User Tools

Site Tools


ires_journal8

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
ires_journal8 [2018/07/29 18:23]
yuhanghe [Project Status]
ires_journal8 [2018/07/29 19:16] (current)
yuhanghe [Project Status]
Line 45: Line 45:
 Last week, I implement the inverse kinematic function and created PODO AL that will transform mocap data to joint data and execute the motion. This week, I focused on filtering the data and implementing joint angle, velocity, and acceleration limit on the output joint data. Last week, I implement the inverse kinematic function and created PODO AL that will transform mocap data to joint data and execute the motion. This week, I focused on filtering the data and implementing joint angle, velocity, and acceleration limit on the output joint data.
  
 +The implementation of joint limit turn out to be more of a challenge then I anticipated. The simplest method to apply joint angle constraint is to limit the angles once they exceed maximum or minimum. The simplest method to limit joint angle velocity and acceleration is to apply a time warp to slow down motion within velocity and acceleration limit. However, both method are not suitable for the project because this project aim at preserving as much original characteristic of motion as possible.
 +
 +In order to accomplish this, I decided to implement the filters developed by [[https://​ieeexplore.ieee.org/​document/​1014737/​|Pollard et al]]. Here are the result of implementation.
 +
 +Joint angle limit:\\
 +{{ :​yuhang:​ires2018:​screenshot_from_2018-07-30_10-50-18.png?​700 |}}
 +The blue lines are the original joint angles and the green lines are joint angles after applying joint angle limit and filtering. The algorithm is not perfect, however, it was able to limit the joint angles while preserving some characteristics of original motion.
 +
 +Joint velocity limit:\\
 +{{ :​yuhang:​ires2018:​screenshot_from_2018-07-30_10-20-20.png?​700 |}}
 +Again, the blue lines are the original joint angles and green lines are joint angles after applying joint velocity limit and filtering. One problem I noticed for this algorithm is that, for relatively small amount of velocity exceed the limit, the algorithm worked very well. However, once the velocity and acceleration exceeds the limit, the filter will result in a flat angle.
 +
 +Another problem I noticed is that the first set of data I collected using mocap system are inaccurate and inconsistent. I need to collect more data from mocap system this week and test the filtering.
ires_journal8.txt ยท Last modified: 2018/07/29 19:16 by yuhanghe