# Research on Kinematic Parameters of Multiple Gait Pattern Transitions
## 4 Discussion
The parameters with early significant differences of the leading limb during L-R DOWN were the angular velocity of the ankle joint and the velocity of the thigh and shank (Table 8). For L-S DOWN see Figure 5a, and for L-R DOWN see Figure 5b. In order to cross the transition boundary more safely, the pace and step length in transition strides will be reduced relative to the level walking to ensure a balanced and stable transition. [PERSON] et al. found that people's walking speed decreased when they transitioned from level walking to stair walking [25]. Moreover, changes in pace and step length are accompanied by corresponding changes in phase and joint angular velocity [22; 23; 24]. During L-S UP (Figure 6a) and L-R UP (Figure 6b), previous studies have revealed some differences in the transitions. [PERSON] et al. studied the changes in limb trajectory and body posture when people transitioned from level to slopes with different gradients, and they found that during the transition from level to ramp, the pitch of the trunk in the sagittal plane and the swing limb changed correspondingly at the beginning and end of the swing [25]. In order to cross the obstacles (stairs) more safely during the transition, the pace and the step length will be reduced [26], and the foot clearance (FC) will be increased [27] compared with that of the level walking, which are the main reasons for the increase in the significant differences of kinematic parameters. In the comparison during L-S UP, we found in the first two phases that the angular velocity of the hip, knee, and ankle joints of the leading limb and the velocity of the thigh and shank changed from faster to slower than that in level walking (Figure 6a). Similarly, the angular velocity of the hip and knee joints of the leading limb during L-R UP also had the same phenomenon (Figure 6b). However, the change in these parameters of the leading limb during L-R UP is not so obvious compared with that during L-S UP. We analyzed the reasons for this phenomenon and found that in L-S UP and L-R UP, people will quickly lift their limb and dorsiflex foot to prevent tripping over obstacles (stairs, ramp); this is a special kind of gait strategy (to keep balance, quickly lift lower limb to prevent stumbling at the same time). According to our statistical results, although the total significant difference points of the angular acceleration of each joint of the leading limb in different gait pattern transitions are not many, in the first two phases of most transition strides, the angular acceleration of the hip, knee, and ankle joints showed significant differences earlier. Therefore, from the practical application point of view, the angular acceleration of each joint of the leading limb can be considered as the reference parameters of the exoskeleton gait recognition. * Trailing limb (left)  
According to our literature survey, there are few studies on the kinematic parameters of the trailing limb in the transition stride. Therefore, this paper also makes a comparative study of the kinematic parameters of the trailing limb between the transition stride and the stride of the former gait pattern during multiple gait pattern transitions in order to provide a more comprehensive data support for the subsequent feature selection and extraction. Firstly, same as the leading limb, the angular velocity of each joint of the trailing limb is significantly different in most gait pattern transition comparisons except for the comparisons of S-L UP and R-L UP (Table 2, as can be seen from the comparison of Figures 3-6). Specifically, the angular velocity of the hip joint of the trailing limb showed a significant difference during S-L UP (Table 2, 51% significant difference points), and the angular velocity of the hip joint in the transition stride is lower than that in up-stair walking (Figure 3a). Therefore, from this point of view, the angular velocity of the hip joint of the trailing limb is a parameter to be focused on when recognizing S-L UP.