Papers by Keyword: Robot Joints

Abstract: In order to establish the application possibilities in transmission parts in humanoid robot joints, wear of reinforced poly-ether-ether-ketone (PEEK) polymer bushes in friction against 7075 aluminium alloy cam plates is investigated. Additionally the transmission error (backlash) in robot joint was measured. The PEEK bush wear requires close examination as well as the input axis-output axis transmission error. Fatigue wear tests were performed on bushes under middle load at 3000 rpm motor speeds, while the cam plate oscillated in the humanoid robot leg joint evaluation system under 1300 kgfcm (132 Nm) load torque. The robot joint using PEEK bush achieved stable small backlash due to good friction perforance.

Abstract: In this work, wear of reinforced poly-ether-ether-ketone (PEEK) polymer bushes in friction against 7075 aluminium alloy cam plates or titanium crankshafts is investigated in order to establish the application possibilities in transmission parts in humanoid robot joints under high load torque. The PEEK bush wear requires close examination as well as the input axis-output axis transmission error (backlash). Sliding wear tests were performed on bushes under 4000 kgfcm (392 Nm) load torque, while the cam plate oscillated in the humanoid robot leg joint evaluation system. The robot joint using PEEK bush achieved quite small backlash after the fatigue wear test.

Abstract: Due to constant exposure to high torque and loads toughness, compressive durability and light weight of joint parts are crucial factors for biped walking humanoid robot parts. When polymer transmission parts are used for the manufacture of humanoid robot joint, wear becomes an important factor in terms of transmission error (backlash) between the input and output axes, ex. between the motor and the robot’s leg joint. In such joint system, a polymer bushes is directly connected to a cam plate, playing an important role in the robot's movement ability. In this work, the influence of wear of reinforced poly-ether-ether-ketone (PEEK) polymer bushes in friction against 7075 aluminium alloy cam plates is investigated in order to establish the application possibilities in transmission parts in humanoid robot’s joint. The PEEK bush surface conditions as well as the input axis-output axis backlash require close examination, so that efficient systems can be built. Sliding wear tests were performed on bushes under 0-50kgfcm loaded torque while the cam plate oscillated. Based on the wear observation, it was found that in a high load range the backlash increased along with number of cycles due to PEEK bush wear. The bush surface roughness also increased during testing. Roughness of PEEK bush surface and the loaded torque for output axis were significantly related to backlash of output axis in robot joint.

Abstract: The LuGre friction model well captures most of the friction behavior, but it was very difficult to identify the parameters of the LuGre model. The LuGre friction model, theory of static and dynamic parameters identification of the LuGre model as well as the algorithm based on particle swarm optimization are summarized according to the previous work. Then the programs for the static and dynamic parameters identification are made and analyzed in the environment of Matlab software in detail, and the identification results are given. The work mentioned above will lay the theoretical foundation for the future experimental validations and provide the detailed models, algorithms and programs for the corresponding research issues.