Skip to main content

Table 3 Case study for the knee energy harvesting device [6,29]

From: Harvesting biomechanical energy or carrying batteries? An evaluation method based on a comparison of metabolic power

      Device mass [kg]    
   0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Walking time [hours] 40 −0.6 −2.9 −5.1 −7.4 −9.7 −12.0 −14.3 −16.7 −19.0 −21.4
50 1.9 −0.3 −2.6 −4.9 −7.2 −9.5 −11.8 −14.1 −16.5 −18.8
60 4.5 2.3 0.0 −2.3 −4.6 −6.9 −9.2 −11.6 −13.9 −16.3
70 7.1 4.8 2.6 0.3 −2.0 −4.3 −6.6 −9.0 −11.3 −13.7
80 9.7 7.4 5.2 2.9 0.6 −1.7 −4.0 −6.4 −8.7 −11.1
90 12.3 10.1 7.8 5.5 3.2 0.9 −1.4 −3.8 −6.1 −8.5
100 15.0 12.7 10.4 8.1 5.9 3.5 1.2 −1.1 −3.5 −5.8
110 17.6 15.4 13.1 10.8 8.5 6.2 3.9 1.5 −0.8 −3.2
120 20.3 18.0 15.8 13.5 11.2 8.9 6.5 4.2 1.9 −0.5
130 23.0 20.7 18.4 16.2 13.9 11.6 9.2 6.9 4.5 2.2
  1. The values in the table are the differences in metabolic power in watts (carrying batteries minus harvesting device scenarios), for given mass and walking times. Positive values indicate that the harvesting device requires less effort than batteries (i.e., energy harvesting is preferred over batteries), negative values (bold) represent combinations were batteries are preferred options. The Italic values refer to the current published device (0.75kg, 100h).