Fig. 4

PARRs with different mechanism configurations. a Rutgers Ankle -“ Rutgers University”; b Reconfigurable ankle robot -“ Gwangju Institute of Science and Technology”; c 3- SPS/SP mechanism -“ King’s College London”; d 3- RSS/S mechanism -“ Heibei University of Technology”; e ARBOT -“ IIT”; f PKAnkle -“ Institute of Industrial Technologies and Automation”; g 2-DOFs parallel ankle robot -“ Karadeniz Technical University”; h 9-DOFs hybrid PARR -“ University of Birmingham”; i 2-DOFs ankle rehabilitation robot -“ Wuhan University of Technology”; j Soft parallel robot(SPR) -“ University of Auckland”; k Compliant ankle robot -“ Nazarbayev University”; l Compliant ankle rehabilitation robot -“ University of Auckland”; m Redundantly actuated ankle robot -“ University of Auckland”; n 3-RUS/RRR -“ Beijing Jiaotong University”; o 3- PRS -“ Universidad Politécnica de Valencia”; p 2-UPS/RRR ankle rehabilitation robot -“ Beijing University of Technology”