# Experimental Study of the Direct Drive Hydraulic System with the Torque Mode

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## Abstract

**:**

## 1. Introduction

## 2. Introduction to the Direct Drive Hydraulic System

## 3. Transfer Function of the Direct Drive Hydraulic System

## 4. Introduction to the Experimental System

## 5. Results and Discussion

## 6. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Conflicts of Interest

## Nomenclature

${p}_{1}$ and ${p}_{2}$ | pressures of the two cavities of the cylinder (Pa) |

${A}_{1}$ and ${A}_{2}$ | piston areas of the two cavities of the cylinder (m^{2}) |

$G$ | gravity load (N) |

${K}_{t}$ | motor torque coefficient (N × m/A) |

${i}_{q}$ | current of the q axis (A) |

$J$ | moment of inertia of the motor-pump unit (kg × m^{2}) |

$B$ | viscous damping coefficient of the motor-pump unit (N × m × s/rad) |

${V}_{p}$ | sum displacement of the coaxial gear pump (m^{3}) |

${D}_{1}$ and ${D}_{2}$ | displacements of the two pump units (m^{3}) |

${p}_{L}$ | load pressure (Pa) |

$\eta $ | volume efficiency |

$n$ | speed of the motor-pump unit (rpm) |

${K}_{ce}$ | leakage coefficient (m^{3}/Pa) |

${B}_{c}$ | damping coefficient of the cylinder (N × s/m) |

${M}_{t}$ | load mass (kg) |

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**Figure 1.**The structure and the direct drive hydraulic system of the direct drive 6-DOF (6 degree of freedom) parallel mechanism.

**Figure 2.**Schematic diagram of the simplified single DOF(degree of freedom) direct drive hydraulic system.

**Figure 7.**The response diagram of the system with the torque mode and PD (proportion differentiation) control strategy.

**Figure 8.**The sinusoidal signal response diagram of the system with the speed mode and proportion control strategy.

**Figure 10.**Bode diagram of the system with both PD control strategy and DPF (dynamic pressure feedback) control strategy.

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**MDPI and ACS Style**

Zhang, C.; Jiang, H.
Experimental Study of the Direct Drive Hydraulic System with the Torque Mode. *Energies* **2021**, *14*, 941.
https://doi.org/10.3390/en14040941

**AMA Style**

Zhang C, Jiang H.
Experimental Study of the Direct Drive Hydraulic System with the Torque Mode. *Energies*. 2021; 14(4):941.
https://doi.org/10.3390/en14040941

**Chicago/Turabian Style**

Zhang, Chenyang, and Hongzhou Jiang.
2021. "Experimental Study of the Direct Drive Hydraulic System with the Torque Mode" *Energies* 14, no. 4: 941.
https://doi.org/10.3390/en14040941