Optimus robot at Tesla event

The video below shows the human-like robot that was shown during the event. It can be seen sitting upright at a table and apparently assembling a replacement robot leg and walking around with other robots.

Musk used Tesla's first investor day to talk about efforts to speed up electric car production and to talk about Tesla's robotics project called Optimus, previously known as Tesla Bot.

He explained that the company has made great strides in robotics, as an earlier version of the robot was unveiled in October of last year and was unable to walk upright at the time.

Musk said the Optimus robot, which is expected to cost less than $20,000 when it goes on sale, and once available, he predicted Tesla robots could be used for both household tasks and in manufacturing environments, eventually outnumbering humans.

"I think we could exceed a ratio of humanoid robots to humans. It's probably the least understood or appreciated part of what we're doing at Tesla, but it's probably going to be worth significantly more than cars in the long run."

The technology company also announced that it has plans to open a fifth manufacturing plant to increase production of electric vehicles, shortly after the company announced its milestone of four million vehicles produced.

The announcement follows a challenging period for the brand in recent months that has seen the company's share price fall and prices for its vehicles cut before making a modest comeback.