A novel six-legged walking machine tool for in-situ operations

Abstract

The manufacture and maintenance of large parts in ships, trains, aircrafts, and so on create an increasing demand for mobile machine tools to perform in-situ operations. However, few mobile robots can accommodate the complex environment of industrial plants while performing machining tasks. This study proposes a novel six-legged walking machine tool consisting of a legged mobile robot and a portable parallel kinematic machine tool. The kinematic model of the entire system is presented, and the workspace of different components, including a leg, the body, and the head, is analyzed. A hierarchical motion planning scheme is proposed to take advantage of the large workspace of the legged mobile platform and the high precision of the parallel machine tool. The repeatability of the head motion, body motion, and walking distance is evaluated through experiments, which is 0.11, 1.0, and 3.4 mm, respectively. Finally, an application scenario is shown in which the walking machine tool steps successfully over a 250 mm-high obstacle and drills a hole in an aluminum plate. The experiments prove the rationality of the hierarchical motion planning scheme and demonstrate the extensive potential of the walking machine tool for in-situ operations on large parts.

Kinematic Analysis and Verification of a New 5-DOF Parallel Mechanism

“…The main factors that affect the workspace of parallel robot are: (1) The limitation of the length of link. The link lengths of each limb are not random and must be limited to a certain range.…”

“…Common parallel mechanisms are Delta and Stewart. Unlike traditional series structure, parallel structure is widely used in automobile, mechanical manufacturing [1][2][3][4][5], aviation [6], medical treatment [7], electronic manufacturing [8], education, and other fields due to its small cumulative error, high precision, light weight of moving part, high speed, fast dynamic response, compact structure, high rigidity, and large bearing capacity [9][10][11][12].…”

Design of a Quadruped Robot with Morphological Adaptation through Reconfigurable Sprawling Structure and Method

“…This extension can be achieved through two primary methods. The first method is to design a multi‐DOF parallel mechanism [ 60 ] or spatial closed‐chain mechanism, [ 61 ] and the second method is to obtain a series‐parallel hybrid mechanism by combining a planar closed‐chain mechanism with a shoulder joint. The latter approach offers a larger working space than the former method and can also efficiently adjust the robot's sprawl posture to adapt to different motion requirements.…”

A portable off‐road crawling hexapod robot

“…In the field, the legged robot has attracted wide attention because of its outstanding mobility and flexibility on complex ground (Chen et al, 2009; Ilhan et al, 2018; Raibert, 1986). Benefitting from the smooth foot trajectory and the discrete footholds, the robot can traverse the rough terrains with great maneuverability, and it is proved to be a reasonable choice regarding stability, redundancy, weight, and energy consumption (Kajita & Espiau, 2008; Liu et al, 2020; Pan & Gao, 2013). The crawling robot is a kind of legged robot, which could be deployed in the search and rescue mission after disasters, such as earthquake, tsunami, mud‐rock flow, etc.…”

“…The spatial closed‐chain leg mechanism could be divided into the parallel leg mechanism with multiple DOFs and the closed‐chain leg mechanism with one DOF. The control mathematical mode of the robot with the parallel leg mechanism usually has multiple input variables, such as a series of parallel‐legged walking robots (Liu et al, 2020; Pan & Gao, 2013) with a leg of three DOFs. Another kind of robot is the one based on the spatial closed‐chain leg mechanism, especially the ones only constructed by revolute joints and driven by cranks.…”