The head of Tesla's Optimus program, Milan Kovac, is leaving the company, casting uncertainty over chief executive Elon Musk's humanoid robot project, Bloomberg News reported on Friday, citing a person familiar with the matter.Kovac, vice president and head of engineering for Optimus, told colleagues on Friday that he was departing, effective immediately. Ashok Elluswamy, who leads Tesla's autopilot teams, will take on Kovac's role, the report said.Musk has earlier said he expected Tesla to make thousands of Optimus robots this year.He said in April that China's export restrictions on rare-earth magnets had affected production of the humanoid robots.Tesla has shifted focus to launching the robots and its robotaxi service, with much of the company's valuation hanging on that bet."The only things that matter in the long term are autonomy and Optimus," Musk told CNBC in an interview in May. WHAT IS A HUMANOID ROBOT?A humanoid robot is a type of robot that is designed to resemble and behave like a human. It typically has a human-like body shape, which may include a head, two arms, a torso, and two legs. Some humanoid robots also mimic facial features and expressions, enabling them to interact more naturally with people.Appearance: Resembles the human form (at least partially).Movement: Can walk, talk, gesture, or even dance like a human.Sensors: Equipped with cameras, microphones, and touch sensors to perceive the environment.Artificial intelligence: Can understand speech, recognise faces, or respond to emotions (in advanced models).