Motorcycle Lean Angle Variation around a Constant Radius Curve at Differing Speeds and Travel Paths with an Evaluation of Data Measurement Systems

Recent studies evaluating motorcycle lean angle have compared theoretical lean angle equations with real-world-tested motorcycle lean angles. These studies have considered several factors affecting lean angle, including the simplified assumptions made when calculating theoretical lean angles, the speed of the motorcycle around a curve, and the geometry of the roadway/curve. This study further evaluates motorcycle lean angle as a function of speed, but primarily focuses on the effects of different travel paths selected by the rider around the same constant radius curve. The testing incorporates nine passes around the same curve traveling three different paths at three different speeds. The real-world-tested lean angles were compared to the predicted calculated lean angles for each tested travel path and speed. The theoretical lean angles were calculated using the graphically reconstructed radius of curvature generated through three-dimensional (3D) laser scans of the roadway and aerial video footage and orthomosaic imagery. The orthomosaic imagery was collected via small Unmanned Aerial Vehicle (sUAV) (commonly referred to as a drone). The analyzed curve is a sweeping constant radius left-hand curve with an approximate 670-ft (204-m) radius of curvature. This study also analyzed the variations in lean angle through the transient entrance of the curve, steady-state middle of the curve, and transient exit of the curve. Lean angles were also analyzed utilizing video analysis and 3D camera matching techniques. The accuracy and effectiveness of this data was compared and analyzed. The results of this testing empirically establish that at a given speed on a given curve, motorcycle lean angles vary depending on the travel path selected by the motorcyclist, the motorcyclist’s efforts to maintain lane position, and intended path of travel.