Muhammad Fahmi Miskon

3-D Biped Robot Walking along Slope with Dual Length Linear Inverted Pendulum Method (DLLIPM)

A new design method to obtain walking parameters for a three-dimensional (3D) biped walking along a slope is proposed in this paper. Most research is focused on the walking directions when climbing up or down a slope only. This paper investigates a strategy to realize biped walking along a slope. In conventional methods, the centre of mass (CoM) is moved up or down during walking in this situation. This is because the height of the pendulum is kept at the same length on the left and right legs. Thus, extra effort is required in order to bring the CoM up to higher ground. In the proposed method, a different height of pendulum is applied on the left and right legs, which is called a dual length linear inverted pendulum method (DLLIPM). When a different height of pendulum is applied, it is quite difficult to obtain symmetrical and smooth pendulum motions. Furthermore, synchronization between sagittal and lateral planes is not confirmed. Therefore, DLLIPM with a Newton Raphson algorithm is proposed to solve these problems. The walking pattern for both planes is designed systematically and synchronization between them is ensured. As a result, the maximum force fluctuation is reduced with the proposed method.

Horizontal Distance Identification Algorithm for Sit to Stand Joint Angle Determination for Various Chair Height Using NAO Robot

This paper presents the development of an autonomous Sit To Stand (STS) motion using NAO robot. NAO robot hip limitation will emulate the limitation faced by people having STS problem. To perform the motion, three main steps have been developed (1) horizontal distance identification, (2) joint angle determination, and (3) stability control. This step was developed based on Alexander STS technique. Results show that NAO robot is able to achieve halfway stand up from chair height between 9.6 and 12.7 cm automatically. The robot’s best performance is at 12.7 cm height with swinging time of 0.52 s in experiment and 0.2914 in simulation. The developed system will contribute to the development of exoskeleton, rehabilitation and evolution of humanoid robot. This system also enhances NAO’s ability for medical study on STS motion or as tools in searching for the best chair design.

The Effect of Swing Arms Posture Motion on Walking Straightness of Humanoid Robot

The study of humanoid robot locomotion has been focusing on the development of walking pattern generation. However, the robot has the possibility of slipping on the ground due to the simultaneous occurrence of translational and rotational motions as a robot is walking. Technically, both issues disrupt the walking straightness of the robot. This study investigates the influence of the robot swing arms posture with a modified walking pattern generation to minimize the problem. Simulations were done by preparing 10 different elbow joint angles with swing arms and each one of them were tested with the same value of Maximum Lifting Height, H. The analysis was done by collecting the data from the Global Positional Sensor (GPS) from the robot and calculating the Root Mean Square Error (RMSE) to determine which variable has the lowest percentage of RMSE. The angular velocity graph was used to analyze the deviation encountered by the robot while walking by determining the average of angular velocity. The results showed that the arm posture of the robot does influence its walking straightness in a small amount.

The Effect of Parameters Variation on Bilateral Controller

Efficiency, reliability, high power quality and continuous operation are important aspects in electric vehicle attraction system. Therefore, quick fault detection, isolation and enhanced fault-tolerant control for open-switches faults in inverter driving systems become more and more required in this filed. However, fault detection and localization algorithms have been known to have many performance limitations due to speed variations such as wrong decision making of fault occurrence. Those weaknesses are investigated and solved in this paper using currents magnitudes fault indices, current direct component fault indices and a decision system. A simulation model and experimental setup are utilized to validate the proposed concept. Many simulation and experimental results are carried out to show the effectiveness of the proposed fault detection approach.The inverter with critical loads should be able to provide critical loads with a stable and seamless voltage during control mode change as well as clearing time. The indirect current control has been proposed for providing stable voltage with critical load during clearing time and seamless control mode transfer of inverters. However, the islanding detection is difficult since with the indirect current control the magnitude and frequency of voltage do not change when the islanding occurs. The conventional anti-islanding method based on the magnitude and frequency of voltage variation cannot apply to the indirect current control. This paper proposes an islanding detection method for the indirect current control. The proposed islanding detection method can detect the islanding using reactive power perturbation and observation when the frequency and magnitude of voltage don’t vary during clearing time. In order to verify the proposed anti-islanding method, the experimental results of a 600W three-phase inverter are provided.

The influence of the swaying arm angle range to the torso torque of the humanoid robot during walking

The swing arm motion is a natural phenomenon that realized in humanoid robot walking. The swaying arm angle range is introduced in this study to utilize the humanoid robot arm during walking. The main idea of this technique is the employment of swinging arm to reduce the torque at the torso in the vertical direction. The torso torque, τt is computed using a method which utilizes the servo torque of hip and shoulder joints. The approach is tested using H25V33 NAO humanoid robot in the Webot™ Robotic Simulator. The result indicates that the method is successful in reducing the torso torque, τt during humanoid robot walking.

Investigating the relation between standing period and stability of humanoid robot when performing STS motion

The main challenge in STS is addressing the lift-off from chair problem. In solving the problem, two method was proposed, 1) phase and trajectory planning based on the Alexander STS technique and 2) motion control which applied IF-THEN rules to control the action given (direction and gain) with aid of proportional velocity control. This paper discussed on the trajectory planning to perform STS motion by, 1) Observation of the relationship between standing velocity i.e standing period, Ts with the stability of the STS motion and 2) Introduce a limitation on bodys angular direction in y-axis on saggital plane, angle y. Nao humanoid robot is used to perform the task. Angle y trajectory and centre of pressure, CoP reading was measured to validate the proposed method. The results show that Standing period, Ts plays important role in order to perform a stable STS motion where stability increased as Ts increased. The lowest RMSE is 8.83° when Ts = 3.0. When the forward momentum decreasing with the implementation of angle y trajectory limitation, the results shows RMSE increased as Ts increased. However, the lowest RMSE is 7.07° when Ts = 1.5 where RMSE was decreased while using much lower standing period, Ts. The proposed angle y limitation has improved the motion stability and able to perform the task faster.

Investigating the relationship between TIP and 3-link models when the links' length are varied

In the field of humanoid and exoskeleton robotics, the ability to perform everyday task as human movement has been crucial point of research. One of the aspects that a lot of researcher put an effort is sit to stand (STS) motion. Study has shown that STS motion can be predicted using Three-link multi segment robot. But the calculation needed to perform the STS motion is complicated and requires high computational resources. One model is found that has much simpler task for planning and analyzing humanoid or exoskeleton robot which is Telescopic Inverted Pendulum (TIP). TIP is using one single link to represent whole body. However it is not clear whether TIP can represent 3L multi segment robot yet. Thus, this paper objective is trying to find the relationship between TIP and 3L model when the length of the limbs is varied. To do so, MATLAB is used to simulate the STS motion for both 3L and TIP model. The torque values at each joint are observed to obtain the relationship between length and the torque. The results show that both TIP and 3L model give a similar result where the limbs length and joint torque have linear relationship.

Investigating the relationship between TIP and three-link models when the mass are varied

In Humanoid robotics field, capability to perform any task that imitates human movement has been the major research focus. One of the critical movements is the Sit to Stand (STS) motion. STS motion can be predicted using three-link (3L) robot inverse kinematic and dynamic model. 3L multi segments is quite complicated and requires high computational resources to calculate. Telescopic Inverted Pendulum (TIP) is another model that much simpler for planning and analyzing humanoid robot since it represent whole body with one single link. However it is not clear whether TIP can represent 3L multi segment robot yet. Thus, this paper objective is to find the relationship between TIP and 3L model when the mass is varied. To do so, simulation setup for 3L and TIP model is developed using MATLAB. The torque values at each joint are observed to obtain the relationship between mass and the torque. The results show that both TIP and 3L model give a similarity result where mass and torque change in linear. For every drop of mass, the torque is also decrease.

Review of trajectory generation of exoskeleton robots

This paper presents a review on the challenges and state of the arts in trajectory generation of exoskeleton robots. The objective of the review is to identify knowledge gaps in trajectory generation in exoskeleton robots for future research in this field. The review is done by categorizing the challenges of the field and investigating the performance of the state of the arts. From the review, challenges in trajectories generation which are trajectory optimization and adaptation to unstructured environment have been elaborated. Following that the state of the arts in the field is presented from the point of view of the off-line, on-line and hybrid trajectory.

Musculoskeletal Robotics Modeling and Simulation

This paper presents the kinematics and dynamics of a musculoskeletal model inspired by humans/animals where the bones (links) are actuated by muscles (linear actuators). Starting from a single-link musculoskeletal structure, the kinematics were addressed to link the joint and muscle variables. From the kinematic constraints, dynamics of the structure were also presented. Later the 3D model of a two-link structure was constructed in ROCOS software to simulate the effect of gravity and environment (floor). In the simulations, the constraints were correctly defined as snapshots show the bones and muscle are intact before and after contact with environment.