During discussions on collaborative robots, power and force limiting robots takes over the discussion. This is because they are the most collaborative robots in existence. The other three types of cobots tend to be overshadowed. These other types are: hand guiding; safety monitored stop; and speed and safety monitored stop.
The major difference that distinguish the three from the power & force limiting robots is the fact that they utilize regular industrial robots with additional safety measures such as Lasers and vision systems.
Power and force limiting cobots are embedded with various kinds of sensors that allow them to detect forces and automatically stop to prevent severe impact with the human operator. The sensors can be located in the cobot’s joints or on its external cover. Most manufacturers of these cobots provide adjustable settings that assist in changing the force limitation degree thereby increasing the flexibility of the cobot.
Additionally, most of the force limited cobots have round shapes to increase the area of contact between the operator and the cobot. This is also a safety precaution because, due to the increased area of contact, the cobot is able to reduce the pressure applied by the operator when an impact occurs. Moreover, some cobots are padded to reduce the direct impact between the cobot and human.
Power and force limiting cobots are of various types which include the following major categories;
Categories of power and force limiting cobots
· Joint sensing
These are the cobots that use their joints to monitor the forces the human operator is applying to it. There are various ways that assists in this cobot’s ability. some of them include: using the current of their motor; and use of force-torque sensors located in their joints. Joint sensing cobots are often easy to operate because they need few settings for them to be fully operational.
· Skin sensing
Despite the high safety of this cobot, skin sensing cobots are not very common in many industries. They have sensors that perceive and monitor the degree of touch applied to it. The sensors also monitor the cobot’s conductivity and directs it to stop once a particular limit is reached. Interestingly, the cobot can stop prior hitting an object, the impact between the human and the cobot is therefore very minimal.
· Force sensor base
In this cobot, a sensor is fitted at its base, usually, large force-torque sensors. These sensors monitor the various forces applied to the cobot. Depending on its programming, the cobot stops once a certain force limit is reached.
· Inherently safe
These cobots as the name suggests, are inherently safe. They utilize any or all types of sensors to improve their collaborative aspect. They therefore rarely hurt the operator when performing tasks.
Additionally, these collaborative robots have low payloads hence too weak to cause hurt or damage in cases of impact with human. However proper settings need to be done to prevent damages or injuries.
Benefits of using power and force limiting cobot
Since these cobots are the most collaborative robots, their benefits are overwhelming. Some of those benefits include the following;
- Comparing to the speed & separation monitoring and safety monitored stop robot, this cobot occupies small spaces in the industries due to their small sizes and can be moved from one location to another in the production line. Since the former, utilizes the traditional industrial robots, their agility is minimal or even impossible.
- Force limited cobot can be easily reprogrammed to perform other tasks. They are able to easily remember the instructions given and perform the repetitive tasks accurately.
- These cobots are more productive. The fact that they are the most collaborative robots allows them to partner efficiently and effectively with human with minimal interruptions. This is in comparison to the safety monitored stop cobot that stops when a human enters the safety zone. The production process thereby slows down due to the frequent interruptions.
- They are fast to set up, due to their small sizes and easy programming an untrained operator can set them up quickly. The functionality of these cobots can therefore be utilized in the production process earlier than the traditional industrial robots. However, risk assessment should be done before making use of cobots.
