end platform.
In theory it offers several advantages over a conventional telescopic fork suspension system in that it allows the steering, braking and suspension functions to be separated and dealt with independently.
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In a hub-centre steering system the braking forces can be redirected horizontally along the suspension arms away from the vertical suspension forces in a quick and direct path to the centre of gravity of the machine. Because suspension and steering geometry are separated from braking, a well designed Hub-centre steer bike will not bottom out under braking, it will still have all of its suspension in place to cope with further road anomalies.
In the past, hub-centre steering designs have overcome several flaws of previous alternate and telescopic systems, yet each of them has created their own set of distinctive problems and challenges.
The relative complexity of a hub-centre steering system can create its own issues. The high number of joints and linkages on most systems can create potential for steering free play which can lead to slack, vague, or even inconsistent steering movement across its range. Some HCS systems have been likened to having power steering at the front end giving little or no feedback to the rider when it is needed the most - entering into and completing a corner.
While reducing steered king pin loads by placing them in the centre of the steering hub, most previous hub-centre systems have introduced oscillation harmonics that are detrimental to the stability of the front end. Many previous designs have also been criticised for having a very heavy feel under cornering and poor lean clearance which can unsettle the bike dramatically.
The configuration of the motoinno TS³ technology addresses and overcomes all the prob-lems associated with telescopic and girder forks, alternate steering systems and hub-centre steering systems of the past, while creating an advanced, tuneable and more compliant front end.
Unique to the TS³, the suspension arms form a parallelogram, together with the patented triangulated steering mechanism it enables the TS³ to maintain constant steering geometry over the full range of suspension travel while carrying many hundreds of times its own weight without corner clearance issues. This in turn leads to consistency in the motorcycle’s handling characteristics under braking, cornering and acceleration to create a safer motorcycle.
The key benefits of the motoinno TS³ are:A triangulated and rigid suspension and steering system that provides a consistent steering geometry throughout the entire suspension travel that removes unpredictable and dangerous flexibility in steering both laterally and horizontally.A high reduction in load transfer and resonant oscillation harmonics from the front end of the motorcycle to the motorcycle’s centre of gravity by the use of advanced geometry and a virtual kingpin that extends from the tyre contact patch to a point above the front wheel.Totally adjustable pro dive/anti dive and rake and trail geometry to accommodate varied road conditions, rider styles and skill levels. Patent applications include this on the fly.Eliminates horizontal or lateral flex under braking and in lean unless designed into the unit.Eliminates corner lean issues experienced by almost all previous hub-centre designs.
The motoinno TS³ aims to capitalise on the theoretical advantages offered by hub-centre steering while eliminating the known disadvantages of both telescopic fork front ends and previous hub-centre steering designs.
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Goals and Methods Employed for Testing the motoinno TS³
In order to properly evaluate the benefits of the motoinno TS³ design, testing was carried out under controlled conditions and in comparison with a production motorcycle recognised and widely accepted as being a well-balanced and superior handling machine.
The production motorcycle selected was a 2005 Suzuki GSX-R 750. It is typical of modern sports motorcycles and this model lacks many of the electronic rider aids that can be found on later model bikes. This eliminated any influence or benefits that might be gained from those aids and since the motoinno prototype also lacks any of these technological aids, the choice of this comparison motorcycle brought the two machines - the Suzuki and the mo-toinno prototype - closer into line than might have been possible with a current model sports bike.
The aim of testing was to provide both an objective and subjective comparison in handling and performance of the prototype compared to the Suzuki. Previous test sessions had pro-vided good feedback from riders and some useful data, but the goal of this series of tests was to capture accurate empirical handling data from each of the motorcycles.
To capture this data and provide objective feedback both motorcycles were fitted with the TrackMotion Inertia Data Analysis system and comments from the test rider were used for subjective comparisons.
The testing was managed by Stephen McDowall. Stephen has over 32 years experience on motorcycles, 8 years experience as a coach and 5 years in motorcycle training and licensing in Queensland. He also has over 20 years experience in IT systems and is trained as a Service Provider with the TrackMotion Inertia Data Analysis system.
Test Rider:
Nik Kalanj was selected as the test rider based on his wealth of experience in both riding and motorcycle dynamics and his ex-ceptional ability in providing consistency in his riding over long periods of time. He has 18 years riding experience, over 10 years as an instructor and advanced level riding educator.
Testing was carried out at the Mt Cotton Training Centre, a Queensland Government oper-ated facility approximately 40km south-east of Brisbane city.
The facility has a road circuit 3.5km in length that has been specifically designed with vary-ing cambers, corners, hairpin bends and sweeping curves. It provides a good “real world” environment and was used for evaluation of the prototype under typical road conditions at normal road speeds of 60 - 80 km/h.
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Nik Kalanj - test rider
For testing, a section of the circuit was selected that included a left hand rising hairpin, fol-lowed by an off camber right hand bend and then a left hand sweeping bend.
The test rider was requested to lap continuously and consistently maintaining similar speeds at every part of the circuit throughout each lap. This process provided data that could be eas-ily used for comparison from lap to lap and between the two motorcycles.
The Mt Cotton facility also has a number of level bitumen areas of varying sizes. One such area, known as the Vehicle Manoeuvring Area (VMA), was used for testing with slow speed manoeuvres. These manoeuvres in-cluded a slalom course with a series of mark-ers spaced at 10m intervals to provide data on the ability of the motoinno prototype to deal with a swerve.
To maintain consistency in the radius of each swerve, extra markers were laid down as a “gate” and the test rider was required to maintain consistent lines through these gates at constant speeds throughout the course.
The turns at each end of the course were also marked with additional markers to maintain consistent lines.
Each particular test exercise was first per-formed with the Suzuki for at least 5 laps over multiple runs to ensure that correct and con-sistent data was being captured. The same process was then applied to the Motoinno prototype.
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VMA track setup
Suzuki in weave test
motoinno prototype in left hand sweeping bend
TrackMotion Inertia Data Analysis System
TrackMotion is an innovative data analysis system that records the characteristic motion of a vehicle. It is specifically designed with motorcycle dynamics in mind but has also been proven in cars, go karts and on bicycles.
The product is the result of over 9 years development and testing by an engineering team with over 40 years experience in motorcycle handling. That same engineering team is also responsible for preparing a number of championship winning race bikes at both national and international levels and commercial production motorcycles.
TrackMotion utilises the sensor arrays available in the Apple iPhone for initial data capture. These sensor ar-rays include a three axis accelerometer, three axis gy-roscope and a magnetometer.
The iPhone’s accelerometer measures the linear ac-celeration of the device so that it can report its roll and pitch.
When the iPhone’s accelerometer measurements are combined with the gyroscope and mag-netometer measurements, motion can be measured on six axes - up and down, left and right, forward and backwards, as well as the roll, pitch and yaw rotations.
Raw data from the sensors is captured by an application on the device and uploaded to a server. Sophisticated software on the server then interprets the data and displays the move-ment of the motorcycle in graphs that are also linked to GPS position and speed.
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Steve McDowall - TrackMotion analyst
The resulting data shows a number of key characteristics of the movement of the motorcycle:
the motorcycle’s rate of turn through a corner
the rotation of the motorcycle left or right as it enters or leaves a turn or swerve
the vertical force through the motorcycle
the lateral force through the motorcycle
forward acceleration and
GPS speed
TrackMotion offers a number of advantages over other data acquisition systems for this type of testing.
It is designed to analyse the true motion of the motorcycle chassis and this gives a far more accurate indication of its exact and overall handling characteristics. This is a vastly different approach than looking at parameters such as suspension travel which, in isolation, cannot reflect how the motorcycle as a whole is performing.
The TrackMotion system, being contained in such a small device, is easy to mount to a motorcycle. This also eliminates complex mounting setups and the risk of the data acquisition equipment interfering with the handling of the motorcycle. As long as the device is correctly and firmly mounted to the frame of the motorcycle
TrackMotion is highly accurate in its data capture.
The system samples all movement parameters at 100 samples per sec-ond, allowing very fine detail to be collected and analysed, whereas an industry standard Motec data collection System only calculates data at 30 samples per second.
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Analysis of Test Data The TrackMotion Inertia Data Analysis system allows for 2 data files, or runs, to be overlaid and a comparison to be made between the two. This allows data to be compared from lap to lap within the same file (run), and between the motorcycles on different runs.
The data obtained from the testing process was first analysed for consistency from lap to lap within the same run, and then from run to run for each motorcycle.
Once the most consistent data was determined for each exercise and for each motorcycle, the sampled data for the motoinno prototype was compared to that of the Suzuki.
This provided, for the first time, a fair and equal comparison of the handling characteristics of the motoinno prototype and the Suzuki GSX-R 750.
Observations Drawn from Test DataObservations taken from the analysis of the test data indicate a number of differences in the handling characteristics of the two motorcycles. The major points of difference are summa-rised below.
It is important to realise that these comments are analytical observations based on captured data of vehicle handling and are not to be interpreted as an engineering study of either motorcycle.
Road Circuit - Entry to hairpin: A consistent difference was identified in the turn rate and rotation of the motoinno prototype compared to the Suzuki GSX-R 750 at the entry to the left hand hairpin.
Data consistently shows that the Suzuki GSX-R 750 (blue line in the following chart) turns to the right first, then turns left into the corner - a movement typical of counter-steering. This is seen in the chart as the blue line dropping below the centre line before then moving above it.
The Suzuki GSX-R 750 also shows a higher rotation rate in the corner as it recovers from the momentary turn to the right.
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Suzuki GSX-R 750 and motoinno TS3 - Ducati 900 - prototype
Road Circuit - Entry to hairpin:
[File references 1391320440 / 1391312600]
Road Circuit - Entry to hairpin: close-up
[File references 1391320440 / 1391312600]
However, despite using the same steering technique and corner entry speed, the motoinno prototype (yellow line) does not exhibit this characteristic. The motoinno prototype then continued to follow the Suzuki’s turn rate and rotation very closely for the duration of the turn.
The conclusion that could be drawn from this observation is that the motoinno TS³ delivers a more direct entry to a corner. It would also suggest that the motoinno prototype required less input to achieve the same turn rate.
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Road Circuit - Exit from hairpin: The exit from the left hand hairpin leads straight into an off camber right hand turn. At this point the front end of the motorcycle feels light and wants to run wide.
The Suzuki (blue line) consistently exhibited a flattening of the turn rate through this turn, indicating that maintaining a smooth and consistent line was more challenging than on the motoinno prototype. It also suggests that the Suzuki required a mid-corner correction in or-der to negotiate the corner and that the suspension movement has affected the steering function in the fork front end.
[File references 1391320845 / 1391312600]
The motoinno prototype (yellow line) maintained a far smoother line throughout this turn suggesting that the inherent isolation of suspension movement and steering functions in the TS³ handled the corner better than the Suzuki. The suspension loads appear to have had no effect on the steering of the motorcycle, a key benefit of the motoinno TS³ technology.
Road Circuit - Sweeping left bend: Feedback from the test rider suggested that the motoinno prototype was less prone to running wide on a constant throttle turn such as this particular sweeping bend. This is supported in the data.
[File references 1391320845 / 1391312600]10
In the following chart the turn rate for the motoinno prototype (yellow line) can be seen to reduce to the zero line at a sharper rate, indicating that it could be pulled out of the corner tighter than the Suzuki (blue line).
Road Circuit - Sweeping left bend: close-up
[File references 1391320845 / 1391312600]
A greater rotation rate at that moment confirms that the motoinno prototype could be straightened faster than the Suzuki and a slightly higher road speed at that point (70km/h for the Motoinno prototype and 60km/h for the Suzuki) suggests that it could hold higher mid turn speed and power could be applied earlier at the exit.
VMA - 10m slalom: Data from the motorcycles during the slalom manoeuvre shows the Su-zuki required a higher turn rate to achieve the same lines through the course at the same speed. This is seen in the chart as a higher and slightly later peak in the blue line relative to the yellow line.
[File references 1391399594 / 1391396461]
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VMA - 10m slalom: close-up
[File references 1391399594 / 1391396461]
Given the motorcycles were being ridden through a controlled course and at the same speed, this would suggest that the motoinno prototype was able to complete the manoeuvre with the same result but less effort required from the rider and the motorcycle.
The same characteristic was seen in a short, sharp swerve.
On The Brakes
Whilst analysing data for this exercise it was also noted that under brakes, before the turn at the end of the course, the Suzuki (blue line) exhibited what appears to be a harmonic oscil-lation in the suspension, whereas the motoinno prototype (yellow line) is not prone to, or affected by, this condition.
[File references 1391407520 / 1391387762]
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Comments from Test Rider
Comments taken from the rider throughout the test program and in a post testing feedback session were consistent with the findings from the data analysis. In some cases, the rider’s subjective feedback provided information that could not be extracted from the data, for ex-ample the rider’s “feel” for the machine and confidence level in cornering was heightened - his comments were also consistent with all previous riders observations.
In summary, his comments pointed to the motoinno having greater stability entering a corner under brakes, greater mid corner speed for less lean and less tendency to run wide as power was applied to exit a corner and the prototype was not affected by mid corner changes to throttle position or braking input.
He also gave feedback that under heavy braking it provided greater stability because of the lack of dive, and even with a locked front wheel it still stopped straight and without the loss of stability that is often felt in a fork front end.
“There was a noted difference in the handling capabilities of the motoinno TS³ vs a fork suspension. A lack of dive on corner entry is possibly the hardest part to become accus-tomed to, however once understood this builds confidence in cornering.”
“Not feeling the chassis shifting its weight from rear to front under braking into turns al-lows different braking points and different entry and exit points to turns.”
“The motoinno seems less prone to running wide on the exit of constant throttle turns. It enables slightly more feedback from the front wheel in turns also. This feedback may aid in improving consistency in rider inputs.”
“The motoinno provided more stability into and on the exit from a corner compared to the Suzuki. It was able to hold its exit line with the throttle on or off and with the clutch in.” (This rider behaviour typically unsettles a motorcycle with a fork front end and is a common cause of single vehicle crashes in corners.)
“There was greater stability under heavy front brake application on the motoinno. The wheel locked easily in the end of testing yet the motorcycle stayed straight and stable.”
“Riding the motoinno was less fatiguing.”
The adjustable rake and trail allows the handling characteristics of the motoinno to be altered from 15 to 24 degrees. The rake was initially set to 19° for all data collection. It was adjusted to 23° after all data was captured and the test rider asked to undertake the course again to provide subjective feedback.
“The steering and braking felt lighter when the rake was set to 23°.”
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Other relevant comments
“To anybody with an appreciation of art or engineering, the chassis and suspension, visually, are something to behold. I could stare at it for hours.”
“The complexity of the front end when one is more familiar with a conventional fork suspension is a little unsettling at first. Once examined and an initial understanding of hub-centre steering has developed, it all makes sense.”
“To sit on at rest, initially the bike felt long and low in the bars. In motion, it is the correct position to reduce fatigue, relax the rider’s posture and instil confidence in being able to hang on to the bike at higher speeds.”
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motoinno at start of circuit data collection
Test rider producing consistant laps
Conclusions
The results obtained from testing tend to indicate that in its current form the motoinno TS³ does offer significant differences to and benefits over a well-mannered motorcycle with a conventional fork based front end and has been able to meet all its design prerequisites.
Under braking the lack of dive offers more stability and builds confidence for the rider.
It appears to be more direct on entry into a corner and requires less input to achieve the same turn rate through a corner.
Changes to throttle position or braking input appear to have little or no effect on the mo-torcycle’s ability to hold a line through a corner and any change does not affect its stability mid corner.
It appears to be less influenced by suspension movement mid corner and therefore less affected by changes in road surface or camber.
On the exit of a corner it appears to have an ability to hold a faster and tighter line with less rider effort.
During the braking test the motoinno TS³ prototype demonstrated that it did not suffer from unsettling oscillations in the front suspension whereas the telescopic Suzuki GSX-R 750 did.
The motoinno TS³ project is worthy of further development.
It could benefit by using an inline 4 cylinder engine that provided a smoother power delivery. This would eliminate some of the vibration felt through the motorcycle from the current v-twin power plant.
It would also benefit from the use of higher quality componentry in the suspension linkages to reduce any “slop” in those linkages.
A comparison test between the motoinno TS³ and other HCS motorcycles would also be worthwhile to see how much further advanced it is from current market HCS systems.
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m o t o i n n o
