Design scheme of pulse output control of the hotte

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Design scheme of pulse output control of hand pulse generator

hand pulse generator plays a very important role in the leather industry through its tension machine. The built-in encoder converts the corner signal into pulse sequence signal. In order to meet the requirements of the control system for direction detection and pulse counting, the hand-held pulse generator generally has two phases a and B output in the form of differential signals. It can produce pulses only when it is shaken, and the frequency of the pulse sequence is proportional to the angular velocity of the shake. As a common component, hand pulse generator has been widely used in all kinds of CNC systems. The control system combines the "magnification selection" of the control board, and takes the product of the number of pulses generated by shaking and the magnification as the total pulse output. At present, the domestic peek market has not been fully opened to stepping or servo motor and other executive parts. When the pulse frequency generated by the hand-operated pulse generator is high and the magnification selection gear is also high (e.g“ × At 100 gear), the control system needs to count the pulse sequence generated by changing the sealing ring by the hand shaking pulse generator at this time, and calculate the number of output pulses after the magnification and output them to the execution part in time. In the actual design process, the hardware structure of some control systems is complex, or the phenomenon of pulse missing or output pulse lag may occur because the control system is too late to deal with it. Based on AT89S52, taking the development of the hand pulse generator module in the CNC lathe control system as an example, this paper explains the software and hardware implementation method of reading the handwheel pulse signal and outputting the pulse to control the motor. Due to the simple method and mature technology of handwheel rotation direction detection, this content is not detailed in the article

design analysis and scheme determination

considering the real-time response characteristics of the handwheel, the pulse signal of the output control motor should follow the input pulse signal of the handwheel in real time, especially when the handwheel is in a high "magnification selection" position, the control system is required to complete continuous input signal detection and output of human pulse in a short time. Many control systems choose the control mode of upper and lower machine tasks, The lower computer detects the pulse signal of the handwheel and counts it. The upper computer reads the pulse count value of the lower computer regularly, calculates and outputs the pulse to the stepping or servo and other executive parts in combination with the magnification selection. The hardware structure of this scheme is relatively complex, and the communication process of the upper and lower computers is likely to affect the lower computer's counting of the handwheel pulse signal and cause pulse missing, or affect the upper computer's output pulse to the executive part, resulting in output lag or discontinuous pulse output and motor vibration. But on the other hand, if the single CPU working mode is adopted, it is bound to put forward higher requirements for the processing speed and computing power of the CPU. Combined with the actual working condition of hand shaking handwheel, for handwheel with scale resolution of 100 pulses/circle and timely reinforcement, the manual quick shaking handwheel is generally 3~4 cycles/s under normal working condition, and the corresponding time range of each pulse occurrence cycle is 2500~3300 us. Assuming that the pulse equivalent of the system is 0.001 mm, select the handwheel "magnification to the gear position“ × 100. Divide the above time into 100 parts, that is, let the motor output 100 pulses evenly in this time cycle, and the output cycle of each pulse can be calculated as 25 ---33 9s. Through experimental verification, this task processing is completely competent for the AT89S52 single chip microcomputer whose working frequency is allowed to be increased to 33 MHz

based on the above analysis, the design scheme is determined as follows: first, measure the shortest pulse period sent by the hand-held pulse generator when the hand wheel is in some extremely fast operating states under the abnormal working condition, and store the value in the memory of the single chip microcomputer. Obviously, in other operating states, the pulse generation cycle tindm requires people to detect each falling edge pulse jump signal sent by the hand-held pulse generator in the way of hardware called J break, and immediately output the number of pulses specified by the magnification to the execution part. The pulses output to the motor driver are evenly arranged in t time, Thus, it can be ensured that the output of the specified number of pulses has been completed before the arrival of the next pulse after T. The above working process is shown in Figure 1

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