Search

A gray-box optimization procedure based on evolutionary algorithms for the initial design of a suspension concept for four wheel independently driven and steered vehicles is developed. With thepresented optimization method, the energy consumption together with state of the art knowledge about the parametrization and design of vehicle suspension systems leads to an optimization setup closely to real world requirements while the vehicle’s topology is exploited. To this, the modelling presented in [1] is considered as a geometric suspension model. Furthermore, to take advantage of the potential of such vehicles, an autonomous closed-loop setup with integrated motion control is utilized. During the optimization, the chassis parameters with the most impact on energy consumption and driving dynamics, namely camber, caster, scrub radius and the steering axis inclination (SAI) depending on a varying caster angle and SAI in relation to the steering angle, will be focused. Therefore, the geometric arrangement of linkages, further considered as optimization parameters, substitutes certain modelling assumptions, leading to a realistic parametrization regarding mechanical design. The proposed chassis design procedure is divided into a five-stage sequence. After the model and controller initialization, roll and pitch centers are determined optimally in step two. In the following step, initial parameters of the suspension are determined in the design attitude with particle swarm optimization (PSO) and static maneuvers. Subsequently, the suspension characteristics, depending on the steering angles as well as the vehicle’s vertical dynamics, during the dynamic ISO double lane change is determined indirectly with genetic algorithms (GA) and the geometric parameters used as optimization variables. Finally, to verify the suspension also for future requirements, the resulting sets of parameters are checked with some unconventional driving maneuvers, which in particular make use of the larger steering angles.

This paper was commissioned for the design and analysis of an entire rear suspension system befitting a Formula Society of Automotive Engineers (FSAE) vehicle. The paper includes a literature review to gain a full understanding of the workings and design decisions applied to the rear suspension in the Society of Automotive Engineers (SAE) competition. After completing the design development process, a final analysis of the designed system was done to ensure the minimum two years-of-life requirement is met. It was found that due to constraints, a major design change was necessary that involves mounting the A-arms further forward on the chassis body than previous generation vehicles. This design increased the stresses present in the system compared to previous designs. As such, careful consid-eration had been given to the analysis aspect of the paper. Full fatigue analysis performed individually on each component proved that the lower A-arm was the most critical component, with a predicted failure at 1466 laps. However, with the given lifespan of two years, this design procured a conservative Factor of Safety of above two years.Notable mention should be given to the complete develop-ment of an FSAE uniaxial force determination code that was produced by Team Recoil. This code greatly improved the confidence in component forces and thus allowed less conservative design choices in several other aspects.

A procedure for the initial design of a suspension concept with four independently driven and steered wheels is developed, whereby, steering angles above conventional values are considered. To fully exploit the potential of such vehicles, an autonomous closed-loop setup with integrated motion control is utilized. The goal is to obtain statements for an optimal suspension design and parametrization maintaining a general approach, while underlying black-box control and the vehicle configuration remains exchangeable. The investigation of the influence of the chassis parameters, with crucial impact on energy consumption, comfort and driving dynamics, namely camber, caster, scrub radius and the steering axis inclination (SAI) depending on a varying caster angle and SAI in relation to the steering angle will be focused. For this sensitivity analysis, an explicit behavioral-oriented model of the suspension is created. This behavior is evaluated with the resulting driving dynamics, specified as the control error, comfort, regarding maximum acceleration on the passengers, and energy demand of the actuators. Scenarios presented are the ISO double lane change and driving a circle while accelerating. The results show clearly that the dependency of the vehicle behavior and the interaction of chassis and controller results in a dominant influence on the driving dynamics, while comfort only improves relatively. Potentials arise during dynamic maneuvers, while stationary driving is mostly influenced by the controller. With the presented design algorithm, different parametrizations obtained with additional maneuvers followed by a cross evaluation result in simulation determined near optimal suspension taking advantage of the exceptional suspension concept.

Two-wheeler represent one of the most used mode of transport in countries like India. The data from NCRB shows that most injuries to two-wheeler motorists are after being thrown off the vehicle. A self-stabilized combined with enclosure prevents serious injury in case of a skidding of the two-wheeler. The primary objective of the work is to create a suspension system for the enclosed self-balancing two-wheeler such that it can withstand the load of the vehicle itself and the extra payload. Ride comfort was primary objective of the work. The suspension system was modeled from the first principles, solved using MATLABTM SIMULINKTM and kinematics simulation was performed to learn the behavior of the system in MSC ADAMSTM. Dynamic simulations were also carried out to check if the forces were under permissible levels for overall design. The parameters considered for the work were hard-points, suspension stiffness and damping. With manual parameter iterations, suspension parameters were tuned for optimal suspension travel, load transmission and power transmission to ground. The work presents a concept for suspension system verified for kinematics and dynamic performance of the suspension.