This time I got to go to Istanbul, Turkey. A city which had three names throughout its life time, seen the rise and fall of three empires and now is hosting a conference on Mechatronics and a session about the Robo-cup robots.
So I got to go to the Robotics Society of Japan’s annual conference. This time it was at Nagoya a place thats said to have the ugliest girls in Japan, well im not 100% sure on that however it might have some truth. I got to do some sight seeing and meet two robots(shown below)
This method takes joint torques(generated by position controller) and converts them into the force domain so that they can be limited(to prevent tipping, twisting, sliding, etc) and finally realized via force control.
So essentially the position controller becomes a reference force generator.
The advantages of this method are:
No ZMP trajectory is needed: ZMP moves freely to realize the desired motion but the forces at the foot are constrained to prevent tipping(ZMP going to edge of support)
Prevent sliding&twisting of the foot and prevent excessive GRF’s after jumping: Limit all 6-axes of the force wrench to prevent unstable/undesirable situations.
Improved robustness: It is proved that this method has the same positioning performance as pure position control(as long as force limiting is not needed). Any position controller can be used since the inputs are the desired joint torques. Therefore motion response depends purely on the position controller used.
Independent joint control: The joints can be moved separately as long as the degrees of freedom dont exceed 6 and the manipulator is not in a singular position.