# Touch, Texture and Haptic Feedback: A Review on How We Feel the World around Us
## 4 Haptic Feedback
### Kinesthetic Feedback
#### 4.1.1 Grounded Force Feedback System  
Grounded force feedback systems are some of the oldest forms of force feedback systems. These systems are commonly used in gathering data regarding position and contact forces on the user. The original Phantom by [PERSON] et al. makes use of an end effector attached to mechanical links with three brushed DC motors to facilitate 3-DOF movement for its user [107]. By representing only a single point within the virtual space, interactions within the environment can easily be calculated. [PERSON] et al. designed a pulley-based force feedback system using string-based actuation [108]. The researchers utilized the pulley-based system to impede the user's movement based on the virtual material being used: hard, soft, movable, or fixed. One common application for grounded feedback systems in their use as data-gathering devices for force-based applications. Unlike most wearable systems, stationary systems offer a more stable and controlled experience which makes them ideal for gathering or testing data with regard to haptic applications such as in textures. These systems allow for much more space to be dedicated for sensors used in data gathering as well as allowing for platforms more dedicated for testing haptic feedback. [PERSON] et al. describe the HapticMaster [109] that is based on an admittance control system wherein the user applies the force onto the device and the device will react with the appropriate amount of force or displacement to simulate force reaction. [PERSON] et al. developed the finger haptic display which utilizes a flat coil actuator to generate force when rendering virtual objects and was used to test the psychophysical reactions of haptic perception [110]. Another application of grounded kinesthetic feedback devices is in the field of rehabilitation. While wearable exoskeleton-based systems have seen increasingly more usage, they are, however, bulky and cumbersome to wear for certain patients which makes grounded feedback systems more appealing compared to their wearable counterparts. This issue can be particularly useful for those suffering leg injuries wherein having stationary platforms help support the patient walk or stand up. [PERSON] et al. developed the virtual walk master which utilizes pneumatic actuators that spread to 15-DOF movement across the foot [111] and is meant to simulate different walking conditions and terrain environments. Similarly, [PERSON] et al. developed the NUVABAT [112] which is an ankle-based balance trainer for rehabilitation. NUVABAT utilizes magnetorheological fluids (MRF) fluids to control the braking system and adjusts itself based on the walking strength of the patient. Grounded feedback systems are also well suited in teleoperation-based systems. In such systems, the user is capable of manipulating objects at a distance by virtually mimicking the objects orientation. These systems are comprised of a leader/follower system. The follower system on the remote site is equipped with different sensors which allow it to sense and perceive the surrounding environment accurately and to relay that information to the leader side of the system. The leader system should then have the proper amount of information to simulate the data in the remote site to feel physically present. In such systems, haptic feedback plays an important role in ensuring the sense of realism or telepresence by the user. Considerations of inertia, clearance, and friction need to be made in these systems while still providing large stiffness and adaptable force feedback to make the user experience more natural. [PERSON] et al. developed the sigma.7 [113], a robotic teleoperation system for minimally invasive robotic surgery. The system is based on the delta haptic device [114] which is made up of three double-bar parallelograms which allow the end effector to maintain a position that is parallel to the base of the plane.