Mohammad M. Aref

• Postdoctoral Researcher
• Researcher at Tampere University

We introduce a localization algorithm that uses an inertial measurement unit (IMU) and wheel odometry on a four-wheel-drive heavy vehicle for positioning. While wheel odometry alone works in simple cases without slippage, in cases that feature wheel slippage, the velocities measured by the wheel rotation show higher values. In the case of side slip...

We have recently proposed two pile loading controllers that learn from human demonstrations: a neural network (NNet) [1] and a random forest (RF) controller [2]. In the field experiments the RF controller obtained clearly better success rates. In this work, the previous findings are drastically revised by experimenting summer time trained controlle...

The bulldozer is a heavy-duty earthmoving machine generating tractive force between its tracks and ground to cut and push soil with an onboard blade. The productivity of the machine is determined by the amount of soil moved per hour, which is influenced by the travel speed and the amount of material carried by the blade. In this paper, we present a...

In this paper, we study the application of simultaneous localization and mapping (SLAM) for estimating the tool center point (TCP) 6 degrees-of-freedom (DOF) pose of a large-scale hydraulic manipulator without a priori knowledge of the environment. We attach a stereo camera near the TCP of the manipulator and perform SLAM by utilizing the open sour...

This paper describes a full closed-loop vehicle model for use in high precision path-following control of heavy-duty field robots. We present a high-performance path-following controller for four-wheeled drive (4WD), steer-articulated vehicles, typically used as mobile bases for aerial work platforms. Our control system promptly evaluates the curva...

This paper benefits from recent developments in learning of visual features by deep nets and highlights the possibility of learning kinematic features to achieve structure information without vision inputs and only by physical variables measured by sensors such as inertial measurement units (IMUs). It proposes to extract structural kinematic inform...

Benefiting from modularity, cable-driven parallel robots (CDPRs) are capable of being reconfigurable by changes in their attachment points and, therefore, significant changes in their kinematic structures. Due to their wide-range motion, measuring CDPRs' fixed attachment points’ location can be limiting. This paper tackles the problem of identifyin...

A velocity feed-forward-based strategy is an effective means for controlling a heavy-duty hydraulic manipulator; in particular , a typical valve-controlled hydraulic manipulator, to compensate for valve dead-zone and other hydraulic valve nonlineari-ties. Based on our previous work on the adaptive learning of valve velocity feed-forwards, manually...

In the cloud-based Internet of Things, the amount of available network bandwidth can become a bottleneck, especially in real-time sensor network applications. This study presents an architecture and an algorithm for context-aware fog data filtering that can map data features and their appearance frequency. This reduces the amount of data sent using...

We study the effects of variable latencies and noise-effects in vision based navigation. Based on the observations, we adapt a new robust estimation solution that is simple to integrate into a path-following controller and shown to provide a smoothed, high-bandwidth feedback for real-time control of a mobile robot. The strong dependency of steering...

This paper represents a systematic way for generation of Aaria, a simulated model for serial manipulators for the purpose of kinematic or dynamic analysis with a vast variety of structures based on Simulink SimMechanics. The proposed model can receive configuration parameters, for instance in accordance with modified Denavit-Hartenberg convention,...

A prototype for eye-in-hand manipulation in the context of remote handling in the International Thermonuclear Experimental Reactor (ITER)¹ is presented in this paper. The setup consists of an industrial robot manipulator with a modified open control architecture and equipped with a pair of stereoscopic cameras, a force/torque sensor, and pneumatic...

We studied the differences in noise-effects, depth-correlated behavior of sensors, and errors caused by mapping between coordinate systems in robotic applications of machine vision. In particular, the highly range-dependent noise densities for semi-unknown object detection were considered. An equation is proposed to adapt estimation rules to dramat...

This paper tackles the problem of integrating Visual Servoing Control (VSC) into the functionalities of an Articulated-Frame-Steering (AFS) hydraulic forklift. The controller is capable of breaking down high-level messages into piecewise commands for the different software modules of the vehicle. It also preserves seamless cooperation of the module...

Mobile manipulators are one of the major pillars in the thriving field of service robotics, perhaps mainly due to the wide workspace provided by the mobile base. Exploitation of this vast workspace entails accurate positioning of the robot while overcoming several complexities, such as nonholonomic constraints and actuator limitations. In this pape...

This paper addresses the problem of pallet picking by an Articulated-Frame-Steering (AFS) hydraulic machine. We propose a macro-micro visual mobile manipulation architecture, where a smooth switching logic navigates the robot to pick an object. The state space is divided into several regions depending on the accuracy of the vision and robot's degre...

This paper describes one of the challenging issues implied by scientific infrastructures on a mobile robot cognition architecture. For a generally applicable cognition architecture, we study the dependencies and logical relations between several tasks and subsystems. The overall view of the software modules is described, including their relationshi...

This paper addresses the macro-micro configuration of a mobile manipulation problem for a forklift; specifically, it investigates pallet picking with visual feedback. A manipulator with limited degrees of freedom and differential constraint mobility, together with the large dimensions of the machine, requires reliable visual feedback (pallet pose)...

Mobile manipulators are one of the most complicated types of mechatronics systems. The performance of these robots in performing complex manipulation tasks is highly correlated with the synchronization and integration of their low-level components. This paper discusses in detail the mechatronics design of a four wheel steered mobile manipulator. It...

This paper addresses a visual servoing problem for a mobile manipulator. Specifically, it investigates pallet picking by using visual feedback using afork lift truck. A manipulator with limited degrees of freedom and differential constraint mobility together with large dimensions of the machine require reliable visual feedback (pallet pose) from re...

In this paper, we address the problem of motion control for a mobile robot with four independently steer and drive wheels. Our solution fully takes advantage of steerability of all wheels and provide capability of independent control of translation and rotation of the robot. Using non-linear control techniques, we provide a motion control law that...

In this paper, the mechatronics design of a four wheel steered mobile robot is discussed in detail. Mechanical structure and electrical interfaces are presented. Low-level software architecture based on embedded pc-based control is designed that enables the robot to operate its eight independent actuators synchronously. Kinematics models are elabor...

We propose a systematic solution for real-time software development for safety critical mechatronic systems. The solution is based on Matlab/Simulink toolboxes and off-the-shelf drivers provided by hardware manufacturers, to address software development challenges in the area of PC based automation. In many cases, developers especially control syst...

Newly developed cable driven redundant parallel manipulators (CDRPM) have numerous advantages compared to that of the conventional parallel mechanisms. However, there exist some challenging issues in over-constrained mechanisms like CDRPMs. In contrast to serial manipulators, complexity of parallel manipulator forward kinematics (FK) is one of the...

Dynamic analysis of parallel manipulators plays a vital role in the design and control of such manipulators. Closed-chain kinematic structure affects the dynamics formulations by several constraints. Therefore, especially for higher degrees of freedom manipulators, manipulation of implicit and bulky dynamics formulation looses the tractability of t...

This paper presents an approach to the control of the KNTU CDRPM using an integrated control scheme. The goal in this approach is achieving accurate trajectory tracking while assuring positive tension in the cables. By the proposed controller, the inherent nonlinear behavior of the cable and the target tracking errors are simultaneously compensated...

Optimal design of parallel manipulators is known as a challenging problem especially for cable driven robots. In this paper, optimal design of cable driven redundant parallel manipulators (CDRPM) is studied in detail. Visual inspection method is proposed as a systematic design process of the manipulator. A brief review of various design criteria sh...

Workspace analysis is one of the most important issues in robotic manipulator design. This paper introduces a systematic method of analysis the wrench feasible workspace for general redundant cable-driven parallel manipulators. In this method, wrench feasible workspace is formulated in term of linear matrix inequalities and projective method is use...

In this paper the dynamic analysis of a cable-driven parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of large adaptive reflector (LAR), the Canadian design of next generation giant radio telescopes. This structure consists of a parallel redundant manipulator actuated...

Optimal design of parallel manipulators is known as a challenging problem especially for cable driven robots. In this paper, optimal design of cable driven redundant parallel manipulators (CDRPM) is studied in detail. Visual Inspection method is proposed as a systematic design process of the manipulator. A brief review of various design criteria sh...

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible implementation of large workspace applications. This newly developed manipulators have several advantages compared to the conventional parable mechanisms. In this paper, the governing dynamic equation of motion of such structure is derived using t...

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible high speed and large workspace applications. This newly developed mechanisms have several advantages compared to the conventional parallel mechanisms. Its rotational motion range is relatively large, its redundancy improves safety for failure in c...

This paper is devoted to the control of a cable driven redundant parallel manipulator, which is a challenging problem due the optimal resolution of its inherent redundancy. Additionally to complicated forward kinematics, having a wide workspace makes it difficult to directly measure the pose of the end-effector. The goal of the controller is trajec...

KNTU CDRPM is a cable driven redundant parallel manipulator, which is under investigation for possible high speed application such as 3D laser cutting machine. This newly developed mechanisms have several advantages compared to the conventional parable mechanisms. Its rotational motion range is relatively large, its redundancy improves safety for f...

This paper is devoted to the control of a cable driven redundant parallel manipulator, which is a challenging problem due the optimal resolution of its inherent redundancy. Additionally to complicated forward kinematics, having a wide workspace makes it difficult to directly measure the pose of the end-effector. The goal of the controller is trajec...