BOULDER - Robotic toymaker Orbotix Inc.'s Series D funding round announced in May got a little bigger in recent days with the closing of another $1 million in equity financing.

Boulder-based Orbotix - maker of the smartphone-controlled Sphero robotic ball - had previously raised $15.5 million in the round to help with marketing efforts and ramp up to the early September launch of its newest toy, Ollie.

Orbotix's chief executive Paul Berberian said the latest infusion of cash comes from some investors who needed a little more time to commit when the Series D round was ongoing, including some existing investors who wanted to put in more money to keep their percentage stake in the company the same from previous funding rounds.

Founded in 2010, Orbotix has ramped up to more than 40 employees, and has raised about $33.6 million in venture capital, with backers like Boulder-based Foundry Group and California-based Shea Ventures.

A specific date for the Ollie launch is yet to be announced. Ollie is a cylinder-shaped robot that can race around at 15 mph and perform tricks in the air.