In complex and ever-changing industrial environments and human-machine collaborative scenarios, collision detection and safety protection are crucial. Six-dimensional force sensors, with their unique functions, play an irreplaceable role in this regard.
I. Collision Detection Principle
Force and torque perception
A six-dimensional force sensor can simultaneously sense three forces (Fx, Fy, Fz) and three torques (Mx, My, Mz) in three-dimensional space. Under normal operating conditions, the forces and torques acting on the robot's end effector are within a relatively stable range, which is preset according to the robot's task.
For example, when a robot is performing material handling tasks, as it smoothly grasps and moves the material, the force sensed by the sensors is mainly the weight of the material and the small frictional force during the handling process, and the torque is also within a stable range.
Threshold setting and signal triggering
By analyzing the robot's tasks, reasonable force and torque thresholds can be set for the sensors. When the robot collides with other objects, the force and torque change instantaneously, exceeding the set thresholds.
Taking industrial robots on automated production lines as an example, during normal operation, the force and torque values experienced by the sensors may be within the range of 0-10N and 0-5Nm. If the collision thresholds are set to 50N and 30Nm, an alarm signal will be immediately triggered once the sensors detect a force or torque exceeding these thresholds.
II. Protecting the Robot Itself
Reduce mechanical damage
When a collision occurs, the six-dimensional force sensor can quickly detect abnormal forces and torques. After receiving the signals from the sensor, the robot's control system can take swift action, such as urgently stopping the robot's movement.
For example, in an automobile manufacturing plant, if a robot collides with surrounding fixtures or other equipment during the welding process, a six-dimensional force sensor will detect the sudden change in force at the moment of impact. Based on the sensor signal, the robot control system will immediately stop the movement of the robotic arm, preventing further damage to the joints, links, and other components, and reducing maintenance costs and time.
Prevent internal system failures
Besides mechanical parts, collisions can also damage a robot's internal electrical and control systems. The rapid response of a six-dimensional force sensor can prevent the impact force from being transmitted to sensitive electrical components and control modules.
For example, in electronic device manufacturing, robots are used for delicate operations such as chip mounting. If a collision occurs, sensors can detect it in time and stop the robot, preventing problems such as short circuits on circuit boards and motor overload caused by the collision, thus protecting the safety of the robot's internal systems.
III. Ensuring Personnel Safety
Applications in human-computer collaboration scenarios
In human-robot collaborative work environments, people and robots are in close contact. A six-dimensional force sensor can detect the contact force between the robot and the human body. When this force exceeds a safety threshold, the robot will immediately stop moving or change its movement to avoid causing harm to the human body.
For example, in the application of surgical robots, sensors can ensure that the robot does not exert excessive force when it comes into contact with medical staff or patients during surgery. If a medical staff member accidentally bumps into the robot arm, the sensors will quickly detect the change in force, causing the robot to stop moving and ensuring the safety of both the patient and the medical staff.
Safety standards and compliance
Many industries have stringent safety standards that require robots to have effective collision detection and safety protection measures. The use of six-dimensional force sensors helps robot systems meet these safety standards.
For example, in the food processing industry, robots work collaboratively with workers on packaging lines. Using six-dimensional force sensors ensures that robots comply with relevant safety regulations when in close contact with workers, such as the force limits specified in standards like ISO 10218-1 (Safety Requirements for Industrial Robots) and ISO/TS 15066 (Safety Requirements for Collaborative Robots).
IV. Signal Processing and Subsequent Response
Signal Filtering and Analysis
The signal output by a six-dimensional force sensor may be affected by factors such as environmental noise. Therefore, signal filtering and analysis are required before the sensor signal is transmitted to the control system.
For example, a low-pass filter can be used to remove high-frequency noise, ensuring that the control system receives accurate force and torque signals. Furthermore, signal analysis can distinguish between normal working force changes and abnormal force changes caused by collisions.
Diverse response strategies
Besides emergency stop, the robot can also take other response strategies based on signals from the six-dimensional force sensor. For example, in some situations, it can adjust its speed, change its direction of movement, or enter a safe standby state.
For example, in a logistics warehouse, if a robot detects a minor collision while handling goods, it can reduce its handling speed and replan its route to avoid further collisions, while continuing to complete the task, thus improving work efficiency and safety.
