Linear electromagnetic actuation system for active vehicle suspension

汽车悬架的基本功能是支撑车辆的重量，最大限度地提高轮胎与路面之间的摩擦力，提供良好的操纵稳定性，并确保乘客的舒适性。汽车运动的动力学通常从两个方面考虑，即乘坐和操纵，三个重要问题是隔振，路面保持和转弯。汽车悬架系统试图通过以下方式来解决每个悬架系统所特有的挑战：（i）在崎岖道路上行驶时吸收能量并将其耗散而不引起车辆的过度振荡，（ii）保持车轮几何形状以最大化轮胎与道路的接触，（iii）在转弯期间对汽车的重量做出反应，以最小化车身侧倾。虽然汽车悬架多年来不断发展和改进，但三个基本部件仍然是弹簧，阻尼器（减震器）和防侧倾杆。实质上，弹簧吸收车轮的振荡运动;减震器通过阻尼振动运动来控制不需要的弹簧运动，悬架运动的动能被转换成热能，该热能被液压流体耗散;并且防侧倾杆提供额外的稳定性，当汽车转弯时，通过阻止一个车轮相对于另一个车轮的垂直运动，这导致更平稳的行驶。当然，悬架有许多变化和不同的配置，汽车的前部和后部通常有不同的设计。然而，虽然悬架系统是任何车辆的基本元件，并且可能看起来相对简单，但设计和实施它们以平衡乘客舒适性和操纵性是一项复杂的任务。软悬架提供平稳的行驶，但在制动、加速和转弯时会导致车身侧倾或俯仰，而硬悬架则最大限度地减少了车身运动，并允许汽车更积极地驾驶，尽管这是以牺牲行驶质量为代价的。为了克服传统悬架系统的局限性，多年来，已经开发了各种替代悬架技术。例如，静压、油气、液压气动和液压--这是一项以前在赛车运动中使用过的创新。然而，这些也有其局限性和/或对于生产汽车来说太昂贵。然而，由于磁性材料、电力电子和数字控制系统的进步，线性电磁电机的最新进展可能会引入一种全新的悬浮技术。这是拟议研究的主题，设想在每个车轮上使用单个线性电机来代替传统的减震器和弹簧系统。采用线性马达的主要好处是，它们可以比传统的基于流体的阻尼器悬架系统移动得快得多，并且因此可以足够快地响应，以在所有驾驶和道路条件下几乎消除车身的所有移动和振动，并且通过在转弯时自动加强悬架来对抗车身侧倾，从而给予驾驶员更大的控制感，并且因此，提高安全性。该研究计划将解决力密集，节能线性电机的设计优化和相关的数学算法，这将是必要的，以提供所需的主动控制的悬架系统。所开发的悬挂技术的实用性将在四分之一汽车试验台上进行演示，由此产生的车辆性能改进也将通过对整个行驶、操纵和稳定性范围的模拟来量化。

The basic function of a car suspension is to support the weight of the vehicle, maximise the friction between the tyres and the road surface, provide steering stability with good handling, and ensure the comfort of the passengers. The dynamics of a moving car are generally considered from two perspectives, viz. ride and handling, three important issues being vibration isolation, road holding and cornering. The car suspension system attempts to solve the challenges unique to each, by (i) absorbing energy while travelling over rough roads and dissipating it without causing undue oscillation of the vehicle, (ii) maintaining the wheel geometry to maximise tyre contact with the road, (iii) reacting the weight of the car during cornering, so as to minimise body roll. Although car suspensions have evolved and improved over the years, the three fundamental components remain springs, dampers (shock absorbers) and anti-roll bars. In essence, the springs absorb the oscillatory motion of the wheels; the shock absorbers control unwanted spring motion by damping vibratory motions, the kinetic energy of the suspension movement being converted into heat energy which is dissipated by hydraulic fluid; and the anti-roll bars provide additional stability, combatting the roll of a car on its suspension as it corners, by resisting the vertical movement of one wheel relative to the other, which results in a more level ride. There are, of course, numerous variations and different configurations of suspension, and a car usually has a different design on the front and back. However, whilst suspension systems are a fundamental element of any vehicle and may appear to be relatively simple, designing and implementing them to balance passenger comfort with handling is a complex task. Soft suspensions provide a smooth ride, but result in body roll or pitch during braking, acceleration and cornering, whilst stiff suspensions minimise body motion and allow cars to be driven more aggressively, albeit at the expense of ride quality. To overcome the limitations of conventional suspension systems, over the years, various alternative suspension technologies have been developed. For example, hydrostatic, hydrogas, hydropneumatic and hydraulic - an innovation which has previously been exploited in motorsport. However, these also have their limitations and/or are too expensive for production cars. Recent advances in linear electromagnetic machines, facilitated by advances in magnetic materials, power electronics and digital control systems, may, however, make it possible to introduce a totally new suspension technology. This is the subject of the proposed research, which envisages using a single linear motor at each wheel in place of the conventional shock absorber and spring system. The main benefit of employing linear motors is that they can move much faster than conventional fluid-based damper suspension systems, and can, therefore, respond quickly enough to virtually eliminate all movement and vibration of the body of a car under all driving and road conditions, and to counter body roll by automatically stiffening the suspension when cornering, thereby giving the driver a greater sense of control and, hence, improving safety. The research programme will address the design optimisation of force-dense, energy-efficient linear electrical motors and the associated mathematical algorithms which will be necessary to provide the required active control of the suspension system. The utility of the developed suspension technology will be demonstrated on a quarter car rig, and the resulting vehicle performance improvements will also be quantified by simulations over the full range of ride, handling and stability.