Skid control method

In a method of of operating a processor controlled system for controlling a wheel braking apparatus in a vehicle, said system including wheel speed sensor means for producing pulses representative of wheel speed a free-running counter for counting clock pulses supplied thereto, and a memory for selectively storing the contents of said free-running counter, said method including determining the wheel speed by the steps of:

• (a) generating processor interrupt signals in response to selected ones of successive pulses from said wheel speed sensor means;
• (b) in response to a respective one of said interrupt signals, storing, in a prescribed location in memory, the contents of said free-running counter at the time said respective interrupt signal is generated, and transferring the contents of said prescribed and successively adjacent locations in memory to the location in memory immediately adjacent said prescribed location and successively adjacent locations in memory, respectively;
• (c) selectively determining the difference between the contents of said prescribed location in memory and the contents of one of said successively adjacent locations in memory;
• and
• (d) determining wheel speed in accordance with the difference determined in step (c).

A method of determining wheel speed for a wheel containing apparatus employing a wheel speed sensor;

• a control circuit including therein a microcomputer, calculating the wheel speed on the basis of the pulse signal from said wheel speed sensor, and delivering a wheel control signal when the wheels slip;
• and a wheel movement control apparatus for controlling the movement of wheels, wherein said microcomputer comprises a free-running counter for counting clock pulses and a memory for storing the content, or count values, of said free-running counter, and wherein the said method comprises:
• a first step of forming an interrupt processing signal by the use of said pulse signal from said wheel speed sensor;
• a second step of interrupting the program under execution and storing in the head location of said memory the count value of said free-running counter at the time when said interrupt processing signal is delivered;
• a third step of transferring the above stored count value of said free-running counter from said head location to the second location in response to the interrupt processing signal delivered after one to several cycles of said pulse signal, storing the count value of said free-running counter at that moment in said evacuated head location, and storing the count values from said head location downward in said memory in order of arrival;
• a fourth step of calculating a difference between the values stored in said head location and a predetermined location;
• a fifth step of determining the number of wheel speed pulses to be used for calculating an average in accordance with the magnitude of said difference obtained in said fourth step and then selecting the location in said memory from which the stored value is taken out;
• a sixth step of calculating a difference between the values stored in said head location and said location selected in said fifth step and then obtaining the average wheel speed;
• and
• a seventh step of calculating the wheel speed from the result obtained by said sixth step.

A method of determining wheel speed in a processor-controlled system for controlling a wheel-containing apparatus, said system including wheel speed sensor means for producing pulses representative of wheel speed, a free-running counter for counting clock pulses supplied thereto, and a memory for selectively storing the contents of said counter, said method including the steps of:

• (a) generating processor interrupt signals in response to selected ones of successive pulses from said wheel speed sensor means;
• (b) in response to a respective one of said interrupt signals, storing, in a prescribed location in memory, the contents of said free-running counter at the time said respective interrupt signal is generated, and transferring the contents of said prescribed and successively adjacent locations in memory to the the location in memory immediately adjacent said prescribed location and successively adjacent locations in memory, respectively;
• (c) selectively determing the difference between the contents of said prescribed location in memory and the contents of one of said successively adjacent locations in memory;
• and
• (d) determining wheel speed in accordance with the difference determined in step (c).