. Author manuscript; available in PMC: 2013 Dec 6.

Published in final edited form as: J Biomech. 2010 Jan 25;43(6):10.1016/j.jbiomech.2009.12.017. doi: 10.1016/j.jbiomech.2009.12.017

Table 4.

Tests of the 3 PD controllers.

PD controller (# of parameters)	Test	Error (deg.)	SS Error (deg.)	Effort (N)	# of Failed Trials (out of 1000)
24	Generality	5.29	1.03	22.18	0
	Robustness	7.28	3.95	15.69	107
	Added friction	5.62	2.97	22.29	2
	Doubled mass	5.98	1.23	30.91	0
16	Generality	5.32	1.09	23.26	0
	Robustness	7.41	4.41	15.99	117
	Added friction	5.70	3.00	23.61	6
	Doubled mass	6.02	1.40	31.88	0
2	Generality	5.50	1.17	25.10	0
	Robustness	7.51	4.59	17.31	122
	Added friction	6.08	4.06	26.83	14
	Doubled mass	6.18	1.55	34.50	0

Values are averaged over 1000 movements. Error (f_error) and Effort (f_effort) values are calculated from (5) and (6), respectively. Precision of movement is quantified by the steady-state (SS) error values, which are an average of shoulder and elbow. The steady-state phase is defined as beginning when both joints reach within 5° of their target angles, and remain within 5° of the target for the remainder of the movement. SS error values are calculated only from successful trials. Failed trials are defined as those in which either joint angle fails to attain a position within 5° of its target within the two second duration of the trial. Added friction was 1.0 N m.