Development of Hydraulic Tough Motors with High Power Density and their Application to a 7-axis Robotic Arm
Development of Hydraulic Tough Motors with High Power Density and their Application to a 7-axis Robotic Arm
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高功率密度液压马达的研制及其在七轴机械臂上的应用
DOI：
10.1109/sii.2019.8700419
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
K. Suzumori
中科院分区：
文献类型：
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作者：
Morizo Hemmi;Ryusuke Morita;Yoshiharu Hirota;Kiyoshi Inoue;Hiroyuki Nabae;G. Endo;K. Suzumori
电动机和减速器的组合被广泛用作机器人致动器。然而，由于机器人存在抗冲击性差、可反向驱动性差等问题，很难在实际灾害环境中使用。工程机械中使用的液压致动器不仅适用于这种环境，而且还具有良好的力密度和功率密度。然而，大多数传统的致动器是大的，重的，并且具有差的可控性，并且难以将这些应用于机器人。在这项研究中，我们开发了两个致动器（半旋转马达和轴向活塞马达），其目的是提高小型化和减轻机器人的重量，并评估其特性。开发的半旋转电机采用纯钛和空心轴形式。它们有助于减轻重量，并简化了液压机器人的组成方法。所开发的轴向柱塞马达是改型的现成马达和特殊的齿型行星齿轮减速器的组合，该齿型行星齿轮减速器预期具有高的反向驱动能力。这两款执行器都能承受35 MPa的高输入压力，并直接配备伺服阀、绝对值编码器和压力传感器，以增强其对机器人的适用性。半旋转马达（高输出、中输出）和轴向活塞马达（中输出、小输出）分别实现了约88.5 [Nm/kg]和105.2 [Nm/kg]的T/M（扭矩/质量）比，这是传统油压马达的5.6倍和8.2倍。在评估测试中，我们确认了通过使用压力传感器估计扭矩的可能性，并发现对于高输出半旋转电机，可以达到额定扭矩的约±13%的精度。此外，作为液压腿式机器人的原型，我们开发了一个具有七个自由度的机器人手臂，它与灾难中使用的四肢电动机器人WAREC-1高度兼容。WAREC-1主要由早稻田大学开发。开发的机器人手臂的长度为1.2米，与WAREC-1相似。机器人的质量为56 kg，比WAREC - 1重;但是，关节扭矩等于或大于WAREC-1。关于可移动范围，通过使用空心轴致动器和旋转接头，WAREC-1能够等于或大于214度。所开发的致动器的功率密度和反向驱动扭矩比（反向驱动扭矩/额定扭矩）比WAREC-1的致动器高5.9倍，小1/26。在演示中，手臂成功地打破了三块混凝土板，每块30毫米厚。
A combination of electric motors and speed reducers are widely used as robot actuators. However, owing to problems such as low impact resistance and poor backdrivability, it is hard to use robots in actual disaster environments. Hydraulic actuators used in construction machines are not only applicable to such environments, but they also have good force density and power density. However, most conventional actuators are large, heavy, and have poor controllability and it is difficult to apply these to robots. In this research, we developed two actuators (a semi-rotary motor and an axial piston motor) with the aim of improving miniaturization and reduce weight for use in robots and evaluated their characteristics. The developed semi-rotary motor utilizes pure titanium and a hollow shaft form. They contributed to weight reduction and facilitated hydraulic robot composing method. The developed axial piston motor is a combination of a remodeled off-the-shelf motor and a special tooth-type planetary gear reducer that is expected to have high backdrivability. Both the actuators can bear high input pressures (35 MPa) and equip servo valve, absolute encoder, and pressure sensors directly to enhance their applicability to robots. The semi-rotary motor (high output, medium output) and axial piston motor (medium output, small output) achieved T/M (torque / mass) ratios of approximately 88.5 [Nm/kg] and 105.2 [Nm/kg], respectively, which are 5.6 times and 8.2 times greater than that of conventional oil hydraulic motors. In the evaluation test, we confirmed the possibility of estimating the torque by using the pressure sensors and found that it is possible with an accuracy of approximately ±13% of the rated torque for the high-output semi-rotary motor. In addition, as a prototype of a hydraulic legged robot, we developed a robot arm with seven degrees of freedom that is highly compatible with the four-limb electrically-actuated robot, WAREC-1, for use in disasters. WAREC-1 was mainly developed at Waseda University. The length of the developed robot arm is 1.2 m, which is similar to that of WAREC-1. The mass of the robot is 56 kg, which is heavier than WAREC – 1; however, the joint torques are equal or greater than those of WAREC-1. With respect to the movable range, it was able to be equal to or more than 214 degrees with WAREC-1 by using hollow shaft actuators and swivel joints. The power density and the backdrive torque ratio (backdrive torque / rated torque) of the developed actuators are 5.9 times higher and 1/26 smaller than those of the actuators of WAREC-1. In the demonstration, the arm succeeded in breaking a stuck of three concrete-boards, each 30mm-thick.