A system comprising: a manipulator arm configured for robotically moving a distal end effector relative to a proximal base, the manipulator arm having a plurality of joints between the distal end effector and the proximal base, the plurality of joints providing sufficient degrees of freedom to allow a range of joint states for a given state of the distal end effector; an input device for receiving a manipulation command to move the end effector with a desired end effector movement; and a processor coupled to the input device and to the manipulator arm, the processor configured to: calculate an end effector displacing movement of the plurality of joints in response to the manipulation command by calculating joint velocities within a null-perpendicular-space of a Jacobian; define a position-based constraint of one or more joints of the plurality of joints within an associated joint space, the position-based constraint being specific to a design and kinematics of the manipulator arm and corresponding to an increased range of movement of the one or more joints, the position-based constraint including one or more paths specifying joint movement within a null-space of the Jacobian for increasing the range of movement; calculate a facilitating movement of the one or more joints within the null-space of the Jacobian, wherein the facilitating movement moves the one or more joints toward the constraint, the null-space being orthogonal to the null-perpendicular-space; and transmit a command to the manipulator arm to drive the plurality of joints according to the end effector displacing and the facilitating movements so as to effect the desired end effector movement concurrent with the facilitating movement of the one or more joints. a manipulator arm configured for robotically moving a distal end effector relative to a proximal base, the manipulator arm having a plurality of joints between the distal end effector and the proximal base, the plurality of joints providing sufficient degrees of freedom to allow a range of joint states for a given state of the distal end effector; an input device for receiving a manipulation command to move the end effector with a desired end effector movement; and a processor coupled to the input device and to the manipulator arm, the processor configured to: calculate an end effector displacing movement of the plurality of joints in response to the manipulation command by calculating joint velocities within a null-perpendicular-space of a Jacobian; define a position-based constraint of one or more joints of the plurality of joints within an associated joint space, the position-based constraint being specific to a design and kinematics of the manipulator arm and corresponding to an increased range of movement of the one or more joints, the position-based constraint including one or more paths specifying joint movement within a null-space of the Jacobian for increasing the range of movement; calculate a facilitating movement of the one or more joints within the null-space of the Jacobian, wherein the facilitating movement moves the one or more joints toward the constraint, the null-space being orthogonal to the null-perpendicular-space; and transmit a command to the manipulator arm to drive the plurality of joints according to the end effector displacing and the facilitating movements so as to effect the desired end effector movement concurrent with the facilitating movement of the one or more joints. calculate an end effector displacing movement of the plurality of joints in response to the manipulation command by calculating joint velocities within a null-perpendicular-space of a Jacobian; define a position-based constraint of one or more joints of the plurality of joints within an associated joint space, the position-based constraint being specific to a design and kinematics of the manipulator arm and corresponding to an increased range of movement of the one or more joints, the position-based constraint including one or more paths specifying joint movement within a null-space of the Jacobian for increasing the range of movement; calculate a facilitating movement of the one or more joints within the null-space of the Jacobian, wherein the facilitating movement moves the one or more joints toward the constraint, the null-space being orthogonal to the null-perpendicular-space; and transmit a command to the manipulator arm to drive the plurality of joints according to the end effector displacing and the facilitating movements so as to effect the desired end effector movement concurrent with the facilitating movement of the one or more joints.