【正文】 Such modification increases performance with reduced silicon area and permits to include the sensor and other important hardware. The fabrication of such microsystem does not require extra technological steps and can be fabricated by usual CMOS digital processes.3. EncoderThe usage of the Hall sensors and special encoders in the known ABS reduces to the significant price rise for the system, especially for 4th wheels. Due to the usage of the active wheel speed inductive sensor the encoder for the proposed sensor microsystem does not require to use the plex construction with oriented magnetic particles. The encoder can be made from the cheaper material, for example, soft steel.The geometrical teeth sizes of encoder and one of the possibleorientation are shown in Figure 2. Some variations of the geometrical teeth sizes and orientation are possible.Figure 2. Teeth geometry for still encoder4. Adaptive Method of Rotation Speed MeasurementsIn the proposed approach, based on the so called programoriented method of dependent count (method with nonredundant reference time interval) [10], the simultaneous synchronous cyclic frequency measurement of sensor signals is carried out. This frequency is proportional to the rotation speed of wheels. The time of measurement for this method is minimum possible. The quantization error as well as the time of measurement practically does not depend on rotation speed no exceed beforehand given values. Therefore the sampling rate of the output signal from the sensor ensures the arrival of information in all 4 channels in real time.Each measuring channel is realised on the virtual level inside the functionallogicalarchitecture of microcontroller.Let us define this sampling rate for the concrete example. Let automobile is driving with speed of 240 km/h, . 67 m/s, and the time of measurement should not exceed sec. (. for this time the automobile will drive no more than m at the maximum speed). Let us define the time of quantization having set the relative error of measurement from % up to % and reference frequency f0 = 1/T0 = 1 MHz:where N is the minimum number of impulses, which should pass to the counter of the reference frequency according to the necessary relative error d. This time interval will varied within the limits 2 184。 4 ms at d = % and 184。 ms at d = %. In case, when f0 = 10 MHz this time can be reduced in 10 times. Therefore, during sec will be carried out 25 184。 50 measurements per second at d = % and 250 184。 500 at d = %.Therefore, the 4 channel frequencytocode conversion of the ABS control block will execute simultaneous synchronous frequency measurements practically in the real time. So high sampling rate of signal allows to reduce specific time of measurement up to sec without accuracy decrease.Adaptive possibilities, . automatic choice of the reference time interval depending on the given error of measurement, allow to use the advanced ABS algorithm. Whereas speed is one of the major ABS performance, the required error of measurement can be selected by the microcontroller depending on the current rotation speed due to the adaptive possibilities of the method. It will allow to increase speed at measurement of critical rotation speeds.The system of measurement will also function successfully at the absence of wheel slip when the rotation speed can be varied in a wide range: from zero speed up to maximum. The essential advantage of the method is the possibility of digital measurement of acceleration with the similar high accuracy and without extra circuitry. It opens the possibility to use the control method not only for speed, but also for acceleration of rotation as well as bined control method. It opens perspectives to develop the modern highend ABS for the future needs. For example, road hazards may cause the ABS to function unexpectedly. With theusage of the proposed approach the ABS will make up for road conditions or bad judgment. Due to minimal possible circuitry necessary for sensor output processing, the metering microcontroller core can be easily embedded into the microsystem.5. Sensors NetworkSensors network with multilayers architecture is widely used in systems, with distributed intelligence like modern car. The advantage of such architecture () consists that high layers use the information ensured with lower layers and do not pressing in detail of operation the last ones.Figure 3. Multilayers ArchitectureThe sensor microsystems (one for each wheel) are connected in the network as shown in Figure 3. The proposed microsystem realises also some interfacing functions. First, it is low level hardware and software interface (sensor microcontroller), at second high level Controller Area Network (CAN) interface, that has been developed for automotive applications to replace the plex cable in cars by a two wire interface [11].6. Experimental Results The aim of the experiments was to test the selected sensor element and to determinate the metrological reliability in specified measuring range 0 184。 3000 rpm at the specific geometrical sizes of the encoder with 44 steel teeth, to determinate the working air gap and determination of the fitness of the sensor element for the usage in microsystem for ABS.The oscillograms of the sensor39。s output at ~ 3000 rpm are shown in Figure 4. The oscillograms correspond to the sensor operation with the input block. The supply voltage for the sensor was +12 V. The sensor has demonstrated the steady operation at change of supply voltage in the range from + up to + 30 V. The measurements were carried out at the working air gap mm.Figure 4. Oscillogram on the sensor’s output at ~ 3000 rpm(1V/div and ms/div)As the rotation speed is connected with the sensor39。s output frequency by the following dependence:(where z = 44 is the number of teeth), the sensor can b