Correction to:       Arab J Sci Eng       https://doi.org/10.1007/s13369-021-06046-z

In the original publication, Figs. 6 and 7 are published incorrectly. The correct figures are given below. The original publication has been updated of the same.

Fig. 6
figure 1

Case 1 Pacing walking cycle results. The graphs show desired and actual values of the relative position of the front legs, \({}^2{\mathbf {p}}_4\), and the hind legs, \({}^6{\mathbf {p}}_8\), as well as the absolute position of Robot A, \({}^1{\mathbf {p}}_2\), and Robot C, \({}^5{\mathbf {p}}_6\). The front legs movement, \({}^2{\mathbf {p}}_4\), is the main task, while \({}^1{\mathbf {p}}_2\), \({}^6{\mathbf {p}}_8\), and \({}^5{\mathbf {p}}_6\) are the secondary tasks in decreasing hierarchy

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Fig. 7
figure 2

Case 4 Counter-lateral leg pairing with equal null-space tasks hierarchy. The graphs show desired and actual values of counter-lateral leg pairing of Robot A and Robot C with the corresponding movement \({}^2{\mathbf {p}}_6\) as the main task. The other legs movement now lies in the null space with equal hierarchy of task execution: front legs pair \({}^2{\mathbf {p}}_4\), Robot A \({}^1{\mathbf {p}}_2\), and hind legs pair \({}^6{\mathbf {p}}_8\)

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