Mobile manipulators have been in the market for quite a while. Universities and research institutes initially began reusing their mobile robots and robot arms to improve dexterity. When ROS was gaining popularity in early 2007, PR2, a mobile manipulator (http://www.willowgarage.com/pages/pr2/overview) from Willow Garage (shown in the following photograph), was the testbed for testing a variety of ROS packages:
PR2 has the mobility to navigate like a human being rationally and the dexterity to manipulate objects in an environment. However, industries didn't prefer PR2 initially as it cost $400k to own one. Soon, mobile robot manufacturers began building robot arms onto their available mobile robot bases and this began gaining popularity due to its lower cost compared to PR2. Some of these well-known manufacturers are Fetch Robotics, Pal Robotics, Kuka, and many more.
Fetch robotics has a mobile manipulator called Fetch (https://fetchrobotics.com/robotics-platforms/fetch-mobile-manipulator/). Fetch is a combination of a 7 degrees of freedom robot arm with an additional degree of freedom—the torso lift mounted on a mobile robot base that was targeted to carry a payload of 100 kg. Fetch is 5 foot tall and can understand the environment through its sensors, such as depth cameras and laser scanners. It is robust and low in cost. Fetch uses a parallel jaw gripper as its end effector and has an additional pan and tilt-based head (with the depth sensor). The arm can carry a payload of 6 kg.
Pal robotics introduced a mobile manipulator called Tiago (http://tiago.pal-robotics.com/), which is similar in design to Fetch. It has good features too, unlike Fetch, and is used by various research institutes across Europe and the world. It also has a 7 degrees of freedom robot arm, but it also has a force-torque sensor on its wrist to carefully monitor manipulation. However, the payload capabilities are slightly lower than Fetch as the arm can only lift around 3 kg of payload and the base can only carry up to 50 kg. Tiago has lots of built-in software features such as NLP systems and face-detection packages that might be handy for ready deployment:
Kinova Robotics also has a mobile manipulator called MOVO (https://www.kinovarobotics.com/en/knowledge-hub/movo-mobile-manipulator), which has two robot arms, like a PR2. Unlike the preceding two mobile manipulators, this robot operation is sophisticated, slow, and smooth.
Other mobile manipulators make use of already available mobile robots and robot arms. For instance, Clearpath robotics has a wide variety of mobile manipulators that make use of their mobile bases—husky and ridgebacks, in combination with Universal robot's UR5 robot arms and the Baxter platform, respectively. Robotnik, on the other hand, has a mobile manipulator that is a combination of its mobile base RB-Kairos and Universal robot's UR5.
Since we now know the basics of mobile manipulators, let's look at its applications.