Kinematics analysis of a FLHL robot parallel-executed cylinder mechanical integration system with force/position hybrid control servo actuator

In this research subtopic, an electro-hydraulic servo four-legged heavy load (FLHL) robot has been designed and developed. This paper proposes an integration layout cylinder design scheme for a non-lightweight hydraulic servo four-legged robot with high loads and torques of hip joint, and derives the mathematical element analysis model for a parallel hydraulic servo cylinder system. The multiple inherent characteristics of the parallel-executed cylinder integration system model are further explored. Based on the controllable functional requirements of interconnected joints and weakening the influence of internal force coupling, a design idea of force/position hybrid control scheme for the parallel-executed cylinder is determined, and then the force/position signal module design unit is used to reversely solve the force/position hybrid control. Considering the inherent requirements of the servo-executed cylinder force control unit module, the implementation process of magnetic flux compensation and speed compensation is discussed in detail. The minimum amplitude controller is applied to the servo-executed cylinder force unit module, and the proportional integrated controller has been determined in the servo-executed cylinder position control unit module. A compound control strategy proposed in this paper is verified on a parallel hydraulic servo platform. The experimental verification results reveal that the values of position/force attenuation amplitude and lag phase are not greater than 9 % and 18°, respectively. In addition, the feasibility of the interconnected implementation of the hybrid control scheme proposed in this paper is further deepened. The effective conclusion of this research will be accepted in the application field of FLHL robot control system

Modelling and simulation of a robust energy efficient AUV controller

Limited on-board energy resources of autonomous underwater vehicles (AUVs) demand design of an appropriate controller to achieve optimal energy consumption while tracking a commanded path accurately for some envisaged applications. The unstructured oceanic environment calls for a robust control law which is capable of handling parametric uncertainties and environmental disturbances. Though switching surface control has been proven to be an effective strategy for underwater operations, it provides no scope for energy optimization. For an energy critical mission, it is desirable to minimize the net control effort through advanced mathematical modelling, even at the cost of compromising accuracy within a reasonable bound. With this aspect in mind, the present work addresses these two issues (i.e. energy and accuracy) together through design of a novel controller based on sliding mode control in association with Euler–Lagrange based classical optimal control. Mathematical modelling and simulation results are presented to demonstrate the effectiveness of the proposed controller with real life parameters of an experimentally validated AUV, designed and developed for 150 m depth of operation at sea