Braking system, which employs angular accelerometer to control wheel braking and results in low level of tire slip, has been developed and tested. Tests indicate that system is feasible for operations on surfaces of different slipperinesses. System restricts tire slip and is capable of adapting to rapidly-changing surface conditions

Dreher, R. C.

Nayadley, J. R., Sr.

Sleeper, R. K.

English

NASA Technical Reports Server

December 1973	 B7340419 
•	 NASA TECH BRIEF 
Langley Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Accelerometer-Controlled Automatic Braking System
- 
.
An automatic braking system, which employs an 
angular accelerometer to control wheel braking and 
results in a low level of tire slip, has been developed 
and tested. The tests, conducted on a rotating-drum 
dynamometer as well as a ground vehicle, indicate that 
this braking system is feasible for operations on surfaces 
of different slipperinesses. The system restricts tire 
slip and is capable of adapting to rapidly-changing 
surface conditions. Tests, which led ultimately to a 
locked-wheel skid, revealed that wheel lockup was 
delayed by the controlled braking action and thus 
provided time for possible corrective action. This system 
results in good steering capability, as it permits little 
slip in the tire-surface interface. 
The basic components of the accelerometer-controlled 
braking system are shown schematically in the illustra-
tion. They consist of a wheel angular accelerometer, a
high-speed solenoid-operated brake-control valve with 
adjustable inlet and outlet orifices, a set of disk brakes 
installed on a wheel-and-tire assembly, and electronic 
circuitry to control the valve in an on-off manner. 
The accelerometer monitors wheel behavior during 
braking; when wheel deceleration exceeds the pre-
selected or threshold command-deceleration level, a 
signal from the electronic control circuitry commands 
the control valve to release the brakes, until an 
acceptable level of deceleration (below command-de-
celeration level) is once more attained. Brake pressure is 
applied as long as wheel deceleration remains below the 
command-deceleration level; it is expressed in terms of 
deceleration and is varied by a potentiometer in the 
electronic circuitry. The adjustable orifices are used to 
optimize the action of the brakes, by controlling the 
rate at which brake hydraulic pressure is allowed to rise 
Supply Pressure 
fL1 Inlet Orifice 
e<o 
Brake- 
Command	 Control	 lh^ 
Deceleration	 Valve
Signal
Electronic	 Pressure 
+	
Circuitry	 c >0 Application e 
Pressure 
Release
Tire 
Brake
Angular 
Accelerometer 
Wheel 
JAt 
I-Surface 1 
Outlet Orifice	 Wheel 
Deceleration 
To Reservoir	 Signal 
•
	
Accelerometer-Controlled Automatic Braking System
(continued overleaf) 
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https://ntrs.nasa.gov/search.jsp?R=19730000419 2020-03-17T07:27:40+00:00Z
and decay. Braking action, with this circuitry, consists 
of the cyclic application and release of the brakes until 
the wheel stops rotating. 
Note: 
The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $1.45) 
Reference: NASA TN D-6953 (N72-33018) Experi-
mental Investigation of an Accelerometer-Controlled 
Automatic Braking System
Patent status: 
NASA has decided not to apply for a patent. 
Source: R. C. Dreher, R. K. Sleeper, and
J. R. Nayadley, Sr.
Langley Research Center
(LAR-1 1383)
. 
fl 
B73-10419	 Category o6,07


Accelerometer-controlled automatic braking system

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