Soon, robots could be doing much more than just vacuuming your house or assembling your next car-they could also invade your investment portfolio. 

That's the gist of a slew of recent reports on the industry's rapid growth. Here's some insight from a recent one by the Boston Consulting Group:

  • Today, robots perform roughly 10% of all manufacturing tasks, but BCG sees that jumping to about 25% by 2025.
  • By the same year, automation will cut manufacturing labor costs by 18% to 33% in countries like South Korea, China, the U.S., Japan and Germany, while boosting productivity by up to 30%.
  • It's not only cheaper labor that's driving the automation trend, it's cheaper robots: the cost of an advanced robotic spot welder, for example, has dropped 27% since 2005, according to BCG, from an average of $182,000 to $133,000. The consulting firm sees that price tag slipping a further 22% by 2025.

As eye-catching as these figures are, there's a good chance they may be conservative. In March, just one month after BCG's report came out, the International Federation of Robotics said industrial robot sales had surged 27% in 2014, to 225,000 units, breaking through the 200,000 mark for the first time.

That's bad news if you're a factory worker, but there's a silver lining, because all of these new robots will require more skilled techs to operate and maintain them.

For investors, the shift is a clear sign that the biggest gains in robotics still lie ahead.

If you're looking for the industry's fastest growth, you'll want to pay particular attention to what's happening on the consumer/office side, where sales are set to grow at a 17% compound annual rate between 2014 and 2019, according to a May report from Business Insider -- seven times quicker than the industrial-robot market. In addition, a number of radical new applications for robotics are emerging in the medical and defense markets, as outlined in this presentation from Investing Daily.

Even though the automation trend is clearly set, there still aren't many pure ways for investors to play it. But that doesn't mean there are no intriguing options out there. Here are five robot makers to keep on your radar screen, two of which we recommend as buys at Investing Daily:

GOOG Chart GOOG data by YCharts

1. Google (GOOG)   (GOOGL)  

When you google "robotics," one of the top hits is a Guardian story about Google itself. That's no surprise: the Internet search giant entered the robotics space in a big way between early December 2013 and late January 2014, during which time it snapped up eight robotics or artificial intelligence firms.

The deal that grabbed the most attention was Boston Dynamics, a privately held company that was spun off from MIT in 1992 and run by a group of researchers working on robots that could move like animals.

Boston Dynamics makes the Cheetah, the world's fastest legged robot, capable of running 29 miles per hour, as well as the Atlas, a two-legged humanoid robot Boston Dynamics founder Marc Raibert showed taking a very human-like hike through the woods in August. Clients include the US Army, Navy and Marine Corps, as well as the Defense Advanced Research Projects Agency (DARPA), which handles research and development for the Pentagon.

But despite its growing robotics business, the search giant is no pure play on the robotics theme, with its automation efforts falling into its collection of "moonshot" projects. Google's online ad business still supplies about 90% of its revenue.

YASKY Chart YASKY data by YCharts

2. Yaskawa Electric (YASKY)  

Yaskawa Electric is one of the leaders in industrial robotics, with roughly 20% of the market.

Like Boston Dynamics, Japan-based Yaskawa is far from a start-up: it's currently marking its centennial year and boasts a current market cap of $2.8 billion.

For many years, the company focused mainly on machine-control systems, but robotics provided 34% of sales in its latest fiscal year. Its machines can be found on factory floors around the world -- particularly in Asia-- performing jobs such as arc welding, packaging, coating and assembly.

Under its Vision 2025 plan, Yaskawa aims to double its forecast full-year 2015 sales ($3.6 billion) by 2025 and nearly triple operating income from this year's goal of ($305 million). Its plans include parlaying its industrial expertise into health care, where it's looking to develop robots that can help patients with limited mobility.

The company is a favorite of Martin Hutchinson, chief strategist at our Pacific Wealth advisory; he recently named the stock "the world's best robot play" and rates it a buy up to $40.

ABB Chart ABB data by YCharts

3. ABB Ltd.  (ABB)  

ABB Ltd. is another major player in the industrial robotics.

The Switzerland-based firm, with a $43 billion market cap, mainly focuses on components for power grids, including transformers, switchgear and circuit breakers -- though its robotics business has installed 300,000 units to date. In ABB's latest quarter, its discrete automation and motion division (including robotics) accounted for 26% of total sales.

ABB just became the first global industrial robotics company to make robots in the United States: on May 20, it cut the ribbon on its new plant in Auburn Hills, Mich., and production is already underway. Right now, about 60% of the automated laborers are assembled in Asia.

The stock jumped in early June after ABB said Swedish activist investment firm Cevian Capital had taken a 3.0% stake (later boosted to 5.1%) in the company. Cevian hasn't said what it has in store for ABB, but its plans could include pushing for a spinoff of its faster-growing automation business from its slower-growth utility operations.

IRBT Chart IRBT data by YCharts

4. iRobot (IRBT)  

iRobot is a rare pure play on robotics.

The maker of the ubiquitous Roomba self-directed vacuum is now moving outside the home, winning the thumbs-up from the FCC for a new automated lawn mower in mid-August. The device -- which is still very much in the concept stage -- would be guided by transmitter stakes driven into the ground at specific intervals.

The company's market cap is just $885 million, but the Roomba dominates the robotic home-vacuum market, with a roughly 75% share. In turn, according to Morningstar, robotic vacuum sales now make up over 18% of all U.S. vacuums above $200 sold annually.

Aside from the Roomba, iRobot makes automated floor scrubbers, mops and pool and gutter cleaners, as well as robots for the U.S. military. In July, it reported stronger-than-expected quarterly earnings, thanks to a 24% sales increase at the Home Robot division, 60% higher revenue in China and a doubling of sales at the Defense and Security business.

EKSO Chart EKSO data by YCharts

5. Ekso Bionics Holdings (EKSO)

On the more speculative end is Ekso, which has been trading publicly since January 2014. Unlike products from the four companies above, Ekso's robots don't aim to replace humans so much as enhance them.

The company makes the Ekso GT, an exoskeleton suit rehab centers use to help patients who've suffered from strokes or other injuries learn how to walk again.

The market for exoskeletons is very much in its infancy, but it's a real and growing opportunity: over 2.5 million Americans with disabilities are candidates for exoskeletons currently available or in development.

But the opportunity goes beyond rehab, with the military -- including DARPA -- and industry (imagine a factory worker capable of lifting twice his or her body weight) also showing interest.

Investing in Ekso, a thinly traded over-the-counter stock with a market cap of just $139 million, is undoubtedly a high-risk proposition. But if you want to put some money into an early-stage technology with big potential, the stock is a good way to do it. You can learn more about the exoskeleton opportunity by clicking here.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.

More from Stocks

It's Harvest Season for Tax Losses

It's Harvest Season for Tax Losses

Santa Claus Rally? Machines Render Old Stock Market Adages Worthless

Santa Claus Rally? Machines Render Old Stock Market Adages Worthless

Procter & Gamble Helps Lead Dow Jones After Upgrade From Morgan Stanley

Procter & Gamble Helps Lead Dow Jones After Upgrade From Morgan Stanley

Hey Investors, Don't Let the Bad Times Pollute Your Mind

Hey Investors, Don't Let the Bad Times Pollute Your Mind

Make This Dividend Aristocrat a Staple of Your Portfolio

Make This Dividend Aristocrat a Staple of Your Portfolio