This type of hill start assist has been developed for a manually driven car and assists the driver to negotiate an inclined terrain by retaining the brakes even after the driver removes his foot from the brake pedal. The brake force gradually decreases depending on the rate of acceleration determined by the clutch position.
There are different sensors placed in the vehicle that give the information regarding the gear position (forward or reverse), gradient and wheel rotation direction.
Whenever a vehicle starts to rollback while moving up an incline, the driver’s first instinct is to apply the brakes (and clutch). In this case IDA engages, enabling the driver to remove the foot from the brake pedal and on to the accelerator pedal without letting the car to rollback again.
If the vehicle stalls in the process of negotiating an incline and the driver applies the brake to hold the vehicle, the moment clutch is pressed fully after starting the engine, IDA is engaged.
The gear position sensors help in determining whether the vehicle is intended to move along the incline or against it. This avoids unnecessary engagement of IDA while parking on inclined surface.
The structural part of IDA comprises of:-
• Piston cylinder arrangement with incompressible fluid inside.
• A reservoir for storing the fluid.
• Valves i.e. Check valve and Solenoid valve.
• A potentiometer to measure the voltage according to the position of the clutch pedal and subsequently controlling the opening and closing of the solenoid valve.
During normal running when IDA is disengaged, solenoid valve remains open thus ensuring return back of the brake pedal. Solenoid valve is closed when the sensors send signals after determining the car is starting to roll back in an incline. Now when the driver starts to accelerate and slowly removes his foot from the clutch pedal, solenoid valve starts to open again according to the position of the clutch and thus releases the brake slowly. Check valve ensures one way flow of the fluid in the piston. It helps keeping the brake pedal engaged when IDA is working.