#Poly bridge hydraulics controller series
The proposed system was validated through a series of experiments. To validate that the new actuator can improve the efficiency of hydraulic systems of mobile robots, a robotic arm incorporating a prototype of the new actuator was designed. The actuator selects the most appropriate combination of the effective areas of plunger pistons like the human muscles, to ensure that the maximal output force aligns with the load force. The design proposed here represents a new class of driving methods. The proposed actuator consists of a single power source and multiple plunger pistons, and imitates the configuration of a human muscle, to improve the efficiency and load capacities. To improve the efficiency of mobile robots, in this paper, a new kind of actuator that imitates the driving mechanism of human muscles is innovatively designed and validated through experiments. And improving the efficiency of the drive system is a key factor in improving the load capacity. Limited load capacity is the bottleneck for the practical application of mobile multi-joint legged robots. Merits and limitations of the current design are identified. After an analysis of the real on-off characteristics of a valve, a prototype hydraulic switching converter, inspired by the electric DC-DC Buck converter, is presented and its performance in pressure control mode, relative to a classical proportional valve-controlled system, are assessed.
"Power hydraulics" is a challenging and little explored technology due to the markedly non-linear behaviour of hydraulic systems and the need of components with dynamic specifications that are not readily available off-the-shelf. One response to this challenge is to revisit traditional on-off hydraulic technology and develop "power hydraulic" devices that behave in analogous manner to their power electronic counterparts. However, the low efficiency of proportional control can be a limitation and it is necessary to go beyond the paradigm of proportional flow/pressure control. In robotic applications where high power density, ruggedness and reliability are key requirements hydraulic actuation can be a sensible choice. Indeed, by analogy it can be seen as the equivalent of resistive (rheostatic) motor control.
However despite the sophistication of such valves, from an energetic viewpoint proportional control is dissipative and inefficient. Hydraulic technology evolved in the opposite direction: switching control was not considered, and more and more accurate proportional flow/pressure control devices (servovalves etc) were developed. Over the last 50 years with advances in power electronics, faster and faster static switches have been developed and applied to the control of motors.
This paper is concerned with the application of switching technology to hydraulic actuation.
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