October 7, 2022

By Tom Atwood

TeslaOptimus400x275Last week at a Tesla AI technology event, Elon Musk introduced multiple versions of Tesla’s Optimus humanoid robot. The event included a production model (prototype photo at left), which Elon Musk hopes to eventually sell in the millions as a personal assistant for under $20,000 each. 

Soon after, the Institute of Electrical and Electronics Engineers (IEEE) posted an interesting list of questions from professional roboticists in industry and academia concerning key next steps in the development of the Tesla Optimus. These key questions will need to be answered as Tesla gears up to produce the Optimus humanoid robot for the mass market. Elon Musk, who has shown himself to be a master at technology innovation from rocket engine design to self-driving car neural networks, has admitted his team may be “barking up the wrong tree” in terms of some of the current technical approaches — showing a level of humility and steadfastness in his approach. Optimus is admittedly a work in progress for Tesla. 

Some of the questions raised include:

  • How will manipulation be solved?
  • The cable-driven hand design has a slow response time, making it harder to do learning-based control with autonomous manipulation — what will follow?
  • How will Tesla develop the required stack of hardware, simulation and data infrastructure?
  • What are the plans for Optimus autonomy? How will the cognitive side of AI be addressed?
  • Will the zero-moment point (ZMP) system for walking, which is not as dynamic as human walking (extend foot, fall, catch, repeat) — be upgraded?
  • The current locomotion stack uses trajectory optimization with reference controllers, what will follow for longer-term operation?
  • How will kinematic efficiency be improved? Optimus uses an old school series chain of actuators (although wrists and ankles are differential roll/pitch).
  • How does Optimus fall down and recover?
  • Can human-level dexterity be achieved?  Optimus has no finger ab/adduction, and only two DOFs in the thumb.
  • What will be the next actuator iteration beyond electric motors with battery support? Optimus actuators appear to use active force loops, which complicates control, reduces efficiency, and raises complexity.
  • How will backdrivability be handled? The upper body actuators have harmonic drives and the leg actuators are screw driven. This suggests low backdrivability, which makes the robot rigid to external forces, and software control loops add a telltale wobble in the 4-hertz range.
  • Will [2.3 kWh] batteries be enough for a full day’s work? Agility Robotics’ Digit batteries last 3 hours under light duty.
  • Is a $20,000 price point feasible?

See selected images of the Tesla Optimus Humanoid in developmental stages through the Tesla AI event at the National Robotics Education Foundation (NREF). Images courtesy of IEEE Spectrum, CNET and bdtechtalks.com

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