A robot arm for end-effector motion comprising: - a first actuator configured to rotate an inner arm-assemblage about a first axis of rotation (29, 29A), 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 (17, 18) such that the outer arm-linkage (17, 18) 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 (17, 18) 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 (17, 18) 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 (17, 18) including the first link, connected to the end-effector platform via end-effector bearings (19, 20) mounted to the end-effector platform, wherein the outer pair of parallel links (17, 18) 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 (29, 29A), 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 (17, 18) such that the outer arm-linkage (17, 18) 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 (17, 18) 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 (17, 18) 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 (17, 18) including the first link, connected to the end-effector platform via end-effector bearings (19, 20) mounted to the end-effector platform, wherein the outer pair of parallel links (17, 18) are the only links of the robot arm that are, via bearings, directly connected to the end-effector platform.