| 摘要 |
An inexpensive system for measuring and controlling the height of the platform of a lift, especially of a non-fixed lift such as fork-lift or scissors-lift. By the use of a time-monitoring microprocessor, this system carries out such measuring and controlling over a continuous range of height even though the direct-measuring operations just involve a small, discrete number of surrogate-height-markers and one or two off/on sensors. This is accomplished by incorporating into the control system (a) a geometric model relating the height of the platform to the value of a surrogate parameter and (b) dynamic model describing how the surrogate parameter changes with time during ascent and descent of the platform. With this data, the microprocessor can control the platform precisely, causing it to move to any vertical position within its normal range. The resolution is limited only by the precision of the geometric and dynamic models. This system can also incorporate in a unified way, and implement, upper and lower end-of-travel limits necessary to prevent damage to the lift mechanism, as well as instructions regarding desired platform movement whenever the platform reaches any particular key height.
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