**2.2 Human model**

Human model is constructed using mechanical structure with revolute joints and rigid body. Thus, each body segment is connected with revolute joint. There are 49 degrees of freedoms (DOF) in each body joint. Such as knee is 1 DOF, shoulder is 3DOFs etc. There are 6 DOFs for global translation and rotation for human system to the inertial reference frame. We put inertial reference frame at the point between the foot on the ground as human model is standing. We assume that body segment is rigid body and there is no muscle and tissue in this study. Therefore, it is assumed that all muscle force is converted to the joint torque. Also, we used GEBOD software to generate dynamic properties of body segment for example thigh, pelvis, and torso [13]. In this study we used 50 percentile male data which is representing average male size. **Figure 2** describes the mechanical structure of current human model to generate weight lifting motion with waist and knee modular exoskeleton robots. Each z-axis has DOF and transformation matrix is combined sequentially from inertial reference frame to the head, hands, and toes as a branch. The virtual branch depicts global DOFs which is mentioned in previous – 3 global translations and 3 global rotations. The torso part of the human model has 4 spine joints and there are total 12 DOFs. Then, it leads to the right arm branch, left arm branch, and head branch. Right arm and left arm branch has 4 joints and 9 DOFs respectively including clavicle joint. Head branch has 2 joints and 5 DOFs. Right leg and

*Optimization Based Dynamic Human Motion Prediction with Modular Exoskeleton Robots…*

*DOI: http://dx.doi.org/10.5772/intechopen.98391*

Denavit-Hartenberg (DH) method is used to analyze the kinematics of human

**r** in **Figure 3** and it can be presented as Eq. (1).

**r** can be transferred to

left leg has 4 joints and 7 DOFs respectively.

**3. Kinematics and dynamics analysis**

the global reference frame as <sup>0</sup>

motion [14]. In the Denavit-Hartenberg method any point *<sup>i</sup>*

**3.1 Kinematics**

**161**

**Figure 2.**

*Mechanical structure of human model.*

**Figure 1.** *The concept design of modular exoskeleton robot.*

*Optimization Based Dynamic Human Motion Prediction with Modular Exoskeleton Robots… DOI: http://dx.doi.org/10.5772/intechopen.98391*

#### **Figure 2.** *Mechanical structure of human model.*

The modeling and simulation for human-exoskeleton is developed in [11]. In this study, we also use optimization-based motion prediction and simulation method with recursive Lagrange's equations of motion which is highly nonlinear. It provides predicted human motion as well as joint torques and ground reaction forces for weight lifting. This

There are many researches about exoskeleton with human-robot cooperation [12]. Due to the wearability, convenience, comfort and easy portability, modular exoskeleton robot is becoming a trend in the industrial work environment nowadays such as construction site, heavy industry, medical care, logistics, maintenance, manufacturing process, etc. In this study, the modular means the modular type according to the body parts of human being. For example, shoulder modular exoskeleton, knee modular exoskeleton. Biggest merit of modular exoskeleton may be the bringing more comfortability rather than full-body exoskeleton robots. Of course, it is possible only in the industrial area. If we look for the purpose of rehabilitation in hospital, it may be different story. Also, once we narrow down the application area, modular exoskeleton robot can be lighter, have more simple structure and can be more compact. Some area, you do not need active exoskeleton robot, and just passive exoskeleton is fine. Also, modular exoskeleton robot is applicable either together or separate case by case. Furthermore, modular exoskeleton is more economical compare to the full-body exoskeleton robot. The following **Figure 1** shows the concept design of modular exoskeleton robot which we are currently developing. In this study, exoskeleton assistive force can be applied

method also gives us pretty fast calculation time and accurate results.

human body as an external force through the optimization process.

Human model is constructed using mechanical structure with revolute joints and rigid body. Thus, each body segment is connected with revolute joint. There are 49 degrees of freedoms (DOF) in each body joint. Such as knee is 1 DOF, shoulder is 3DOFs

**2. Mechanical modeling**

**2.2 Human model**

**Figure 1.**

**160**

*The concept design of modular exoskeleton robot.*

**2.1 Modular exoskeleton robot**

*Collaborative and Humanoid Robots*

etc. There are 6 DOFs for global translation and rotation for human system to the inertial reference frame. We put inertial reference frame at the point between the foot on the ground as human model is standing. We assume that body segment is rigid body and there is no muscle and tissue in this study. Therefore, it is assumed that all muscle force is converted to the joint torque. Also, we used GEBOD software to generate dynamic properties of body segment for example thigh, pelvis, and torso [13]. In this study we used 50 percentile male data which is representing average male size. **Figure 2** describes the mechanical structure of current human model to generate weight lifting motion with waist and knee modular exoskeleton robots. Each z-axis has DOF and transformation matrix is combined sequentially from inertial reference frame to the head, hands, and toes as a branch. The virtual branch depicts global DOFs which is mentioned in previous – 3 global translations and 3 global rotations. The torso part of the human model has 4 spine joints and there are total 12 DOFs. Then, it leads to the right arm branch, left arm branch, and head branch. Right arm and left arm branch has 4 joints and 9 DOFs respectively including clavicle joint. Head branch has 2 joints and 5 DOFs. Right leg and left leg has 4 joints and 7 DOFs respectively.
