MSc Dissertation: Active Suspension Design
Design, simulation, and packaging study for an active suspension system
Project Overview
I completed my MSc dissertation project in collaboration with The Landrovers.
The aim was to investigate whether a fully active suspension system could be realistically integrated into a compact vehicle architecture while improving body control and ride response.
Rather than treating the suspension purely as a controls problem, I approached it as a complete engineering system. The work included technology and supplier research, requirement definition, suspension modeling, controller development, actuator assessment, motion-ratio studies, and CAD packaging.
A major part of the project was connecting these areas together. The mechanical geometry influenced the force available at the wheel, which then affected the actuator model and controller performance. This allowed the final concept to be assessed as a complete system rather than simply comparing controller outputs in simulation.
My Role
This was an individual MSc dissertation, completed with technical input and requirements from The Landrovers.
My responsibilities include:
Researching fully active and semi-active suspension technologies
Finding and assessing potential actuator suppliers
Comparing suspension architectures using weighted decision methods
Developing and validating a passive quarter-car model
Developing active suspension models in MATLAB and Simulink
Designing and tuning LQR, H∞ and adaptive H∞ control strategies
Creating representative road inputs and performance test cases
Analyzing body acceleration, displacement, suspension travel and actuator demand
Performing frequency-response and vehicle-mass sensitivity studies
Developing the suspension packaging and rocker geometry in SolidWorks
Using CAD motion studies to calculate motion ratio through suspension travel
Linking the measured suspension geometry back into the control model
Evaluating the final concept against the original project requirements
Engineering Methodology
The project followed a V-cycle development process from requirements through concept selection, modeling, mechanical design, and final evaluation.
MATLAB/Simulink was used to develop and validate the suspension and control models, while SolidWorks was used for packaging and motion-ratio studies. The mechanical and control work was then combined to evaluate the final concept as a complete system.
Suspension Concept Development
Several suspension and actuator arrangements were considered before developing the final concept.
The packaging study had to account for the existing vehicle architecture while maintaining the required suspension travel and keeping the system adaptable to future vehicle configurations.
I used SolidWorks sketches, assemblies, and motion studies to investigate different rocker and actuator layouts. The geometry was evaluated throughout wheel travel rather than only at static ride height, allowing changes in motion ratio, actuator travel, and component position to be understood.
The final concept used a rocker-based arrangement that allowed the actuator packaging to be separated from the wheel-side suspension geometry. This produced a practical route for integrating an active actuator while retaining the required suspension movement and modularity.
The detailed geometry and packaging dimensions are confidential and therefore are not shown publicly.
Simulation and Control
A two-degree-of-freedom quarter-car model was developed in MATLAB and Simulink to represent the sprung mass, unsprung mass, suspension, tyre and road input.
I first developed the passive suspension and checked the model using analytical calculations and published reference cases. Once the baseline behavior was understood, an active actuator was introduced between the sprung and unsprung masses.
Three control approaches were then developed and compared:
LQR — used as a structured baseline controller
H∞ — developed to improve robustness to disturbances and modeling uncertainty
Adaptive H∞ — introduced to vary controller response as operating conditions changed
The simulation also included real-world limitations such as actuator response, force limits, controller sampling, system delay, and power demand, rather than assuming an ideal force source.
Testing and Analysis
The controllers were not assessed using a single road input. I created several simulation cases to understand where each approach performed well and where limitations appeared.
These included:
Large transient disturbances
Raised-road and settling-response tests
Frequency sweeps
ISO-style random road profiles
Different road severity levels
Vehicle-mass sensitivity studies
For each case I analysed a combination of:
Body acceleration | Body displacement | Suspension travel | Tyre response | Settling time | Actuator force | Current demand | Energy use
This gave a much better understanding of the trade-offs between ride response, suspension control and actuator demand than choosing a controller from one performance metric alone.
Results
The biggest takeaway from the project was that there was not one controller that was best in every situation.
The LQR controller performed particularly well during large transient inputs, but it also demanded a higher short-duration actuator force.
The H∞ controllers produced stronger settling behavior following disturbances, while the adaptive H∞ approach gave the most balanced performance during continuous road inputs by improving body and suspension response without requiring the same actuator demand as the fixed controller.
The frequency-response work was equally useful because it highlighted areas where active control alone could not solve the complete ride problem. This helped identify actuator bandwidth, system delay, and controller tuning as important areas for future development.
The mass-sensitivity study also showed that the control system remained predictable as the simulated vehicle mass changed, although future versions would benefit from calibration that adapts to vehicle configuration.
Outcome
The final project produced a prototype-level active suspension concept combining:
Electromagnetic actuatio
Rocker-based mechanical packaging
Variable suspension geometry
Active control development
Simulation-based performance validation
The concept was evaluated against the original mechanical and performance requirements, with the work showing a viable path toward further development and physical testing.
The next stages would include final actuator selection, structural validation, more detailed full-vehicle modeling and hardware testing before progressing toward vehicle-level implementation.
The final dissertation specifically identified further actuator selection, structural analysis, hardware-in-the-loop/rig testing and extension of the model to include pitch, roll and axle interaction as the logical next steps.