Table 1.

NRMSE between the estimated joint torque of different models and the measurements (“true” values) of all subjects (mean ± std).

		2 m/s	3 m/s	4 m/s	5 m/s
Speed-dependent	GP	0.1788 ± 0.0756	0.1802 ± 0.0475	0.1604 ± 0.0483	0.1718 ± 0.0356
	NARX-GP	0.0046 ± 0.0016	0.0039 ± 0.0023	0.0031 ± 0.0023	0.0041 ± 0.0021
Multi-speed	GP	0.1850 ± 0.0735	0.1745 ± 0.0489	0.1712 ± 0.0457	0.1874 ± 0.0510
	NARX-GP	0.0052 ± 0.0028	0.0033 ± 0.0010	0.0030 ± 0.0011	0.0035 ± 0.0011
Speed-independent	GP	0.2075 ± 0.0697	0.1852 ± 0.0560	0.1910 ± 0.0563	0.2174 ± 0.0746
	NARX-GP	0.0086 ± 0.0086	0.0039 ± 0.0014	0.0046 ± 0.0030	0.0066 ± 0.0072