Mohd Bazli Bahar

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 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.

Development of rubber tire gantry crane (prototype) obstacles avoidance method using a single sensor on microcontroller based

RTG crane is used to stack containers at the wharf. Because the size of the crane is too large and the operated at high place, it is nearly impossible for the operator to monitor the area under the crane. Currently, a pointing sensor system is installed but the crane still fails to stop if the obstacle is inside of the track due to low coverage of the pointing sensor system. In this paper, a new method is developed on a prototype system of RTG, to improve the current obstacle avoidance. The system is using servo motor to rotate an infrared sensor in order to cover the total area in the track. The results of new method is compared with the pointing sensor system and shown that the develop system has better performance from the pointing sensor system by increasing the sensing area to three point or almost all the track area by rotating the infrared sensor 68° continuously and taking the possibility of obstacles outside the tracking area.