Novel control, haptic and calibration methods for teleoperated electrohydraulic servo systems

摘要

The aim of this thesis is to propose a novel control method for teleoperated electrohydraulic servosystems that implements a reliable haptic sense between the human and manipulator interaction, andan ideal position control between the manipulator and the task environment interaction. The proposedmethod has the characteristics of a universal technique independent of the actual control algorithmand it can be applied with other suitable control methods as a real-time control strategy. Themotivation to develop this control method is the necessity for a reliable real-time controller forteleoperated electrohydraulic servo systems that provides highly accurate position control based onjoystick inputs with haptic capabilities. The contribution of the research is that the proposed controlmethod combines a directed random search method and a real-time simulation to develop anintelligent controller in which each generation of parameters is tested on-line by the real-timesimulator before being applied to the real process. The controller was evaluated on a hydraulicposition servo system.The simulator of the hydraulic system was built based on Markov chain Monte Carlo (MCMC)method. A Particle Swarm Optimization algorithm combined with the foraging behavior of E. colibacteria was utilized as the directed random search engine. The control strategy allows the operatorto be plugged into the work environment dynamically and kinetically. This helps to ensure the systemhas haptic sense with high stability, without abstracting away the dynamics of the hydraulic system.The new control algorithm provides asymptotically exact tracking of both, the position and the contactforce.In addition, this research proposes a novel method for re-calibration of multi-axis force/torquesensors. The method makes several improvements to traditional methods. It can be used withoutdismantling the sensor from its application and it requires smaller number of standard loads forcalibration. It is also more cost efficient and faster in comparison to traditional calibration methods.The proposed method was developed in response to re-calibration issues with the force sensorsutilized in teleoperated systems. The new approach aimed to avoid dismantling of the sensors fromtheir applications for applying calibration. A major complication with many manipulators is the difficulty accessing them when they operate inside a non-accessible environment; especially if thoseenvironments are harsh; such as in radioactive areas.The proposed technique is based on design of experiment methodology. It has been successfullyapplied to different force/torque sensors and this research presents experimental validation of use ofthe calibration method with one of the force sensors which method has been applied to.