Steering Damper Research Articles

Variable Steering Damper to Suppress Weave and Wobble

Variable Steering Damper to Suppress Weave and Wobble

Design and testing of a steering damper for motorcycles based on a shear-thickening fluid

This work is intended to show the feasibility of the utilisation of a shear-thickening fluid as working fluid in a steering damper for motorcycles. To that end, a prototype of a steering damper has been designed and then tested under different working conditions. Unlike conventional models, this new steering damper bases its performance on the combination of very simple rod geometries and a shear-thickening fluid of different concentrations. The experiments carried out with a test machine demonstrate that, despite its simplicity and reduced cost of manufacturing, the prototype shows similar behaviour to a conventional high-performance racing steering damper. The Bouc–Wen model has been used to reproduce the behaviour of the shear-thickening fluid-based damper prototype. The parameters of the model have been obtained following an optimization process to fit the model’s response to the experimental data when exciting the damper at different speeds. Results show that the damper’s behaviour can be properly modelled with a single combination of parameters.

Design of a Motorcycle Steering Damper for a Safer Ride

Powered-two-wheelers (PTWs) are increasingly popular because of their lower cost compared to cars, and therefore the riders’ exposure risk is increasing. Due to their complex dynamics characterized by high non-linearity and inherent instability, PTWs are more difficult to control compared to four-wheeled vehicles. Wobble is a high-frequency instability mode affecting the steering assembly of the PTW, and which often causes the rider to lose control and crash when it occurs. In this paper, we present the design of a new motorcycle semi-active steering damper integrated into the steering column and utilizing a magnetorheological fluid (MRF) for variable damping torque. An analytical model of the concept was first used to perform the preliminary sizing, followed by concept validation using a 3D FE multiphysics magnetic-fluid analysis. The final innovative design offers several advantages compared to traditional steering dampers: (i) a wide range of adjustable damping torque values, with a multiplication factor up to 10 with a maximum electrical current of 2 A; (ii) total integration into the motorcycle steering column enabled by its axial design and limited radius; (iii) a simple chamber geometry that allows for easy manufacture; (iv) longer seal life due to the absence of direct contact between seals and the MRF.

An Axiomatic Design Approach for a Motorcycle Steering Damper

The main function of a motorcycle steering damper is to stop the steering oscillations that could be generated during the vehicle motion around the steering axis, a typical motorcycle instability known as wobble or shimmy. However, in normal conditions, the damping function of the device on the steering can be harmful, causing rider's wearying and thus decreasing his comfort and safety. Moreover, a recent trend of steering dampers is the size optimization with a higher integration of the device into the steering head and consequent greater constraints on its dimensions. In this paper, a model of motorcycle is considered to define the damping factors generally required on the steering axis to ensure safety and comfort in all conditions. Moreover, an Axiomatic Design approach is used to analyze the critical aspects and to propose an innovative architecture for a steering damper based on magneto-rheological (MR) fluid and fully integrated in the steering head of the motorcycles.

Steering Damper for Street Motorcycle

We introduce a research on steering dampers using MR fluid (Magnetorheological Fluid). In recent years, steering dampers have been used in on-road and off-road motorcycles. Steering dampers stabilize the front end of motorcycles. The advantage of a steering damper is increased stability, but hydraulic steering dampers give rise to the problem of 'Heavy Steering'. In order to resolve this heavy steering, we need to set the restrictions on the maximum damping force and avoid it from interfering when the rider is steering. However only reducing the damping force will lead to insufficient damping force when the handle, unresponsive because of kickback, shakes. We solved this problem with the development of an electric control damper which generates sufficient damping force at low steering angle rates and also allows for mechanically limiting the maximum damping force. The damper design uses Direct Shear Mode and features a steering angle sensor built into the damper, which results in easier and smoother steering. To test its effectiveness, we installed our new steering damper and asked for feedback from riders. From the received feedback, we were able to confirm the effectiveness and efficiency of our new design as well as its superiority over other traditional designs. In particular, we were able to improve stability when entering a corner or riding over gaps by generating more damping force from a low steering angle rate in comparison to traditional dampers. We also succeeded in keeping the nimble handling while riding by reducing the maximum damping force. Language: en

Suppression of Burst Oscillations in Racing Motorcycles

Burst oscillations occurring at high speed, and under firm acceleration, can be suppressed with a mechanical steering compensator. Burst instabilities in the subject racing motorcycle are the result of interactions between the wobble and weave modes under firm-acceleration at high speed. Under accelerating conditions, the wobble-mode frequency (of the subject motorcycle) decreases, while the weave mode frequency increases so that destabilizing interactions can occur. The design analysis is based on a time-separation principle, which assumes that bursting occurs on time scales over which speed variations can be neglected. Even under braking and acceleration conditions linear time-invariant models corresponding to constant-speed operation can be utilized in the design process. The influences of braking and acceleration are modeled using d’Alembert-type inertial forces that are applied at the mass centers of each of the model’s constituent bodies. The resulting steering compensator is a simple mechanical network that comprises a conventional steering damper in series with a linear spring. In control theoretic terms, this network is a mechanical lag compensator. A robust control framework was used to optimize the compensator design because it is necessary to address the inevitable uncertainties in the motorcycle model, as well as the nonlinearities that influence the machine’s local behavior as the vehicle ranges over its operating envelope.

Dynamic stability of an aerodynamically efficient motorcycle

Motorcycles exhibit two potentially dangerous oscillatory modes known as ‘wobble’ and ‘weave’. The former is reminiscent of supermarket castor shimmy, while the latter is a low frequency ‘fish-tailing’ motion that involves a combination of rolling, yawing, steering and side-slipping motions. These unwanted dynamic features, which can occur when two-wheeled vehicles are operated at speed, have been studied extensively. The aim of this paper is to use mathematical analysis to identify important stability trends in the on-going design of a novel aerodynamically efficient motorcycle known as the ECOSSE Spirit ES1. A mathematical model of the ES1 is developed using a multi-body dynamics software package called VehicleSim [Anon, VehicleSim Lisp Reference Manual Version 1.0, Mechanical Simulation Corporation, 2008. Available at http://www.carsim.com]. This high-fidelity motorcycle model includes realistic tyre–road contact geometry, a comprehensive tyre model, tyre relaxation and a flexible frame. A parameter set representative of a modern high-performance machine and rider is used. Local stability is investigated via the eigenvalues of the linearised models that are associated with equilibrium points of interest. A comprehensive study of the effects of frame flexibilities, acceleration, aerodynamics and tyre variations is presented, and an optimal passive steering compensator is derived. It is shown that the traditional steering damper cannot be used to stabilise the ES1 over its entire operating speed range. A simple passive compensator, involving an inerter is proposed. Flexibility can be introduced deliberately into various chassis components to change the stability characteristics of the vehicle; the implications of this idea are studied.

Single-Sensor Control Strategies for Semi-Active Steering Damper Control in Two-Wheeled Vehicles

Recent research has led to the design of effective steering control strategies that employ, as controlled variables, the steering velocity and the yaw rate. The yaw rate can be measured by an inertial platform, which is usually already installed on modern motorcycles for advanced traction and braking control systems. Thus, there is an interest in developing effective steering angle estimators to implement single-sensor control strategies without introducing any additional cost for the semi-active steering damper control system. This paper proposes a robust minimum variance linear time-invariant filter and a linear parametrically varying observer to estimate the steering angle based on yaw rate and vehicle speed measurements, the performance of which is compared both via simulation and experimental data. The closed-loop performance of the single-sensor control strategies is finally evaluated and compared with that obtained with the two-sensor algorithm.

Semi-Active Steering Damper Control in Two-Wheeled Vehicles

This work presents the design of innovative control strategies for a semi-active steering damper aimed at improving two-wheeled vehicles steering stability by controlling the weave and wobble modes. The proposed control strategies arise from a parallelism between steering and vertical dynamics of a motorcycle. According to this parallelism, the Sky-Hook (SH) and Ground-Hook (GH) damping concepts are adapted to the control of steering dynamics. A detailed analysis of the two approaches shows that a tradeoff arises between the damping of wobble and weave mode. It is then shown that the tradeoff can be solved by mixing the SH and GH strategies according to a frequency-range selector. The closed-loop stability properties are investigated via passivity theory. Further, both a multibody simulator and experimental data are employed to validate both the modeling phase and the control strategies performance.

Study on the Return Control of the Electro-Controlled Steering Damper Based on Magnetorheological Fluid

The paper introduces an electro-controlled steering damper’s working principle, which uses the magnetorheological fluid as the working medium, and derives the damper’s controlling and calculating method. The steering wheel’s return control strategies of it are investigated. In order to compare the control effect of the PD controller with the fuzzy controller, a simulation model of the vehicle’s steering system is established on MATLAB/SIMULINK. Then simulate the returning process of the front wheels at medium and high vehicle speed. The results show that the vehicle’s steering system equipped with the electro-controlled damper can restrain effectively the returning overshoot of front wheels when the steering wheel is returning automatically, and the effect of the fuzzy controller is excelled the PD controller, but it demands much more to the hardware for its larger calculation amount.

Study on the Control System of the Electro-Controlled Steering Damper Based on Magnetorheological Fluid

This paper introduces a kind of electro-controlled steering damper’s structure and working principle which uses the magnetorheological fluid as the working medium. In order to design the controll system of the electro-controlled steering damper, the model of the steering system and the damper based on magnetorheological fluid are established through the dynamic equations, and a PID controller is used. At last, the paper simulates the controll system using a simulation language Modelica on Works, which is a simulation flatform for comp lex physical system modeling and simulation. The results show that the damper can effectively increase the stabilizing speed of the steering system, decrease the over run of the vehicle’s yaw speed, and improve the vehicle’s steering stabilization, especially when the vehicle running in high speed.

Design of semi-active steering damper control strategies for sport motorcycles

This work presents the design of a novel control approach for a semi-active steering damper of motorcycles. The goal is to improve two-wheeled vehicles steering stability by damping the weave and wobble modes. The proposed control strategies stem from a parallelism between steering and vertical dynamics of a motorcycle. According to this parallelism, the Sky-Hook and Ground-Hook damping concepts are adapted to the control of steering dynamics. A detailed analysis of the two approaches is presented and the semi-active control strategies are shown to yield better attenuation of both modes than a passive steering damper. Further, both a multi-body simulator and experimental data are employed to validate the proposed control approach.

Control of motorcycle steering instabilities

The establishment of damper settings that provide an optimal compromise between wobble- and weave-mode damping is discussed. The conventional steering damper is replaced with a network of interconnected mechanical components comprised of springs, dampers and inerters - that retain the virtue of the damper, while improving the weave-mode performance. The improved performance is due to the fact that the network introduces phase compensation between the relative angular velocity of the steering system and the resulting steering technique

Mechanical Steering Compensators for High-Performance Motorcycles

This paper introduces the idea of using mechanical steering compensators to improve the dynamic behavior of high-performance motorcycles. These compensators are seen as possible replacements for a conventional steering damper and comprise networks of springs, dampers, and a less familiar component called the inerter. The inerter was recently introduced to allow the synthesis of arbitrary passive mechanical impedances, and finds a potential application in the present work. The design and synthesis of these compensation systems make use of the analogy between passive electrical and mechanical networks. This analogy is reviewed alongside the links between passivity, positive reality, and network synthesis. Compensator design methods that are based on classical Bode-Nyquist frequency-response ideas are presented. Initial designs are subsequently optimized using a sequential quadratic programing algorithm. This optimization process ensures improved performance over the machine’s entire operating regime. The investigation is developed from an analysis of specific mechanical networks to the class of all biquadratic positive real functions. This aspect of the research is directed to answering the question: “What is the best possible system performance achievable using any simple passive mechanical network compensator?” The study makes use of computer simulations, which exploit a state-of-the-art motorcycle model whose parameter set is based on a Suzuki GSX-R1000 sports machine. The results show that, compared to a conventional steering damper, it is possible to obtain significant improvements in the dynamic properties of the primary oscillatory modes, known as “wobble” and “weave.”