Variable Displacement Hydraulic Pump for Mobile Robotics Efficiency
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Solution Overview
Problem
Existing hydraulic actuation systems for mobile robotics are inefficient, particularly when powered by batteries, due to the low efficiency of hydraulic servo valves, leading to significant energy wastage and heat loading, and current alternatives like electric motors with high inertia or pneumatic actuators are not suitable for intensive mobile applications.
Innovation Solution
A high-efficiency hydraulic actuation system utilizing a single miniature variable displacement hydraulic pump driven by a common electric motor, where each axis is controlled by a variable displacement pump with an individual displacement motor, optimizing energy use and reducing inertia by reflecting all loads back to a single drive shaft, enabling bidirectional control and power regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydraulic servo valves are used for control, then control performance is improved, but system efficiency deteriorates significantly
Solution Approach 1:
The patent extracts the problematic hydraulic servo valve from the system and replaces it with a variable displacement pump. This removes the source of energy inefficiency while preserving the control function through electronic displacement control of the pump, thereby resolving the contradiction between control performance and energy efficiency.
Solution Approach 2:
The patent replaces the mechanical hydraulic servo valve control system with an electronically controlled variable displacement pump system. This substitution eliminates the need for dissipative valve mechanisms while maintaining precise control through electronic displacement adjustment, thus improving efficiency without sacrificing control performance.
2Measurement precision
If electric motors with high ratio transmission are used, then control precision is improved, but inertia at the axis increases
Solution Approach 1:
The patent segments the control function from the power transmission function. By using a variable displacement pump, the control precision is achieved through electronic displacement control rather than mechanical transmission components, thereby eliminating the need for high ratio transmissions and reducing axial inertia while maintaining control precision.
Solution Approach 2:
The patent replaces mechanical transmission systems (harmonic drives, ball screws) with a variable displacement pump system that provides direct drive. This substitution eliminates heavy transmission components while maintaining precise control through electronic displacement adjustment, thus reducing inertia without compromising control precision.
3Device complexity
If fixed displacement pumps are used, then system simplicity is improved, but energy efficiency deteriorates due to inability to match flow demand
Solution Approach 1:
The patent transforms the static fixed displacement pump into a dynamic variable displacement pump. This allows the pump to adjust its flow output dynamically to match the actual hydraulic demand of the system, eliminating energy waste from constant flow generation while maintaining relatively simple system architecture through a single pump unit.
Solution Approach 2:
The patent changes the displacement parameter of the pump dynamically to match system demand. By adjusting the pump displacement based on actual hydraulic needs, the system achieves high energy efficiency without requiring complex multiple pump configurations, thus resolving the contradiction between simplicity and efficiency.
4Ease of operation
If multiple electric motors are used for each axis, then independent control is improved, but system weight and complexity increase
Solution Approach 1:
The patent merges multiple drive functions into a single variable displacement pump system. By using one pump with electronic displacement control instead of multiple independent motors, the system achieves independent control of each axis through electronic management while significantly reducing overall system weight and complexity.
Solution Approach 2:
The variable displacement pump serves multiple functions: it provides hydraulic power to multiple axes simultaneously and enables independent control of each axis through electronic displacement adjustment. This multi-functionality eliminates the need for separate motors for each axis, reducing weight while maintaining independent control capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system achieves higher efficiency and control bandwidth than traditional hydraulic servo valve systems, reduces energy consumption, and allows for power regeneration, making it suitable for battery-powered mobile applications while minimizing weight and noise.
Implementation Method 1
Like a fixed displacement pump they convert rotary shaft motion into hydraulic fluid motion but, unlike a fixed displacement pump, a variable displacement pump has a rotary shaft input and an additional input that controls the displacement of the pump
Implementation Method 2
The power input shaft of each variable displacement pump is connected to a common rotary drive shaft, and each variable displacement pump has an individual electric motor controlling the displacement of that variable displacement pump
Data Source
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AI summary
The invention is directed to controlling a hydraulic actuation system (50) having at least one degree of freedom, a prime mover (101), at least one actuation module (110, 120, 130) and a controller (103), with each actuation module (110, 120, 130) including: an over-center variable displacement pump (112 and 113; 601; 801) having a power input connection configured to power the pump from the prime mover (101) and a displacement varying input for varying the displacement of the pump; a displacement varying actuator (111, 121, 131) configured to modulate the displacement varying input of the pump; an output actuator (1 15) in direct communication with the pump, the output actuator (115) configured to drive a corresponding degree of freedom; and at least one sensor (116, 126) establishing a feedback measurement that represents a force or motion of the output actuator (115). Based on a value of each feedback measurement, the force or motion of the output actuator (115) is regulated by controlling the prime mover (101) and the displacement actuator (111, 121, 131) for the output actuator (115).