Youdong Chen

Sambot: A Self-Assembly Modular Robot System

The design and structure of a self-assembly modular robot (Sambot) are presented in this paper. Each module has its own autonomous mobility and can connect with other modules to form robotic structures with different manipulation abilities. Sambot has a versatile, robust, and flexible structure. The computing platform provided for each module is distributed and consists of a number of interlinked microcontrollers. The interaction and connectivity between different modules is achieved through infrared sensors and Zigbee wireless communication in discrete state and control area network bus communication in robotic configuration state. A new mechanical design is put forth to realize the autonomous motion and docking of Sambots. It is a challenge to integrate actuators, sensors, microprocessors, power units, and communication elements into a highly compact and flexible module with the overall size of 80 mm × 80 mm × 102 mm. The work describes represents a mature development in the area of self-assembly distributed robotics.

Look-Ahead Algorithm with Whole S-Curve Acceleration and Deceleration

Tool paths of a complex contour machining generated by commercial CAD/CAM systems are mainly composed of many short linear/circular blocks. Though the look-ahead algorithms can improve speed and accuracy in the machining of short linear/circular segments, most of them just deal with linear segments with trapezoid acceleration and deceleration (acc/dec). In addition, the look-ahead algorithms with S-curve acc/dec are too complex to adopt the equivalent S-curve profile by approximation algorithm. To increase the smoothness of feedrate profile and machining efficiency of continuous short line and circle machining, this paper presents a feedrate profile generation approach and corresponding look-ahead algorithm with whole S-curve acc/dec. With the proposed look-ahead scheme, the feedrate profiles with S-curve acc/dec can work efficiently in a lot of short line and circle segments. Thus, the machining productivity can be increased and the feedrate profiles are smooth. The simulation and experiments verify the feasibility and validity of the proposed approach.

Swarm Robots

Inspired by the swarm behaviours of social insects, research into the self-assembly of swarm robots has become an attractive issue in the robotic community. Unfortunately, there are very few platforms for self-assembly and locomotion in the field of swarm robotics. The Sambot is a novel self-assembling modular robot that shares characteristics with swarm robots and self-reconfigurable robots. Each Sambot can move autonomously and connect with the other. This paper discusses the concept of combining self-assembly and locomotion for swarm robots. Distributed control algorithms for self-assembly and locomotion are proposed. Using five physical Sambots, experiments were carried out on autonomous docking, self-assembly and locomotion. Our control algorithm for self-assembly can also be used to realize the autonomous construction and self-repair of robotic structures consisting of a large number of Sambots.

Optimal trajectory planning for industrial robots using harmony search algorithm

Purpose – This paper aims to present a technique for optimal trajectory planning of industrial robots that applies a new harmony search (HS) algorithm.Design/methodology/approach – The new HS optimization algorithm adds one more operation to the original HS algorithm. The objective function to be minimized is the trajectory execution time subject to kinematical and mechanical constraints. The trajectory is built by quintic B‐spline curves and cubic B‐spline curves.Findings – Simulation experiments have been undertaken using a 6‐DOF robot QH165. The results show that the proposed technique is valid and that the trajectory obtained using quintic B‐spline curves is smoother than the trajectory using cubic B‐spline curves.Originality/value – The proposed new HS algorithm is more efficient than the sequential quadratic programming method (SQP) and the original HS method. The proposed technique is applicable to any industrial robot and yields smooth and time‐optimal trajectories.

Development and Implementation of a Real Time Embedded Control System for Machine Tools

In this paper, the architecture of real time embedded control system for machine tool is briefly introduced. The hardware of the control system is composed of ARM, DSP and FPGA, for these microprocessors provide the control system with high performance, better reliability and low cost. The design of hardware that is divided into motherboard design and IP design is detailed. The control software system is implemented based on the RTAI-Linux that is a real-time operating system. The components of the software system and communication among the components are described. Finally the control system was implemented

Smooth and Accurate Trajectory Planning for Industrial Robots

This paper proposes a smooth and accurate trajectory planning for industrial robots using geodesics. The workspace of a robot is split into positional and orientational parts. A Riemannian metric is given on each space such that the desired motion is a geodesic for the given metric. By regarding joint variables as local coordinates of the position space and the orientation space, Cartesian trajectories are represented by joint trajectories. A smooth and accurate motion of the robot end-effector and smooth joint trajectories corresponding to the motion can be obtained by calculating geodesics on the position space and the orientation space. To demonstrate the effectiveness of the proposed method, simulation experiments are conducted using the PUMA 560 robot.

Docking System Design and Self-Assembly Control of Distributed Swarm Flying Robots

This paper presents a novel docking system design and the distributed self-assembly control strategy for a Distributed Swarm Flying Robot (DSFR). The DSFR is a swarm robot comprising many identical robot modules that are able to move on the ground, dock with each other and fly coordinately once self-assembled into a robotic structure. A generalized adjacency matrix method is proposed to describe the configurations of robotic structures. Based on the docking system and the adjacency matrix, experiments are performed to demonstrate and verify the self-assembly control strategy.

A general framework integrating exploration, self-assembly and locomotion control for swarm robots

In this paper, we proposed a general control framework for the swarm robots with self-assembly in real environments. There are three tasks: exploration task, self-assembly task and locomotion task. At the start, the swarm robots explore the environment using their sensors and make decision to form some robotic structures to finish the task. Then the swarm robots execute the self-assembly task to construct the corresponding configuration. For the locomotion, a unified CPG controller model as well as unity configuration representation is combined to generate locomotive motions for robotic structure and improve self-adaptation according to any configuration. Based on Sambot simulation platform, we demonstrate simulation experiments that the swarm robots form different robotic structures to adapt to the different environments. Finally, the effectiveness and scalability of the framework are discussed.

An off-line programming system for palletizing robot

Off-line programming systems are essential tools for the effective use of palletizing robots. This article presents a dedicated off-line programming system for palletizing robots. According to the user practical requirements, there are many user-defined patterns that can’t be easily generated by commercial off-line robot programming systems. This study suggests a pattern generation method that users can easily define their patterns. The proposed method has been simulation and experiment. The results have attested the effectiveness of the proposed pattern generation method.

Smooth Geodesic Interpolation for Five-Axis Machine Tools

The smoothness of tool trajectories would be as important as that of axis trajectories for five-axis machining. The present study proposes a geodesic interpolation for five-axis machine tools. The tool positions and orientations are fitted to geodesics, respectively, to achieve smooth accurate motions of the tool center point (TCP), smooth axis motions, and the constant velocities of the TCP position and orientation. Not only the linear and circular geodesic interpolation are proposed, but also the acceleration/deceleration and block connection schemes are considered. The method is illustrated by simulations and experiments on a five-axis machining center, and compared to the interpolator with the TCP control. The real-time implementation of geodesic interpolation is well within the scope of modern CNC systems.