There are many options to connect two rotating shafts together. The most obvious path is to use a rotary coupling. Unfortunately, while there are many couplings that can be purchased or made, choosing the right one takes some practice and a little bit of luck.
Robots have evolved from moving big things around in large areas to working collaboratively with humans in tight or uncaged environments. Robot designers are continuously challenged to reduce motorized joints’ size and weight while improving accuracy and response. This recording will discuss how direct drive motors coupled to high ratio precision gearing are an excellent choice to meet these challenges.
The selection of a proper coupling for a motion-control application requires consideration of numerous performance factors that must be taken into consideration for the coupling to work properly. These factors include including torque levels, the type and amount of shaft misalignment, inertia, torsional stiffness, rotational speed, space requirements, and others.
Through innovations in design, drive technology has taken a leap forward from mechanisms used since the 1950s. At the same time, design upgrades have allowed for smaller footprint, lighter weight, and higher torque densities.
We spent some time with Carlos Hoefken, CTO & Co-Founder, and asked him questions regarding the Motus CAM and CAM Generator™ software. In the video, Carlos uses the ML100 as an example, but the same CAM concept applies to the ML1000 series.
Humans know intuitively or from experience that if we put weights on our wrists or elbows, it becomes more difficult to move our arms. If we apply the same force we used without any weights, our arm will move more slowly.
It’s no surprise, then, that we see the same result in robots: as joints get heavier, the arm moves more slowly when the same force (or torque) is applied. Conversely, removing weight from the wrist or elbow actuator using a lighter weight transmission/gear drive results in higher speeds for the same applied torque.
What does a 10-15% increase in robot speed imply for robot owners?
As we mentioned in the last post, we will be looking at how torque density influences different robot parameters, including reach, speed, and lifetime. Each of these in turn has a direct and important impact on the economic value of a robot to the end-user.
In the context of robotic actuators, the term torque density refers to how much torque the actuator is able to produce per unit weight or unit volume. The term can be applied to the actuator as a whole or separately to the motor or gearbox that is contained within the actuator. Why should we be interested in torque density? Because the torque densities of a robot’s components can limit nearly every facet of a robot’s performance.
Recent technical paper contributed by Greg Zancewicz & Carlos Hoefken at the 5th International Conference on Control and Robotics Engineering. The paper discusses electric actuators adding weight along an articulated robot arm and how the torque and speed limitations impose additional dynamic constraints including useful life of a robot and the extent to which each actuator operates at or near its torque ratings.
Although strain wave, or “harmonic,” gearing can deliver high reduction ratios in a relatively small form factor, it is well known that the technology also impairs the dynamic performance of robot arms due to elastic deformation that occurs even well below the drive’s rated torque.