Mohd Razali Daud

Kinematics, Navigation, and Path Planning of Hexapod Robot

In Chap. 3, fundamental analysis on COMET-IV’s leg kinematics and dynamics has been briefly discussed. On further research progress on this robot, the developed kinematics and dynamics are exploited to be used for end-effector force on foot detection and overall COMET-IV stability for force-attitude control purposes. In COMET-IV research progress, the total force on foot is calculated for center of mass (CoM) identification as an input for robot attitude during walking session. This method is based on shoulder coordination system (SCS) kinematics on vertical position and total of force on foot for each touching leg on the ground. On the other hand, the designed force delivery on foot value is categorized phase by phase and threshold sensing method is applied for dynamic trajectory walking named force threshold-based trajectory. This method is done to achieve the novel end-effector force sensorless method that is applicable for large-scale legged robot that required expensive sensor on each leg’s tip.

Optimal Impedance Control with TSK-Type FLC for Hard Shaking Reduction on Hydraulically Driven Hexapod Robot

This paper presents a control strategy for improving the performance of force-based foot motion trajectory generation with optimal impedance control for a hydraulically driven hexapod robot known as COMET-IV. This technique facilitates walking/operating on extremely uneven and unstructured terrain. The trajectory module is stabilized using the derived impedance control with optimal force input. The robot’s body moment of inertia is calculated (instead of employing environmental modeling) and adapted as an impedance control input with improvement of TSK-FLC that is locally optimized via the solution of the algebraic Riccati equation of virtual robot dynamic itself. The proposed control strategy aims to generate a smooth dynamic signal in order to reduce the shaking of the robot’s foot while placing it on the ground during a walking session. The proposed control strategy is verified using an actual robot system while walking/operating on a setup consisting of an unstructured terrain and on actual extremely uneven terrain.

Design and Optimization of Hydraulically Actuated Hexapod Robot COMET-IV

The development of COMET-III resulted in a completely self-contained drive system that closely approximated a practical robot. However, various problems emerged in the course of research and development. In general, there was significant scope for improvement in terms of adaptability to terrain and speed of movement. For example, owing to an insufficient amount of oil and poor durability, sustained tripod walking could not be achieved, and the achieved walking speed was slow; the possible range of motion of the legs, which lacked the ability to move sideways or diagonally, was small, and the robot could not move omnidirectionally. In particular, the preeminence of legged robots as locomotive robots is ascribed to their superior capability of discrete walking in specific environments (such as minefields) and outstanding ability in general to adapt to the terrain. These capabilities enable legged robots to easily move over difficult and uneven terrain—even in environments wherein crawler robots and wheeled robots are incapable of motion. Therefore, there is an urgent need to overcome the fatal flaws in COMET-III—for example, in terms of terrain adaptability and speed of movement.

Historical and Modern Perspective of Walking Robots

Study of historical evolution and modern point of view on a complex subject like robotics invokes motivations and professionalisms among the researchers. Research on walking machines started at the time of Leonardo da Vinci and that ultimately culminated into the development of the modern walking robots through the transformations and refinements of the ideas and design methodology over the centuries. Obviously, the allied technology of mechatronics, particularly for sensing, actuation, and control, available at various points of time in the past influenced the design and implementation of walking robot quite heavily. The urge for mimicking the walking creatures in the past and the various efforts to apply the knowledge gathered from the observations of the biological world in the design and control of walking robots has added a new dimension as well as posed many new challenges in the walking robot research. However, the various challenges faced during the design and implementation of walking robots in the past and lessons learned from them to overcome those challenges enriched the technology of walking robot and drove it toward maturity. Therefore, the knowledge of the historical evolution of walking robotics research and its modern point of view will definitely inspire a robotics researcher for undertaking new challenges for the design and development of walking robots and will also guide him to take correct design decision. This chapter presents the historical evolution of walking robots and its perspective in a condensed manner.

LRF Assisted Autonomous Walking in Rough Terrain for Hexapod Robot COMET-IV

This paper presents an autonomous navigation system for a hydraulically driven hexapod robot COMET-IV. This work aims to improve the capabilities and increase autonomy of the robot by improving mapping technique for unknown environment, obstacle avoidances, and leg motion control assistance using a laser range finder (LRF) 3D point clouds data. In the previous research, the Grid-based Walking Trajectory for Legged Robot (GWTLR) algorithm, in which the A* algorithm and Growing Obstacle methods are referenced, was developed (Molfino et al. J Ind Rob 2:163–170, 2005) and successfully applied to the COMET-IV, for avoiding obstacles. In this work, the capabilities of the legged robot to cross over, step on, ascending and descending a cliff are capitalized by reconditioning leg swing trajectory based on obstacles geometric. Experimental results of the proposed methods show that the trajectory planning can be done autonomously under the unknown environment. Therefore, the proposed methods were proven to be highly potential to be applied as a part of the overall system for actual stochastic terrain navigation.

Vehicle Detection System Using Tunnel Magnetoresistance Sensor

Vehicle detectors are useful to provide essential information such as parking occupancy and traffic flow. To create one robust vehicle detector which works not only in controlled environment (i.e. indoor), but it should also work in outdoor environment, a vehicle detection using magnetic approach is proposed. The magnetic signal of a vehicle will be measured based on magnetic remanence technique where it will be processed to a cloud database. To achieve a low-cost and sensitive system, a Tunnel Magnetoresistance (TMR) sensor is employed. With the combinations of software filter and state machine’s algorithm, the occupancy of the car park can be identified with high accuracy. After a few series of real field testing, it is shown that a vehicle in a parking lot can be detected by measuring the surrounding magnetic field that is disrupted by the presence of vehicles. The proposed system is tested for forward and reverse parking, and it shows a high accuracy detection for a B-segment sedan car. It can be expected that by using the proposed technique, detection of vehicles using a low-cost system with capability of online monitoring can be realized.

SKF-Based Image Template Matching for Distance Measurement by Using Stereo Vision

In this paper, a novel image template matching approach to tackle distance measurement problem has been proposed. There are many conventional algorithms to increase the accuracy of distance measurement as reported in the literature such as Semi-global algorithm to produce the disparity map. Meanwhile, in this paper, the reverse engineering technique had been implemented to get the correct depth value by applying the image template matching method as reference for the distance measurement. The traditional algorithm to solve image matching problem take a lot of memory and computational time. Therefore, image matching problem can be considered to optimization problem and can be solved precisely. The search of the image template has been performed exhaustively by using Simulated Kalman Filter (SKF) algorithm. The experiment is conducted with a set of images taken by using stereo vision system. Experimental results show the accuracy of the distance measurement by using stereo camera, after applying (1) the estimate error model, (2) SKF and (3) PSO algorithm are 89.95%, 96.09%, 95.29% and 58.51% respectively. The limitation of estimate error model that it can only be applied into the same setup of the experiment, environment, parameters of the camera and acquired images. Instead, the proposed algorithm which is SKF can be applied to original image and image under the vision problems like illumination and partially occluded. The SKF algorithm shows more robust, more efficient and more accurate to solve the distance measurement problem.

Stereo camera — Based 3D object reconstruction utilizing Semi-Global Matching Algorithm

a 3D reconstruction using stereo cameras still becomes an issue among researchers specialized in computer vision. The corresponding pixel between two images from stereo camera needs to be estimated accurately. One of the widely used methods is Semi-Global Matching (SGM), which uses mutual information (MI) in the form of entropy between two pixels to determine the level of similarity based on the smallest energy (lower cost). The reconstruction result shows the percentage of registered pointcloud is equal to 62.11% where the observation distance ranges are between 1 to 4 meters. In this research, a nearest-neighbor filter is utilized to improve the pointcloud quality where the variations of the neighbors number are 4 to 128 pixels. The results show that this technique can eliminate the outliers up to 4.9% with the standard deviation of nearest-neighbor distances means equals to 1.0.

Intelligent control of robot gripper considering feature conditions

This paper deals with the analysis of three fingered robot manipulator to pick up objects intelligently with the appropriate force in order to avoid it damaging the object. In this project, three fingered gripper is designed to grasp an object without slipping or damaging the object with Fuzzy Logic approach. The fuzzy logic controller is used with many types of different membership types and number of fuzzy sets to evaluate the effect and performance of the grasping system. Based on the preliminary results, the triangular type of membership shows the simplest membership functions as the parameter are clear and easily understood and has faster computation time. However, the Gaussian membership shows better results when accuracy is considered.

Fully Autonomous Locomotion Control of Hexapod Robot with LRF

This chapter proposes several methods for crossing over an obstacle and descending and ascending a cliff based on LRF 3D point clouds data. The experimental results show that the proposed methods are useful for performing assigned tasks. The reliability and the accuracy of the LRF are basically satisfied to capitalize the capabilities of the legged robot COMET-IV, to increase the autonomy of the robot. Also, in order to increase the robustness of the system, another sensor, such as a stereo-vision camera, can be fused with the LRF. The capability of the stereo-vision camera to recognize colored object can help the system to distinguish between obstacles and not obstacles, such as the grasses.