1. Consider the force and moment range
Evaluate the range of forces and moments in the application scenario
First of all, it is necessary to conduct a detailed analysis of the specific application scenarios of industrial robots. For example, in the body welding scene in automobile manufacturing, the robot mainly applies a small contact force to ensure a good fit between the welding *** and the body surface, which is generally between a few Ox and dozens of Ox; In heavy machinery assembly scenarios, such as the assembly of large engines, robots may need to withstand and measure hundreds or even thousands of N forces and large moments.
For electronics assembly scenarios, such as chip packaging, the force during robot operation is usually very small, and only a sensor with a range of a few milliN to a few N may be required to precisely control the force and avoid damage to delicate electronic components.
Reserve a certain amount of margin
When determining the force and moment ranges, it is recommended to choose a range that is slightly larger than the larger possible value in the actual application. This is to prevent the sensor from being damaged due to overload in unexpected situations, such as when the robot collides or encounters a load that exceeds expectations. In general, a margin of 10% - 30% is appropriate. For example, if you expect a relative force of 100N, it is safer to choose a sensor with a range of 120 - 130N.
2. Accuracy requirements
Analyze the extent to which your application requires precision
Different industrial robot applications have very different requirements for precision. In the application scenario of high-precision medical surgical robots, the precision requirements are extremely high. For example, in neurosurgery, the accuracy of a six-dimensional force sensor may need to be in the milliN or even higher order to ensure that the surgical instruments do not cause damage to the nerve tissue during operation.
In some scenarios with relatively low precision requirements, such as ordinary logistics handling robots, the accuracy requirements can be appropriately relaxed. This kind of scenario mainly focuses on whether the robot can handle goods stably, and the requirements for accurate measurement of force and torque are not particularly high, and the sensor accuracy of several bulls may be enough to meet the demand.
Consider the linearity and repeatability of the sensor
Linearity refers to the degree of linear relationship between the output signal of the sensor and the input force and torque. Good linearity ensures accurate measurement results, especially in applications where precise force control is required. For example, in pressure testing equipment for electronic components, the linearity deviation of the sensor is required to be within a small range to ensure the reliability of the test results.
Repeatability refers to the ability of a sensor to take multiple measurements with the same input conditions to produce the same result. In the automated production line of industrial robots, repeatable sensors can ensure consistency every operation. For example, in the tightening of automotive parts, the sensor needs to have good repeatability to ensure that the tightening torque of each screw meets the standard.
3. Response frequency
Determine the speed and frequency requirements of the action in the application scenario
Observe the movement speed and action frequency of industrial robots in application scenarios. In the application scenario of high-speed packaging robots, the robot's arm may need to quickly grasp and place items, in which case a six-dimensional force sensor with a high response frequency is required. If the sensor response is too slow, it may miss the peak of the change in force, resulting in the inability to accurately control the robot's movements.
On the contrary, in some slow machining scenarios, such as the grinding of large ship parts, the robot moves slowly and has relatively low requirements for the response frequency of the sensor. In this case, you can choose a sensor with a slightly lower response frequency but a better performance advantage.
Match the control cycle of the robot
The response frequency of the sensor should match the robot's control cycle. Generally speaking, the response frequency of the sensor should be at least several times the frequency of the robot control cycle, so as to ensure that the information of force and torque can be received and processed by the robot control system in time. For example, if the robot's control cycle is 10ms, the sensor's response frequency is better than 100Hz.
4. The installation method and size
Consider the structural and space constraints of the robot's end-effector
The structure of the end effectors of industrial robots (such as grippers, suction cups, tools, etc.) is different, and there are different requirements for the installation of six-dimensional force sensors. On some end-effectors with complex constructions, it may be necessary to choose a sensor that is small and flexible in installation. For example, in the case of robotic grippers for the sorting of small electronic parts, due to the limited space in the grippers, it is necessary to choose a sensor with a smaller size that can be easily integrated into the gripper.
For heavy tools used by large industrial robots, such as large welding equipment or heavy assembly tools, the mounting firmness and stability of the sensor need to be considered. The sensor may need to be installed in such a way that it can withstand large forces and moments, and that it does not come loose during long periods of operation of the robot.
Make sure that the installed sensors do not interfere with the normal operation of the robot
After the installation of the six-dimensional force sensor, the function and normal operation of the robot end effector cannot be affected. For example, when the robot suction cup is used to handle objects with smooth surfaces, the installation of the sensor cannot change the adsorption performance of the suction cup, nor can it block the contact area between the suction cup and the object, otherwise the handling effect will be affected.
5. Adaptability to the working environment
Evaluate the environmental conditions of the application scenario
The working environment of industrial robots is varied, including temperature, humidity, dust, oil, electromagnetic interference, and other factors. In high-temperature metallurgical industry scenarios, such as continuous casting robots in steel plants, six-dimensional force sensors need to be able to withstand high-temperature environments, and generally require the sensor to be able to work normally at high temperatures of several hundred degrees Celsius, and ensure that the measurement accuracy is not greatly affected.
In wet or corrosive liquid environments, such as chemical production workshops, the sensor needs to have good waterproof and anti-corrosion performance, and the housing material may need to be made of special anti-corrosion materials and have good sealing performance to prevent liquids from entering the sensor and damaging the electronic components.
Consider electromagnetic compatibility
If industrial robots work in an environment with strong electromagnetic interference, such as near some large electrical equipment or high-frequency welding equipment, the six-dimensional force sensor needs to have good electromagnetic compatibility. This means that the sensor is able to work properly in this electromagnetic environment and does not generate erroneous measurement signals due to electromagnetic interference, which can affect the control and operation of the robot.