Several key sensor technologies that play a major role in modern robotics include magnetic position sensors, presence sensors, gesture sensors, force and torque sensors, environmental sensors, and power management sensors.
Magnetic position sensor
Magnetic angle position sensor integrated circuits (ICs) are among the sensor technologies used today in consumer, service professional, social, and even industrial robots. Currently, almost every joint in consumer, service professional, or social robots uses two or more magnetic angle position sensor ICs.
For each axis of motion or joint rotation, at least one magnetic angular position sensor is used. Many robots today use small but powerful brushless DC motors (BLDC) to move the robot's joints and limbs. Motor position feedback is required for proper motor drive.
Furthermore, closed-loop motor control of robot joints also requires feedback on the angle position of the joint gears. Therefore, for each robot joint, two magnetic angle position sensors are needed on each motion axis. The magnetic angle position sensor IC provides motor commutation feedback to the combined motor controller. (A robotic arm with magnetic position sensors is described.)
For example, a total of four magnetic position sensors are used for a robot ankle that needs to perform axial movement in both pitch and roll. The fact that each joint has this type of multiple connections, and the large number of joints required in most robots, explains why magnetic angular position sensors are so prevalent in today's robotic products.
Presence Sensor
Today, several on-premises sensor technologies have been integrated into modern robots, and their information is fused together to provide robots with spatial visual sensing as well as object detection and avoidance. 2D and 3D stereo vision cameras are prevalent in many new consumer and professional service robots today.
However, new and advanced sensor technologies, including time-of-flight sensors such as LiDAR (Light Detection and Ranging) sensors, are increasingly being deployed in robots. LiDAR provides a high-resolution 3D map of the space in which the robot is operating and its surrounding environment, enabling it to better perform tasks and move around. LiDAR mapping
Similarly, ultrasonic sensors are used for presence sensing. Like their counterparts in cars used in backup security alarm systems, ultrasonic sensors in robots are used to detect nearby obstacles and prevent them from colliding with walls, objects, other robots, and humans.
Furthermore, they can play a role in robots performing primary functional tasks. Therefore, ultrasonic sensors play a crucial role in near-field navigation and obstacle avoidance, providing overall improvements in robot performance and safety.
However, ultrasonic sensors have a limited range, ranging from about one centimeter to several meters, and a relatively large directional cone of about 30°. They are relatively inexpensive and have good accuracy at short distances, but their accuracy decreases as the range and measurement angle increase.
They are also susceptible to changes in temperature and pressure, and are vulnerable to interference from other nearby robots that use ultrasonic sensors tuned to the same frequency. However, when used in conjunction with other presence sensors, they can provide useful and reliable position information.
When all these presence sensor data (2D/3D cameras, LiDAR, and ultrasound) are fused together, as we are now beginning to see in consumer/professional service robots and industrial robots, these robots are able to achieve spatial awareness and move and perform more complex tasks without damaging themselves, people, or the surrounding environment.
gesture sensor
Gesture sensors are increasingly being integrated into some of today's more complex robots to help provide user interface commands. Gesture sensor technology includes optical sensors and sensors worn by robot operators on control arms.
Using optical-based gesture sensors, robots can be trained to recognize specific hand movements and perform certain tasks based on those gestures or hand movements. These types of gesture sensors offer numerous opportunities for people with disabilities and those with limited communication capabilities in homes or hospitals, as well as in smart factories.
Using armband control sensors, the wearer can communicate and control collaborative, industrial, and medical robots based on how the operator moves and their own arms to perform and/or mimic certain tasks. For example, a surgeon wearing armband sensors on each arm can control a pair of remote medical robotic arms to perform surgery, possibly as far as the other side of the world.
Force and torque sensor
Force and torque sensors are increasingly being used in today's next-generation robots. They are not only used in robot end effectors and grippers, but now also in other parts of the robot, such as the torso, arms, legs, and head. These specialized force and torque sensors are used to monitor limb velocity movements, detect obstacles, and provide safety alerts to the robot's processor.
For example, when the force and torque sensors in a robotic arm detect a sudden and unexpected force generated by the arm hitting an object, its control safety software may cause the arm to stop moving and retract into its position.
Force and torque sensors are also used in conjunction with presence sensors and other safety monitoring sensors (such as environmental sensors) to provide overall safety area monitoring capabilities.
(Force and torque sensor)
Environmental sensors
Various environmental sensors are also being introduced into the industrial and consumer robotics sectors. These include sensors that can detect VOCs (volatile organic compounds) related to air quality, temperature and humidity sensors, pressure sensors, and even sensors that detect lighting. These sensors not only help ensure that robots can continue to operate effectively and safely, but also make robot-local personnel aware of unsafe environmental conditions.
Power management sensor
Power management sensors are also integrated into today's autonomous robots to help extend the robot's working time between charges and ensure that lithium-ion batteries (common in today's autonomous robots) do not overheat or deplete during use.
Power management sensors are also used in voltage regulation and power and thermal management of robot joint motors. All onboard robot electronics, such as microprocessors, sensors, and actuators, require low-noise ripple power supplies and regulation to ensure they operate efficiently and correctly.
Sensor solutions for robot power management include coulomb counters for battery discharge and charging, accurate and reliable overheat monitoring sensors for voltage regulators, and current sensors in battery management devices.
Thanks to the integration and fusion of all these new sensor technologies, today's robots can operate more safely. Furthermore, due to significant improvements in computing power, software, and artificial intelligence, and working in conjunction with these new sensor technologies, this next-generation robot can more easily adapt to a wide range of application needs.
Moreover, they can perform tasks more accurately and faster than their predecessors. They can collaborate and work safely with humans in home, business, and manufacturing environments.
