A surgical instrument holder for use with a robotic surgical system, the surgical instrument holder comprising: a base (310, 402, 500, 602, 908, 1012, 1102, 1202) configured to be mechanically coupled to a robotic arm of the robotic surgical system, the base comprising: a second channel having an interior surface with a tapered cylindrical shape sized to accommodate a surgical instrument (606, 800, 902) therethrough such that movement of the surgical instrument is constrained in all directions except along an axis defined by the second channel surface, characterized in that the base further comprises: a first channel having an interior surface sized and shaped to accommodate a tightening screw (410, 1014, 1204) configured to securely attach the base directly or indirectly to a robotic arm of the robotic surgical system, a first tapered curved surface extending along the axis of the second channel configured to be engaged by a surgical instrument when the surgical instrument is secured in the second channel, wherein first channel and the second channel intersect, and one or more pins (408, 1002, 1104, 1210) inserted into the base such that the one or more pins, upon mechanically coupling the base to the robotic arm, engage one or more openings in a tool support thereby precisely locating the surgical instrument holder relative to the robotic arm; and the surgical instrument holder further comprises a clamp (404, 604, 700, 904) configured to engage the surgical instrument when placed through the second channel such that the surgical instrument is securely held between the clamp and the base upon tightening of a nut (406, 906). a base (310, 402, 500, 602, 908, 1012, 1102, 1202) configured to be mechanically coupled to a robotic arm of the robotic surgical system, the base comprising: a second channel having an interior surface with a tapered cylindrical shape sized to accommodate a surgical instrument (606, 800, 902) therethrough such that movement of the surgical instrument is constrained in all directions except along an axis defined by the second channel surface, characterized in that the base further comprises: a first channel having an interior surface sized and shaped to accommodate a tightening screw (410, 1014, 1204) configured to securely attach the base directly or indirectly to a robotic arm of the robotic surgical system, a first tapered curved surface extending along the axis of the second channel configured to be engaged by a surgical instrument when the surgical instrument is secured in the second channel, wherein first channel and the second channel intersect, and one or more pins (408, 1002, 1104, 1210) inserted into the base such that the one or more pins, upon mechanically coupling the base to the robotic arm, engage one or more openings in a tool support thereby precisely locating the surgical instrument holder relative to the robotic arm; and the surgical instrument holder further comprises a clamp (404, 604, 700, 904) configured to engage the surgical instrument when placed through the second channel such that the surgical instrument is securely held between the clamp and the base upon tightening of a nut (406, 906). a second channel having an interior surface with a tapered cylindrical shape sized to accommodate a surgical instrument (606, 800, 902) therethrough such that movement of the surgical instrument is constrained in all directions except along an axis defined by the second channel surface, a first channel having an interior surface sized and shaped to accommodate a tightening screw (410, 1014, 1204) configured to securely attach the base directly or indirectly to a robotic arm of the robotic surgical system, a first tapered curved surface extending along the axis of the second channel configured to be engaged by a surgical instrument when the surgical instrument is secured in the second channel, wherein first channel and the second channel intersect, and one or more pins (408, 1002, 1104, 1210) inserted into the base such that the one or more pins, upon mechanically coupling the base to the robotic arm, engage one or more openings in a tool support thereby precisely locating the surgical instrument holder relative to the robotic arm; and the surgical instrument holder further comprises a clamp (404, 604, 700, 904) configured to engage the surgical instrument when placed through the second channel such that the surgical instrument is securely held between the clamp and the base upon tightening of a nut (406, 906).