4751 4.4 Relative Velocity:Translational and Rotational V.Mechanical Revolution Counters and Timers Mechanical Revolution Counters(with or without built-in timers) are available. They are usually supplied with a variety of rubber-tipped wheels which transmit by friction the motion to be measured to the counter input shaft. 48/51 4.4 Relative Velocity:Translational and Rotational I.Calibration ll.Velocity by Electrical Differentiation of Voltage Signals Il.Average Velocity from Measured△xand△t IV.Mechanical Flyball Angular-Velocity Sensor V.Mechanical Revolution Counters and Timers VL.Tachometer(转速表)Encoder Methods VII.Laser-Based Methods VIII.Radar(Microwave)Speed Sensors IX.Stroboscopic Methods X.Translational-Velocity Transducers(Moving-Coil and Moving-Magnet Pickups) XI.DC Tachometer Generators for Rotary-Velocity Measurement XII.Eddy-Current Drag-Cup TachometerV. Mechanical Revolution Counters and Timers ‹ Mechanical Revolution Counters (with or without built-in timers) are available. ‹ They are usually supplied with a variety of rubber-tipped wheels which transmit by friction the motion to be measured to the counter input shaft. 4.4 Relative Velocity: Translational and Rotational 47/51 4.4 Relative Velocity: Translational and Rotational I. Calibration II. Velocity by Electrical Differentiation of Voltage Signals III. Average Velocity from Measured ∆x and ∆t IV. Mechanical Flyball Angular-Velocity Sensor V. Mechanical Revolution Counters and Timers VI. Tachometer (转速表) Encoder Methods VII. Laser-Based Methods VIII. Radar (Microwave) Speed Sensors IX. Stroboscopic Methods X. Translational-Velocity Transducers (Moving-Coil and Moving-Magnet Pickups) XI. DC Tachometer Generators for Rotary-Velocity Measurement XII. Eddy-Current Drag-Cup Tachometer 48/51