Robot parts selection logic and space geometry

Tesla released Optimus, a humanoid robot, which sparked a boom in the industry. 14 rotary joints + 14 linear joints + 12 hand joints; rotary joint composition: frameless motor + harmonic reducer + angular contact bearing + cross roller bearing + encoder + torque sensor; linear joint composition: frameless Motor + planetary roller screw + cnc machining robotic parts + deep groove ball bearing + four-point contact ball bearing + torque sensor + encoder.

We focus on the parts selection logic of each link:

  • 1) Motor: The core reason why Tesla bot chooses torque motor is that it can provide higher torque in low-to-medium speed movement compared with servo motor and stepper motor, which is especially suitable for low-speed + high-torque requirements of humanoid robots , the difficulty is relatively large, and the best overseas is currently Kollmorgen; the spherical motor is not yet very mature, and may be used in the shoulders and wrists of Tesla robots in the future, and domestic manufacturers are mainly Megmeet;
  • 2) Reducer: The advantage of the harmonic reducer lies in its simple structure, high transmission ratio, and high precision. In the rotary joint, we estimate that the harmonic is relatively difficult to replace, but the harmonic also needs to improve its durability and other aspects. capacity, so it is not ruled out that the reducer still has some room for modification; in the linear joint, the use of planetary reducer is not ruled out in the future, but this has no substitute for harmonics;
  • 3) Sensors: Torque sensing is a joint component that must be used by humanoid robots. It forms a motor-reducer-sensor joint assembly design. The core of the torque is the force-sensing module. It is currently a key component to improve the safety of the robot and is difficult to be detected. Replaced by the current measurement of the motor itself, overseas ATI is the leader in this field;
  • 4) Upper limb transmission mode: Ball screw is a kind of mechanical transmission mode, which mainly converts the reciprocating motion of the ball into the linear motion of the screw. Compared with the general belt, chain and other transmission modes, the friction is small and the maintenance cost is low;
  • 5) Transmission mode of the lower limbs: the planetary roller screw used for the thigh + calf, the current number of single robots used is 8, the performance is significantly better than the ball screw, especially the performance of external impact resistance + life; the lower limbs It is also possible to use connecting rod structure + motor + planetary reducer + roller bearing, the main reason is the advantages of wide application and low processing difficulty;
  • 6) Hand joints: Tesla’s hand contains 12 joints, and its main feature is the use of hollow cup motor products, which are actually a simpler motor product in design;
  • 7) The bearings selected for linear & rotary joints include angular contact bearings, crossed roller bearings, deep groove ball bearings, four-point contact ball bearings, etc.; these bearings are generally characterized by light weight, compact design, high precision, and good rigidity (no Easy to deform), etc., but the maintenance cost is more frequent.

Calculation of space and elasticity: We calculate Tesla robots machining under the scenario of Tesla‚Äôs shipment of 5/100,000 robots, assuming that the market share of the main target can reach 30%, and the net profit rate is consistent with the previous industry level. Give the main target profit flexibility: In the scenario of shipment of 100,000 units, according to the optimistic unit value, Kinco, Topzhi Technology, Qinchuan Machine Tool, Keli Sensing, Zhongda, Xinjian Transmission, etc. are more flexible, and MOONS’ The harmonic elasticity of Electric Appliances, Best, and Green is between 15-40%. Although the elasticity of Sanhua Zhikong, Tuopu Group, Hengli Hydraulics, and Shuanghuan Transmission is small, they are all directly connected to Tesla, which cannot be ignored. white horse breed.