Ocena przydatności modułów nawigacji bezwładnościowej w bezdotykowych pomiarach położenia kątowego członów maszyn roboczych

Advantages of automation in industrial vehicles and work machines are numerous. Even partial automation of work machine’s functions contribute to significant improvement in safety, efficiency and precision. For example, risk of accidental damage of power cables and water or gas pipes planted underground can be reduced by application of excavation control system with digging depth limiter. Industrial vehicles equipped with operator assistance systems, e.g. dozers and graders fitted with blade positioning systems, can be driven at higher speed then conventional ones, while performing the same duties. They are also able to accomplish particular task after smaller number of iterations. What is more, costs of surveyors’ and highly experienced operators’ salaries can be declined. Eventually, machines enriched by operator assistance systems, e.g. excavator having a grade control system onboard, can be involved in very unusual and precise works as slope grading, underwater digging and any works conducted after dusk. On the other hand, purchase and installation costs of operator assistance system are relatively high, especially when compared with prices of small industrial vehicles, e.g. so called mini excavators. Cost of said systems could be reduced in many different ways, for example, if cheaper electronic components, e.g. MEMS sensors, were used. Following article presents a contactless method and system for measurement of industrial vehicle’s bodies angular position. The method engages two Attitude and Heading Reference System (AHRS) modules which shall be attached to different work machine bodies. It was empirically verified using two self-made, inexpensive AHRS modules. Both of them consisted of STM32 F4 microcontroller and a triad of triaxial, MEMS sensors: a gyroscope, an accelerometer and a magnetometer. During tests first of modules was fixed to the frame and the second to the bucket of Avant 218 mini loader. Angular position of bucket with respect to vehicle frame was measured. Industrial grade, electronic GEMAC IS2A60P20-0 inclinometer and an optical instrument were used as reference tolls. Achieved results revealed overall error of examined system which is smaller than 1.05O . Further calculations, based on actual dimensions of IHI 35N3 and Komatsu PC750 LC-6 excavators’ arms, proved that the examined system is applicable for excavator arm bodies angular position identification. The distortion of bucket tip coordinates estimation using presented system was computed. In case of bigger Komatsu PC750 vertical and horizontal distortion equaled, respectively, 350 mm and 195 mm. In case of smaller IHI 35N3 both errors turned out to be at least 2.3 times smaller. Summing up, solution examined within the article fits small industrial vehicles particularly well. That is why an idea of a simple and readily available digging depth control system for mini excavators based on presented solution has been conceived. In order to embody said idea, presented system shall be enriched with two additional AHRS modules and operator-system interface, which would enable necessary adjustments. The system should be provided with dimensions of each body of excavator arm and maximum allowable digging depth. A LED or a sound signal could alert the operator in case of exceeding the established limit.