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Table 2 Subactive and passive kinematic pairs of PSAARR

From: Type Synthesis of Self-Alignment Parallel Ankle Rehabilitation Robot with Suitable Passive Degrees of Freedom

Category

Subactive kinematic pair

Passive kinematic pair

Type

Quantity

2R3P

Rsa

Non-existent

Non-existent

0

Psa

\(\text{PP}\hat{\text{R}}\hat{\text{R}}\)

\(\left( {\text{P}_{{{\text{sa}}}} \text{PP}} \right)\hat{\text{R}}\hat{\text{R}}\)

3

\(\left( {\left( {\overline{\text{P}}{\tilde{\text{P}}}\text{R}_{1} } \right)\text{R}} \right)\)

\(\left( {\left( {\dot{\text{P}}_{{{\text{sa}}}} \overline{\text{P}}\tilde{\text{P}}\text{R}_{1} } \right)\text{R}} \right)\)

24

3R2P

Rsa

\(\text{PP}\hat{\text{R}}\hat{\text{R}}\)

\(\left( {R_{{1{\text{sa}}}} \text{PP}} \right)\hat{\text{R}}_{1} \hat{\text{R}}\)

3

\(\left( {\left( {\overline{\text{P}}{\tilde{\text{P}}}\text{R}_{1} } \right)\text{R}} \right)\)

\(\left( {\left( {\overline{\text{P}}{\tilde{\text{P}}}\text{R}_{1} } \right)\left( {\text{R}_{2} \text{R}_{{2{\text{sa}}}} } \right)} \right)\)

12

Psa

\(\left( {\left( {\overline{\text{P}}\text{R}_{1} \text{R}_{1} } \right)\text{R}} \right)\)

\(\left( {\left( {{\dot{\text{P}}}_{{{\text{sa}}}} {\overline{\text{P}}\text{R}}_{{1}} {\text{R}}_{{1}} } \right){\text{R}}} \right)\)

24

4R1P

Rsa

\(\left( {\left( {\overline{\text{P}}R_{1} R_{1} } \right)R} \right)\)

\(\left( {\left( {\overline{\text{P}}R_{1} R_{1} } \right)\left( {R_{2} R_{{2{\text{sa}}}} } \right)} \right)\)

12

Psa

\(\left( {\left( {{\text{R}}_{{1}} {\text{R}}_{{1}} {\text{R}}_{{1}} } \right){\text{R}}} \right)\)

\(\left( {\left( {\dot{\text{P}}_{{{\text{sa}}}} {\text{R}}_{{1}} {\text{R}}_{{1}} {\text{R}}_{{1}} } \right){\text{R}}} \right)\)

8

5R

Rsa

\(\left( {\left( {{\text{R}}_{{1}} {\text{R}}_{{1}} {\text{R}}_{{1}} } \right){\text{R}}} \right)\)

\(\left( {\left( {{\text{R}}_{{1}} {\text{R}}_{{1}} {\text{R}}_{{1}} } \right)\left( {{\text{R}}_{2} {\text{R}}_{{{\text{2sa}}}} } \right)} \right)\)

4

  1. Note: (i) R2R2 indicates that the axes of the revolute pairs were parallel, (ii) \(\dot{{\text{P}}}\) indicates that the axis of the prismatic pair was not perpendicular to that of the revolute pair R1, (iii) Points (i) and (ii) are equally valid in the following