Aircraft braking control

Apparatus for controlling an aircraft braking system that comprises at least one first side braking means for braking a wheel positioned on a first side of a longitudinal axis of an aircraft and at least one second side braking means for braking a wheel positioned on a second side of the longitudinal axis, said apparatus comprising control means for processing respective indications of braking effect of the braking means and in response to the result of said processing issuing control signals for controlling braking forces applied by the braking means, said indications of braking effect being determined based on wheel speed of the respective wheel and an aircraft speed value obtained without reference to wheel speed, each indication of braking effect comprising a brake slip ratio calculated using the equation:

• brake
• 
• 
• slip
• 
• 
• ratio
• =
• air
• 
• 
• craft
• 
• 
• speed
• -
• wheel
• 
• 
• speed
• aircraft
• 
• 
• speed
• said control signals being calculated to equalize said brake slip ratios, thereby to cause the braking force applied on said first side of the longitudinal axis by said at least one first side braking means to balance the braking force applied on the second side of the longitudinal axis by said at least one second side braking means.

A method of controlling brakes on an aircraft having at least one first side braking unit for braking a respective wheel positioned on a first side of a longitudinal axis of an aircraft and at least one second side braking unit for braking a respective wheel positioned on a second side of the longitudinal axis, said method comprising processing respective measurements of performance of the braking units which are calculated using a wheel rotational speed for the respective wheel and an indication of aircraft speed obtained without reference to the wheel speed, the respective measurements of performance are a slip ratio being calculated using the equation:

• brake
• 
• 
• slip
• 
• 
• ratio
• =
• air
• 
• 
• craft
• 
• 
• speed
• -
• wheel
• 
• 
• speed
• aircraft
• 
• 
• speed
• and, according to a processing output, issuing command signals for controlling the respective braking forces applied by the braking units calculated to equalize said brake slip ratios, thereby to obtain a force balance between the braking forces applied on the first side of the longitudinal axis by the at least one first side braking unit and the force applied on the second side of the longitudinal axis by the at least one second side braking unit.