In the field of industrial automation, robots rely on sensors to provide essential information for executing operations correctly.
One report forecasts that the global industrial robot sensor market will grow steadily at a compound annual growth rate (CAGR) of approximately 8% by 2021. For robotics sensing applications spanning consumer and automotive sectors, another report explicitly states that vision systems alone will achieve a $5.7 billion market by 2027, while the force sensor market will exceed $6.9 billion.
Below are the most commonly used sensors in industrial robots.
2D Vision Sensors
2D vision refers to a camera capable of performing various tasks, from detecting moving objects to locating parts on conveyor belts. Many smart cameras can detect parts and assist robots in determining their positions, enabling robots to adjust their movements based on the received information.
3D Vision Sensors
3D vision systems require two cameras or laser scanners positioned at different angles to detect an object's third dimension. For instance, part picking utilizes 3D vision technology to detect objects, create three-dimensional images, analyze them, and select the optimal grasping method.
Force/Torque Sensors
If vision sensors provide robots with eyes, force/torque sensors grant them tactile perception. Robots use these sensors to sense the force exerted by their end effectors. Typically positioned between the robot and the gripper, force/torque sensors ensure all forces applied to the gripper are monitored by the robot.
Force/torque sensors enable applications such as assembly, manual guidance, teaching, and force limiting.
Collision Detection Sensors
These sensors come in various forms, primarily designed to provide operators with a safe working environment-collaborative robots rely on them most.
Some sensors function as tactile recognition systems, detecting pressure through soft surfaces and sending signals to limit or halt the robot's movement.
Others can be directly integrated into the robot. Some companies utilize accelerometer feedback, while others employ current feedback. In both cases, when the robot detects abnormal force, it triggers an emergency stop to ensure safety.
To enable industrial robots to collaborate with humans, the first step is identifying methods to guarantee worker safety. These sensors take various forms, from cameras to lasers, designed to inform the robot about its surroundings. Some safety systems can be configured so that when a person enters a specific zone/space, the robot automatically slows down. If the person continues to approach, the robot stops operating.
The simplest example is the laser safety sensor on elevator doors. When the laser detects an obstacle, the elevator doors immediately stop and retract to prevent collision.
Other Sensors
Numerous sensors are available on the market for diverse applications. Examples include weld seam tracking sensors.
Tactile sensors are also gaining popularity. Typically mounted on grippers, these sensors detect and perceive the nature of grasped objects. Sensors can usually detect force and determine its distribution, revealing the object's precise location. This enables control over the gripping position and the force applied by the end effector. Additionally, some tactile sensors can detect changes in heat.
Vision and proximity sensors, similar to those required for autonomous vehicles, include cameras, infrared, sonar, ultrasonic, radar, and lidar. Multiple cameras may be used in certain scenarios, particularly for stereoscopic vision. Combining these sensors enables robots to determine dimensions, identify objects, and measure distances.
RFID (Radio Frequency Identification) sensors provide identification codes and allow authorized robots to access additional information.
Microphones (acoustic sensors) help industrial robots receive voice commands and recognize abnormal sounds in familiar environments. When paired with piezoelectric sensors, they can identify and eliminate vibration-induced noise, preventing misinterpretation of voice commands. Advanced algorithms can even enable robots to understand the speaker's emotions.
Temperature sensing forms part of a robot's self-diagnostics, helping it determine its surroundings and avoid potentially harmful heat sources.
Using chemical, optical, and color sensors, robots can assess, adjust, and detect issues present in their environment.
For humanoid robots capable of walking, running, or even dancing, stability is a major concern. They require sensors similar to those in smartphones to provide precise positional data. Applications employ 9-degree-of-freedom (9DOF) sensors or inertial measurement units (IMUs) featuring 3-axis accelerometers, 3-axis gyroscopes, and 3-axis magnetometers.
Sensors are critical components enabling software intelligence; without them, many complex operations would be impossible. They not only facilitate intricate tasks but also ensure these operations remain well-controlled throughout execution.