Jamaludin Jalani

Robust Fuzzy Logic Controller for an Intelligent Gantry Crane System

The use of gantry crane systems for transporting payload is very common in industrial application. However, moving the payload using the crane is not an easy task especially when strict specifications on the swing angle and on the transfer time need to be satisfied. To overcome this problem, an intelligent gantry crane system had been introduced. Fuzzy logic controllers were adopted, designed and implemented for controlling payload position as well as the swing angle of the gantry crane. In this paper, robustness of the proposed intelligent gantry crane system is evaluated and compared with an automatic gantry crane controlled by the classical PID controllers. The result shows that the intelligent gantry crane system is more robust to parameter variation than the automatic gantry crane system

Underactuated fingers controlled by robust and adaptive trajectory following methods

Choosing an appropriate control scheme to alleviate nonlinearities and uncertainties is not a trivial task, especially when models are not easily available and practical evaluation provides the only means for actual performance assessment. Various factors can contribute to these nonlinearities and uncertainties, such as friction and stiction. Thus, this article investigates four different control schemes, namely PID, adaptive, conventional sliding mode control (SMC) and integral sliding mode control (ISMC) which are implemented in the Bristol Elumotion Robot Hand (BERUL) to analyse and overcome the aforementioned problems. The hand has five fingers with 16 joints and all fingers are underactuated. The implementation of the proposed control schemes are challenging since the BERUL fingers have significant friction, stiction and unknown parameters. The fingers are light in weight and fragile. Comparative performance characteristics have shown that the ISMC is the most suitable candidate to provide good experimental trajectory following and positioning control for underactuated BERUL fingers.

Robotic hand posture and compliant grasping control using operational space and integral sliding mode control

This paper establishes a novel approach of robotic hand posture and grasping control. For this purpose, the control uses the operational space approach. This permits the consideration of the shape of the object to be grasped. Thus, the control is split into a task control and a particular optimizing posture control. The task controller employs Cylindrical and Spherical coordinate systems due to their simplicity and geometric suitability. This is achieved by using an integral sliding mode controller (ISMC) as task controller. The ISMC allows us to introduce a model reference approach where a virtual mass-spring-damper system can be used to design a compliant trajectory tracking controller. The optimizing posture controller together with the task controller creates a simple approach to obtain pre-grasping/object approach hand postures. The experimental results show that target trajectories can be easily followed by the task control despite the presence of friction and stiction. When the object is grasped, the compliant control will automatically adjust to a specific compliance level due to an augmented compliance parameter adjustment algorithm. Once a specific compliance model has been achieved, the fixed compliance controller can be tested for a specific object grasp scenario. The experimental results prove that the Bristol Elumotion robot hand (BERUL) can automatically and successfully attain different compliance levels for a particular object via the ISMC.

Active robot hand compliance using operational space and Integral Sliding Mode Control

This paper establishes a novel approach of robust active compliance control for a robot hand via an Integral Sliding Mode Controller (ISMC). The ISMC allows us to introduce a model reference approach where a virtual mass-spring damper system can be used to design a compliant control. In order to allow for practical grasping, we consider the shape of the object to be grasped. Hence, the work exploits a grasping technique via Cylindrical and Spherical coordinate systems due to their simplicity and geometric suitability. The control uses the operational space approach. Thus, the control is split into a task control and a particular optimizing posture control. The experimental results show that target trajectories can be easily followed by the task control despite the presence of friction and stiction while the posture controller maintains a desired finger posture. When the object is grasped, the compliant control will automatically adjust to a specific compliance level. Once a specific compliance model has been achieved, the fixed compliance controller can be tested for a specific scenario. The experimental results prove that the BERUL hand can automatically and successfully attain different compliancy levels for a particular object via the ISMC.

Robust active compliance control for practical grasping of a cylindrical object via a multifingered robot hand

It is essential to devise a safe compliant control scheme for grasping robots when active multifingered robot hands are interacting with a human or a fragile object. Hence, in this study, a novel active and robust compliant control technique is proposed by employing Integral Sliding Mode Control (ISMC). The ISMC allows us to use a model reference approach for which a virtual mass-spring damper can be introduced to enable compliant control. In addition, it is vital to have practical grasping to ensure a particular grasped object is reachable. For this, a cylindrical coordinate system is exploited due to its simplicity and geometric suitability, for the shape of objects to be grasped. This cylindrical coordinate system is centered at the grasped object. The performance of the ISMC is validated for the constrained underactuated BERUL (Bristol Elumotion Robot fingers) fingers. The results show that the approach is feasible for compliant interaction with objects of different softness in cylindrical space. Moreover, the compliance results show that the ISMC is robust towards nonlinearities and uncertainties in the robot fingers in particular friction and stiction.

A Novel Approach of Robust Active Compliance for Robot Fingers

In order to guarantee that grasping with robot fingers are safe when interacting with a human or a touched object, the robot fingers have to be compliant. In this study, a novel active and robust compliant control technique is proposed by employing an Integral Sliding Mode Control (ISMC). The ISMC allows us to use a model reference approach for which a virtual mass-spring damper can be introduced to enable compliant control. The performance of the ISMC is validated for the constrained underactuated BERUL (Bristol Elumotion Robot fingers) fingers. The results show that the approach is feasible for compliance interaction with objects of different softness. Moreover, the compliance results show that the ISMC is robust towards nonlinearities and uncertainties in the robot fingers in particular friction and stiction.

A new approach of active compliance control via fuzzy logic control for multifingered robot hand

Safety is a vital issue in Human-Robot Interaction (HRI). In order to guarantee safety in HRI, a model reference impedance control can be a very useful approach introducing a compliant control. In particular, this paper establishes a fuzzy logic compliance control (i.e. active compliance control) to reduce impact and forces during physical interaction between humans/objects and robots. Exploiting a virtual mass-spring-damper system allows us to determine a desired compliant level by understanding the behavior of the model reference impedance control. The performance of fuzzy logic compliant control is tested in simulation for a robotic hand known as the RED Hand. The results show that the fuzzy logic is a feasible control approach, particularly to control position and to provide compliant control. In addition, the fuzzy logic control allows us to simplify the controller design process (i.e. avoid complex computation) when dealing with nonlinearities and uncertainties.

Adaptive friction compensation for hand grasping and compliant control

Attaining a good positioning control is an important step to be achieved for a robotic hand to safely grasp an object. The safety of the grasped object can be enhanced by providing a compliant control strategy. This paper presents a model reference adaptive compliance controller where a mass spring damper system can be introduced. The performance of model-based adaptive controller with the effect of friction and stiction is investigated. A few mathematical models of friction are considered i.e. static friction (stiction), coulomb friction (dry friction), viscous friction, drag friction and square root friction. It is observed that a good positioning and compliant control are feasible in the presence of friction and stiction in simulation. It is evident that the level of compliant control can be achieved during the object grasped.

Forward kinematics analysis of a 5-axis RV-2AJ robot manipulator

This paper presents the forward kinematics analysis for the Mitsubishi Melfa RV-2AJ industrial robot with a five degree of freedom (DOF) revolute joints. The kinematics problem is defined as the transformation from the joint space to the Cartesian space and vice versa. An analytical solution using Denavit-Hartenberg (D-H) representation to describe the position and orientation of the robot end-effector is presented. Several lab experiments to verify the developed kinematics equations have been conducted. In this study, the developed kinematics solutions were found to be accurate (98.68%) compared to the real robot. These findings have important implication for developing dynamic simulation model that can be used to evaluate position and force control algorithm.

Force control for a 3-Finger Adaptive Robot Gripper by using PID controller

In order to ensure that a robotic hand can successfully grasp objects without damaging them, an active compliance control can be a very useful technique to provide a safe grasping. In particular, this paper establishes a direct force control for a 3-Finger Adaptive Robot Gripper by using a PID control. A modified FSR force sensor where a plastic cover is used to ensure the contacted force during grasping can be measured and recorded. A series of grasping tests were performed to observe the performance of PID control. The experimental results show that the PID control can be a simple and reliable control scheme to provide an active compliance control through direct force control. In addition, different compliance level is feasible particularly for a stiff spongy ball.