Design Of Pedal Adjustment Mechanism For Ergonomics Test Bench Of Agricultural Equipment Cab

With the rapid development of science and technology,agricultural equipment has been widely used in tractors,sprayers,harvesters and other agricultural machinery.Because the working environment of agricultural equipment is complex and driving environment is bad,it is very important to improve the safety and comfort of agricultural equipment cab.In the development of agricultural equipment cab,the use of cab ergonomics test-bed can evaluate the comfort of cab,and help manufacturers develop cabs that conform to ergonomics principles.Among them,pedal is one of the main components affecting the comfort of agricultural equipment drivers.Uncomfortable driving easily causes driving fatigue,muscle soreness,and even causes driving safety accidents.Therefore,in the design of agricultural equipment cab,it is of great significance to develop a pedal mechanism with automatic regulation function.In this paper,the pedal adjusting mechanism is developed on the basis of the original ergonomics test-bed for the cab of agricultural equipment.The mechanism is mainly composed of pedal adjusting mechanical structure and control system with PLC as the core.The pedal adjusting mechanism can restore the relative position of pedal center point and seat sign point(SIP)of almost all agricultural equipment cabs on the market.The ergonomics is used to quantitatively evaluate the driver’s operational comfort and provide reasonable layout scheme and guidance for cab layout design.Firstly,on the basis of J833 human body size data standard created by SAE,the reference point(H point)of pedal adjusting mechanism design is determined,the simplified model of human body rigidity is established,and the motion range of human ankle reference point(BOF point)is calculated in MATLAB.Combining this range with national standard,the spatial adjusting range of pedals in pedal adjusting mechanism is determined.Secondly,according to the design requirements of the pedal regulating mechanism,the mechanical structure design of the pedal regulating mechanism and the selection of related components are completed.The ANSYS static analysis module is used to check the strength of key components and complete the physical construction of pedal regulating mechanism.Then,the control system of pedal adjusting mechanism is designed.With the MT6103ip HMI as the upper computer,the configuration control interface of HMI is compiled in EB Pro,Siemens S7-200 CPU224 PLC as the lower computer,and the PLC control program is compiled in STEP7.The communication between PLC and HMI is realized through RS485 bus.Finally,the pedal adjusting mechanism is assembled into the agricultural equipment cab test-bed,and the PLC program and HMI interface are simulated to verify the rationality of the program design,and the debugging of the mechanism is completed.The reliability of the pedal adjusting mechanism.motion is tested by the accuracy test of the pedal adjusting mechanism motion control.The test results show that the maximum linear repetitive positioning accuracy R=0.468 mm and the maximum axis positioning accuracy A＝0.942 mm of the pedal adjusting mechanism meet the design index of the pedal adjusting mechanism.