A robot arm for end-effector motion comprising: - a first actuator configured to rotate an inner arm-assemblage about a first axis of rotation , the inner-arm assemblage comprising an arm link being rigidly connected to a joint that is connected to a first link of an outer arm-linkage such that the outer arm-linkage is pivotably arranged around a second axis of rotation of the joint , the outer arm-linkage being connected to an end-effector platform , thereby forming a first kinematic chain from the first actuator to the end-effector platform, which gives a first degree of freedom for positioning the end-effector platform; - a second actuator (5; 5b) configured to rotate the outer arm-linkage around a second axis of rotation , thereby forming a second kinematic chain from the second actuator to the end-effector platform, which gives a second degree of freedom for positioning the end-effector platform; - a third actuator (6; 6b, 512) configured to rotate a shaft around a third axis of rotation (33; 99) such that the outer arm-linkage is rotated via a joint (16; 161) around the third axis of rotation (33; 99), thereby forming a third kinematic chain from the third actuator (6; 6b) to the end-effector platform, which gives a third degree of freedom for positioning the end-effector platform; - wherein the outer arm-linkage comprises an outer pair of parallel links including the first link , connected to the end-effector platform via end-effector bearings mounted to the end-effector platform , wherein the outer pair of parallel links are the only links of the robot arm that are, via bearings, directly connected to the end-effector platform . - a first actuator configured to rotate an inner arm-assemblage about a first axis of rotation , the inner-arm assemblage comprising an arm link being rigidly connected to a joint that is connected to a first link of an outer arm-linkage such that the outer arm-linkage is pivotably arranged around a second axis of rotation of the joint , the outer arm-linkage being connected to an end-effector platform , thereby forming a first kinematic chain from the first actuator to the end-effector platform, which gives a first degree of freedom for positioning the end-effector platform; - a second actuator (5; 5b) configured to rotate the outer arm-linkage around a second axis of rotation , thereby forming a second kinematic chain from the second actuator to the end-effector platform, which gives a second degree of freedom for positioning the end-effector platform; - a third actuator (6; 6b, 512) configured to rotate a shaft around a third axis of rotation (33; 99) such that the outer arm-linkage is rotated via a joint (16; 161) around the third axis of rotation (33; 99), thereby forming a third kinematic chain from the third actuator (6; 6b) to the end-effector platform, which gives a third degree of freedom for positioning the end-effector platform; - wherein the outer arm-linkage comprises an outer pair of parallel links including the first link , connected to the end-effector platform via end-effector bearings mounted to the end-effector platform , wherein the outer pair of parallel links are the only links of the robot arm that are, via bearings, directly connected to the end-effector platform . <EOS>