Striking a balance between simulation realism and immersion is essential for the development and evaluation of a prototyping environment (set-up and methodology) for Mixed Reality Road bicycle racing applications. Multi-sensory immersion, safety, usability, and design process iterability are hard requirements for the proposed prototyping environment in which a tandem rides on a treadmill with a participant riding up-front wearing a Virtual Reality headset. In the virtual environment, with interactable interface artefacts in a 360-video sphere, participants’ needs and preferences are dis-covered as participants configure their own 3D user-interface for Mixed Reality capable cycling glasses. Sessions that simulate a cycling race, focus on two distinct scenarios of ascending and descending. Two prototyping methods, while standing and while riding a bicycle, are evaluated and compared. Cyclists’ preferences include types of information, their placement in the visual field, size, and colour, depicted in heatmap visualisations. These insights are essential for designers of Mixed Reality systems with real-time information for outdoor bicycle racing.

Infants are transported in strollers and in baby seats mounted in cargo bicycles. The infants experience whole-body vibration during the associated walking and cycling trips, but there is little existing knowledge about associated comfort and health effects. To improve this, we measure the seat pan acceleration of five strollers and two styles of cargo bicycles with dummy infants representing ages 0 to 9 months over six different road surfaces of varying road roughness at typical travel speeds. The five strollers included three modern systems and two vintage systems with some level of suspension. One cargo bicycle had electric support enabling speeds up to 25 km/h. We report average seat pan acceleration for 78 different scenarios and investigate the effects of road surface, vehicle, seat type, and travel speed. Using the whole-body vibration ISO standards, we show that rough road surfaces, amplified by travel speed, may have health risks for travel durations as low as 10 min to 30 min. Stroller designs from 50 years ago significantly reduce vibrations, relative to most modern strollers we tested, indicating the need for return of suspension elements. Cargo bicycles ridden at the maximum electric bicycle speed over paver bricks can cause accelerations that should likely be avoided except for only the shortest of durations until more direct evidence of risks to infants is studied. Standards are needed for infant transport testing and evaluation, designers need to incorporate better suspension for infants, and research is needed to develop clear and direct connections to health and comfort effects.

The ollie is the base aerial human–board maneuver, foundational to most modern skateboarding tricks. We formulate and solve an optimal control problem of a two-dimensional simplified human model and a rigid body skateboard with the objective of maximizing the height of the ollie. Our solution simultaneously discovers realistic human-applied force trajectories and optimal board geometry. We accomplish this with a direct collocation formulation using a null seed initial guess by carefully modeling the discontinuous aspects of board–ground impact and foot–board friction. This leads to efficient and robust solutions that are 10 times more computationally efficient than prior work on similar problems. The solutions show that ollie height can increase 3% by decreasing the wheelbase and that a smaller board with a back-foot-dominated force strategy can give 12% higher ollies. Our model can be used to inform jump strategy and the effects of changes to the essential board geometry.

This project was designed to understand the causes and mechanisms of bicycle disc brake noise and use that information to formulate and evaluate possible mitigation techniques. Brake noise was generated by a real bicycle running on a treadmill and recorded by microphone and laser vibrometer. Six independent variables, brake force, rotor thickness, front fork stiffness, weather conditions, spoke tension, and friction coefficient, were varied according to a one-quarter fractional factorial design. A finite element model of the rotor, pads, and calliper was also formulated and analysed. The results of these two methods, particularly the disc mode shapes and frequencies, suggest that doublet mode splitting and reconverging plays a role in noise generation and that changing the rotor mass or breaking its symmetry could interfere with such noise generation. Finally, of these mitigations, breaking disc symmetry proved the most fruitful, with noise magnitude reductions from 72% to 99%, depending on frequency.

Measurement of lateral characteristics of bicycle tyres performed through indoor test-rig VeTyT (Department of Mechanical Engineering, Politecnico di Milano, Milan IT). The test-rig for bicycle tyres complies with the standard ISO 9001-2015. Specifically, we measured lateral force and self-aligning torque varying vertical load, inflation pressure, camber angles, for a batch of bicycle tyres. Authors’ disclaimerThe data produced in this paper are not -and cannot be- related in any way on the quality of the products that have been tested. Actually, only one single tyre per type has been tested and the data have been acquired in a laboratory, which is not the real environment. Relevant factors defining the quality of tyres are not -and cannot be- addressed in this paper.

We previously presented a narrow-track tilting tricycle with a variable stability mechanism integrated between the swing arms that support a pair of rear wheels, in the so-called “delta” configuration, and with recumbent seating. We now examine adopting that variable stability mechanism to work on a tricycle with a split-parallelogram linkage between a pair of front wheels, in the so-called “tadpole” configuration, and with upright seating. It was fairly straightforward to allow for tilting by replacing the front wheel and fork with a split parallelogram comprising two paired A-arms and kingpins, controlling the motion of the two halves with a bell crank and two tie rods, and then varying the handling of the vehicle by moving the connection point of the tie rods on the bell crank, just as we did with the swing arms of the previous vehicle. We have also separated the two tasks of positioning the tie rod ends on the bell crank and enforcing symmetry of the tie rods. The former does not require much force and can be easily implemented with Bowden cables, but the latter does require large forces and is better implemented with a local rigid-bar linkage. Implementing decent Ackermann steering geometry, allowing for both large tilt and steer angles, and decoupling tilting from steering, however, proved to be quite a challenge, at least while we attempted to implement it with bar linkages. Fortunately, we discovered a 2006 paper by Prof Drstvenšek et al. describing a Bowden cable and cam system that looked promising. Finally, the resulting vehicle handles very nicely. When in “full bicycle” mode, it handles quite similar to the original bicycle that we had converted into the tricycle. When in “rigid tricycle” mode, it keeps the rider upright when stationary or when riding at a walking pace. In between these two extremes, it handles even better than the original bicycle in a slalom course and when slowly following a straight line.

The development of computationally efficient and validated single-track vehicle-rider models has traditionally required handcrafted one-off models. Here we introduce BRiM, a software package that facilitates building these models in a modular fashion while retaining access to the mathematical elements for handcrafted modeling when desired. We demonstrate the flexibility of the software by constructing the Carvallo-Whipple bicycle model with different numerical parameters representing different bicycles, modifying it with a front fork suspension travel model, and extending it with moving rider arms driven by joint torques at the elbows. Using these models we solve a lane-change optimal control problem for six different model variations which solve in mere seconds on a modern laptop. Our tool enables flexible and rapid modeling of single-track vehicle-rider models that give precise results at high computational efficiency.

Learning to ride a bicycle is challenging, and can be dangerous, as it involves acquiring several motor skills, including balance and coordination while interacting with a complex dynamical system. Haptic assistance could potentially help to enhance the learning of this especially complex task in a safe environment. We propose the use of a Model Predictive Controller (MPC) to provide steering assistance while training to learn a complex cycling task. We conducted a feasibility study with ten participants riding a steer-by-wire bicycle on a treadmill. The goal of the task was to collect laterally positioned virtual stars, shown on a display mounted in front of the treadmill. Participants trained under two conditions in random balanced order: with or without assistance from the MPC. Short-term learning was compared between conditions. We did not find evidence that training with MPC-based assistance improves the performance in steering the bicycle to collect the virtual stars after training compared to training without assistance. However, we found initial evidence that training with the MPC could be beneficial for less-skilled cyclists to learn the steering task. In conclusion, haptic steering assistance using MPCs may be a promising tool for enhancing bicycle steering skills, especially in initially less-skilled bicyclists.

Bicycles are more difficult to control at low speeds due to the vehicle’s unstable low-speed dynamics. This issue might be exacerbated by factors such as aging, disturbances, and multi-tasking. To address this issue, we developed a prototype ‘balance assist system’ with Royal Dutch Gazelle and Bosch eBike Systems at Delft University of Technology, which includes an electric motor capable of providing additional steering torque. We implemented a speed-adaptive feedback controller to generate the additional steering torque to that of the rider. We conducted a study with 18 older and 14 younger cyclists to first examine the effect of aging, disturbances, and multi-tasking on cycling at lower forward speeds, and evaluate the effectiveness of the system in improving the stability of the rider-bicycle system while facing these challenges. The study consisted of two scenarios: a single-task scenario where participants rode the bicycle on a marked narrow straight-line track, and a multi-task scenario where participants performed a shoulder check task and followed visual cues while tracking the straight-line. We introduced handlebar disturbances using the steer motor in half of the trials in both scenarios. All trials were repeated with and without the balance assist system. We calculated the bicycle mean magnitude of roll and steering rate—as indicators of bicycle balance control and required steering actions, respectively—and the rider’s mean magnitude of lean rate with respect to the ground to investigate the effect of the balance assist system on rider’s lateral motion. Our results showed that aging, disturbances, and multi-tasking increased the roll rate, and the balance assist system was able to significantly reduce it. The effect size of the balance assist system in reducing the roll rate across all conditions was found to be larger in older cyclists, indicating a more substantial impact compared to younger cyclists. Disturbances and multi-tasking increased the steering rate, which was successfully reduced by the balance assist system. Aging did not significantly affect the steering rate. The rider’s lean rate was not significantly affected by age, disturbances, or the balance assist, indicating that the upper body plays a minor role when riders have good steering control authority. Overall, our findings suggest that lateral motion and required steering action can be affected by age, multi-tasking, and handlebar disturbances which can endanger cyclists’ safety, and the balance assist system has the potential to improve cycling safety and reduce the incidence of single-actor crashes. Further investigation on riders’ contribution to control actions is required.

Microscopic traffic simulation is a popular tool in traffic research and planning. It enables the evaluation of interventions in a traffic system based on the movement of individual simulated agents. These can be for example infrastructural changes or the introduction of new road users like automated vehicles. To simulate cyclists, traditional simulation techniques have to be adapted. We propose a microscopic model describing bicycle interaction using the social force paradigm. Here we take into account bicycle kinematics, to create realistic bicycle paths. Qualitative evaluation shows simulated interactions with plausible cyclist trajectories.

Modeling and Implementation of a Reaction Wheel Stabilization System for Low Speed Balance of a Cargo Bicycle

Despite the publication of many bicycle models, there is yet to exist a common framework for building and extending bicycle-rider models that can be easily shared between researchers. To fill this gap, we have developed BRiM, a modular and extensible open-source framework for creating Bicycle-Rider Models. It uses an established bicycle model, like the Carvallo-Whipple model, which can be extended using components from BRiM's extensive library, or user-defined custom subclasses. It leverages the open-source Python package SymPy, a computer algebra system, to compute the equations of motion. This results in symbolic equations of motion, which, after code generation, can be used to simulate and optimise the model. The effectiveness of BRiM is demonstrated by solving a trajectory tracking problem using a direct collocation algorithm.

The Python Control Systems Library (python-control) is an open source set of Python classes and functions that implement common operations for the analysis and design of feedback control systems. In addition to support for standard LTI control systems (including time and frequency response, block diagram algebra, stability and robustness analysis, and control system synthesis), the package provides support for nonlinear input/output systems, including system interconnection, simulation, and describing function analysis. A MATLAB compatibility layer provides an many of the common functions corresponding to commands available in the MATLAB Control Systems Toolbox. The library takes advantage of the Python “scientific stack” of Numpy, Matplotlib, and Jupyter Notebooks and offers easy interoperation with other category-leading software systems in data science, machine learning, and robotics that have largely been built on Python.

Bicycle paths or even bicycle lanes have not emerged as key priorities in traditional pavement systems analysis. Most cities rely on route preferences (e.g., common school routes) or visual checks to prioritize pavement conditions on bicycle facilities. We used 31 bike path sections with a representative range of pavement surface conditions to collect acceleration data, GPS location data, bicycle steering angle, surface displacement data, and mean texture depth (MTD) data. We also recruited cyclists to complete a post-ride survey on ride quality. Using these data, we specified two ordered logit regression models to separately examine the relationships between bicycle ride quality and traditional pavement roughness measurement (or surface defect density on trajectories) while holding other parameters (e.g., bicycle accelerations and steering angle) constant. Our study shows that a surface defect index can replace the MTD test for bicycle facilities and can produce better performance in predicting ride quality, especially when pavement condition needs moderate repair to avoid becoming much worse. We also examine ride quality, specifically the vertical acceleration effect on ride experience, for different types of bicycles (e.g., a mountain bike with a suspension system versus a touring bike).

Speed control is not a prevalent feature found in electric bicycles. Many electric bicycles implement a pseudo speed controller that does not include feedback based on sensing speed. As with automobiles, speed control can be desirable for driver comfort and safety. Additionally, accurate speed control is also very helpful when validating dynamic models of single-track vehicles, which is our motivation. This paper describes a low cost feedback speed controller for an instrumented electric bicycle. To achieve this, we used grey box system identification to fit a second order linear model of the longitudinal dynamics of the bicycle to a measured step time response. The resulting fitted plant model was used to design a robust PID controller. We implemented the controller with a custom Arduino-based microcontroller. The resulting implementation was able to maintain the interquartile range of measured speeds at steady state within ±0.1m/s of a desired setpoint speed.