Highly-Integrated Hydraulic Smart Actuators and Smart Manifolds for High-Bandwidth Force Control

Abstract

Hydraulic actuation is the most widely used alternative to electric motors for legged robots and manipulators. It is often selected for its high power density, robustness and highbandwidth control performance that allows the implementation of force/impedance control. Force control is crucial for robots that are in contact with the environment, since it enables the implementation of active impedance and whole body control that can lead to a better performance in known and unknown environments. This paper presents the hydraulic Integrated Smart Actuator (ISA) developed by Moog in collaboration with IIT, as well as smart manifolds for rotary hydraulic actuators. The ISA consists of an additive-manufactured body containing a hydraulic cylinder, servo valve, pressure/position/load/temperature sensing, overload protection and electronics for control and communication. The ISA v2 and ISA v5 have been specifically designed to fit into the legs of IIT's hydraulic quadruped robots HyQ and HyQ-REAL, respectively. The key features of these components tackle 3 of today's main challenges of hydraulic actuation for legged robots through: (1) built-in controllers running inside integrated electronics for high-performance control, (2) low-leakage servo valves for reduced energy losses, and (3) compactness thanks to metal additive manufacturing. The main contributions of this paper are the derivation of the representative dynamic models of these highly integrated hydraulic servo actuators, a control architecture that allows for highbandwidth force control and their experimental validation with application-specific trajectories and tests. We believe that this is the first work that presents additive-manufactured, highly integrated hydraulic smart actuators for robotics.

Development of Novel Bioreactor Control Systems Based on Smart Sensors and Actuators

“…In some studies, it refers to actuators made of "smart materials" that have intrinsic characteristics of built-in sensors, actuators, and control mechanisms in their microstructures. In the second case, it refers to an intelligent instrument (like a DC motor or valves) that serves as an actuator in process control (Barasuol et al, 2018). Here, we will discuss smart actuators according to the second definition.…”

“…Smart actuators have been widely used for the control of vehicles and robots and in the biotechnology industry (Perotti et al, 2006;Van Loon, 2015;Barasuol et al, 2018). Perotti et al (2006) reported a VHM smart actuator for a liquid hydrogen storage system, with emphasis on its self-diagnosing function.…”

A Data-Driven Multi-Scale Online Joint Estimation of States and Parameters for Electro-Hydraulic Actuator in Legged Robot

“…Then combine the above two equations (Equation (16) and (17)) (14). Bring equation (18) into equation (14), and finally get the function form of parameter measurement matrix as follows. From equation (19), C θ k contains the generalized state vector χ 2 , so it is an iterative variable on the fast-varying time scale.…”

“…On the basis of all measurable states, Yuan et al [15], [16] and Peran [17] have used the open-loop input and output data of electro-hydraulic system collected from the experiment to estimate the parameters of a nonlinear gray box model offline on MATLAB's System Identification Toolbox. Victor et al [18] has measured the servo spool displacement, flow and input current curves on the experimental platform and estimated the servo valve parameters (port gain) by a fitting method. Moon [19] has adopted the recurrent incremental credit assignment neural network and genetic algorithm to off-line estimate the system parameters of nonlinear electro-hydraulic servo system, such as mass, viscosity coefficient, spring constant and effective bulk modulus.…”

Active Compliance Control on the Hydraulic Quadruped Robot With Passive Compliant Servo Actuator

“…Therefore, the responsiveness of the hydraulic servo actuator to impact is poorer than that of the torque motor. To solve this problem, a new integrated smart actuator (ISA) developed by Moog in collaboration with IIT [23] has been successfully applied to the quadruped robot. Its body is additively manufactured (AM) in a titanium alloy, allowing a very compact design with integrated flow paths and wire channels.…”