ET Braking System Pty Ltd has devised a novel system to reduce the braking distance of a vehicle. The ET Braking System Pty Ltd (ETBS) links braking operation to the top end of the accelerator pedal motion, with the remainder of the motion of the accelerator pedal operating in its usual manner – see Figure 1 below. It can be applied to cars, trucks buses and duel control vehicles, by either retrofit or as part of the original equipment of the vehicle provided the vehicle has automatic transmission.
An ETBS equipped vehicle continues to comply with the requirements of the applicable Australian Design Rules (ADRs) for motor vehicles, specifically with ADR 31/02 Brake Systems for Passenger Cars and ADR 35/03 Commercial Vehicle Brake Systems.
A test program, which compared an ETBS equipped vehicle to one without, was conducted. The test evaluated the effect of the ETBS on emergency braking.
When decelerating from 80km/h, the ETBS equipped vehicle would reach 20 km/h 5.1 metres before the vehicle without ETBS. The vehicle without ETBS would be still travelling at 35.2 km/h. The research results relating impact speed to pedestrian injury obtained by Ashton SJ and Mackay1 (1979) shows that in an impact with a pedestrian at a speed of 35km/h for the standard vehicle, there is a possibility of fatal injury occurring to a pedestrian, a 65% chance of serious injury and about a 32% chance of slight injury. While at an impact speed of 20 km/h for the ETBS equipped vehicle, the injuries are most likely to be slight with only a 10 to 15% risk of being severe.
A pedestrian impact involving braking from speed, the vehicle with ETBS gives a significant reduction in injury risk. Similarly, in a vehicle to vehicle impact involving braking from speed, the vehicle with ETBS gives a significant reduction in injury risk as well.
The device aims to reduce driver fatigue, increase productivity and decrease stopping distance in emergency braking situations. It is expected that this change will reduce both the number of accidents and injury severity sustained by crash victims.
During normal vehicle operation, the ETBS eliminates the need for using the brake pedal. This is achieved when the driver’s foot is removed from the accelerator pedal resulting in the brake pedal being actuated by a solenoid via a cable and pulley system. The braking process begins when the standard fully-closed throttle position is passed. As ‘negative travel’ of the throttle pedal increases the braking force increases up to the point where there is sufficient brake force to cause the vehicle to decelerate at a “normal” rate and cause the vehicle to come to a stop.
Acceleration from the stop position is achieved by the driver simply accelerates as normal. The ETBS first brings the ‘negative travel’ back to zero, reducing the braking force applied, before finally opening the throttle of the car sufficiently to begin accelerating. The rate and magnitude of the solenoid force can be adjusted with the microcontroller however were unchanged during the testing reported here. The normal operational characteristics of the ETBS were not evaluated during this testing. The following significant point can be noted and observed;
- No interference with existing devices in the vehicle including AEB.
- No modifications has been done to the accelerator or to the brake system.
- It works independent to autonomus braking system, only one system can be active at any time.
- Due to the nature of the device, it does not work in cruise control mode.
When a driver suddenly removes their foot from the accelerator pedal at a fast rate, the ETBS applies a force of significant magnitude to the brake pedal. The engine throttle may still be open when the brakes are applied as the actuation of the solenoid is governed by the rate of the pedal release and not the pedal position. This force is applied sufficiently fast enough such that it applies significant force to the brake pedal during the critical time in which the driver is removing their foot from the accelerator pedal and placing it onto the brake pedal. Thus the ETBS is able to begin the process of vehicle deceleration at greater efficiency in comparison to the traditional method in which a delay exists whilst the driver responds and then applies foot pressure to the brake pedal.
The driver can select between ETBS ON or OFF by pressing a button on the dashboard or by placing their foot on the brake pedal which switches the ETBS to OFF.