14 accepted papers
This letter proposes a novel backdrivable servovalve to implement a torque-controlled electro-hydraulic actuator. The proposed backdrivable servovalve simultaneously contains the characteristics of a flow-control servo valve (=feedback spring) and a pressure-control servovalve (=pressure feedback po
This paper presents a robust compliance control scheme for an electro-hydraulic robot manipulator with an electrohydraulic torque actuators (EHTAs) and joint torque sensors. The EHTA, a torque-sourced hydraulic actuator, consists of electrohydraulic backdrivable servovalve and a rotary hydraulic van
Robust particle manipulation is a challenging but essential technique for single-cell analysis and processing of microfluidic devices. This paper proposes a micro-particle manipulation system with a microfluidic channel network. We built gravity-induced pressure actuators, which can generate high-re…
In this study, a forward dynamics-based control (FDC) framework is proposed for task space control of a nonredundant robot manipulator. The FDC framework utilizes forward dynamic robot simulation and an impedance controller to solve the inverse kinematics problem. For the practical use of the propos
With increased human-robot interactions in industrial settings, a safe and reliable collision detection framework has become an indispensable element of collaborative robots. The conventional framework detects collisions by estimating collision monitoring signals with a particular type of observer,
This letter proposes an intrinsically backdrivable electro-hydraulic torque actuator (EHTA) and associated control algorithms that could lead to the design of a high-performance interactive robot system. The EHTA consists of (electro-hydraulic) backdrivable servovalves and double vane rotary hydraul
Position-based proportional derivative (PD) controllers are known to be able to render compliant behaviors to a robot, and they are usually used in conjunction with a friction compensator to improve control performance. Existing methods are effective when applied to actuation systems with mechanical…
There has been consistent trials to make a hydraulic actuator to be effective in interactive robot applications that require high power and durability. However, conventional strategies to obtain this goal, such as force/torque servo control or adding elastic components, suffer from complexity, senso…
A position-based proportional-derivative (PD) controller with inner torque feedback loops can be used as a simple controller to render compliant behaviors to hydraulic robots. However, using this control framework involves a tradeoff between the stability and performance of the closed-loop system (w…
Admittance control is a well-established and popular control strategy in modern robotics. However, the standard admittance controller has several limitations. First, the passivity can be guaranteed by finding a set of control parameters that makes the admittance function positive real. However, this…
This paper proposes joint torque servo control of an electro-hydrostatic actuator (EHA) for effective dynamic control of robot manipulators. In the control design, the fluid parameters are not considered to develop a simple low-level controller used for multi degree-of-freedom (DOF) robot manipulato…
This paper proposes a simple model-free joint torque control strategy for hydraulic robots. The undesirable effect called “natural velocity feedback effect” is discussed by introducing mechanical impedance of the system. The proposed model-free joint torque control consists of internal-loop control
This paper proposes a passivity-based nonlinear disturbance observer (DOB) design for a powered upper-limb robot control. The proposed DOB allows for the nonlinearities of the robot dynamics, whereas the typical DOB designs cannot. Moreover, by virtue of the passivity property, human operator and en
Carrying unknown heavy payload is one of the classical problems in robotics. To realize heavy payload capability, the use of high reduction gears, which causes large motor-side inertia and large friction, is inevitable. This paper proposes a disturbance observer (DOB)-based approach that (1) reduces…