The controls subsystem focuses primarily on the driver interface and braking systems of the car. This includes the steering system, dash display, ABS system, brake calipers, pedal box, throttle system, ergonomics, seat and clutch. Controls must try to balance driver comfort and performance with weight and cost. A significant amount of detailed analysis goes into this system as the car must fit both the 5% female and the 95% male templates safely and comfortably.
What We Do
This system, as with all others on the team, uses Solidworks for CAD modeling, along with a variety of other tools to achieve design objectives. A general overview of the main components follows:
- Ergonomics: The car must safely and comfortably accommodate drivers of diverse sizes and shapes. In addition, it must minimize the number of distractions to the driver and improve his or her ability to control and receive feedback from all systems on the car.
- Steering/Driver Interface: The primary goal of the steering system is to allow the driver to efficiently and effectively control the car as is provides feedback to the driver allowing him or her to drive the car to its limit. In addition, the dash and controls present on the wheel are designed for minimal driver distraction, allowing the driver attention to remain focused. The dash can be programmed with various screens selected for the driver’s benefit. This can be adapted and changed for each dynamic event to display any relevant information.
- Pedal Box: As part of the requirements to accommodate differing drivers, the pedal configuration of the car must be adjustable. This means varying the position of both the throttle and brake pedals and mounting them securely, while allowing adjustment without the use of tools.
- Brakes: One of the unique elements of GTMS cars is the use of custom brake calipers. For over 10 years our team has developed and manufactured its own brake calipers and rotors to meet exact design requirements.
Controls has a long history of effective design and manufacturing, much like the other subsystems. Team members have tested many iterations of different materials and designs to improve component weight and structural integrity. New systems in recent years include pneumatic shifting, ABS, carbon fiber steering wheels, and a new display system. Some of the original GTMS vehicles had a traditional three pedal assembly for the clutch and jockey handle for shifting gears while driving.
Perhaps the most complex part of the controls subsystem is the brake assembly, as there are several dynamic factors to consider. Essentially, the brakes must convert kinetic energy to thermal energy in order to slow the car down, while also dissipating this thermal energy at the maximum rate at which the car can produce energy.
Brake calipers are machined from billet aluminum stock with a CNC mill, and fitted with carbon PFC motorcycle race pads. The brake system also utilizes a Bosch ABS unit to improve driver control.
The acceleration and brake pedals are both primarily constructed of aluminum with carbon fiber heel and toe cups to keep the driver’s feet snug on the pedals. The brake pedal is designed to work with foot pressure, not distance.
We use a lightweight Miltera steering rack with a pinion gear for the carbon tubing (not carbon fiber) to connect to the steering wheel. Two universal joints help change the translational motion of the wheel to steering rack to move the wheels. The steering wheel has a digital screen with a fully programmable display to show the driver whatever information he/she needs to know for that specific event. It also includes several buttons around the dash which will control the Driver-To-Cockpit communications, amongst other things. The steering wheel itself is constructed of carbon fiber.
Currently the car is using pneumatic shifting to enable the use of the paddle shifters. The driver only uses the clutch for starting.
Future Goals and Projects
This subsystem is looking to complete a revised rotor and caliper analysis for the brake system to reduce manufacturing complexity and weight. Additionally, we plan to implement additional sensors and data collection systems to improve understanding of the diver-car interaction.