Six-Axis Articulated Robots for Light Duty

April 10, 2014
Weighing 55 pounds or less and designed to handle payloads of up to 22 pounds, these new lightweight robots from Universal Robots expand the possibility of robot application in industry.

When you think of industrial robots, chances are you thinking of big, expensive robots used in industrial applications such as automotive manufacturing or warehousing. But robot applications are increasingly trending toward small, more precise applications as evidenced by the release of the new UR 5 and UR 10 robots from Universal Robots.

Key to the flexibility of these robots are the KBM direct drive motors from Kollmorgen. In designing these robots, Universal Robots embedded the motors directly into the articulation axes. The UR 5 model weighs 39 pounds and can handle up to 11 lb. payloads; the UR 10 weighs 55 pounds and can handle up to 22 lb. payloads. (The robots’ names are derived from their handling capacity in kilograms, e.g., UR 5 can handle payloads up to 5 kilograms or 11 lbs.).

The dead weight-to-loading capacity of these robots is the result of a “sophisticated lightweight construction that does not contain anything it does not need,” says Ian Young, key account manager at Kollmorgen. “By integrating Kollmorgen's frameless kit motors directly into the articulation axes, the robot takes on the function of the motor housing, while the gear unit simultaneously serves as the primary bearing of the rotor. This reduces the number of mechanical components such as ball bearings, couplings, or shafts considerably, thus decreasing overall system weight and form factor.”

In robot designs such as this, where the motors are embedded in the robot housing and directly drive the load, targeted force control is critical because the robots constantly have to precisely move objects of different size and shape.

“The robots recognize the size and elasticity of the objects and adjust the force to be applied accordingly,” says Young. “With a precision of ± 10 newtons and an accuracy of ± 5 millimeters, the required force and desired position can be programmed and executed for each of the six joints.”

Plus, the high efficiency of these KBM motors used in the robots means less heat is produced, allowing the motors to stay cooler and operate below their maximum ratings, thereby achieving a longer service life. The improved temperature behavior also prevents the entire construction from heating up.

"The motors we used in the past became pretty hot when in continuous operation,” says Esben H. Östergaard, technical business manager of Universal Robots. “Because of the lower losses, the KBM motors from Kollmorgen stay colder. We can therefore run our robots in continuous operation without derating," he says.

Though the focus for the UR 5 and UR 10 models has been to use the robots as a tool for performing simple tasks, Universal Robots is exploring the use of these robots in applications such as welding and gluing. The safety technology used on both models allow them to be employed without additional shielding, says Östergaard.

This video shows the UR 5 in action.

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