Brake control and anti-skid system

A combined brake and anti-skid controller for a wheeled vehicle comprising:

• a continuous source of pressurized hydraulic fluid;
• a hydraulically actuated wheel rotation braking device which responds to applied hydraulic pressure to apply a braking force to a wheel of the vehicle to arrest wheel motion;
• a low pressure hydraulic fluid return;
• a flow control valve in a circuit between the source, the return, and the braking device for selectively directing fluid from the source to the braking device and from the braking device to the return;
• means for sensing the fluid pressure applied to the wheel rotation braking device;
• and
• means responsive to the sensed pressure and for controlling the control valve to thereby influence the flow and distribution of fluid between the braking device and the return.

A process of monitoring the motion of a vehicle braked wheel and controlling the application of a hydraulically applied braking force to the wheel comprising the steps of:

• introducing a controlled slip between the wheel and a surface on which the wheel rolls to arrest wheel motion;
• deriving signals indicative of the slip and of the braking force;
• periodically incrementing the slip indicative signal;
• sensing the resulting change in braking force indicative signal;
• and
• effecting one of reducing the hydraulically applied braking force in the event the resulting change proceeds opposite from the increment and increasing the hydraulically applied braking force in the event the resulting change proceeds in the same direction as the increment.

A combined brake and anti-skid controller for a wheeled vehicle comprising:

• means for computing an estimate of the speed of a wheel of the vehicle including means for sensing wheel motion and providing a signal indicative thereof, means for combining the motion indicative signal with a computed estimate signal representing the detected motion to form a third signal which is the difference between the detected motion and the calculated estimate thereof, means for integrating the third signal to provide a signal representative of the first derivative of the wheel motion, means for performing a second integration of the third signal, and means for feeding back the result of the second integration as the computed estimate of the speed of the wheel;
• means for comparing the estimated speed of the wheel to the theoretical speed the wheel should be experiencing in a free wheeling condition;
• a hydraulic braking system for applying a brake force to the wheel;
• and
• means including a flow control valve for reducing the braking force applied by the hydraulic system when the comparison indicates estimated wheel speed is a calculated threshold difference below the theoretical wheel speed.

A combined brake and anti-skid controller for a wheeled vehicle comprising:

• means for sensing the motion of a vehicle wheel;
• means for comparing the sensed motion of the vehicle wheel to the theoretical motion the wheel should be experiencing in a free wheeling condition;
• a flow control valve in a circuit between a source of pressurized hydraulic fluid, a low pressure hydraulic fluid return, and a hydraulically actuated braking device, the flow control valve directing selectively fluid from the source to the braking device and from the braking device to the return;
• and
• means including the flow control valve for diverting additional fluid to the return when the comparison indicates actual wheel motion is a predetermined threshold difference below the theoretical wheel motion.