Cable-Driven Parallel Robot Actuators: State of the Art and Novel Servo-Winch Concept

Abstract

Cable-Driven Parallel Robots (CDPRs) use cables arranged in a parallel fashion to manipulate an end-effector (EE). They are functionally similar to several cranes that automatically collaborate in handling a shared payload. Thus, CDPRs share several types of equipment with cranes, such as winches, hoists, and pulleys. On the other hand, since CDPRs rely on model-based automatic controllers for their operations, standard crane equipment may severely limit their performance. In particular, to achieve reasonably accurate feedback control of the EE pose during the process, the length of the cable inside the workspace of the robot should be known. Cable length is usually inferred by measuring winch angular displacement, but this operation is simple and accurate only if the winch transmission ratio is constant. This problem called for the design of novel actuation schemes for CDPRs; in this paper, we analyze the existing architectures of so-called servo-winches (i.e., servo-actuators which employ a rotational motor and have a constant transmission ratio), and we propose a novel servo-winch concept and compare the state-of-the-art architectures with our design in terms of pros and cons, design requirements, and applications.

A Practical Approach for the Hybrid Joint-Space Control of Overconstrained Cable-Driven Parallel Robots

“…Cables are coiled and uncoiled by servocontrolled winches, characterized by a nominally constant transmission ratio. Their length varies proportionally to the actuator rotations if elasticity and hysteresis are neglected [6].…”

“…σ ⋆ is by definition, the minimum value of σ for every j -th cable set (Eq. (6). As an example, for the HRPCable σ ⋆ max is equal to 2N.…”

Force-Sensor-Free Implementation of a Hybrid Position–Force Control for Overconstrained Cable-Driven Parallel Robots

“…Using cables guarantees a larger workspace and fewer moving masses compared to other robots, allowing CDPRs to achieve high dynamic performances even in wide areas. In most cases, the actuation system comprises a motor (with or without a gearbox) connected to a drum on which the cable is coiled [2]. After exiting each drum, the cable often engages a set of transmission pulleys before arriving at the end-effector.…”

Theoretical and Numerical Study on Dynamic Response of Propellant Actuator

“…The actuator is the key component of the active vibration control and the important part of active control system, and it has a wide range of applications in the fields of machinery, robotics and aerospace [1][2][3][4][5][6][7]. The propellant actuator is a kind of driver that ignites the propellant through electric energy and uses the pressure of the propellant gas to apply the work [8][9][10][11].…”